United States
Environmental Protection
Agency
Industrial Environmental Research EPA 600 2 78 004w
Laboratory August 1978
Cincinnati OH 45268
Research and Development
Source Assessment
Acrylic Acid
Manufacture
State of the Art
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-004W
August 1978
SOURCE ASSESSMENT:
ACRYLIC ACID MANUFACTURE
State of the Art
by
R. W. Serth, D. R. Tierney, and T. W. Hughes
Monsanto Research Corporation
Dayton, Ohio 45407
Contract No. 68-02-1874
Project Officer
Ronald J. Turner
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory-Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
11
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FOREWORD
When energy and material resources are extracted, processed,
converted, and used, the related pollutional impacts on our
environment and even on our health often require that new arid
increasingly more efficient pollution control methods be used.
The Industrial Environmental Research Laboratory - Cincinnati
(lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both effici-
ently and economically.
This report contains an assessment of air emissions from the
acrylic acid industry. This study was conducted to provide a
better understanding of the distribution and characteristics of
emissions from acrylic acid manufacture. Further information on
this subject may be obtained from the Organic Chemicals and Pro-
ducts Branch, Industrial Pollution Control Divisioh.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
111
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PREFACE
The Industrial Environmental Research Laboratory (IERL) of the
U.S. Environmental Protection Agency (EPA) has the responsibil-
ity for insuring that pollution control technology is available
for stationary sources to meet the requirements of the Clean Air
Act, the Federal Water Pollution Control Act, and solid waste
legislation. If control technology is unavailable, inadequate,
or uneconomical, then financial support is provided for the
development of the needed control techniques for industrial and
extractive process industries. Approaches considered include:
process modifications, feedstock modifications, add-on control
devices, and complete process substitution. The scale of |:he
control technology programs ranges from bench- to full-scale
demonstration plants.
IERL has the responsibility for developing control technology
for a large number of operations (more than 500) in the chemical
and related industries. As in any technical program, the first
step is to identify the unsolved problems. Each of the indus-
tries is to be examined in detail to determine if there is
sufficient potential environmental risk to justify the develop-
ment of control technology by IERL.
Monsanto Research Corporation (MRC) has contracted with EPA to
investigate the environmental impact of various industries that
represent sources of pollutants in accordance with EPA's respon-
sibility, as outlined above. Dr. Robert C. Binning serves as
MRC Program Manager in this overall program, entitled "Source
Assessment," which includes the investigation of sources in each
of four categories: combustion, organic materials, inorganic
materials, and open sources. Dr. Dale A. Denny of the Industrial
Processes Division at Research Triangle Park serves as EPA Pro-
ject Officer for this series. Reports prepared in this program
are of two types: Source Assessment Documents, and State-of-
the-Art Reports.
Source Assessment Documents contain data on pollutants from
specific industries. Such data are gathered from the literature,
government agencies, and cooperating companies. Sampling and
analysis are also performed by the contractor when the available
information does not adequately characterize the source pollu-
tants. These documents contain all of the information necessary
for IERL to decide whether a need exists to develop additional
control technology for specific industries.
iv
-------
State-of-the-Art Reports include data on pollutants from spe-
cific industries which are also gathered from the literature,
government agencies and cooperating companies. However, no
extensive sampling is conducted by the contractor for such
industries. Results from such studies are published as State-
of-the-Art Reports for potential utility by the government,
industry, and others having specific needs and interests.
This study of acrylic acid plants was undertaken to. provide
information on air emissions. The study was initiated by IERL-
Research Triangle Park in November 1975. Mr. Edward J. Wooldridge
served as EPA Project Leader. The project was transferred later
to the Industrial Pollution Control Division, lERL-Cincinnati
and Mr. Ronald J. Turner served as EPA Project Leader through
completion of the study.
v
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ABSTRACT
This document reviews the state of the art of air emissions from
acrylic acid manufacture. The composition, quality, rate, and
environmental effects of emissions are described.
Acrylic acid is a monomer produced in the United States by either
the catalytic vapor-phase oxidation of propylene or the high-
pressure Reppe process which is based on acetylene. Organic com-
pounds such as acrylic acid and propylene are emitted from
storage tanks, reactor process vents, and recovery and purifica-
tion column vents. Carbon monoxide and nitrogen oxides are
emitted when waste streams are incinerated.
To assess the severity of emissions from this industry, a repre-
sentative plant was defined based on specific mean values for
various plant parameters. Source severity was defined as the
ratio of the maximum time-averaged ground level concentration of
a pollutant to the primary ambient air quality standard for
criteria pollutants or to a reduced threshold limit value for
noncriteria pollutants. At a representative plant, source sever-
ities for hydrocarbons, carbon monoxide, and nitrogen oxides are
less than 0-7, less than 0.003, and less than 0.6, respectively.
Controlled emissions from acrylic acid manufacture contribute
less than 0.006%, less than 0.002%, and less than 0.0009%,
respectively, to national emissions of hydrocarbons, carbon
monoxide, and nitrogen oxides from stationary sources. Very
little increase in emissions from this industry is expected
through 1980.
Hydrocarbon emissions are mainly controlled by the use of thermal
incinerators. Other control technology used includes nitrogen
blankets in pressurized storage tanks and water-chilled vent
condensers.
This, report was submitted in partial fulfillment of Contract No.
68-0^-1874 by Monsanto Research Corporation under the sponsorship
of the U.S. Environmental Protection Agency. This report covers
the period December 1975 to December 1977, and work was completed
as of December 1977.
VI
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CONTENTS
Foreword iii
Preface iv
Abstract , . . . vi
Figures viii
Tables ix
Abbreviations and Symbols , . . xi
Conversion Factors and Metric Prefixes xiii
1. Introduction 1
2. Summary , . . . , 2
3. Source Description 6
Process description .... 6
Geographical distribution 23
4. Emissions .25
Selected pollutants 25
Location and description 25
Emission data 30
Emissions burden , ... 30
Definition of a representative source ...... 30
Environmental effects ..... 33
5. Control Technology , . 39
State of the art 39
Future considerations 41
6. Growth and Nature of the Industry 42
Present technology 42
Emerging technology 42
Marketing strengths and weaknesses 43
References T . . 46
Appendices
A. Derivation of source severity equations 52
B. Calculated emission factors for acrylic acid storage
tanks t T . 65
Glossary
68
VII
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FIGURES
Number Page
1 SOHIO process for the production of acrylic acid ... 7
2 Locations of acrylic acid plants 23'
3 Incinerator used for the control of organic
emissions from acrylic acid manufacture 40
4 Production and sales record of acrylic acid 45
Vlll
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TABLES
Number Page
1 Controlled Emission Factors and Source
Severities for a Representative Plant ........ 3
2 Solvents Given in Patent Literature for Acrylic
Acid Recovery
3 Acrylic Acid Polymerization Inhibitors Obtained
from Patent Literature ............... 19
4 Summary of Tankage Requirements for a 95,000 Metric
Ton/Yr Acrylic Acid Plant ........ - ...... 21
5 Acrylic Acid Plants .................. 24
6 Compounds Identified in Acrylic Acid Processing
Streams ....................... 26
7 Health Effects and Atmospheric Reactivity of
Selection Compounds in Acrylic Acid Production ... 27
8
9
«x
10
11
12
Location of Emission Points
Acrylic Acid Emission Factors by Compound . .
Controlled Acrylic Acid Emission Factors by
Location
Emission Height Data for Acrylic Acid Plants
Contribution of Criteria Pollutants from Aery
28
31
31
• • • * * 3 £»
lie
Acid Production to National Stationary Source
Emissions 32
13 Acrylic Acid Contributions to State Emissions of
Criteria Pollutants 32
14 Summary of Data for a Representative Plant 33
15 Maximum Time-Averaged Ground Level Concentrations;
for Compounds Emitted 35
IX
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TABLES (continued)
Number - Page
16 Maximum Time-Averaged Ground Level Concentrations
for Emission Points 35
17 Source Severities for Compounds Emitted 36
18 Source Severities for Emission Points 36
19 Affected Population for a Representative Plant .... 38
20 Acrylic Acid Consumption 43
21 Consumption of Acrylic Acid Esters 44
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ABBREVIATIONS AND SYMBOLS
a,b,c,d,f — constants used in dispersion calculations
C — diameter factor
Cap — production capacity
D •— distance from the source to the near'est
plant boundary
D' " tank diameter
e — 2.72
E — emission factor
F — hazard factor
F — equivalent gasoline working loss
F — paint factor
H — emission height
H1 •"- tank outage
K — turnover factor
L —- total petrochemical loss
LI -L- petrochemical loss
L — t6tal equivalent gasoline loss
L — equivalent gasoline breathing loss
M — molecular weight of chemical stored
N -— number of turnovers per year
P —» production rate
AP — change in pressure
Q — mass emission rate
S — source severity
t — averaging time
t — short-term averaging time
o
AT — average ambient temperature change
TLV -*- threshold limit value
u "-*- wind speed
u — average wind speed
V -*- tank capacity
W -*- liquid density of chemical stored
x •*- downwind dispersion distance from source
of emission release
y -— horizontal distance from centerline of
dispersion
XI
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ABBREVIATIONS AND SYMBOLS (continued)
IT — 3.14
P — vapor pressure of material stored at bulk
temperature
Oy -- standard deviation of horizontal dispersion
crz -- standard deviation of vertical dispersion
X -- downwind ground level concentration at
_ reference coordinate x and y
X -- mean ambient concentration
Xjnax — maximum ground level concentration
Xmax — maximum time-averaged ground level concentration
xn
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CONVERSION FACTORS AND METRIC PREFIXES
To convert from
Degree Celsius (°C)
Gram/kilogram (g/kg)
Kilogram (kg)
Meter (m)
Meter (m)
Meter2 (m2)
Meter3 (m3)
Metric ton
Pascal (Pa)
Pascal (Pa)
Second (s)
CONVERSION FACTORS
To
Degree Fahrenheit
Pound/ton
Pound-mass (avoirdupois)
Foot
Inch
Mile2
Foot3
Ton (short, 2,000 Ib
mass)
Inch of water (60°F)
Pound-force/inch2 (psi)
Minute
Multiply by
1.8 toc + 32
2.000
2.205
3.281
3.937 x 101
3.861 x 10"7
3.531 x 101
1.102
4.019 x 10"3
1.450 x I0~k
1.667 x 10"2
Prefix
Kilo
Milli
Micro
Symbol
k
m
y
METRIC PREFIXES
Multiplication factor
103
10"3
10~6
Example
1 km = 1 x 103 meters
1 mm = 1 x 10"3 meter
1 ym = 1 x 10"6 meter
Standard for Metric Practice. ANSI/ASTM Designation:
E 380-76£, IEEE Std 268-1976, American Society for Testing and
Materials, Philadelphia, Pennsylvania, February 1976. 37 pp.
Xlll
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SECTION 1
INTRODUCTION
Acrylic acid and its derivatives are used in the production of
polymers which include plastic sheet and molding powders; emul-
sion polymers for water-based paints, leather finishing, and
paper coating; and polymers for the sizing, treating, and finish-
ing of textiles. Acrylates also find use in acrylic fibers
(as comonomers with acrylonitrile), pigment binders, adhesives,
and polishes.
Acrylic acid is produced in this country by two processes: the
high-pressure Reppe process and the propylene oxidation process.
These two processes and at least three others are being used
throughout the world to produce acrylic acid.
The purpose of this study is to assess the atmospheric emissions
from the production of acrylic acid by the propylene oxidation
process. The composition, quantity, and rate of emissions are
described. Data were obtained from appropriate literature
sources and industry communications.
Section 2 of this document summarizes the major findings of this
study. Section 3 provides a detailed description of the acrylic
acid production process. Section 4 gives data on emissions and
provides an assessment of the environmental impact of acrylic
acid plants based on source severity and affected population.
Control technology is described in Section 5, and Section 6
relates the growth and nature of the industry.
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SECTION 2
SUMMARY
Acrylic acid is manufactured by the catalytic vapor-phase oxida-
tion of propylene and by the high-pressure Reppe process. The
propylene.oxidation process accounts for 93% (255,000 metric
tons/yra) of the installed capacity. The high-pressure Reppe
process, based on acetylene, accounts for 7% (18,000 metric
tons/yr). There are currently four acrylic acid plants in the
United States; three use the propylene oxidation process and the
other uses the high-pressure Reppe process. In 1975, these
plants were operating at 40% to 50% of production capacity.
Since no expansion of the Reppe process is anticipated in the
United States, it is not covered in the present study.
Iji those acrylic acid plants using the propylene oxidation proc-
ess, organic compounds are emitted from fugitive sources and from
vents located in the propylene oxidation section, product re-
covery and purification sections, transport loading facility,
and storage tanks. Depending on the individual plant, part or
all of the vented organics are sent to a thermal incinerator for
disposal. The incinerator emits carbon monoxide (CO), hydrocar-
bons, and nitrogen oxides (NOV) .
A,
A representative plant was defined for the purpose of assessing
the environmental impact of atmospheric emissions from acrylic
acid plants. The representative plant has a production capacity
of 85,000 metric tons/yr and utilizes the SOHIO technology for
propylene oxidation. It also uses a thermal incinerator to
control emissions of organic compounds from various vents in the
process. Emission points and controlled emission factors for the
representative plant are given in Table 1.
In order to quantify the hazard potential of acrylic acid manu-
facture, source severity was defined as the ratio of the maximum
time-averaged ground level concentration, Xmax, of a pollutant
emitted from the representative plant to the hazard level of
exposure F for the pollutant. The hazard level of exposure was
defined as the primary ambient air quality standard for criteria
al metric ton equals 106 grams; conversion factors and metric
system prefixes are presented in the prefatory material.
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TABLE 1. CONTROLLED EMISSION FACTORS AND SOURCE
SEVERITIES FOR A REPRESENTATIVE PLANT
Emission point and material emitted
Criteria pollutants:
Hydrocarbons :
Propylene storage tank vents
Heat-transfer circuit vents
Solvent storage tank vents
Intermediate acrylic acid storage
tank vents
Vacuum column steam jets
Acrylic acid storage tank vents
Transport loading facility vents
Incinerator stack
Fugitive emissions
Nitrogen oxides: Incinerator stack
Carbon monoxide: Incinerator stack
Chemical substances:
Acetaldehyde
Acetic acid
Acetone
Acrolein ''
Acrolein dimer
Acrylic acid
Benzene
Diphenyl-diphenyl oxide eutectic
Ethyl acrylate
Formaldehyde
Isopropyl ether
Maleic acid
Phenol
Propane
Propylene
Emission
factor,
g/kg
<0.6b
U
~h
u
~u
D
<0.02
<0.2b
U
~b
U
<0.4
_C
<0.7
<0.7
c
~~c
~c
c
~c
~c
~c
~c
~"c
~c
~c
c
\*
c
~c
~ c
Source
severity
<0
0
0
0
<0
<0
0
0
<0
0
<0
<0
.7
.05
.2
.3
.6
.002
d
~d
~d
~d
~d
~d
~d
~d
~d
~d
~d
~d
vt
~d
~d
~d
JIncludes all organic compounds except methane.
^Emissions vented to incinerator.
'Species emitted but not quantified due to lack of data;
hence, emission factors cannot be estimated.
Not calculated due to lack of data.
-------
pollutants.9 For noncriteria pollutants, F is a surrogate pri-
mary ambient air quality standard defined as a reduced threshold
limit value [(TLV)(8/24)(1/100)]. Using Gaussian plume disper-
sion theory, together with the controlled emission factors in
Table 1, source severities were calculated for each emission
point and for each species of emission. The results are also
presented in Table 1. Source severities may exceed 0.1 for
nitrogen oxides emitted from the incinerator stack, and for
hydrocarbons emitted from the vacuum column steam jet and the
incinerator stack.
Total emissions from acrylic acid production by propylene oxida-
tion are less than 160 metric tons/yr for hydrocarbons and less
than 200 metric tons/yr for both carbon monoxide and nitrogen
oxides. These emissions represent less than 0.0006%, less than
0.0002%, and less than 0.0009%, respectively, of total national
emissions of these compounds from stationary sources. The above
hydrocarbon emissions represent less than 0.002% and less than
0.006% of state hydrocarbon emissions in Louisiana and Texas,
respectively. The corresponding values for carbon monoxide are
less than 0.0008% in Louisiana and less than 0.002% in Texas.
For nitrogen oxides, the values are less than 0.01% in both
Louisiana and Texas.
The average rmmber of persons exposed to an annual average con-
centration, \, of a pollutant from the representative plant for
which x/F J-s greater than 0.1 was estimated and designated as
the "affected population." This calculation was made for hydro-
carbons and nitrogen oxides since the upper bounds on source
severity are greater than 0.1 for these compounds. The affected
populations are less than 600 persons for hydrocarbons and less
than 1,200 persons for nitrogen oxides.
In addition to the thermal incinerator that controls vented hy-
drocarbons, one plant employs surface condensers followed by a
chilled-water vent condenser to control hydrocarbon emissions
from vacuum column steam jets. The control efficiency of this
system is estimated to be 75% under the worst conditions. This
plant also employs pressurized nitrogen blankets together with
chilled-water vent condensers to reduce hydrocarbon emissions
from the intermediate acrylic acid storage tanks. The control
efficiency of incinerators at acrylic acid plants is estimated
to be greater than 98%.
There is no primary ambient air quality standard for hydro-
carbons. The value of 160 yg/m3 used for hydrocarbons in this
report is an EPA-recommended guideline for meeting the primary
ambient air quality standard for oxidants.
-------
Production of aerylie-acid in the 5-yr period from 1975 through
1980 is expected to increase by 7% annually, or 40% over the
5-yr period. In 1980, an estimated 140,000 metric tons of
acrylic acid will be produced. However, incinerators are pres-
ently operating at a fraction of their organic feed capacity
because production is well below existing capacity. Increased
production will result primarily in the partial substitution of
organic wastes for natural gas as fuel for the incinerators.
Hence, very little increase in emissions from acrylic acid pro-
duction is expected through 1980.
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SECTION 3
SOURCE DESCRIPTION
PROCESS DESCRIPTION
Currently there are five commercial processes for the production
of acrylic acid via propylene oxidation: the SOHIO process, the
Rohm & Haas process, the Toyo Soda process, the Mitsubishi Petrol-
eum process, and the Japan Catalytic process. The processes are
similar, involving the two-stage oxidation of propylene to
acrylic acid followed by recovery and purification of the acid.
The processes differ primarily in the catalysts used and in the
details of the recovery and purification operations. Of the
three U.S. plants employing propylene oxidation, two are based
on SOHIO technology, while the third uses the Rohm & Haas
process.
A flow diagram for the SOHIO process is presented in Figure 1.
The process itself is described in the following subsections.
Chemistry
Acrolein--
The catalytic vapor-phase oxidation of propylene to acrolein and
the subsequent oxidation of acrolein to acrylic acid can be
represented by the following stoichiometric equations:
CH2=CH-CH3 + 02 *• CH2=CH-CHO + H2O (1)
propylene oxygen acrolein water
CH2=CH-CHO + 1/2 02 »> CH2=CH-COOH (2)
acrolein oxygen acrylic acid
Studies on the catalytic oxidation (oxidative dehydrogenation)
of propylene using bismuth molybdate catalysts have shown that
acrolein is formed by a free-radical mechanism (1-10).
(1) Adams, C. R., and T. J. Jennings. Investigation of the
Mechanism of Catalytic Oxidation of Propylene to Acrolein and
Acrylonitrile. Journal of Catalysis, 2(l):63-68, 1963.
(2) Adams, C. R., H. H. Voge, C. Z. Morgan, and W. E. Armstrong.
(continued)
6
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STEAM
_L
*
WATER
PREH EATER
SOLVENT
EXTRACTION RECOVERY SOLVENT
COLUMN TOWER STRIPPER
LIGHLENDS
STRIPPER
^_
Jf\
4
i
ENVIRONMENTAL EMISSIONS
-^ PROPYLENE STORAGE TANK VENT GAS
HEAT TRANSFER-CIRCUIT VEM5
INCINERATOR STACK GAS
ACRYLIC ACID STORAGE TANK VENT GAS
VACUUM COLUMN STEAM JETS
9^ TRANSPORT LOADING FACILITY VENT GAS
INTERMEDIATE ACRYLIC ACID
STORAGE TANK VENT CAS
SOLVENT STORAGE TANK VENT GAS
Figure 1. SOHIO process for the production of acrylic acid.
-------
A free-radical reaction usually involves a combination of or
series of complex reaction steps. Presently, it is not possible
to give a quantitative mechanistic description of the chemistry
involved in the oxidation of propylene to acrolein (or acrylic
acid) because the sequence of reaction steps is unknown. In
addition, several mechanisms may be operating simultaneously.
Therefore, the chemistry of the catalytic oxidation of propylene
must necessarily be limited to a qualitative discussion.
The one conclusion that seems to have been established, and the
one universally accepted mechanism, is that the rate-determining
step involves an initial abstraction of hydrogen from the propy-
lene methyl (a^lylic) group to form a symmetric, labile allyl
intermediate:
(continued)
Oxidation of Butylenes and Propylene Over Bismuth Molybdate.
Journal of Catalysis, 3(4):379-386, 1964.
(3) Adams, C. R., and T. J. Jennings. Mechanism Studies of the
Catalytic Oxidation of Propylene. Journal of Catalysis,
3(6):549-558, 1964.
(4) Keulks, G. W., and M. P. Rosynek. Mechanistic Studies of
Propylene Oxidation on Bismuth Molybdate. Preprints,
Division Petroleum Chemistry, American Chemical Society,
14(4):C55-C61, 1969.
(5) Callahan, J. L., R. K. Grasselli, E. C. Milberger, and
H. A- Strecker. Oxidation and Ammoxidation of Propylene
Over Bismuth Molybdate Catalyst. Preprints, Division of
Petroleum Chemistry, American Chemical Society, 14(4):
C13-C27, 1969.
(6) Peacock, J. M., A. J. Parker, P. G. Ashmore, and J. A.
Hockey. The Oxidation of Propene Over Bismuth Oxide,
Molybdenum Oxide, and Bismuth Moiybdate Catalysts. IV.
The Selective Oxidation of Propene. Journal of Catalysis,
15(4) :398-406, 1969.
(7) Margolis, L. Ya. On the Mechanism of Catalytic Oxidation
of Hydrocarbons. Journal of Catalysis, 21(1):93-101, 1971.
(8) Keulks, G. W. The Method of Oxygen Atom Incorporation into
the Products of Propylene Oxidation Over Bismuth Molybdate.
Journal of Catalysis, 19(2):232-235, 1970.
(9) Keulks, G. W., M. P. Rosynek, and C. Daniel. Bismuth
Molybdate Catalysts. Industrial and Engineering Chemistry,
Product Research and Development, 10(2):138-142, 1971.
(10) Keulks, G. W., C. Daniel, and J. R. Monnier. Evidence for
Surface Initiated Homogeneous Reactions During the
Catalytic Oxidation of Propylene. Preprints, Division of
Petroleum Chemistry, American Chemical Society, 17(1):
B5-B11, 1972.
8
-------
CH2=CH-CH3 + [0] V ;> [CH2 CH CH2] (3)
propylene oxygen allyl
intermediate
Since, according to kinetic studies, the interaction of hydro-
carbons at the catalyst surface, is the rate-limiting step, it
has been postulated that in the first step propylene forms a IT
complex (through its double bond) with the catalyst surface (7).
The methyl group is adsorbed, simultaneously, onto a molecular
oxygen ion (0~2) which abstracts hydrogen to form an "allyl-type"
intermediate (1, 7-9). This intermediate is bound to the cata-
lyst surface as a ir-ally! complex (7) . There is evidence that
the initial removal of a hydrogen atom produces a "pre-allyl
intermediate," which rapidly isomerizes by means of an electron
shift and then becomes attached to the catalyst surface as a
7r-allyl intermediate complex (1, 7) .
The sites for propylene reactivity are believed to be "anion
vacancies on the metal atom in the oxygen boundary layer" (7).
The bismuth molybdate structure is composed of layers of bismuth
oxide cations and molybdenum oxide cations connected by layers of
molecular oxygen ions. The oxygen boundary layers occur on the
molybdenum cation layers creating anion vacancies on the molyb-
denum atoms (8) . Molybdenum is also known to form TT and TT-allyl
complexes with olefins. Consequently, it can be surmised that
when a propylene molecule enters an area of an anion vacancy (in
a molybdate), it becomes attached to the surface of the catalyst
by forming a IT bond with the molybdenum. Concomitantly, the
methyl group would be in the vicinity of a (negative) molecular
oxygen ion in the oxygen boundary layer, and it would be adsorbed
because it carries a fractional electronic positive charge.
Acrolein can be formed from the allyl intermediate by parallel
mechanisms that could be operating simultaneously (10). One
mechanism that has been proposed (1, 3, 5, 7-10) is that the
initial hydrogen abstraction is followed immediately by abstrac-
tion of a second hydrogen from either end of the symmetric
intermediate to form the diradical:
[CH2rT-r^-.CH.-T-r-r-.CH2] + [0] ("H) > [CH2=CH-CH] (4)
allyl oxygen acrolein
intermediate precursor
diradical
a[0] denotes a reactive form of oxygen; i.e., it could be the
ground state diradical, triplet oxygen, chemisorbed, or ionic
oxygen.
-------
The diradical, being highly reactive, would readily incorporate
oxygen, presumably from the oxide lattice (6, 8, 10), to form
acrolein, which desorbs into the gas phase:
[CH2=CH-CH] + [0] - > CH2=CH-CHO (5)
•
acrolein oxygen acrolein
precursor
diradical
The overall kinetics for this mechanism are first order in propyl-
ene pressure and zero order in oxygen pressure because the
oxygen in the product comes from the catalyst (6, 10). Bismuth,
cobalt, and tin molybdates are three catalysts that produce
acrolein by this mechanistic pathway. The activation energy is
80 to 130 MJ/kg mole over the temperature range 350°C to 500°C
(2, 9). The exothermic heat of reaction is 290 MJ/kg mole (2).
The oxygen boundary layers are not only the site of hydrogen
abstraction; they also serve as the source of the oxygen that is
incorporated into the products. The removal of oxygen from the
boundary layers leaves the surface in a reduced state. The sur-
face layers are reoxidized to their original valence state by
diffusion of molecular oxygen ions from the catalyst bulk rather
than by gas-phase oxygen (8) . The oxygen content of the cata-
lyst is replenished by oxygen from the gas phase, which becomes
adsorbed on the catalyst surface and then rapidly diffuses
throughout the bulk of the catalyst (8). These diffusional steps
take place rapidly compared with the reaction steps, so that no
kinetic dependence on oxygen partial pressure is observed.
Until recently, the first mechanism was the most widely accepted
theory of acrolein formation because earlier work had strongly
suggested that acrolein was produced from metal oxide catalysts,
in general, by this mechanism (1, 3, 10) . However, recent
kinetic studies have indicated that a second mechanism may be
operating simultaneously; namely, oxygen is incorporated before
abstraction of the second hydrogen atom (1, 10) . In this paral-
lel or second mechanism, the allyl intermediate adds oxygen
before abstraction of the second hydrogen atom to form a peroxide
or hydroperoxide intermediate which decomposes on the surface to
produce acrolein:
+ 02 - >• [CH2=CH-CH2-O-0- (H) ] (6)
allyl molecular peroxy or
intermediate oxygen (hydroperoxy)
intermediate
— T-TO •
[CH2=CH-CH2-0-0-(H) ] (HO) * CH2=CH-CHO (7)
peroxy or acrolein
(hydroperoxy)
intermediate
10
-------
A kinetic dependence on oxygen partial pressure is observed
(first order in oxygen partial pressure and Zero order in propy-
lene pressure) because the oxygen comes from a chemisorbed layer
or from the gas phase rather than from the lattice structure.
These kinetics have been observed over copper and its oxides and
gold, suggesting that acrolein is formed by the second mechanism
in the presence of these catalysts.
The second mechanism more nearly corresponds to accepted theories
of free-radical organic chemistry and free-radical polymerization
(personal communications with J. M. Butler and G. A. Richardson,
Monsanto Research Corp., Dayton, Ohio, 18 August 1977). Oxygen
is usually incorporated before hydrogen abstraction in these
types of reactions; i.e., the oxygen is incorporated as the
hydroperoxide, which then decomposes.
In addition to the possibility of several simultaneously operat-
ing mechanisms, kinetic studies have indicated that the catalytic
oxidation of olefins may be further complicated by homogeneous
gas-phase reactions. These surface-initiated homogeneous reac-
tions become important at high propylene-to-oxygen ratios, in
reactors having large postcatalytic volume, or with a catalyst
having a large void fraction (9, 10).
The mechanism and kinetics of the surface-initiated homogeneous
reactions are similar to those in the second mechanism described
above. The mechanism probably involves the desorption of the
allyl intermediate as an ally radical (7, 10), or the allyl
intermediate adds oxygen before abstraction of the second hydro-
gen atom to form an allyl peroxide intermediate (10). This
peroxide intermediate or the allyl radical, on desorption into
the gas phase, can react with propylene by a free-radical
mechanism to produce propylene oxide (10):
L CH 2 » • • • •CH * * * » • CH 2 J
allyl
intermediate
desorption
02
[CH2=CH-CH2-0-0(H)
peroxy or
( hy droper oxy )
intermediate
•C-CH=CH2
allyl
radical
(8)
[CH2=CH-CH2-0-0(H)
peroxy or
(hydroperoxy)
intermediate
CH2=CH-CH3
propylene
CH2-CH-CH3
V
propylene
oxide
(9)
11
-------
The kinetics of this mechanism are typically first order in
oxygen pressure and zero order in propylene pressure. Copper-
molybdenum, iron-molybdenum, and manganese-molybdenum oxide
catalysts were studied under conditions in which the surface-
initiated homogeneous reaction mechanism should be operative;
i.e., at high propylene-to-oxygen ratios, or in a reactor having
a large postcatalytic volume, or with a catalyst having a large
void fraction. In each case, propylene oxide was produced, sug-
gesting that the surface-initiated homogeneous reaction mechanism
was operating. Combinations of the above conditions also yielded
propylene oxide (10).
The surface-initiated homogeneous reactions are independent of
the commonly accepted mechanisms leading to acrolein and, under
the proper conditions of reactor design, catalyst type, and pro-
pylene/oxygen ratio, are probably operating simultaneously.
Acrylic Acid--
The oxidation of acrolein to acrylic acid is usually conducted
over catalysts containing molybdenum or vanadium oxides (see Cat-
alysts, p. 13). This process appears to be more straightforward
than the oxidation of propylene to acrolein. Acrylic acid can
be formed by the reaction of acrolein with surface oxygen:
CH2=CH-CHO + [0] *-CH2=CH-COOH (10)
acrolein surface acrylic acid
oxygen
An alternative, albeit less likely, mechanism may involve an
additional hydrogen abstraction by an oxygen atom or hydroxy
radical, followed by the addition of a hydroxy radical (11):
0 0
CH2=CH-CH + HO* »• CH2=CH-C* + H20 (11)
acrolein hydroxy radical water
radical intermediate
0 O
II II
CH2=CH-C» + HO* »CH2=CH-C-OH (12)
radical hydroxy acrylic acid
intermediate radical
(11) Luskin, L. S. Acrylic Acid, Methacrylic Acid, and the
Related Esters. In: High Polymers, E. C. Leonard, ed.,
Vol. 24, Part 1. Wiley-Interscience, New York, New York,
1970. pp. 105-203.
12
-------
Byproducts —
It has been shown that when propylene is reacted with excess oxy-
gen, virtually all of the side products produced, including car-
bon monoxide and carbon dioxide, result from the further oxidation
of acrolein or its surface species precursors (9) . However/ a
pathway becomes available for carbon dioxide formation directly
from propylene in a deficiency (less than the stoichiometric
amount required for complete oxidation) of oxygen (9) .
Acetaldehyde, acetic acid, and carbon oxides are the major by-
products formed in the propylene oxidation process. Other bypro-
ducts which have been reported include maleic acid, phthalic
acid, formic acid, formaldehyde, propionic acid, propionaldehyde,
acetone, allyl alcohol, ethylene, and hydrogen. In addition some
high-boiling materials are formed by dimerization, polymeriza-
tion, and condensation reactions of acrylic acid and acrolein;
e.g., poly(acrylic acid/acrolein) (1-11). In commercial pro-
duction of acrylic acid, the formation of byproducts is minimized
by the addition of steam', which improves catalyst selectivity
(see Feed Materials, p. 15).
Catalysts
The catalysts employed in commercial processes for the Oxidation
of propylene to acrolein are complex mixtures of the oxides of
polyvalent metals. Cobalt and molybdenum are usually the pre-
dominant metals, frequently in the form of cobalt molybdate. In
one example the catalyst consists of cobalt molybdate, iron
oxide, and/or iron molybdate, and an oxide of tellurium (12) .
The atomic proportions of the metal components of the catalyst
can be represented by the formula
where "a" is a number from 0.01 to 10, "b" is from 0*5 to 2, "c"
is from 0.5 to 2, and "d" is from 0-01 to 0.1. A propylene con-
Version of 82% was obtained in the presence of steam with a catal
yst having the specific composition Fe0 f 288coi . 0M°1 . oTeo . o 1 5 • In
the absence of steam, a conversion of 82% was obtained with a low
iron catalyst having • the composition Fe0 . QJ 2Col . QHol . QTeQ . 01 5 •
In another example, the catalyst composition is expressed by the
general formula
Mo Co, Fe Bi ,A O.p
a b c d e f
(12) Kiff, B. W., and N. R. Cox. Oxidation of 1,2-Olefins to
Oxygenated Products. U.S. Patent 3,467,716 (to Union
Carbide), September 16, 1969.
13
-------
where "a" is equal to 12, "b" is 7 to 12, "c" is 0.3 to 4, "d" is
0.4 to 2.5, "e" is 0.1 to 3, and "f" is 47 to 73 (13). In this
formula, "A" represents tin or a composite system of tin and one
or more of the elements aluminum, nickel, tungsten, chromium,
indium, and niobium. The maximum conversion of propylene (90.1%)
was obtained with a catalyst having the composition
M0l 2Co i 0Fe ! . 0Bi i . 0Sn0 . 5W0 . 5056 . 5 -
The catalyst in a recent patent is represented by the formula
MoaC°bTecXd°e
where "X" represents boron or rhodium (14). When "a" is 100, "b"
is 40 to 200, "c" is 0.1 to 7, "d" is either 5 to 75 (when "X" is
boron) or 0.1 to 3 (when "X" is rhodium), and "e" is 300 to 900.
The maximum conversion of propylene (93%) was obtained with a
catalyst having the composition Mo^ Q oCos sTe2 . 6^no . k o®k 72 •
The above catalysts may be used in the form of pellets, or they
may be used with a carrier or support such as silica, alumina,
silicon carbide, alumina-silica, or titania.
In addition to the above catalysts, the SOHIO process reportedly
uses a bismuth phosphomolybdate catalyst for producing acrolein
(15) . The catalyst composition in one example was Mo =12,
Bi = 2, Mg = 4.5, Fe = 4 , P = 0.5 (16).
Catalysts containing molybdenum and vanadium oxides are typically
used for the oxidation of acrolein to acrylic acid. For example,
one patented catalyst for this process is characterized by the
formula
VaMobWcCrdCue
where "a" is from 14 to 24, "b" is 12, "c" is from 4 to 20, "d"
is from 1 to 10, and "e" is from 0 to 12 (17). An acrolein con-
version of 97.5% and a one-pass acrylic acid yield of 90.5% were
(13) Ono, I., and M. Akashi. Catalyst for the Production of
Acrolein and Acrylic Acid. U.S. Patent 3,786,000 (to Rohm
and Haas), January 15, 1974.
(14) Levy, L. B. Catalyst for Oxidation of Olefins. U.S. Patent
3,875,078 (to Celanese Corporation), April 1, 1975.
(15) Propylene Gets the Nod. Chemical Week, 112(4) :37, 1973.
(16) Grasselli, R. K., et al. Oxidation of Olefins. German
Patent 2,203,710 (to Standard Oil), August 17, 1972.
(17) Ohara, T., N. M. Ninomiya, I. Yanaqisawa, I. Wada, and
M. Wada. Process for the Preparation of Acrylic Acid. U.S.
Patent 3,775,474 (to Nippon Shokubai Kagaku Kogyo Co.),
November 27, 1973.
14
-------
obtained with a catalyst having the specific composition
V15Mo12W6-8Cr2>0Cu5>2.
Feed Materials
The feed materials used in the SOHIO process consist of commer-
cial grade (90% to 95%) propylene, air, and steam. The principal
impurity is propane, which behaves as an inert in the reaction.
Small amounts of butane and butylene may also be present in the
feedstock. Liquid propylene is vaporized and fed to the first-
stage reactor. Vaporization is achieved by circulating (heated)
cooling water from the quench tower circulation loop.
Reactor feed steam is generated from recycled process water which
contains organic impurities consisting of reaction products and
byproducts. Excess process water is sent from the steam genera-
tor to a thermal incinerator for disposal.
Process air is passed through a preheater and then fed to the
first-stage reactor.
Feed ratios have not been published for the SOHIO process.
However, the propylene/steam/air fractions for the Toyo Soda
process are 5/35/60 mole percent (18).
The purpose of 'the steam introduced with the feed is threefold
(18, 19) :
• To increase the operating propylene/air ratio by narrow-
ing the explosion range of propylene-air mixture.
• To facilitate temperature control by removing part of the
energy liberated by the reaction in the form of sensible
heat of the steam.
• To improve catalyst selectivity by increasing the
desorption rate of reaction products.
Reaction Section
Propylene is oxidized to acrylic acid in a two-stage, fixed-bed,
tubular reactor system. Propylene is oxidized to acrolein in the
first stage. The effluent from the first reactor is fed to the
second stage where the acrolein is oxidized to acrylic acid. The
reactor system operates at a gage pressure of 103 kPa to 207 kPa
(18) Nakatani, H. Toyo's New Aerylate Process. Hydrocarbon
Processing, 48 (5):152-154, 1969.
(19) Sakuyama, S., T. Ohara, N. Shimizu, and K. Kubota. A New
Oxidation Process for Acrylic Acid from Propylene. Chem-
tech, 3(6) :350-355, 1973.
15
-------
and temperatures between 290°C and 400°C (20). The first-stage
reaction is carried out at 290°C to 333°C and the second-stage
reaction at 360°C to 400°C. Temperature control in both reactors
is maintained by circulating Dowtherm A® (diphenyl-diphenyl oxide
eutectic) or a similar organic heat-transfer fluid to remove the
heat of reaction. The energy liberated in the two reactors is
used to produce steam in waste heat boilers.
The yield from the process is 1.1 kg to 1.3 kg acrylic acid per
kilogram 100% propylene feed (18, 19). The theoretical yield is
1.7 kg acrylic acid per kilogram propylene.
Acrylic Acid Recovery
The effluent from the second-stage reactor is sent to the quench
towep where acrylic acid is condensed and recovered as a 20% to
30% aqueous solution (18, 19). The off-gas from the quench tower,
consisting primarily of carbon oxides, nitrogen, oxygen, propane,
and unreacted propylene, is sent to the incinerator for disposal.
The aqueous acrylic acid solution is sent to the extraction col-
umn where the acrylic acid is separated from the water by extrac-
tion with an organic solvent. The extract is fed to the solvent
stripping column, where the solvent is separated from the acrylic
acid by vacuum distillation. The recovered solvent is taken
overhead, condensed, and recycled to the extraction column.
Crude acrylic acid is obtained as the bottoms product from the
solvent stripping column.
The raffinate from the extraction column is sent to the solvent
recovery tower where the solvent is separated from the water by
distillation at atmospheric pressure. The recovered solvent is
taken overhead, condensed, and recycled to the extraction column.
The bottoms from the solvent recovery tower, which consist of
water containing organic impurities, are recycled to the steam
generator.a
A large number of solvents can be used in the extraction step.
Solvents described in the patent literature are listed in
Table 2.
Acrylic Acid Purification
The crude acrylic acid from the solvent stripping column is fed
to the light-ends stripping column where the more volatile
One plant sends this stream to a central wastewater treatment
facility for disposal. Another plant employs a wastewater
treatment facility dedicated solely to the acrylic acid and
acrylic esters processes.
(20) Acrylic Acid (SOHIO Process). Hydrocarbon Processing,
52(11):95, 1973.
16
-------
TABLE 2. SOLVENTS GIVEN IN PATENT LITERATURE
FOR ACRYLIC ACID RECOVERY
Distribution coefficient
Solvent of acrylic acid
Ethyl acetate 2.7
Ethyl acrylate 1.4
Isopropyl ether 1.6
Ethyl butyl ether 1.6
Methyl isobutyl ketone 2.9
Methyl phenyl ketone 2.2
Isopropyl acetate 2.3
Ethyl 3-ethoxypropionate 2.8
Methyl acrylate 2.3
Methyl ethyl ketone + benzene or toluene 1.2
N-ethyl-2-hexyl-pyrrolidone 7.8
2-Ethylhexanol 1.9
n-Butanol 2.9
Methyl isobutyrate -P
Ethyl isobutyrate -•
g-alkyloxy propionate -,
3,3,5-Trimethylcyclohexanone + isophorone -.
Butyl acetate + butanol -.
Isophorone -.
Diisobutyl ketone -.
Butyl acrylate
a
The distribution coefficient is the ratio of the concentration of
acrylic acid in a given solvent to the concentration of acrylic
acid in water when the two phases (solvent and water) are in
equilibrium.
b
Not available.
impurities (chiefly acetic acid and residual solvent) are removed
by vacuum distillation. The overhead from the light-ends strip-
per is condensed and sent to the solvent recovery tower. The
bottoms from the light-ends stripper, which contain the acrylic
acid, are split into two streams. One stream is sent to the
esterification plant for production of acrylates. The other
stream is sent to the rectification column where less volatile
impurities (chiefly acrylic polymers and maleic acid) are
separated (as bottoms) in a vacuum distillation step.
The bottom stream from the rectifier is sent to the incinerator
for disposal. The overhead product, consisting of refined
acrylic acid, is condensed and sent to a storage tank. Alterna-
tively, the refined acrylic acid can be diverted to the esteri-
fication section of the plant for production of acrylates.
17
-------
Refined acrylic acid is pumped from storage tanks to the trans-
port loading facility for shipment in tank cars and/or tank
trucks.
Polymerization Inhibition
Since acrylic acid readily polymerizes, addition of a polymeriza-
tion inhibitor is required at various points in the recovery and
purification sections of the process to prevent fouling of equip-
ment and maintain uninterrupted plant operation. Hydroquinone
and monoethanolamine are used as polymerization inhibitors in the
SOHIO process. However, a large number of compounds can be used
for this purpose. Inhibitor systems obtained from the patent
literature are summarized in Table 3 (21-47).
(21) Recovery of Acrylic Acid. British Patent 1,293,848 (to
Toyo Soda Co.), October 25, 1972.
(22) Otsuki, S., K. Hori, and I. Miyanohara. Polymerization
Inhibition of Acrylic Acid. U.S. Patent 3,674,651 (to
Toyo Soda Co.), July 4, 1972.
(23) Otsuki, S., and I. Miyanohara. Stabilization of Acrylic
Acid or Esters Thereof. U.S. Patent 3,666,794 (to Toyo
Soda Co.), May 30, 1972.
(24) Stabilization of a,$-Ethylenic Aldehydes. Netherlands
Patent Application 65,16553 (Shell International Research),
June 23, 1966.
(25) Preparation of Esters. British Patent 1,185,069 (to British
Titan Products), March 18, 1970.
(26) Alkoxy Phenol Stabilizers. Netherlands Patent 134846 (to
ICI), March 15, 1972.
(27) Yamagishi, A., et al. Method for Inhibiting the Polymeriza-
tion of Unsaturated Carboxylic Acid Esters. U.S. Patent
3,636,086 (to Sumitomo Chemical), January 18, 1972.
(28) Improvements in the Handling of Acrylic Acid. British
Patent 958,226 (to Celanese Corporation), May 21, 1964.
(29) Brown, C. J., et al. Distillation of Acrylic Acid. British
Patent 1,265,419 (to BP Chemicals), March 1, 1972.
(30) Hexamethylene Tetramine as Stabilizer for (Meth) Acrylate
Esters. French Patent 2,085,773 (To Japanese Geon),
December 31, 1971.
(31) Stabilizing Unsaturated Acids. French Patent 2,100,376 (to
Japanese Geon), March 17, 1972.
(32) Hartel, H. Polymerization Inhibitors for Monomeric Vinyl
Esters, Acrylic Acid Esters, or Styrene. German Patent
(Continued)
18
-------
TABLE 3. ACRYLIC ACID POLYMERIZATION INHIBITORS
OBTAINED FROM PATENT LITERATURE (21-47)
Inhibitor system
Diphenylamine
Hydroquinone
Oxygen
N-methy Idipheny lamine
Hydroquinone
Air
N-c-chlorophenylaniline
Oxygen
N-o-methylphenylaniline
Air
( N , N ' -dipheny 1 -p -pheny lened iamine
Air
Diphenylamine
Benzoquinone
Oxygen
N-methy Idipheny lamine
Benzoquinone
Air
N-o-methylphenylaniline
Benzoquinone
Air
N-o-methylphenylaniline
Benzoquinone
Air
Diphenylamine
Hydroquinone monomethyl ether
Air
Phenothiazine
Cupric dithiocarbamate
4-Alkoxyphenols
Hydroquinone \
Condensed phosphoric acid salts >
Silicic acid salts J
Hydroquinone
Phenol
Oxygen - containing gas
Diphenylamine
Oxygen - containing gas
Hydroquinone monomethyl ether
Phenothiazine
Nitric oxide - containing gas
Hexamethylenetetramine
Phosphorous acid (or oxide) )
Hydroxyl compound such as a cresol >
Phosphoric acid esters, phosphines, or benzaldehyde J
Oximes or hydrazones of p-benzoquinone
2 , 6-Di-t-butyl-p-cresol
Semicarbazone or semicarbazide compounds
Ethylene thiourea
Copper dimethyldithiocarbamate
Copper dialkyldithiocarbamate
Ammonium chloride
Chromium acetate
Phenothiazine
Hydroquinone monomethyl ether)
Benzoquinone /
Oxygen - containing gas J
Protoanemonine
Dialkyl nitroxide
Thiosemicarbazide
Iodine and alkali iodide
N-alkylpyrroles
Phosphates
Concentration
3,000
200
(1.0 vol %)
3,000
200
(5.0 vol %)
3,000
(1.0 vol %)
3,000
(5.0 vol %)
3,000
(5.0 vol %)
500
500
(0.5 vol %)
500
500
(3.0 vol %}
500
500
(3.0 vol %)
500
500
(3.0 vol %)
500
500
(3.0 vol %)
10,000
20 to 50
0.5 to 5.0
10 to 10,000
<50
<200
<2,000
50 to 5,000
(0.02 to 2 vol %)
10 to 200
1 to 550
(0.01 to 0.2 vol %)
10 to 30,000
10 to 50,000
(10-6 to 1.0 mole I)
10 to 50,000
<1.0
2 to 300
500 to 10,000
10 to 50,000
10 to 50,000
<50
1 to 10,000
<50
5 to 5,000
10 to 1,000
1 to 300
50 to 5,000
10 to 1,000
100 to 1,000
19
-------
Process operations such as distillation and quenching involve
both a vapor and a liquid phase. Thus, inhibitors usually
consist of a volatile and a nonvolatile component. A typical
(Continued)
1,233,869 (to Dynamit Nobel), February 7, 1967.
(33) Sato, R., et al. 2,6-Di-tert-p-Cresol as Polymerization
Inhibitor for Acrylic Acid Derivatives. German Offen.
Patent 2,112,053 (to Japanese Geon), October 7, 1971.
(34) Acrylic Esters. Japanese Patent 42-23404 (to Asahi Chemical
Industry), November 13, 1967.
(35) Stabilized Vinyl Compounds. Japanese Patent 43-201 (to Toa
Gosei Chemical Industry), January 6, 1968.
(36) Sudo, M., et al. Methyl Acrylate. Japanese Patent 43-10611
(to Japan Synthetic Chemical Industry), May 4, 1968.
(37) Sudo, M., et al. Prevention of Polymerization During the
Preparation of Unsaturated Carboxylates. Japanese Patent
43-29926 (to Mitsubishi Rayon), December 23, 1968.
(38) Acrylic or Methacrylic Acids. Japanese Patent 44-26285 (to
Mitsui Toatsu Chemicals), November 5, 1969.
(39) Polymerization Inhibition of (Meth) Acrylic Acids. Japanese
Patent 45-35285 (to Nippon Kagaku), November 11, 1970.
(40) Kawamura, Y., et al. Polymerization Inhibitor of Acrylate
or Methacrylate. Japanese Patent 46-30173 (to Nitto
Chemical Industry), September 2, 1971.
(41) Unsaturated Acid Distillation. Belgian Patent 778,869 (to
Rohm and Haas), August 2, 1972.
(42) Inhibition of Polymerization of Aqueous Acrylic Acid
Solution. Japanese Patent 47-17714 (to Nippon Kayaku),
September 9, 1972.
(43) Bailey, H. C. Stabilization of Acrylic Acid. British
Patent 1,127,127 (to BP Chemicals), September 11, 1968.
(44) Stabilization of Vinyl Monomer. Japanese Patent 42-1415 (to
Toa Gosei Chemical Industry), January 24, 1967.
(45) Stabilization of Methyl Methacrylate and Methyl Acrylate.
Japanese Patent 42-7765 (to Toyo Rayon), March 29, 1967.
(46) Girvan, I. J. M. Stabilization of Acrylic and Methacrylic
Monomers. British Patent 1,124,836 (to ICI), August 21,
1968.
(47) Shima, T., et al. Stabilization of a,3-Unsaturated
Aldehydes. Japanese Patent 46-13009 (to Sumitomo Chemical),
April 3, 1971.
20
-------
example is the hydroquinone-phenol system (21). Many inhibitors
also require air or oxygen to effectively suppress the
polymerization reaction (22).
Storage Tanks
Tanks are used to store quantities of propylene, acrylic acid,
heat-transfer fluid, polymerization inhibitor and solvents during
processing. Tank capacities range from 1.9 m3 to 930 m3.
The temperature of the stored liquids is kept between 21°C and
27°C. A summary of tankage requirements for a typical acrylic
acid plant is given in Table 4.
TABLE 4. SUMMARY OF TANKAGE REQUIREMENTS FOR A 95,000
METRIC TON/YR ACRYLIC ACID PLANT9
Tank
No.
1-8
9
10
11
12
13-14
15
16-17
18-19
Material stored
Propylene
Heat- transfer fluid
Polymerization inhibitor
Isopropyl ether
Acrylic acid
Acrylic acid
Acrylic acid
Acrylic acid
Acrylic acid
Capacity,
m3
114
76
15
76
76
216
284
443
920
Turnovers
per year
_b
_c
_c
_c
230
40
30
40
10
Tank height,
m
21.5
6.1
_C
4.6
7.3
11.6
9.7
9.7
9.7
Data obtained from confidential industry sources.
Storage tanks are a backup source for normal propylene feed via pipe-
line.
C
Data not available.
Heat-Transfer Circuits
The SOHIO process employs two heat-transfer systems to control
the temperatures in the two reactors. Dowtherm A or a similar
organic heat-transfer fluid is circulated between the reactor and
the waste heat boiler. The fluid is vaporized in the reactor to
remove the heat of reaction. The vapor is condensed in thfe waste
heat boiler by heat exchange with boiler feed water to produce
steam. The condensate is then pumped back to the reactor and
the cycle is repeated.
Although details of the heat-transfer circuits used in the SOHIO
process are not available, the general characteristics of organic
21
-------
heat-transfer fluid systems are discussed in the literature (48-
50). Provision must be made for venting of noncondensables from
these systems. Noncondensables which can accumulate include
water, phenol, and benzene (48). The latter two compounds are
degradation products of Dowtherm A.
Plant Shutdown, Turnaround, and Startup5
Acrylic acid plants are shut down an average of four times per
year. Shutdown requires 8 hr and the subsequent start-up opera-
tion requires 12 hr. In addition, process upset conditions
(tripouts) occur an average of once per month and may last for
several hours to a day, with an average duration of 4 hr.
During process upsets and shutdowns, a mixture of acrylic acid
and solvent is temporarily stored in insulated storage tanks.
Organic vapors may be emitted from these tanks due to working
and breathing losses, especially during filling operations.
These tanks are either vented to the incinerator for emission
control or provided with nitrogen blankets and chilled-water
vent condensers.
Natural gas-fired startup heaters are employed to heat the
reactor cooling medium prior to start-up and to maintain coolant
temperature during tripouts. Periods of continuous heater oper-
ation range from several hours to several days. Emissions from
these heaters consist of flue gases from the combustion of
natural gas.
One plant employs two smokeless flares for emission control
during incinerator maintenance shutdowns and during severe proc-
ess upsets. One flare is used to burn the off-gas from the
quench tower. The other flare handles the suction vent gases
from the solvent stripper, light ends stripper, and rectifier.
Cleaning and repair of process equipment during periods of proc-
ess shutdown can result in emissions of organic compounds. One
plant employs a controlled ventilation area for performing these
operations. The vent gass from this area is fed to the inciner-
ator for disposal. Solid waste from cleaning and repairing
operations is incinerated in a separate solids incincerator.
This section is based on data supplied by the operating
companies.
(48) Frikken, D. R., K. S. Rosenberg, and D. E. Steinmeyer.
Understanding Vapor-Phase Heat-Transfer Media. Chemical
Engineering, 82 (12):86-90, 1975.
(49) Conant, A. R., and W. F. Seifert. Dowtherm Heat Transfer
Medium. Chemical Engineering Progress, 59(5):46-49, 1963.
(50) Fried, J. R. Heat-Transfer Agents for High-Temperature
Systems. Chemical Engineering, 80 (12):89-98, 1973.
22
-------
Startups, shutdowns, and process upsets can also result in emis-
sions of heat-transfer fluid from the heat-transfer circuits.
These emissions can be controlled by venting the circuits to the
incinerator.
GEOGRAPHICAL DISTRIBUTION
Acrylic acid is currently manufactured by four companies at four
locations in the United States with a combined capacity of 2.7 x
105 metric tons/yr. The manufacturers, plant locations, plant
capacities, county population densities, and process types are
listed in Table 5. It can be seen that production is confined
to the Gulf Coast area. A map showing the locations of these
plants is given in Figure 2. It should be noted that the present
study covers only the three plants utilizing the propylene
oxidation process. In addition to the four plants listed in
Table 5, there are currently two plants which produce acrylic
esters, but not acrylic acid. Dow Chemical Company's plant at
Freeport, Texas, has a capacity of 4,500 metric tons/yr for 2-
hydroxypropyl acrylates (51). At Deer Park, Texas, the Rohm and
Haas Co., also produces acrylates by a modified Reppe process in
which the ester is obtained directly without acrylic acid as an
intermediate (51, 52). This unit has a capacity of 1.81 x 105
metric tons/yr of acrylates. Part of this capacity was placed
on standby status when the propylene oxidation unit came onstream
in 1977 (51) .
(51) Chemical Profile: Acrylates. Chemical Marketing Reporter,
211(17):9, 1977.
(52) Ohara, R. Production of Acrylic Ester and Its Economics -
Propylene Oxidation Process. Chemical Economy & Engineering
Review, 4(7):24-29, 1972.
23
-------
TABLE 5. ACRYLIC ACID PLANTS (51, 52)
Company
Celanese Chemical Co.
Rohm & Haas Co.
Union Carbide Corp.
Dow-Badische Co.
Total
Location
Clear Lake, TX
Deer Park, TX
Hahnville, LA
Freeport , TX
Normal
capacity,
10^ metric
tons/yr
100
90
65
18
273
County
population
density,
persons/km2
386
386
37
29
Process
Propylene oxidation
Propylene oxidation
Propylene oxidation
High-pressure Reppe
table is also based on information supplied by industry sources.
- BAD ISCHE, FREEPORT, TX
*~ ' ^ UNION CARBIDE, HAHNVILLE,LA
CELANESE, CLEAR LAKE, TX \ RQHM & HMS( D£ER pARK> -
Figure 2. Locations of acrylic acid plants.
24
-------
SECTION 4
EMISSIONS
SELECTED POLLUTANTS
Compounds which have been identified in process streams in
acrylic acid plants are listed in Table 6.a Methane and ethane
originate from the natural gas used as supplemental fuel in the
thermal incinerator; propane and propylene are from process feed
materials; ethyl aerylate and isopropyl ether are solvents (see
Table 2). All other compounds are reaction products of the
oxidation of propylene. The compounds listed in Table 7 were
selected for study as potential environmental pollutants.
In addition to the above compounds, nitrogen oxides are formed
in the incinerator and emitted with the stack gas. DOWTHERM A
heat-transfer fluid and its degradation products, phenol and
benzene, are emitted from the vents in the heat-transfer circuits,
A number of other compounds may be emitted depending on the sol-
vent and polymerization inhibitor systems (see Section 3) em-
ployed in the process.
Atmospheric reactivity and health effects of selected compounds
evident in acrylic acid production are shown in Table 7 (53, 54).
Available threshold limit values (TLV®) are also shown.
LOCATION AND DESCRIPTION
The locations of emissions from the propylene oxidation process
are given in Table 8. These locations are pictured in the pro-
cess flow diagram, Figure 1. In the following description, each
emission point is discussed along with the specific technology
that may be used for its control.
Based on confidential information supplied by operating
companies.
(53) TLV® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. 94 pp.
(54) Sax, N. I. Dangerous Properties of Industrial Materials,
Third Edition. Reinhold Book Corporation, New York,
New York, 1968. 1258 pp.
25
-------
TABLE 6. COMPOUNDS IDENTIFIED IN ACRYLIC ACID PROCESSING STREAMS
Compound
Formula
Acetaldehyde
Acetic acid
Acetone
Acrolein
Acrolein dimer
(3,4-Dihydro-2H-pyran-2-carboxaldehyde)
Acrylic acid
Acrylic dimer
(2-Carboxylethyl acrylate)
Acrylic polymer
Ethyl acrylate
Formaldehyde
Maleic acid
Propionic acid
Propane
Propylene
Isopropyl ether
Carbon oxides
Methane
Ethane
CH3CHO
CH3COOH
(CH3)2CO
CH2=CHCHO
-CHO
CH2=CHCOOH
CH 2=CHCOOCH 2CH 2COOH
-/CH2-CH-CH2-CH V
\ COOH COOH/n
CH2=CHCOOCH2CH3
ECHO
HC-COOH
HC-COOH
CH3CH2COOH
CH3CH2CH3
CH2=CHCH3
CH3CH3
CH3CHOCHCH3
CO, C02
CH3CH3
26
-------
TABLE 7. HEALTH EFFECTS AND ATMOSPHERIC REACTIVITY OF
SELECTED COMPOUNDS IN ACRYLIC ACID PRODUCTION
Compound
(53),
mg/m3
Atmospheric
reactivity
Health effects (54)
Acetaldehyde
Acetic acid
Acetone
Acrolein
Acrolein dimer
Acrylic acid
Acrylic dimer
Benzene
Ethyl acrylate
Formaldehyde
Isopropyl ether
Maleic acid
Phenol
Propane
Propylene
Carbon monoxide
180
25
2,400
0.25
80
100
3
1,050
19
Contributes to
photochemical smog
55
Toxic effects evident at moderately chronic levels.
Caustic irritant at chronic levels.
No injurious effects reported; possibility of skin
irritations.
Extremely toxic.
Unknown.
Similar to acetic acid; strong irritant.
Unknown.
Recognized carcinogen at chronic levels; anemia,
leukopenia, macrocytosis may result.
Very toxic at acute levels.
A suspected carcinogen; main toxic effect is
irritation.
Irritating to skin and mucous membranes.
Irritant; highly toxic.
Prolonged exposure to low concentration results in
digestive disturbances, nervous disorders and
skin eruptions.
Asphyxiant; shows little toxic effect.
Simple asphyxiant; no irritating effects.
Causes readily reversible effects at chronic levels.
9Blanks indicate no TLV has been established.
-------
TABLE 8. LOCATION OF EMISSION POINTS
Location Emission point
A Propylene storage tank vents
B Heat-transfer circuit vents
C Solvent storage tank vents
D Intermediate acrylic acid storage tank vents
E Vacuum column steam jet vent
F Acrylic acid storage tank vents
G Transport loading facility vents
H Incinerator stack
Fugitive emissions
Identification letters shown in Figure 1.
Location unknown.
Propylene Storage Tank Vents
Propylene may be stored in tanks prior to vaporization and oxi-
dation. In one plant, propylene is produced onsite and held in
bulk storage tanks, which are the source of propylene for the
acrylic acid process. A venting system releases excess pressure
within these storage tanks by venting propylene to the atmosphere,
Another plant receives process propylene directly via pipeline
from an offsite source. This plant has a number of backup pro-
pylene storage tanks which are vented to an incinerator.
Heat-Transfer Circuit Vents
Dowtherm A or a similar organic heat-transfer fluid is used in
both acrolein and acrylic acid reactors to maintain proper tem-
peratures. A venting system prevents the buildup of gaseous
heat-transfer fluid by releasing vapors to the atmosphere. These
emissions may be controlled by venting them to the incinerator.9
Solvent Storage Tank Vents
Solvents (see Table 2) are stored prior to their use as extrac-
tion agents in the recovery of acrylic acid. Emissions of
evaporated solvent from the storage tanks may be controlled by
venting them to the incinerator.3
Retrofitting an existing installation to vent storage tanks,
heat-transfer circuits, distillation columns, and transport
loading facilities to an incinerator may not be feasible due to
economic and safety considerations (personal communication with
T. L. Rapp, Union Carbide Corp., Hahnville, Louisiana, Decem-
ber 21, 1977).
28
-------
Intermediate Acrylic Acid Storage Tank Vents
Intermediate storage tanks are used to temporarily store an
acrylic acid-solvent mixture while process equipment is being
serviced. Vents on these tanks represent an intermittent source
of organic compound emissions. Emissions are greatest during the
period of tank filling, which may last from several hours to
several days. These operations are performed an average of once
per month. Emissions are controlled in one of two ways: organic
vapors are vented to the incinerator in the first method; in the
second, a pressurized nitrogen blanket is maintained in the stor-
age tanks to inhibit the formation of organic vapors, and a
chilled water vent condenser is used to remove organics from the
vent gas.
Vacuum Column Steam Jets
Vacuum distillations are required to recover and purify acrylic
acid. Steam jets, which produce the vacuum, emit acrylic acid
and other organics along with steam. One plant makes use of a
water-chilled surface condenser to control these emissions. The
other two plants vent these emissions to the incinerator.
Acrylic Acid Storage Tank Vents
Acrylic acid vapors are emitted from acrylic acid storage tanks
prior to loading and transport. These emissions may be con-
trolled by venting them to the incinerator.3
Transport Loading Facility Vents
Acrylic acid emissions occur from the loading of acrylic acid
into tank cars. These emissions are a result of acrylic acid
atomization and evaporation during loading procedures. Control
of emissions from loading facilities can be accomplished by
venting them to the incinerator.3 However, these emissions are
minimal since most acrylic acid is consumed onsite for produc-
tion of acrylic esters.
Incinerator Stack
Although the incinerator is not required for the oxidation of
propylene to acrylic acid, it is of paramount importance as an
emission control device. Of the two plants utilizing SOHIO
technology, one vents all waste streams from point sources to
the incinerator, while the other vents all waste streams to the
incinerator except those from intermediate acrylic acid storage
tanks, and transport loading facilities. The other plant
employing the propylene oxidation process vents all waste
See footnote on page 28.
29
-------
streams to the incinerator except those emanating from two field
storage tanks. In all cases, greater than 90% of the organic
wastes from the process are controlled by incineration. Emis-
sions from the incinerator stack consist of carbon monoxide,
nitrogen oxides, and organic compounds resulting from incomplete
combustion of waste organics and auxiliary fuel.
Fugitive Emissions
Fugitive losses of organic compounds result from leaks in process
equipment, from process material spills, and from the repair and
cleaning of process equipment. Fugitive emissions are generally
controlled through proper plant maintenance and careful loading
procedures. Acrylic acid plants tend to be tightly controlled
because of the low odor threshold of some of the compounds, such
as acrolein, that are involved in the process. In addition, much
of the process equipment operates under vacuum, so that leaks
result in air entering the system rather than process chemicals
leaking out.
EMISSION DATA
Emission factors for compounds emitted from the production of
acrylic acid by propylene oxidation are given in Table 9. The
emission factors for the various sources of emissions are given
in Table 10. Emission height data for acrylic acid plants are
given in Table 11. These tables represent composite data sets
based on information supplied by the companies which utilize the
propylene oxidation process.
EMISSIONS BURDEN
The controlled emission factors given in Table 10 were used
together with the plant capacity data in Table 5 to calculate
annual emissions of criteria pollutants from acrylic acid manu-
facture via propylene oxidation. Nationwide emissions are given
in Table 12, and emissions in the states of Texas and Louisiana
are given in Table 13.
DEFINITION OF A REPRESENTATIVE SOURCE
A representative plant is defined as one utilizing SOHIO tech-
nology for the production of acrylic acid by propylene oxidation.
The use of control technology for the abatement of hydrocarbon
emissions is considered as part of the representative plant. The
three actual plants that produce acrylic acid by propylene oxida-
tion use incineration to control more than 90% of their process
emissions. It should be noted that, despite the representative
plant definition, an emission factor, a maximum time-averaged
ground level concentration, and a source severity value for un-
controlled hydrocarbon emissions from acrylic acid production
are given along with the respective values for a representative
30
-------
TABLE 9. ACRYLIC ACID EMISSION FACTORS BY COMPOUND
(g/kg)
Material emitted
Emission factor
Uncontrolled Controlled
Criteria pollutants:
Hydrocarbons
Carbon monoxide
Nitrogen oxides
Chemical substances:
AcetaIdehyde
Acetic acid
Acetone
Acrolein
Acrolein dimer
Acrylic acid
Benzene
Diphenyl-diphenyl oxide eutectic
Ethyl acrylate
Formaldehyde
Isopropyl ether
Maleic acid
Phenol
Propane
Propylene
110c
NAC
NA
Note.
a
<0.6
<0.7
<0.7
Slanks indicate emission factors unknown.
Data based on information provided by confidential industry
sources. Quality of data unknown.
Includes all organic compounds except methane.
Not applicable; emissions result from control device.
TABLE 10. CONTROLLED ACRYLIC ACID EMISSION FACTORS BY LOCATION
(g/kg)
a ,b
Emission point
Propylene storage tank vents
Heat-transfer circuit vents
Solvent storage tank vents
Intermediate acrylic acid
storage tank vents
Vacuum column steam jets
Acrylic acid storage tank
vents
Transport loading facility
vents
Incinerator stack
Fugitive emissions
Carbon
monoxide
NAd
NA
NA
NA
NA
NA
NA
<0.f
Emission factor
Hydrocarbons
_e
_e
<0.02
<0.2
e
<0.4
Nitrogen
oxides
NA
NA
NA
NA
NA
NA
NA
<0.7
Data based on information provided by confidential industry
sources; data quality unknown.
Emission factors are representative of plants with control
technology.
""Includes all organic compounds except methane.
Not applicable; species not emitted.
Emissions vented to incinerator.
Emission factor not known.
31
-------
TABLE 11. EMISSION HEIGHT DATA FOR
ACRYLIC ACID PLANTS3
Emission point
Intermediate acrylic acid storage tank vents
Vacuum column steam jet
Incinerator stack
Height, m
13.7
19.8
25.9
a
Data based on information provided by confidential
industry sources.
TABLE 12. CONTRIBUTION OF CRITERIA POLLUTANTS FROM ACRYLIC ACID
PRODUCTION TO NATIONAL STATIONARY SOURCE EMISSIONS
Criteria
pollutant
Hydrocarbons
Carbon monoxide
Nitrogen oxides
Total national
emissions,
10 6 metric tons/yr (55)
25
97
22
Emissions from
acrylic acid
manufacture ,
metric tons/yr
<160
<200
<200
Percent of
national
emissions
<0.0006
<0.0002
<0.0009
TABLE 13. ACRYLIC ACID CONTRIBUTIONS TO STATE
EMISSIONS OF CRITERIA POLLUTANTS
Criteria
pollutant
Hydrocarbons
Carbon monoxide
Nitrogen oxides
State
Louisiana
Texas
Louisiana
Texas
Louisiana
Texas
State emissions ,
10 metric tons/yr (55)
1,920
2,219
5,634
6,898
423
1,304
Emissions from
acrylic acid
manufacture ,
metric tons/yr
<38
<130
<46
<160
<45
<160
Percent
of
state
emissions
<0.002
<0.006
-------
plant utilizing control technology. Production capacity, popula-
tion density, emission heights, and emission factors for a repre-
sentative plant are taken from data provided by the operating
companies. Data for a representative plant are summarized in
Table 14.
TABLE 14. SUMMARY OF DATA FOR A REPRESENTATIVE PLANT3
Parameter
Value for
representative plant
Process
Raw material
Production capacity, metric tons/yr
Population density, persons/km2
Control technology
Emission heights, m:
Intermediate acrylic acid
storage tank vents
Vacuum column steam jet
Incinerator stack
Emission factors, g/kg:
Intermediate acrylic acid
storage tank vents
Vacuum column steam jet
Incinerator stack:
Carbon monoxide
Hydrocarbons
Nitrogen oxides
Propylene oxidation
Propylene
85 x 103
297
Incineration
13.7
19.8
25.9
<0.02
<0.2
<0.7
<0.4
<0.7
Values of the representative plant parameters comprise a com-
posite data set based on information supplied by the companies
utilizing the propylene oxidation process. They do not corres-
pond exactly to any of the operating plants.
ENVIRONMENTAL EFFECTS
Maximum Ground Level Concentration
The short-term (3 min average) maximum ground level concentration,
Xraax, for materials emitted by acrylic acid production was esti-
mated by Gaussian plume dispersion theory. Xmax, in grams per
cubic meter, is calculated by the following equation (56):
X.
_ 2 Q
max
irH2eu
(13)
(56) Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
Public Health Service Publication No. 999-AP-26, U.S.
Department of Health, Education, and Welfare, Cincinnati,
Ohio, May 1970. 84 pp.
33
-------
where Q = emission rate, g/s
H = effective emission height, m
e = 2.72
TT = 3.14
u = average wind speed = 4.5 m/s
Maximum Time-Averaged Ground Level Concentration
The maximum ground level concentration averaged over a given
period of time, Xmax, is calculated from Xmax by the following
equation (56) :
where tQ = short-term averaging time (3 min)
t = averaging time
The averaging time is 3 hr for hydrocarbons and 24 hr for non-
criteria pollutants. Since nitrogen oxides have a 1-yr averaging
time, a special equation must be used; it has been derived in
Appendix A. Table 15 gives X"maj, for compounds emitted from a
representative plant, while Table 16 gives Xmax f°r specific
emission points within a representative plant. Values in
Table 15 were computed using emission factors from Table 9 and
emission heights for specific compounds given in Table 11.
Values in Table 16 are based on emission factors in Table 10 and
emission heights for individual emission points given in Table 11.
Source Severity
The hazard potential of acrylic acid manufacture can be quanti-
fied by determining a source severity, S, which is defined as the
ratio of the maximum time-averaged ground level concentration to
F, the hazard exposure level for a pollutant. For criteria pol-
lutants, F is defined as the primary ambient air quality standard
for the particular pollutant. * For noncriteria pollutants, F is
defined as follows:
F E (TLV) (8/24) (0.01) (15)
Source severities for compounds emitted from a representative
acrylic acid plant are given in Table 17. _ These values were
obtained by dividing the concentrations, Xmax, in Table 15 by the
appropriate value of F. Source severities for individual emis-
sion points within a representative plant are given in Table 18.
There is no primary ambient air quality standard for hydro-
carbons. The value of 160 yg/m3 used for hydrocarbons in this
report is an EPA recommended guideline for meeting the primary
ambient air quality standard for oxidants.
34
-------
TABLE 15. MAXIMUM TIME-AVERAGED GROUND LEVEL
CONCENTRATIONS FOR COMPOUNDS EMITTED
(mg/m3)
"max
Material emitted Uncontrolled Controlled
Criteria pollutants:
Hydrocarbons 19. <0.1
Carbon monoxide NA <0..09
Nitrogen oxides NA <0.06
Chemical substances:
Acetaldehyde
Acetic acid
Acetone
Acrolein
Acrolein dimer
Acrylic acid
Benzene
Diphenyl-diphenyl oxide eutectic
Ethyl acrylate
Formaldehyde
Isopropyl ether
Maleic acid
Phenol
Propane
Propylene
Note.—Blanks indicate x unknown, see Table 10.
Includes all organic compounds except methane.
Not applicable; emissions result from control device.
TABLE 16. MAXIMUM TIME-AVERAGED GROUND LEVEL
CONCENTRATIONS FOR EMISSION POINTS9
(mg/m3)
Emission point
Propylene storage tank vents
Heat-transfer circuit vents
Solvent storage tank vents
Intermediate acrylic acid
storage tank vents
Vacuum column steam jet
Acrylic acid storage tank
vents
Incinerator stack
Fugitive emissions
Transport loading facility
vents
Carbon
monoxide
NAC
NA
NA
NA
NA
NA
<0.09
_e
d
Hydrocarbons
d
~d
~d
<0.007
<0.03
H
<0.04
_e
d
Nitrogen
oxides
NA
NA
NA
NA
NA
NA
<0.06
_e
d
aValues for x are representative of plants with control
technology. max
Includes all organic compounds except methane.
Not applicable; species not emitted.
Emissions vented to incinerator.
X~ not calculated due to lack of emission data.
35
-------
TABLE 17. SOURCE SEVERITIES FOR COMPOUNDS EMITTED
Source severity
Material emitted Uncontrolled Controlled
Criteria pollutants:
Hydrocarbons3 120. <0.7
Carbon monoxide NAU <0.002
Nitrogen oxides NA <0.6
Chemical substances:
Acetaldehyde
Acetic acid
Acetone
Acrolein
Acrolein dimer
Acrylic acid
Benzene
Diphenyl-diphenyl oxide eutectic
Ethyl acrylate
Formaldehyde
Isopropyl ether
Maleric acid
Phenol
Propane
Propylene
Note.—Blanks indicate severity not calculated due to lack of
emission data.
alncludes all organic compounds except methane.
Not applicable; emissions result from control device.
TABLE 18. SOURCE SEVERITIES FOR EMISSION POINTS3
Emission point
Propylene storage tank vents
Heat-transfer circuit vents
Solvent storage tank vents
Intermediate acrylic acid
storage tank vents
Vacuum column steam jet
Acrylic acid storage tank
vents
Incinerator stack
Fugitive emissions
Transport loading facility
vents
Carbon .
monoxide Hydrocarbons
NA°
NA
NA
NA
NA
NA
<0.002
_d
d
_d
— j
a
<0.05
<0.2
.
-
<0.3
_d
H
Nitrogen
oxides
NA
NA
NA
NA
NA
NA
<0 . 6
_d
A
Source severities are representative of plants with control
technology.
Includes all organic compounds except methane.
Not applicable; species not emitted.
Source severity not known or emissions vented to incinerator.
36
-------
These values were derived in a similar manner from the concen-
trations given in Table 16.
Affected Population
A measure of the population which is exposed to a high contam-
inate concentration due to a representative acrylic acid plant
can be obtained as follows: The values of x, downwind distance
from the source, for which
= o.l (16)
are determined by iteration. The value of X(x), the annual mean
ground level concentration, is computed from the equation (56):
(17)
a ux
z
where Q = emission rate, g/s
H = effective emission height, m
x = downwind distance from source, m
u = average wind speed (4.5 m/s)
oz = vertical dispersion coefficient, m
For atmospheric stability class C (neutral conditions) , az is
given by (57) :
az = 0.113 x°-911 (18)
The affected area is then computed as
A = u(x22 - X!2) , km2 (19)
where xi and x2 are the two roots of Equation 16.
The (capacity-weighted) mean population density, D , is calcu-
lated as follows:
E ciDPi
D = l=-~ - , persons/km2 (20)
where Cj^ = production capacity of plant i
Dp^ = county population density for plant i
(57) Eimutis, E. C. , and M. G. Konicek. Derivations of Continu-
ous Functions for the Lateral and Vertical Atmospheric Dis-
persion Coefficients. Atmospheric Environment, 6(11):
859-863, 1972.
37
-------
The product (A)»Dp is designated the "affected population."
The area and population affected by a representative acrylic
acid plant were calculated for hydrocarbons and nitrogen oxides
since the upper bounds on source severity for both species
exceed 0.1. The results are summarized in Table 19.
TABLE 19. AFFECTED POPULATION FOR A REPRESENTATIVE PLANT3
Parameter Hydrocarbons Nitrogen oxides
Population density, persons/km2 297 297 ,
Emission height, m 19.8 25.9
Emission rate, g/s <1.6 <1.9
Affected area, km2 <2.3 <4-7
Affected population, persons <600 <1,200
Affected areas and populations are for a source severity of
0.1 or greater.
38
-------
SECTION 5
CONTROL TECHNOLOGY3
STATE OF THE ART
Control technology for acrylic acid manufacture is described via
emission points where specific controls are used. The emission
points concerned are the vacuum column steam jet, intermediate
acrylic acid storage tank, other emission points, and fugitive
emissions. All control technology discussed is designed for the
control of organic compounds which are emitted during the pro-
duction of acrylic acid.
Vacuum Column Steam Jets
Vacuum-producing steam jets emit organics from the venting of
steam during acrylic acid recovery and refining. Emissions may
be controlled by utilizing surface condensers which are placed
after each stage of the steam jet, together with a chilled-water
vent condenser. The surface condensers condense part of the
steam, thereby reducing the volume pf the vent gas. The chilled-
water condenser then removes organic compounds from the vent gas.
The control efficiency of this system is estimated to be 75%
under the worst conditions. In a second method of control, steam
and organic vapors from the vacuum jets are vented to a centrally
located incinerator."
Intermediate Acrylic Acid Storage Tanks
The temporary storage of acrylic acid-solvent mixture during pro-
cess upsets results in emissions of organic compounds from load-
ing and breathing losses. These emissions are controlled by
means of a nitrogen blanket at a gage pressure of 0.5 kPa togeth-
er with a chilled-water vent condenser. Alternatively, these
tanks may be vented to the incinerator for emission control.13
Information in this section was provided by confidential
industry sources.
See footnote on page 28.
39
-------
Other Emission Points
All three plants that produce acrylic acid by propylene oxidation
make use of incinerators to control more than 90% of their total
organic compound emissions. Emission points that are vented to
the incinerator include storage tank vents, reactor vents, re-
covery and purification process vents, and transport loading
facility vents.
Contaminated air and fresh air are mixed and blown into the in-
cinerator by means of a fan. Organic vapors from process vents,
wastewater, and waste organics are also injected into the incin-
erator, along with a sufficient amount of natural gas to maintain
a stable flame region and adequate operating temperature. Com-
bustion area temperatures in the range of 760°C to 980°C, and a
mean residence time of 1 s for contaminants have been reported.8
Following combustion, the hot gases pass through a waste heat
boiler which produces superheated steam while reducing the tem-
perature of the stack gases to 260°C. Figure 3 shows a schematic
of an incinerator used for controlling organic emissions 'from
acrylic acid manufacture. The control efficiency of the incin-
erator is estimated to be greater than 98%.
STACK
CONTAMINATED
AIR
FRESH AIR
PROCESS VENTS
FRESH WATER
Figure 3. Incinerator used for controlling organic
emissions from acrylic acid manufacture.
Information provided by confidential industry sources,
40
-------
Fugitive Emissions
As mentioned in Section 4, fugitive emissions from acrylic acid plants tend
to be tightly controlled as a result of the low odor threshold of compounds
involved in the process. One plant employs the following methods for con-
trolling fugitive emissions:
Mechanical seals are exclusively used as opposed to
packing glands on pumps.
Spare pumps are provided at all continuous service
locations so that a faulty pump can be taken out of
service immediately for repairs.
All pumps are mounted above drip pans which drain any
leaks to a sump which is vented to the incinerator.
Valves are located inside areas that are diked or
curbed to prevent escape of leaked material to
surrounding areas. These diked areas drain to the
above sump system which is vented to the incinerator.
Another plant employs a controlled ventilation area for dismantling, repair-
ing, and cleaning process equipment. This area is vented to the main pro-
cess incinerator. A separate solid waste incinerator is employed to dispose
of any solid wastes resulting from these operations.
FUTURE CONSIDERATIONS
No additional control technology is expected in the acrylic acid industry.
Incineration is considered an adequate and effective means of control for
emissions from acrylic acid manufacture. However, if dilute streams of
organics (less than 1,000 ppm) have to be incinerated, operating temperatures
higher than 760°C to 980°C may be required.
41
-------
SECTION 6
GROWTH AND NATURE OF THE INDUSTRY
PRESENT TECHNOLOGY
Technology for producing acrylic acid is largely based on the
two-stage oxidation of propylene. This process is employed by
three of the four plants operating in the United States and
accounts for 93% of production capacity. Two plants utilize
SOHIO technology for propylene oxidation while the third (Rohm &
Haas) employs technology developed in-house.a The remaining 7%
of production capacity is held by one plant that uses the high-
pressure Reppe process. This process employs a nickel compound
as a catalyst for a high-pressure reaction in which acetylene
and carbon manoxide are reacted with water to synthesize acrylic
acid (52).
The Reppe process, conceived in 1939, is the older, more conven-
tional method for acrylic acid production. The propylene oxida-
tion process, developed around 1960, is considered more economi-
cal due to its low-cost feedstock materials (52). Union Carbide
established the first commercial plant in the United States for
acrylic acid production by propylene oxidation in 1969 (52).
EMERGING TECHNOLOGY
Since the propylene oxidation process is relatively new, it still
offers the opportunity for technical improvements. The low cost
of acrylic acid produced by this process makes it possible to
develop new applications for the acid and its derivatives. These
new applications include their use as food additives, coagulants,
paper sizing agents, and high molecular weight reforming
agents (52).
The propylene oxidation process is in a considerably advanced
stage. However, further research and development work on the
Rohm & Haas process utilizes catalyst technology licensed
from Japan Catalytic Chemical Industry, as well as certain
aspects of propylene oxidation technology licensed from
Toyo Soda Manufacturing Co.
(58) Japan Catalytic Chemical Industry Will Supply Catalyst
Know-How. Chemical Week, 112 (19): 33-34, 1973.
42
-------
oxidation and rectification steps, especially with respect to
catalysts, will assume great importance. The expected result
of this development work is to further decrease the cost of pro-
ducing acrylic acid by propylene oxidation (52).
MARKETING STRENGTHS AND WEAKNESSES
Approximately 83% of the acrylic acid produced in the United
States is used for the production of acrylic esters, as shown
in Table 20 (59). The remaining 17% is used for miscellaneous
purposes, which include production of water-soluble resins and
salts, production of specialty acrylates, and use as a comonomer
in acrylic emulsion and solution polymers (59).
TABLE 20. ACRYLIC ACID CONSUMPTION (59)
End use Quantity, %
Ethyl and methyl acrylate 52
n-Butyl and isobutyl acrylate 26
2-Ethylhexyl and other acrylates 5
Miscellaneous applications9 • 17
TOTAL 100
Includes merchant and captively consumed
acrylic acid for uses other than ester
intermediates.
The principal end uses of acrylic acid esters are given in
Table 21. The two largest users of acrylates are acrylic sur-
face coatings, which account for 41% of consumption, and textile
applications, which account for 20% of consumption. No other
market accounts for more than 10% of acrylic ester consumption
(51). Thus, the demand for acrylic acid is primarily determined
by the markets for acrylic surface coatings and textile
applications.
Acrylic surface coatings consist of acrylic latex paints, acrylic
lacquers, and acrylic enamels. The principal market for acrylic
latex paint is in trade sales paints; e.g., interior and exterior
house paints. Acrylic lacquers and enamels are used primarily
for automobile finishes. Thus, demand for the latter materials
follows the fluctuations in the automobile industry. In addi-
tion, acrylic lacquers and enamels contain considerable amounts
of solvents; they are therefore prime candidates for replacement
by water-base or solventless systems as a pollution control
measure.
(59) Chemical Origins and Markets. Stanford Research Institute,
Menlo Park, California, 1977. 118 pp.
43
-------
TABLE 21. CONSUMPTION OF ACRYLIC ACID ESTERS (51)
End use Quantity, %
Surface coatings 41
Textiles 20
Paper 5
Polishes 4
Leather 3
Adhesives 4
Acrylic fibers 4
Miscellaneous 6
Exports 13
TOTAL 100
Most acrylates used for textile applications are in the form of
straight acrylic emulsions, although some vinyl acrylics are
also used. Ethyl acrylate and n-butyl aerylate are the major
acrylate monomers used in these applications, which include
adhesives, backcoatings, fabric finishes, pigment binders, soil
release agents, and thickeners.
Acrylic latex adhesives are used as fabric-to-fabric bonding
agents, flocking adhesives, and binders for nonwoven and imita-
tion (paper) fabric. Foams and adhesives based on polyurethane
resins are the major competitors with acrylic latex in this area.
Acrylic latexes are used in backcoatings for automotive and furn-
iture upholstery, draperies, and pile fabrics. Acrylics, as well
as other synthetic latexes and natural resins, such as starch
and gum, are used to improve the feel and body of fabrics. The
feel and body of the finished fabric can vary from soft to hard
(stiff) depending on the formulation of the acrylic finish applied.
Pigment binders are used in printing and dyeing fabrics.
Binders based on acrylic latexes account for about 50% of this
market, the remainder belonging to styrene-butadiene latexes.
Anticipated growth rates in the principal acrylate markets are
as follows: 7% per year for surface coating and 9% per year
for textiles (51). Total demand for acrylic acid is expected
to increase at an annual rate of 6% to 8% over the next several
years (51). Based on the 1975 production of 97,000 metric tons
(51), this rate of growth will result in acrylic acid production
of 130,000 to 143,000 metric tons in 1980. Overcapacity is
anticipated in the industry for the next several years (51).
44
-------
Historically, acrylic acid production increased at a rate of 12%
to 15% per year in the period 1967 to 1976 (51). The production
and sales trends of acrylic acid are shown graphically in
Figure 4 (60) . The difference between the two curves reflects
captive consumption of the acid.
1958 1964 1970 1976
YEAR
Figure 4. Production and sales record of acrylic acid (60)
(60) Synthetic Organic Chemicals, U.S. Production and Sales.
U.S. International Trade Commission (formerly U.S. Tariff
Commission), Washington, D.C., 1961-1975.
45
-------
REFERENCES
1. Adams, C. R., and T. J. Jennings. Investigation of the
Mechanism of Catalytic Oxidation of Propylene to Acrolein
and Acrylonitrile. Journal of Catalysis, 2(l):63-68, 1963.
2. Adams, C. R., H. H. Voge, C. Z. Morgan, and W. E.
Armstrong. Oxidation of Butylenes and Propylene Over Bis-
muth Molybdate. Journal of Catalysis, 3(4):379-386, 1964.
3. Adams, C. R. , and T.-J. Jennings. Mechanism Studies of the
Catalytic Oxidation of Propylene. Journal of Catalysis,
3(6) :549-558, 1964.
4. Keulks, G. W., and M. P. Rosynek. Mechanistic Studies of
Propylene Oxidation on Bismuth Molybdate. Preprints,
Division Petroleum Chemistry, American Chemical Society,
14(4):C55-C61, 1969.
5. Callahan, J. L., R. K. Grasselli, E. C. Milberger, and H. A.
Strecker. Oxidation and Ammoxidation of Propylene Over Bis-
muth Molybdate Catalyst. Preprints, Division of Petroleum
Chemistry, American Chemical Society, 14(4) :C13-C27, 1969.
6. Peacock, J. M., A. J. Parker, P. G. Ashmore, and J. A.
Hockey. The Oxidation of Propene Over Bismuth Oxide,
Molybdenum Oxide, and Bismuth Molybdate Catalysts. IV.
The Selective Oxidation of Propene. Journal of Catalysis,
15(4):398-406, 1969.
7. Margolis, L. Ya. On the Mechanism of Catalytic Oxidation
of Hydrocarbons. Journal of Catalysis, 21(1) :93-101, 1971.
8. Keulks, G. W. The Method of Oxygen Atom Incorporation into
the Products of Propylene Oxidation Over Bismuth Molybdate.
Journal of Catalysis, 19 (2) :232-235, 1970.
9. Keulks, G. W., M. P. Rosynek, and C. Daniel. Bismuth
Molybdate Catalysts. Industrial and Engineering Chemistry,
Product Research and Development, 10(2):138-142, 1971.
10. Keulks, G. W., C. Daniel, and J. R. Monnier. Evidence for
Surface Initiated Homogeneous Reactions During the Cata-
lytic Oxidation of Propylene. Preprints, Division of
Petroleum Chemistry, American Chemical Society, 17(1):
B5-B11, 1972.
46
-------
11. Luskin, L. S. Acrylic Acid, Methacrylic Acid, and the
Related Esters. In: High Polymers, E. C. Leonard, ed.,
Vol. 24, Part 1. Wiley-Interscience, New York, New York,
1970. pp. 105-203.
12. Kiff, B. W., and N. R. Cox. Oxidation of 1,2-Olefins to
Oxygenated Products. U.S. Patent 3,467,716 (to Union
Carbide), September 16, 1969-
13. Ono, I., and M. Akashi. Catalyst for the Production of
Acrolein and Acrylic Acid. U.S. Patent 3,786,000 (to Rohm
and Haas), January 15, 1974.
14. Levy, L. B. Catalyst for Oxidation of Olefins. U.S. Patent
3,875,078 (to Celanese Corporation), April 1, 1975.
15. Propylene Gets the Nod. Chemical Week, 112(4):37, 1973.
16. Grasselli, R. K., et al. Oxidation of Olefins. German
Patent 2,203,710 (to Standard Oil), August 17, 1972.
17. Ohara, T., N. M. Ninomiya, I. Yanaqisawa, I. Wada, and
M. Wada. Process for the Preparation of Acrylic Acid. U.S.
Patent 3,775,474 (to Nippon Shokubai Kagaku Kogyo Co.),
November 27, 1973.
18. Nakatani, H. Toyo's New Acrylate Process. Hydrocarbon
Processing, 48(5):152-154, 1969.
19. Sakuyama, S., T. Ohara, N. Shimizu, and K. Kubota. A New
Oxidation Process for Acrylic Acid from Propylene. Chem-
tech, 3(6):350-355, 1973.
20. Acrylic Acid (SOHIO Process). Hydrocarbon Processing,
52(11):95, 1973.
21. Recovery of Acrylic Acid. British Patent 1,293,848 (to
Toyo Soda Co.), October 25, 1972.
22. Otsuki, S., K, Hori, and I. Miyanohara. Polymerization
Inhibition of Acrylic Acid. U.S. Patent 3,674,651, (to Toyo
Soda Co.), July 4, 1972.
23. Otsuki, S., and I. Miyanohara. Stabilization of Acrylic
Acid or Esters Thereof. U.S. Patent 3,666,794 (to Toyo
Soda Co.), May 30, 1972.
24. Stabilization of a,6-Ethylenic Aldehydes. Netherlands
Patent Application 65,16553 (Shell International Research),
June 23, 1966.
47
-------
25. Preparation of Esters. British Patent 1,185,069 (to British
Titan Products), March 18, 1970.
26. Alkoxy Phenol Stabilizers. Netherlands Patent 134846 (to
ICI), March 15, 1972.
27. Yamagishi, A., et al. Method for Inhibiting the Polymeriza-
tion of Unsaturated Carboxylic Acid Esters. U.S. Patent
3,636,086 (to Sumitomo Chemical), January 18, 1972.
28. Improvements in the Handling of Acrylic Acid. British
Patent 958,226 (to Celanese Corporation), May 21, 1964.
29. Brown, C. J., et al. Distillation of Acrylic Acid. British
Patent 1,265,419 (to BP Chemicals), March 1, 1972.
30. Hexamethylene Tetramine as Stabilizer for (Meth) Aerylate
Esters. French Patent 2,085,773 (to Japanese Geon),
December 31, 1971.
31. Stabilizing Unsaturated Acids. French Patent 2,100,376 (to
Japanese Geon), March 17, 1972.
32. Hartel, H. Polymerization Inhibitors for Monomeric Vinyl
Esters, Acrylic Acid Esters, or Styrene. German Patent
1,233,869 (to Dynamit Nobel), February 7, 1967.
33. Sato, R., et al. 2,6-Di-tert-p-Cresol as Polymerization
Inhibitor for Acrylic Acid Derivatives. German Offen.
Patent 2,112,053 (to Japanese Geon), October 7, 1971.
34. Acrylic Esters. Japanese Patent 42-23404 (to Asahi Chemical
Industry), November 13, 1967.
35. Stabilized Vinyl Compounds. Japanese Patent 43-201 (to Toa
Gosei Chemical Industry), January 6, 1968.
36. Sudo, M., et al. Methyl Acrylate. Japanese Patent 43-10611
(to Japan Synthetic Chemical Industry), May 4, 1968.
37. Sudo, M., et al. Prevention of Polymerization During the
Preparation of Unsaturated Carboxylates. Japanese Patent
43-29926 (to Mitsubishi Rayon), December 23, 1968.
38. Acrylic or Methacrylic Acids. Japanese Patent 44-26285 (to
Mitsui Toatsu Chemicals), November 5, 1969.
39. Polymerization Inhibition of (Meth)Acrylic Acids. Japanese
Patent 45-35285 (to Nippon Kagaku), November 11, 1970.
48
-------
40. Kawamura, Y., et al. Polymerization Inhibitor of Acrylate
or Methacrylate. Japanese Patent 46-30173 (to Nitto
Chemical Industry), September 2, 1971.
41. Unsaturated Acid Distillation. Belgian Patent 778,869 (to
Rohm and Haas), August 2, 1972.
42. Inhibition of Polymerization of Aqueous Acrylic Acid
Solution. Japanese Patent 47-17714 (to Nippon Kayaku),
September 9, 1972.
43. Bailey, H. C. Stabilization of Acrylic Acid. British
Patent 1,127,127 (to BP Chemicals), September 11, 1968.
44. Stabilization of Vinyl Monomer. Japanese Patent 42-1415
(to Toa Gosei Chemical Industry), January 24, 1967.
45. Stabilization of Methyl Methacrylate and Methyl Acrylate.
Japanese Patent 42-7765 (to Toyo Rayon), March 29, 1967.
46. Girvan, I. J. M. Stabilization of Acrylic and Methacrylic
Monomers. British Patent 1,124,836 (to ICI), August 21,
1968.
47. Shima, T., et al. Stabilization of a,3-Unsaturated
Aldehydes. Japanese Patent 46-13009 (to Sumitomo Chemical),
April 3, 1971.
48. Frikken, D. R., K. S. Rosenberg, and D. E. Steinmeyer.
Understanding Vapor-Phase Heat-Transfer Media. Chemical
Engineering, 82(12):86-90, 1975.
49. Conant, A. R., and W. F. Seifert. Dowtherm Heat Transfer
Medium. Chemical Engineering Progress, 59(5):46-49, 1963.
50. Fried, J. R. Heat-Transfer Agents for High-Temperature
Systems. Chemical Engineering, 80 (12):89-98, 1973.
51. Chemical Profile: Acrylates. Chemical Marketing Reporter,
211(17):9, 1977.
52. Ohara, R. Production of Acrylic Ester and Its Economics -
Propylene Oxidation Process. Chemical Economy & Engineering
Review, 4(7):24-29, 1972.
53. TLV® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. 94 pp.
49
-------
54. Sax, N. I. Dangerous Properties of Industrial Materials,
Third Edition. Reinhold Book Corporation, New York, New
York, 1968. 1258 pp.
55. 1972 National Emissions Report; National Emissions Data
System (NEDS) of the Aerometric and Emissions Reporting
System (AEROS). EPA 450/2-74-012, U.S. Environmental Pro-
tection Agency, Research Triangle Park, North Carolina,
June 1974. 434 pp.
56- Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
Public Health Service Publication No. 999-AP-26, U.S.
Department of Health, Education, and Welfare, Cincinnati,
Ohio, May 1970. 84 pp.
57. Eimutis, E, C., and M. G. Konicek. Derivations of Con-
tinuous Functions for-the Lateral and Vertical Atmospheric
Dispersion Coefficients. Atmospheric Environment, 6(11):
859-863, 1972.
58. Japan Catalytic Chemical Industry Will Supply Catalyst
Know-How. Chemical Week, 112 (19):33-34, 1973.
59. Chemical Origins and Markets. Stanford Research Institute,
Menlo Park, California, 1977. 118 pp.
60. Synthetic Organic Chemicals, U.S. Production and Sales.
U.S. International Trade Commission (formerly U.S. Tariff
Commission), Washington, D.C., 1961-1975.
61. Martin, D. O., and J. A. Tikvart. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. Presented at the 61st Annual
Meeting of the Air Pollution Control Association, St. Paul,
Minnesota, June 23-27, 1968. 18 pp.
62. Tadmor, J., and Y. Gur. Analytical Expressions for the
Vertical and Lateral Dispersion Coefficients in Atmospheric
Diffusion. Atmospheric Environment, 3(6):688-689, 1969.
63. Gifford, F. A., Jr. An Outline of Theories of Diffusion in
the Lower Layers of the Atmosphere. In: Meteorology and
Atomic Energy 1968, Chapter 3, D. A. Slade, ed. Publication
No. TID-24190, U.S. Atomic Energy Commission Technical
Information Center, Oak Ridge, Tennessee, July 1968.
p. 113.
50
-------
64. Hydrocarbon Pollutant Systems Study; Volume I, Stationary
Sources, Effects, and Control. APTD-1499 (PB 219 073),
U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, 20 October 1972. 377 pp.
65. Code of Federal Regulations, Title 42 - Public Health,
Chapter IV - Environmental Protection Agency, Part 410 -
National Primary and Secondary Ambient Air Quality
Standards, April 28, 1971. 16 pp.
66. Evaporation Loss from Fixed Roof Tanks. API Bulletin 2518,
American Petroleum Institute, New York, New York, 1962.
38 pp.
67. Use of Variable Vapor Space Systems to Reduce Evaporation
Loss. API Bulletin 2520, American Petroleum Institute,
New York, New York, 1964. 14 pp.
68. Petrochemical Evaporation Loss from Storage Tanks. API
Bulletin 2523, American Petroleum Institute, New York,
New York, 1969. 14 pp.
51
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APPENDIX A
DERIVATION OF SOURCE SEVERITY EQUATIONS
SUMMARY OF SEVERITY EQUATIONS
The severity of pollutants may be calculated using the mass
emission rate, Q, the height of the emissions, H, and the thresh-
old limit value, TLV. The equations summarized in Table A-l are
developed in detail in this appendix.
TABLE A-l. POLLUTANT SEVERITY EQUATIONS
FOR ELEVATED SOURCES
Pollutants _ Severity equation
Particulate S = 7fLQ
H^-
* -
Hydrocarbon S =
Carbon monoxide S =
Other S = 5<5 Q
TLV • H2
DERIVATION OF Y FOR USE WITH U.S. AVERAGE CONDITIONS
max
The most widely accepted formula for predicting downwind ground
level concentrations from a point source is (56):
X =
52
-------
where x = downwind ground level concentration at reference
coordinate x and y with emission height of H, g/m3
Q = mass emission rate, g/s
OTT = 3.14
^y = standard deviation of horizontal dispersion, m
z = standard deviation of vertical dispersion, m
u = wind speed, m/s
y = horizontal distance from centerline of dispersion, m
H = height of emission release, m
x = downwind dispersion distance from source of emission
release, m
xmax is assumed to occur when x is much greater than 0 and when
y equals 0. For a given stability class, standard deviations
of horizontal and vertical dispersion have often been expressed
as a function of downwind distance by power law relationships
as follows (61) :
ay = axb (A-2)
a = cxd + f (A-3)
Z
Values for a, b, c, d, and f are given in Tables A-2 and A-3.
Substituting these general equations into Equation A-l yields :
x = - r—^ - r- expf" -- ^ - (A-4)
L 2(cxd +
Assuming that Xmax occurs at x less than 100 m or the stability
class is C, then f equals 0 and Equation A-4 becomes:
acirux
For convenience , let :
[rfial
|_2c^x'i J
exp (fl-5)
Q j T, -H2
= _~— a"^ R =
acTru
so that Equation A-5 reduces to:
R - .._.. — "R 2C2
(61) Martin, D. O., and J. A. Tikvart. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. Presented at the 61st Annual
Meeting of the Air Pollution Control Association, St. Paul,
Minnesota, June 23-27, 1968. 18 pp.
53
-------
TABLE A-2. VALUES OF a FOR THE
COMPUTATION OF a a (57)
TABLE A-2.
VALUES OF a FOR THE
COMPUTATION OF a a (57)
Stability class
A
B
C
D
E
F
a
0.3658
0.2751
0.2089
0.1471
0.1046
0.0722
TABLE A-3.
For the equation
where x = downwind distance
b = 0.9031 (from
Reference 62)
VALUES OF THE CONSTANTS USED TO
ESTIMATE VERTICAL DISPERSION3 (61)
Usable range, m
>1,000
100 to 1,000
Stability
class Coefficient
A
B
C
D
E
F
A
B
C
D
E
F
C!
0.00024
0.055
0.113
1.26
6.73
18.05
C2
0.0015
0.028
0.113
0.222
0.211
0.086
di
2.094
1.098
0.911
0.516
0.305
0.18
d2
1.941
1.149
0.911
0.725
0.678
0.74
fl
-9.6
2.0
0.0
-13
-34
-48.6
*2
9.27
3.3
0.0
-1.7
-1.3
-0.35
<100
A
B
C
D
E
F
0.192
0.156
0.116
0.079
0.063
0.053
0.936
0.922
0.905
0.881
0.871
0.814
0
0
0
0
0
0
For the equation
az = ex
+ f
(62) Tadmor, J., and Y. Gur. Analytical Expressions for the
Vertical and Lateral Dispersion Coefficients in Atmospheric
Diffusion. Atmospheric Environment, 3(6):688-689, 1969.
54
-------
X = ARx-(bsHa) expl-^l (A-6)
aking the first derivative of Equation A-6
r -2dl/ \ b-d i(
+ exp BRx (- b - djx j (A-7)
and setting this equal to zero (to determine the roots which
give the minimum and maximum conditions of x with respect to x)
yields:
(exp[BRx-2d])[- 2dBRx-2d - b - d] (A-8,
Since we define that x ^ 0 or °° at Xmax, the following expres-
sion must be equal to 0:
- 2dBDx~2d - d - b = 0 (A-9)
K
or
(b + d)x2d = - 2dBR (A-10)
or
- 2dBT
b + d 2c2(b + d)
or
c2(b + d)
or
\c2(b + d)/
Thus Equations A-2 and A-3 become:
a = a /-2-Ji: (A-14)
y \c2(d + b)/
55
-------
= c
The maximum will be determined for U.S. average conditions of
stability. According to Gifford (63), this is when a = az .
Since b = 0.9031, and upon inspection of Table A-2 under U.S.
average conditions, a = oz, it can be seen that
0.881 < d < 0.905 (class C stability3). Thus, it can be assumed
that b is nearly equal to d or:
a =
z
/2
and
(A-17)
Under U.S. average conditions, cr = oz and a =s c if b =* d and
f = 0 (between class C and D, but closer to belonging in class C) .
Then
a = - (A-1
Y /2
Substituting for a and a into Equation C-l and letting y = 0 :
2 Q
=
TruH2
(A-19)
The values given in Table A-3 are mean values for stability
class. Class C stability describes these coefficients and
exponents, only within about a factor of two (64) .
(63) Gifford, F. A., Jr. An Outline of Theories of Diffusion in
the Lower Layers of the Atmosphere. In: Meteorology and
Atomic Energy 1968, Chapter 3, D. A. Slade, ed. Publication
No. TID-24190, U.S. Atomic Energy Commission Technical
Information Center, Oak Ridge, Tennessee, July 1968.
p. 113.
(64) Hydrocarbon Pollutant Systems Study; Volume I, Stationary
Sources, Effects, and Control. APTD-1499 (PB 219 073) ,
U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, 20 October 1972. 377 pp.
56
-------
or
Vax = -Hr (A-20)
ireuH7
For ground level sources (H = 0), Xmax occurs by definition at
the nearest plant boundary or public access. Since this occurs
when y = Of Equation A-l becomes:
For U.S. average conditions, u = 4.47 m/s so that Equation A-20
reduces to:
X - °-0524 Q (A-22)
Amax H2
DEVELOPMENT OF SOURCE SEVERITY EQUATIONS
The general source severity, S, relationship has been defined as
follows :
s = Jjp* (A-23)
where Xmax = time-averaged maximum ground level concentration
F = hazard factor
Noncriteria Emissions
The value of Ymax may be derived from Xmax, an undefined "short-
term" concentration. An approximation for longer term concen-
tration may be made as follows (56) :
For a 24-hr time period,
/t \°-17
Xmax = *max (^) (A-24)
or
/ - \0-17
— _ / 3 mm \ ra-9^\
xmax ~ xmax I 1,440 min 1 (A z*>
= Y (0.35) (A-26)
Amax
57
-------
Since the hazard factor is defined and derived from TLV values
as follows:
, . (TLV) (A-27)
F = (3.33 x 10~3) TLV (A-28)
then the severity factor, S, is defined as:
Xmax (0'35)XTIiax
S = -5^1 = - E!^ - (A-29)
F (3.33 x 10~3) TLV
105 xmax
q - max
b -
If a weekly averaging period is used, then:
- - ( 3 V'17
xmax xmax\10,0807
or
and
F =
F = (2.38 x 10~3)TLV (A-34)
and the severity factor, S, is:
S - *max {0-25)xraax
s - J^L = !^x (A_35)
F (2.38 x 10~3)TLV
or
58
-------
which is entirely consistent, since the TLV is being corrected
for a different exposure period.
Therefore, the severity can be derived from Xmax directly without
regard to averaging time for noncriteria emissions. Thus, com-
bining Equations A-36 and A-22, for elevated sources, gives:
S =
5.5 Q
TLV • H'<
(A-37)
Criteria Emissions
For the criteria pollutants, established standards may be used
as F values in Equation A-23. These are given in Table A-4.
However, Equation A-24 must be used to give the appropriate aver-
aging period. These equations are developed for elevated sources
using Equation A-22.
TABLE A-4.
SUMMARY OF NATIONAL AMBIENT
AIR QUALITY STANDARDS (65)
Pollutant
Particulate
matter
S0x
A
Carbon
monoxide
Nitrogen
dioxide
Photochemical
oxidants
Hydrocarbons
(nonme thane)
Averaging
time
Annual (geometric
mean)
2 4 -hour b
Annual (arith-
metic mean)
2 4 -hour b
3 -hour b
8 -hour b
l-hourb
Annual (arith-
metic mean)
l-hourb
3 -hour
(6 a.m. to 9 a.m.)
Primary
standards
75 yg/m3
260 ijg/m3
80 yg/m3
365 yg/m3
-
10,000 yg/m3
40,000 Mg/m3
100 yg/m3
160 yg/m3
160 yg/m3d
Secondary
standards
60a Hg/m3
160 yg/m3
60 yg/m3
260C yg/m3
1,300 yg/m3
(Same as
primary)
(Same as
primary)
(Same as
primary)
(Same as
primary)
The secondary annual standard (60 yg/m3) is a guide for assess-
ing implementation plans to achieve the 24-hour secondary
standard.
Not to be exceeded more than once per year.
CThe secondary annual standard (260 yg/m3) is a guide for assess-
ing implementation plans to achieve the annual standard.
There is no primary ambient air quality standard for hydro-
carbons. The value of 160 yg/m3 used for hydrocarbons in this
report is an EPA recommended guideline for meeting the primary
ambient air quality standard for oxidants.
(65) Code of Federal Regulations, Title 42 - Public Health,
Chapter IV - Environmental Protection Agency, Part 410 -
National Primary and Secondary Ambient Air Quality
Standards, April 28, 1971. 16 pp.
59
-------
Carbon Monoxide Severity—
The primary standard for CO is reported for a 1-hr averaging time,
Therefore,
t = 60 min
t = 3 min
\ 0. 17
U (A~38)
\ 0.17
_3 (A_39)
ireuHz \60/
2-2 (0.6) (A-40)
(3.14)(2.72)(4.5)H2
xmax
- = 0.12 x 10-2)Q
Amax
Severity, S = (A-43)
r
Setting F equal to the primary standard for CO, i.e., 0.04 g/m3,
yields :
s = Xmax = (3.12 x 10~2)Q (A-44)
F 0.04 H2
or
S = ^I^Q (A_45)
CO H2
Hydrocarbon Severity —
The primary standard for hydrocarbon is reported for a 3-hr
averaging time .
t = 180 min
60
-------
t = 3 min
f 3 V"17
max ~ xmax \180/ (A-46)
" °-5Xmax (A-47)
= CO-5) (0.052) Q (A-48)
H2
For hydrocarbons, F - 1.6 x 10"^ g/m3 (as discussed in
Section 4) , and
S = = - - (A-50)
F 1.6 x IQ-^ H2
or
S = 1^1^
HC H2
Particulate Severity —
The primary standard for particulate is reported for a 24-hr
averaging time.
/ \0. 17
xmax = Xmax \1,4407 (A-52)
= (0.052) Q (0.35) (A-53)
H2
= (0.0182) Q
Amax H2
For particulates, F = 2.6 x ID"4 g/m3, and
0.0182 Q - (A_55)
2.6 x IQ~k H2
61
-------
Sp = - (A_56)
P H2
SOX Severity —
The primary standard for SO is reported for a 24-hr averaging
time. x
X
Amax
= (0-0182) Q (A-57)
H2
The primary standard is 3.65 x 10~4 g/m3,
and
xmax (0.0182)Q
(A-58)
F 3.65 x lO"1* H2
or
Sqo = 52_a (A-59)
b(J TTo
X Hz
N0y Severity —
Since NOx has a primary standard with a 1-yr averaging time, the
^max correction equation cannot be used. As an alternative, the
following equation was selected :
(A-60)
A difficulty arises, however, because a distance x, from emission
point to receptor, is included; hence, the following rationale is
used:
The equation
^
TT6UH2
is valid for neutral conditions or when a == a . This maximum
occurs when
H
and since, under these conditions,
a = ax
z
62
-------
then the distance, x , where the maximum concentration occurs is
luciX
For class C conditions,
a = 0.113
b = 0.911
Simplifying Equation A-60,
rr = 0 11 "i x 0-911
°z U-11J xmax
and
u = 4 . 5 m/s
Letting x = x__w in Equation A-60,
In 3.x
- 4
X =
xmax
_Q_ exJ_ 1 /if! (A-61)
1.911 I 2 Vaz/J
where
1 .098
x = 7.5 H1'098 (A-63)
max
and
4 Q = _ i_Q - (A_64)
x !'911 (7.5 H1-098)1-911
max
Therefore,
X - e,P-
0 = O.llSx0-911 (A-66)
z
63
-------
o = 0.113 (7.5 H1'1)°'
(A-67)
Therefore,
a = 0.71 H
z
- = 0.085 Q
H2.1
H
(A-68)
(A-69)
0.71
0.085 Q
(0.371)
H2.1
- _ 3.15 x IP"2 Q
(A-70)
(A-71)
Since the NO standard is 1.0 x 10~"tf g/m3, the NO severity
equation is: X
NO
(3.15 x 10~2) Q
1 x I0~k H2-1
(A-72)
315 Q
NO
X H
2. 1
(A-73)
64
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APPENDIX B
CALCULATED EMISSION FACTORS FOR ACRYLIC ACID
STORAGE TANKS3
Uncontrolled emission factors for the acrylic acid storage tanks
listed in Table 4 have been determined by calculating the breath-
ing and working losses of stored acrylic acid. These losses
occur due to daily ambient temperature changes and loading proce-
dures. The following equations and calculation procedures were
developed and reported in the referenced API Bulletins (66-68) .
Step 1. Calculate the equivalent gasoline breathing loss:
t
*
1'73 (H'}°<51 (AT}°'5° F C
(H ' Ui) *C
.
Y 1,000 \14.7 - P/
where Ly = equivalent gasoline breathing loss, bbl/yr
P = vapor pressure of material stored at bulk
temperature, psia
D = tank diameter, ft
H" = tank outage, ft
AT = average ambient temperature change, °F
Fp = paint factor
C = diameter factor
Nonmetric units are used in this appendix because they corres-
pond to those used in computer calculations.
(66) Evaporation Loss from Fixed Roof Tanks. API Bulletin 2518,
American Petroleum Institute, New York, New York, 1962.
38 pp.
(67) Use of Variable Vapor Space Systems to Reduce Evaporation
Loss. API Bulletin 2520, American Petroleum Institute,
New York, New York, 1964. 14 pp.
(68) Petrochemical Evaporation Loss from Storage Tanks. API
Bulletin 2523, American Petroleum Institute, New York,
New York, 1969. 14 pp.
65
-------
Step 2. Calculate the equivalent gasoline working loss:
Fg = 107000 PWKT (B'2)
where F = equivalent gasoline working loss, bbl/yr
V = tank capacity, bbl
N = number of turnovers per year
K = turnover factor = 1.0 for N - 36
_ 180 + N
6N
Step 3. Compute total equivalent gasoline loss, L :
L = L + F (B-3)
g y g
Step 4. Compute petrochemical losses:
L = 0.08(|)Lg (B-4)
where L = total petrochemical loss, bbl/yr
M = molecular weight of chemical stored
W = liquid density of chemical stored, Ib/gal
Step 5. Calculate emission factor in metric units:
L! = L(42)(W) (B-5)
Li
E' = ^— (B-6)
Cap
E = |^- (B-7)
where LJ = petrochemical loss, Ib/yr
Cap = production capacity, ton/yr
E1 = emission factor, Ib/ton
E = emission factor, g/kg
The yearly average bulk temperature of acrylic acid was given as
70°F. Acrylic acid vapor pressure at bulk temperature was calcu-
lated at 2.3 psia. Tank dimensions and number of turnovers per
year were obtained through communications with industry repre-
sentatives (see Table 4). The average ambient temperature change,
AT, was estimated at 19°F, which is the national average value.
Diameter factors, C, were determined from a graph given in Ref-
erence 66; they are between 0.6 and 1.0. Paint factors, F , were
determined by the outside colors of the tanks.
66
-------
Table B-l lists the input data for each storage tank and its
calculated emission factor. The total emission factor for all
8 tanks is 1.07 g/kg. These emission factors represent uncon-
trolled emissions. As noted in the main body of the report,
these emissions can be controlled by venting to the incinerator.
In addition, the emission factors correspond to a plant operating
at 100% of rated capacity. Emission factors for tank losses are
non-linear functions of the percent of capacity at which the plant
is operated.
TABLE B-l.
INPUT DATA AND EMISSION FACTORS FOR
FIXED-ROOF TANKS STORING ACRYLIC ACID
Tank number
Input data
Annual production capacity, tons/yr
Average ambient temperature, °F
Average ambient temperature change, °F
Molecular weight of stored material, Ib/lb-mole
Liquid density, Ib/gal
True vapor pressure at bulk temperature, psia
Bulk temperature, °F
Tank diameter, ft
Tank height, ft
Paint factor
Diameter factor
Turnover factor
Number of turnovers per year
Tank capacity, bbl
12
95,000
64
19
72.06
8.76
2.3
70
12
24
1.3
0.6
0.3
230
481
13-14
95,000
64
19
72.06
8.76
2.3
70
16
38
1.3
0.78
0.95
40
1,362
15
95,000
64
19
72.06
8.76
2.3
70
20
32
1.3
0.9
1.0
30
1,786
16-17
95,000
64
19
72.06
8.76
2.3
70
25
32
1.3
0.97
0.95
40
2,786
18-19
95,000
64
19
72.06
8.76
2.3
70
36
32
1.3
1.0
1.0
10
5,786
Emission factor, g/kg
0.0415 0.0788 0.0989 0.1751 0.2098
Tanks are numbered according to those in Table 4.
67
-------
GLOSSARY
acrolein: Simple unsaturated aliphatic aldehyde which is a
chemical intermediate in the production of acrylic acid.
acrylic esters: Monomer at high molecular weight used in the
production of acrylic fibers, emulsions, and resins.
affected population: Number of nonplant persons exposed to con-
centrations of airborne materials which are present in
concentrations greater than a determined hazard potential
factor.
criteria pollutant: Emission species for which ambient air
quality standards have been established.
emission factor: Weight of material emitted to the atmosphere
per unit of acrylic acid produced; e.g., g material/kg
product.
heat-transfer fluid: High-boiling eutectic capable of transfer-
ring heat energy over distance.
nitrogen blanket: Layer of nitrogen gas under pressure which
lies on the surface of stored volatile organics; designed
to control hydrocarbon emissions from storage tanks.
noncriteria pollutant: Emission species for which no ambient air
quality standards have been established.
polymerization inhibitor: Substance which prevents the polymeri-
zation of acrylic acid during its recovery and purification.
propylene: Unsaturated hydrocarbon and homolog of ethylene C^E&.
source severity: Ratio of the maximum mean ground level concen-
tration of emitted species to the hazard factor for the
species.
stability class: Factor which characterizes the atmosphere and
is determined from cloud cover, wind speed, and time of day.
68
-------
TECHNICAL REPORT DATA
(Fleese read instructions on the rrvtnt before completing)
. REPORT NO.
EPA-600/2-78-004W
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Source Assessment:
Acrylic Acid Manufacture
State of the Art
6 REPORT DATE
Aucrust 1978
issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
R. W. Serth, D. R. Tierney and T. W. Hughes
8. PERFORMING ORGANIZATION REPORT NO.
MRC-DA-784
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
10. PROGRAM ELEMENT NO.
1AB604
11. CbNTRACT/GRANT NO.
68-02-1874
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laborator
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE Of REPORT AND PERIOD COVERED
TASK FINAL'] 2/75-1 2/77
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
IERL-Ci project leader for this report is R. J. Turner, 513-684-4481
16. ABSTRACT
This report summarizes data on air emissions from the production of
acrylic acid. Hydrocarbons, carbon monoxide and nitrogen oxide are
emitted from various operations. Hydrocarbon emissions consist of
acetaldehyde, acetic acid, acetone acrolein, acrylic acid, benzene,
phenol, propane, propylene and other materials. To assess the en-
vironmental impact of this industry, source severity was defined as
the ratio of the time-averaged maximum ground level concentration
of a pollutant from a representative plant to the ambient air qual-
ity standard (for criteria pollutants) or to a reduced threshold
limit value (for noncriteria pollutants). Source severities were
not greater than 1.0 for any criteria or noncriteria pollutant.
Emissions from acrylic acid plants are not expected to increase in
the future as plants are installing incinerators on new plants to
control emissions.
u.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution
Assessments
Acrylic Acid
b.lDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Source Assessment
COS ATI Field/Group
68D
18. DISTRIBUTION STATEMEN1
Release to Public
19. SECURITY CLASS (Tht) Report)
Unclassified
U. NO. OF PAGES
83
20 SECURITY CLASS (Thlspagt)
Unclassified
22. PRICE
EPA Form 2220-1 O-73)
69
a U.S. GOVERNMENT PRINTING OFFICE; 1978— 657-060/1476
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