United States
                    Environmental Protection
                    Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
                    Research and Development
EPA/600/S2-85/041 July 1985
v>EPA         Project  Summary

                    Parametric   Evaluation  of
                    VOC/HAP  Destruction  Via
                    Catalytic  Incineration
                    M. A. Palazzolo, J. I. Steinmetz, D. L. Lewis, and J. F. Beltz
                      A pilot-scale catalytic incineration
                    unit/solvent generation system was
                    used to investigate the effectiveness of
                    catalytic incineration as a  way to de-
                    stroy  volatile  organic compounds
                    (VOCs) and hazardous/toxic air pollu-
                    tants (HAPs).  The objectives  of the
                    study  were to: (1)  investigate  the
                    effects of operating and design varia-
                    bles on the destruction efficiency of
                    VOC/HAP mixtures, and (2) evaluate
                    destruction  efficiencies for specific
                    compounds in  different  chemical
                    classes. The study results verified that
                    the  following  factors affect catalyst
                    performance: inlet temperature, space
                    velocity, superficial gas velocity, cata-
                    lyst geometry, compound  type, com-
                    pound inlet concentration, and mixture
                    composition.  Tests showed that
                    destruction efficiencies exceeding 98
                    percent  were  possible  (given suffi-
                    ciently  high inlet  temperatures/low
                    space velocities) for the following com-
                    pounds/compound classes: alcohols,
                    acetates,  ketones, cellosolves/diox-
                    ane. aldehydes, aromatics, and ethyl-
                    ene/ethylene   oxide.  Destruction
                    efficiencies of at least 97 percent were
                    achieved for acrylonitrile and cresol.
                    Chlorinated  hydrocarbons  were  not
                    effectively destroyed with the type of
                    catalyst used in this study.
                      This Project Summary was  devel-
                    oped by EPA's Air and Energy Engi-
                    neering Research Laboratory. Research
                    Triangle Park,  NC, to announce  key
                    findings of the research project that is
                    fully documented in a separate report of
                    the same title (see Project Report order-
                    ing information at back).
Introduction

  A test program has been completed to
investigate on an experimental scale the
effectiveness of catalytic incineration as
a way to  destroy volatile organic com-
pounds (VOCs) and hazardous/toxic air
pollutants (HAPs). A pilot-scale catalytic
incineration unit and a solvent vapor gen-
eration system were used for the testing.
Prior to the completion of  this study,
limited data  were  publicly available on
the performance of catalytic incinerators
for a large number of compounds over a
wide range of operating conditions. Thus,
objectives of this study were to (1) inves-
tigate the effects of key incinerator oper-
ating and design parameters on mixture
destruction efficiency, and (2) measure
component specific destruction efficien-
cies for compounds in different chemical
classes.
Test System

  The effects of key operating and design
parameters on the destruction efficiency
of a skid-mounted catalytic  incinerator
were investigated using a solvent vapor
generation system. The vapor generation
system, consisting of a pump, dry gas
meter,  tube  furnace,  glass mixing
chamber,  and  motor-driven syringes,
was used to produce a spiked air stream
with  the   desired  concentrations  of
organic vapors. The skid-mounted unit,
leased from Englehard  Industries, was
equipped with a blower, preheater, mass
flowmeter, catalytic reactor, and temper-
ature controls.  The design gas flowrate

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                      Exhaust

                       r
              Incinerator

Catalyst Electric Heater
                           ~]
 Air In
   Rotary Vane
                                                                          Vent
                        Dry Gas
                                Tube Furnace     Mixing Chamber
     Pump     Activated  Meter
               Carbon
Figure 1.    Incinerator and solvent vapor generation system.
for the catalytic test unit was 275 cfh (4.6
scfm).* Figure 1 is a schematic of the test
system.

Experimental  Design
  In designing the experimental  pro-
gram, conditions were selected to (1) pro-
vide data on a large number  of solvent
types, (2) give an indication of the operat-
ing conditions required for destruction
efficiencies near 98 or 99 percent, and (3)
represent operating conditions typically
used in industrial  applications. The major
operating parameters that were varied
during the testing included: catalyst inlet
temperature, compound concentration,
space velocity, compound type, catalyst
geometry, and catalyst volume. Much of
the testing was conducted to character-
ize compound destruction across the pre-
heater and catalyst bed as a  "system."
However, heater and catalyst destruction
efficiencies were also measured separ-
ately at a number of conditions.
  Most of the test work involved the mea-
surement of destruction efficiencies for
low concentrations of VOC/HAP mix-
tures in air. A short series of tests was
also conducted with a low oxygen gas
stream, intended  to simulate the off-gas
from an  ethylene oxide production pro-
cess. Components of the VOC/HAP mix-
tures and compositions of the simulated
ethylene  oxide off-gases  are  shown in
Tables 1  and  2, respectively. For  the
VOC/HAP mixtures, total system inlet
concentrations were  typically  main-
tained near  1200  ppm  carbon  (by
volume).  Mixtures were generally pre-
pared to  provide equal amounts of each
component on a per carbon or ppm car-

*1 ft3 = 28.3 L.
bon (by volume) basis. At all test condi-
tions,  total  mixture  destruction
efficiencies  were  measured with  EPA
Method  25A, and component  specific
efficiencies  were  determined by  EPA
Method 18.
  The  ranges of  incinerator  operating
conditions tested during this  study are
summarized  in  Table  3.  As shown  in
Table 3, space velocities, based  on  total
catalyst volume and standard gas  flow
rates, were varied from 15,000 to 80,000
hr°  with catalyst inlet  temperatures
ranging  from  500  to  800 F.*  Two
volumes of two different catalyst types
were tested. Both catalyst types  had the
same precious metals formulation. How-
ever, the ceramic honeycomb substrates
had different cell sizes and, hence, differ-
ent catalyst surface areas.
*5/9(°F-32) =
Table 1.  Lists of Components in Multi-
         component VOC/HAP Mixtures

     Mixture 1 - Control Mixture
        Isopropanol
        Methyl ethyl ketone
        Ethyl acetate
        Benzene
        n-Hexane
     Mixture 1A - Hexane Substitution
        Isopropanol
        Methyl ethyl ketone
        Ethyl acetate
        Benzene
        Cyclohexane
     Mixture IB - Hexane Substitution
        Isopropanol
        Methyl ethyl ketone
        Ethyl acetate
        Benzene
        Iso-octane
     Mixture 1C - Hexane Substitution
        Isopropanol
        Methyl ethyl ketone
        Ethyl acetate
        Benzene
        n-Octane
     Mixture 2 - Industrial Mixture
        Methyl ethyl ketone
        Toluene
     Mixture 3 - Alcohols/Acetates
        Methanol
        Ethanol
        Isopropanol
        n-Butanol
        Ethyl acetate
        n-Propyl acetate
        Isobutyl acetate
     Mixture 4 - Ketones/Miscellaneous
               Oxygenated Compounds
        Acetone
        Methyl ethyl ketone
        Methyl isobutyl ketone
        Cyclohexane
        Ethyl cellosolve
        Butyl cellosolve
        Dioxane
     Mixture 5 - Aldehydes
        Propionaldehyde
        Isobutyl aldehyde
        Isovaleraldehyde
        n-Butyl aldehyde
        n-Valeraldehyde
     Mixture 6 - Alkanes/Aromatics
        n-Hexane
        n-Octane
        n-Decane
        Benzene
        Toluene
        m-Xylene
        Isopropyl benzene
     Mixture 7 - Non-Chlorinated HAPs
        m-Cresol
        Acrylonitrile
     Mixture 8 - Chlorinated HAPs
        Methylene chloride
        Carbon tetrachloride
        Ethylene dichloride
        Trichloroethylene
        Tetrachloroethylene
        1,1 -Dichloroethane
        1,1,2-Trichloroethane
Test Results
  Results from the pilot-scale catalytic
incineration  testing  identified  and/or
verified the effects of a number of operat-
ing and design parameters on catalytic
incinerator performance.  Parameters
found  to  have the  greatest  effect on
destruction  included  catalyst  inlet
temperature, space velocity, compound
type,  catalyst  geometry,  and catalyst
volume.  Other  parameters  generally
showing a lesser effect  included inlet
concentration and mixture composition.

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Table 2.   Components and Concentrations in the Ethylene Oxide Off-Gas

  Test Parameter                              Conditions or Values Tested
Stream Composition 1
(percent by volume)




Stream Composition II
(percent by volume)




Ethylene
Ethane
Ethylene oxide
Nitrogen
Carbon dioxide
Oxygen
Ethylene
Ethane
Ethylene oxide
Nitrogen
Carbon dioxide
Oxygen
0.43%
0.09%
0.01%
86.0%
12.0%
1.5%
0.64%
0.09%
0.01%
85.3%
11.5%
2.5%
Table 3.   Ranges of Operating Conditions Tested
Catalyst
Geometry/
Volume"
A/0.006 ft3
B/ 0.006 ft3
A/0.012 ft3
A/0.012 ft*
B/ 0.01 2 ft3
Mixture(s)
Tested
1 through 8
plus pure
compounds11
1,6
1,2,4,6
Ethylene
Oxide
Ethylene
Oxide
Range of
Space
Velocity
hr~'
20,000 to
80,000
30,000 and
50,000
15,000 to
50,000
30,000 and
50,000
30,000 and
50,000
Inlet
Concentrations
ppmCc
1.200/6.000
10,000
1,200
1.200
/,//d
/"
Catalyst Inlet
Temperatures
°F
500 to 800
600 to 800
600 to 800
500 and 600
500 and 600
  Catalyst A had a catalyst surface area of 270 ft2/ft31 and Catalyst B had an area of 660 ft2/ft3.
  Sixteen single components tested with this catalyst.
  ppmC = parts per million by volume as carbon.
  Compositions shown in Table 2.
  ft2 = 0.0929m2
The  test results  provided  data  on: (1)
potential partial oxidation products, (2)
carbon monoxide emissions, and (3) cata-
lyst temperature rise relationships. The
capability of  catalytic  incineration  to
achieve destruction efficiencies in the 98
to 99 percent range was also verified for
compounds  in seven different chemical
classes.
  Multi-component mixture effects on
compound specific destruction efficien-
cies  were evaluated by comparing pure
compound destruction efficiencies with
efficiencies of these compounds as com-
ponents of the VOC test mixtures. In addi-
tion, destruction  efficiencies  for
compounds tested in more than one mix-
ture  were compared.  A  mixture  effect
was  found on pure compound destruc-
tion efficiencies for 6 of 13 compounds.
In most cases, these compounds showed
higher destruction efficiencies as mix-
ture components  than as  pure com-
pounds.  However, two linear alkanes,
n-hexane  and  n-octane,  showed
decreased destruction as components of
one mixture.
  An effect  of mixture composition was
also found for two of five compounds
tested  in more than one mixture. This
effect appeared to be greatest at lower
catalyst inlet temperatures.
  The effects of catalyst inlet tempera-
ture and space velocity on system de-
struction  efficiency   are  shown  for
Mixture 1 in Figure 2. The trends shown
in Figure 2 of increasing destruction with
increasing  inlet  temperature  and
decreasing space velocity are typical of
those observed for the other mixtures.
System destruction efficiencies for Mix-
ture 3 (alcohols and acetates) showed a
particularly strong dependence on cata-
lyst inlet temperature at a space velocity-
of  50,000  hr"1.  In addition,  system
destruction  efficiencies for Mixtures 3
and 6 (alkanes and aromatics) showed a
strong dependence on space velocity.
  Test Mixture 5, which consisted of dif-
ferent  aldehyde  compounds,  generally
showed the highest system destruction
efficiencies of the mixtures tested. Mix-
ture 8, which contained  seven chlori-
nated hydrocarbons, showed by far the
lowest destruction. Except for Mixture 8,
all mixtures showed system destruction
efficiencies ranging  from  85 to 99 per-
cent for the conditions tested in this
study. Mixture 8 destruction efficiencies
ranged from 0.0 to 80 percent.
  The  preheater on the test unit con-
sisted of a pipe or tube wrapped with a
high temperature electrical  resistance
heater element.  At low space velocities
and/or high inlet temperatures with the
small catalyst volumes, heater (thermal)
destruction efficiencies were as high as
80 to 90 percent for some mixtures. With
the larger catalyst volume, gas flow rates
through the system  were doubled at a
given space velocity and heater destruc-
tion decreased to between 10and 76 per-
cent. The degree to which the heater
destruction efficiencies observed on the
test unit may represent destruction in the
natural gas burner  zones of full-scale
incinerators  is  not  known. However,
burner designs that  provide direct con-
tact of the waste gas with the flame are
expected to provide an opportunity for a
significant  amount  of compound
destruction.
  At a  given space velocity,  catalyst
destruction efficiencies for the mixtures
were found to be higher for the larger
catalyst volume. The higher destruction
for the large volume results from a higher
gas velocity through the catalyst cells,
which  apparently   improved  mass
transfer and increased the overall  reac-
tion rate. With the larger catalyst volume,
catalyst destruction  efficiencies of  98
percent or higher were obtained for Mix-
tures 1, 3, 4, and 6.
  The effect of catalyst inlet temperature
and  space  velocity  on  component
destruction efficiencies varied consider-
ably for the different compounds. Com-
pounds of the same chemical class often
showed similar destruction efficiencies
and trends with inlet temperature.
  Other results from the catalytic incin-
eration testing included:
  - Tests with the chlorinated hydrocar-
   bon mixture were found to have par-
   tially deactivated  the catalyst.

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- Higher destruction efficiencies were
  observed for the catalyst type with
  the higher surface area (catalyst B),
  as expected.
- Inlet  concentration  was found  to
  slightly  affect  destruction,  with
  higher  efficiencies  at   higher
  concentrations.
- Tests with the  simulated ethylene
  oxide off-gas showed VOC destruc-
  tion efficiencies  in excess of 99 per-
  cent at all conditions tested.
- The pilot-scale efficiencies for Mix-
  ture 2 agreed well with those for a
  full-scale unit treating this same mix-
  ture in exhaust  gas from a  foil coil
  coating line.
- Mass spectroscopy analysis identi-
  fied partial oxidation products from
  the catalytic combustion test unit.
- Carbon monoxide emissions  from
  catalytic combustion were found to
  be less than 5 ppmv for most test
  conditions.
- Catalyst bed temperature rise  was
  found to be  directly related to the
  mass of solvent destroyed in the cata-
  lyst bed.
- Method 25A and Method 18  mixture
  destruction efficiencies were in very
  good agreement, with Method  25A
  efficiencies being 2.4 percent lower
  on average for the entire test effort.

Conclusions
  Results from this study identified or
verified that the following factors affect
the performance of catalytic incinerators:
    - catalyst inlet temperature;
    - space velocity;
    - superficial  gas  velocity (at  the
      catalyst inlet);
    - catalyst geometry;
    - compound type;
    - inlet VOC concentration; and
    - mixture composition.
  In addition, the testing  verified  that
destruction efficiencies in the 98 to 99
percent range are  achievable with cata-
lytic incineration for the following com-
pounds or classes  at sufficiently  low
space  velocities  and/or  high enough
catalyst inlet temperatures:
    - alcohols;
    - acetates;
    - ketones;
    - cellosolve compounds/dioxane;
    - aldehydes;
    - aromatics; and
    - ethylene/ethylene oxide.
Destruction efficiencies  of at least 97
percent are also achievable for acryloni-
trile and cresol, while chlorinated hydro-
carbons  appear unsuitable for  control
     700 _
 •a   90
      80
 CO
      70
                          /
                 L
                           ©
                                         O   80.000 hr'1

                                         A   50,000 hr''

                                         [•]   30,000 hr~1

                                         (•}   20,000 /ir'1

                                        Hi  Shaded - Method 25A

                                        I   I  Open-Method 18
Ht
                 500
                       600            700

                       Catalyst Inlet Temperature, °F
                                                              800
                                                                            900
Figure 2.
  Mixture 1  system destruction efficiency vs. inlet temperature for small volume
  catalyst A.
with the type of catalyst tested in this
study. Other catalyst formulations might
be more favorable for destroying chlori-
nated hydrocarbons.
  M. A.  Palazzolo, J. I. Steinmetz, D. L. Lewis, and J. F. Beltz are with Radian
     Corporation, Research Triangle Park, NC 27709.
  Bruce A. Tichenor is the EPA Project Officer (see below).
  The complete report, entitled "Parametric Evaluation of VOC/HAP Destruction
     Via  Catalytic Incineration," (Order No. PB 85-191  187/AS; Cost: $25.00,
     subject to change) will be available only from:
           National Technical Information Service
           5285 Port Royal Road
           Springfield, V'A 22161
           Telephone: 703-487-4650
  The EPA Project Officer can be contacted at:
           Air and Energy Engineering Research Laboratory
           U.S. Environmental Protection Agency
           Research Triangle Park, NC 27711
                                                                           U. S. GOVERNMENT PRINTING OFFICE: 1985/559-111/20613

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Information
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EPA/600/S2-85/041

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