United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S2-86/079 Jan. 1987
Project Summary
Destruction of Chlorinated
Hydrocarbons by Catalytic
Oxidation
M. A. Palazzolo, C. L Jamgochian, J. I. Stienmetz, and D. L. Lewis
j...
This report gives results of a study
determine the effectiveness of catalyti
oxidation for destroying vapor-phase chic
rinated hydrocarbons. The study was cor
ducted on two pilot-scale catalytic incinei
ators: one employed a metal oxide catalys t
in a fluidized-bed configuration; and th j
other, a fixed-bed proprietary catalyst
supplemented with ultraviolet (UV) light
and ozone injection. Both systems wers
tested under a variety of temperatures an
space velocities. The test vapor streams
consisted of low concentrations (3 to 20 )
ppmv) of mixtures of organic compound:
• and included three streams which repre
sented emissions from air strippers use
to treat contaminated groundwater at U.S
Air Force bases. Study results showed the t
the fluidized-bed catalytic incinerator was
capable of achieving total organic destruc
tion efficiencies of greater than 98%. Th 3
UV/ozone catalytic system failed to a-
chieve high destruction efficiencies: with
ozone injection, total destruction was
75%; and without ozone, the maximum
destruction efficiency was 64%.
This Project Summary was developed
by EPA's Air and Energy Engineering Re-
search Laboratory, Research Triangle Park,
NC, to announce key findings of the re-
search project that is fully documented in
a separate report of the same title (see
Project Report ordering information at
back).
Introduction
A test program has been completed for
the EPA and the Air Force to investigate,
on an experimental scale, the effective-
ness of catalytic oxidation as a means of
destroying specific volatile organic com-
pounds (VOCs) and hazardous/toxic air
pollutants (HAPs). Two pilot-scale cata-
lytic oxidation units and a test mixture va-
por generation system were used for the
testing. Objectives of the study were
broad and two-fold: (1) to generate addi-
tional publicly available data on the perfor-
mance of commercial catalytic oxidizers,
with particular emphasis on chlorinated
hydrocarbons; and (2) to investigate the
performance of commercially available
catalytic oxidation systems that may be
suitable for the treatment of gas streams
from air strippers used in groundwater
cleanup. Three of the four VOC/HAP mix-
tures tested were representative of actual
off-gases from such air strippers.
Test System
Parametric testing of two skid-mounted
catalytic oxidation systems was perform-
ed to assess the effects of operating and
design parameters on destruction effi-
ciency. The oxidation systems tested were
a 500 scfm* fluidized-bed catalytic incin-
erator leased from ARI International and
a 20 scfm ultraviolet (UV)/catalytic oxi-
dizer leased from Ultrox International. A
test compound vapor generation system,
which included a pump, a glass mixing
chamber, and motor-driven syringes, was
used to produce spiked air streams with
the desired concentration of organic
vapors. Figures 1 and 2 are diagrams of
the fluidized-bed and UV catalytic sys-
tems, respectively.
Experimental Design
Before the tests, major vendors of cata-
lytic oxidation systems were contacted to:
(1) investigate the availability of catalysts
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Exhaust
to Stack
- Catalyst Bed
- Alumina Balls
Combustion Air
Natural Gas
Ambient
Air
Ambient
Air
VOC/HAP-Spiked
Air Stream
Tube
Furnace
Mixing Chamber
Pump
Figure 1. Fluidized-bed catalytic test system.
Motor-Driven Syringe
Ambient
Heated
Head Pump
Heat-Traced
Tube
Ambient
Dilution Air
Pump
Heat-Traced
Stainless Steel
Tubing
Rootsmeter
i'l'l'l'l^-T-^
—.. Vent
Dry Gas
Meter
Injection Mixing Chamber
Ports
UV/Catalytic
Reactor
Figure 2. UV/catalytic test system.
and catalytic systems suitable for destroy-
ing chlorinated hydrocarbons, and (2) iden-
tify vendors with existing laboratory- or
pilot-scale units that could be tested under
this program. This effort identified only the
two systems tested.
Overflow
Exhaust
Vent
Major operating parameters that were
varied during the fluidized-bed incinerator
testing included VOC/HAP mixture, cata-
lyst inlet temperature, space velocity, and
inlet concentration. Testing was generally
conducted to characterize destruction
across the gas-fired preheater and th
catalyst bed as a "system." Howeve
heater and catalyst destruction efficier
cies were also determined separately 6
most test conditions.
Operating parameters that were varie
during the UV/catalytic oxidizer testing ir
eluded space velocity, inlet concentratior
UV intensity, humidity, and ozone additior
Components and target concentration
for the test mixtures are shown in Tabl
1. All four mixtures shown in Table 1 wer
tested with the fluidized-bed system, bi
only one mixture was tested with the U\
catalytic oxidizer. The ranges of operatin
conditions tested for the two catalyti
systems are summarized in Table 2. A
shown in Table 2, the fluidized-bed syster
was tested at two space velocities for ca
alyst inlet temperatures ranging from 65
to 950 °F. Two inlet concentrations fc
Mixture 4 were also tested. The UV/cat;
lytic oxidizer was tested at three spac
velocities, two humidities, and with/witf
out ozone addition. Two inlet concentn
tions for Mixture 1 were also tested.
Fluidized-Bed Incinerator Results
Results for the fluidized-bed incinerate
showed average system destruction eff
ciencies for total VOCs in the 97 to 99°,
range for all four test mixtures. Catalys
inlet temperature showed a strong effec
on destruction efficiency, while mixtur
composition, air-to-gas (fuel) ratio, spac
velocity, and inlet concentration a
showed marginal or statistically insign.
icant effects.
The effect of catalyst inlet temperatur
on mixture system destruction efficiencie
is shown in Figure 3 for a space velocil
of 10,500 hr~1. Comparison of destru<
tion efficiencies for the different mixture
shows that the highest efficiencies wei
observed for Mixture 2 and the lowest, f(
Mixture 4. The low destruction efficienc
of Mixture 4 is attributed to the presenc
of tetrachloroethylene, which showed th
lowest destruction efficiency of the 1
compounds tested.
The effect of catalyst inlet temperatui
on component destruction efficiency we
similar for all test compounds excei
trichloroethylene and benzene in Mixtui
2. These compounds (in particular bei
zene) showed a very sharp increase
destruction between 650 and 800 °F. Or
possible explanation for the observed e
'Readers more familiar with the metric system m
use the conversion factors at the back of tl
Summary.
-------
tble 1. Mixture Compositions and Target Concentrations
for Catalytic Oxidation Tests
Mixture Concentration
Designation Level Mixture Compounds
1 Baseline Trichloroethylene
1,2 dichloroethylene
1 Low Trichloroethylene
1,2 dichloroethylene
2 Baseline Trichloroethylene
Benzene
Ethylbenzene
Pentane
Cyclohexane
3 Baseline Vinyl Chloride
Trichloroethylene
4 Baseline 1,2 dichloroethane
Trichloroethylene.
1, 1, 2- trichloroethane
Tetrachloroethylene
Target Inlet
Concentration
ppmv8
6.3
8.5
14.8
1.9
1.0
2.9
2.7
1.5
5.6
11.5
14.1
35.4
7.5
1.8
9.3
10
10
10
10
ypmv = parts per million by volume as compound.
40
4 High 1,2 dichloroethane
Trichloroethylene
1,1,2-trichloroethane
Tetrachloroethylene
50
50
50
50
200
rable 2. Summary of Operating Conditions Tested
Catalytic System
r/uidized-Bed
'ncinerator
Test Parameter
VOC/HAP Mixture
Conditions
Or Values Tested
Mixtures 1, 2, 3, 4
UV/Oxidizer
Space Velocity
Operating Temperature
(Catalyst Inlet)
Inlet Concentration
VOC/HAP Mixture
Space Velocity
Inlet Concentration
Humidity
Ozone
UV Intensity
7,000 and 10,500, hr'1
650 to 950°F
Baseline and High3
Mixture 1
200 to 3000 hr'1
(1 to 15 scfm)
Baseline and Low3
Ambient
150% Ambient
Without Ozone
With Ozone
UV Lamps On
UV Lamps Off
aMixtures and concentrations are summarized in Table 1.
feet is the low concentration of benzene
and trichloroethylene in Mixture 2 relative
to the other three compounds.
Destruction efficiency across the gas-
fired preheater generally ranged from 15
to 55% for Mixtures 1, 3, and 4, which
contained only chlorinated hydrocarbons.
Heater destruction efficiencies for Mixture
2 were slightly higher (40 to 60%).
Other results from the fluidized-bed
incinerator testing included:
— Low concentrations of several chlo-
rinated products of incomplete oxi-
dation were identified by mass spec-
trometry.
— Incinerator outlet CO concentrations
were less than 100 ppmv for most
test conditions.
— No statistically significant effect
was found for space velocity on de-
struction efficiency (although an ap-
parent trend is seen when compar-
ing mean values).
— Inlet concentration had no effect on
Mixture 4 destruction efficiency over
the range tested.
— Method 18 and the Tenax-GC sam-
pling method destruction efficien-
cies showed good agreement for all
species and mixtures, except ben-
zene in Mixture 2.
— Maximum theoretical HCI emissions
from Mixtures 1, 2, and 3 were esti-
mated to range from 0.06 to 0.3
Ib/hr (6.3 to 28 ppmv) for a 1,000
scfm inlet gas stream.
UV/Oxidizer Results
Test results for the UV/catalytic system
without ozone showed total VOC destruc-
tion efficiencies ranging from 16 to 67%.
The single most important parameter af-
fecting destruction efficiency was space
velocity, and the highest efficiencies were
observed at a space velocity of 200 hr~1
(or a residence time of 18 seconds).
With ozone addition, complete oxidation
of the test mixture components was
achieved, but high concentrations of
several unidentified reaction products
were observed. Two of these products
were identified by mass spectrometry as
methyl formate and methyl acetate.
Conclusions
The fluidized-bed incinerator testing ver-
ified that overall destruction efficiencies
of total VOCs in the 97 to 98% range are
achievable with catalytic incineration for
chlorinated hydrocarbon mixtures. Results
from this testing also indicate that cata-
lytic incineration may be a viable option
for the control of VOC/HAP emissions
from groundwater air strippers.
-------
100
.o
fed
u
Q
E
90
80-
70
O Mixture 1
Q Mixture 2
A Mixture 3
0 Mixture 4
Total Inlet
VOC, ppm
14,8
35.4
9.3
40
700 800 900
Catalyst Inlet Temperature, °F
1000
The UV/catalytic oxidizer testing show
ed that unreasonably long gas residenc
times are required to achieve acceptabl
destruction without ozone addition an
that high concentrations of reaction prc
ducts are observed with ozone addition fc
this system. At this time, the UV/catalyti
oxidizer would not be considered appropr
ate for controlling VOC/HAP emissions,
Conversion Factors
Readers more familiar with the metri
system may use the following factors t
convert the nonmetric units used in thi
Summary.
Nonmetric Times
Yields Metri
cfm
°F
Ib
1.70
5/9(°F-32)
0.454
m3/hr
°C
kg
Figure 3.
Fluidized-bed catalytic system destruction efficiencies (total organics) for four test
mixtures.
M. A. Palazzolo, C. L Jamgochian, J. I. Steinmetz, andD. L Lewis are with Radian
Corporation, Research Triangle Park, NC 27709.
Bruce A. Tichenor is the EPA Project Officer (see below).
The complete report, entitled "Destruction of Chlorinated Hydrocarbons by
Catalytic Oxidation," (Order No. PB 87-101 234/AS; Cost: $16.95, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 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
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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