EPA/AA/CTAB/88-08
Technical Report
Evaluation of a Resistively Heated
Metal Monolith Catalytic Converter
On An Ml00 Neat Methanol-Fueled Vehicle
by
David M. Blair and
Gregory K. Piotrowski
August 1988
NOTICE
Technical Reports do not necessarily represent final EPA
decisions or positions. They are intended to present technical
analysis of issues using data which are currently available.
The purpose in the release of such reports is to facilitate the
exchange of technical information and to inform the public of
technical developments which may form the basis for a final EPA
decision, position or regulatory action.
U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Mobile Sources
Emission Control Technology Division
Control Technology and Applications Branch
2565 Plymouth Road
Ann Arbor, Michigan 48105
-------
A \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ANN ARBOR. MICHIGAN 48105
OFFICE OF
AIR AND RADIATION
August 31, 1988
MEMORANDUM
SUBJECT: Exemption From Peer and Administrative Review
FROM
TO:
Karl H. Hellman, Chief
Control Technology and Applications Branch
Charles L. Gray, Jr., Director
Emission Control Technology Division
The attached report entitled "Evaluation of a Resistively
Heated Metal Monolith Catalytic Converter On An M100 Neat
Methanol-Fueled Vehicle," (EPA/AA/CTAB/88-08) describes
emission tests results obtained from testing a resistively
heated catalytic converter on a methanol-fueled 1981 Volkswagen
Rabbit.
Since this report is concerned only with the presentation
of data and its analysis and does not involve matters of policy
or regulations, your concurrence is requested to waive
administrative review according to the policy outlined in your
directive of April 22, 1982.
Concurrence ;
/* -
Date ;
. 3/
_
Charles L. G r a y , /J r . , D i r . , ECTD
Nonconcurrence :
Date :
Charles L. Gray, Jr., Dir., ECTD
cc: E. Burger, ECTD
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EPA/AA/CTAB/88-08
Technical Report
Evaluation of a Resistively Heated
Metal Monolith Catalytic Converter
On An M100 Neat Methanol-Fueled Vehicle
by
David M. Blair and
Gregory K. Piotrowski
August 1988
NOTICE
Technical Reports do not necessarily represent final EPA
decisions or positions. They are intended to present technical
analysis of issues using data which are currently available.
The purpose in the release of such reports is to facilitate the
exchange of technical information and to inform the public of
technical developments which may form the basis for a final EPA
decision, position or regulatory action.
U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Mobile Sources
Emission Control Technology Division
Control Technology and Applications Branch
2565 Plymouth Road
Ann Arbor, Michigan 48105
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Table of Contents
Page
Number
I. Summary 1
II. Introduction 1
III. Catalytic Converter Description 1
IV. Vehicle Description 2
V. Test Facilities and Analytical Methods 3
VI. Test Procedure 3
VII. Discussion 5
A. Heating Strategy Evaluation 5
B. Exhaust Gas Temperature Behavior 9
During Resistive Heating
C. Evaluation of Resistively Heated Catalyst . . 12
VIII.Conclusions 17
IX. Future Effort 18
X. Acknowledgments 19
XI. References 19
APPENDIX A - Garnet Resistively Heated Catalytic .... A-l
Converter Specifications and Power
Requirements
APPENDIX B - Test Vehicle Specifications B-l
APPENDIX C - Heating Strategy Evaluation Tests C-l
APPENDIX D - Modification of the Proposed Methanol- . . D-l
Fueled Vehicle Test Procedures
APPENDIX E - Catalyst Evaluation - Detailed FTP .... E-l
Results
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I. Summary
A prototype metal monolith catalytic converter, which may
be resistively heated, was emission-tested on a M100 neat
methanol-fueled vehicle. This catalytic converter, when tested
as a 3-way catalyst without resistive heating, controlled
emissions over the Federal test procedure (FTP) [1] to levels
previously obtained by ceramic substrate converters coated with
noble metal catalyst formulations. Resistively heating the
catalyst substantially lowered emissions of hydrocarbons (HC)
and formaldehyde (HCHO) compared to those from the unheated
tests.
II. Introduction
The major portion of HC and HCHO emissions measured from a
catalyst-equipped methanol-fueled vehicle over the FTP cycle
are generated during cold start and warmup of the catalyst.[2]
These emissions are difficult to control because engine-out
emissions are high and catalytic converters have low conversion
efficiency during their warm-up phase of operation.
A prototype resistively heated metal monolith catalyst has
also been tested by EPA; that converter was a predecessor
design to the subject of this report. Results from this
previous testing indicated the feasibility of the concept of a
resistively heated metal monolithic substrate as a quick
light-off catalyst support.[3] The time it took to warm up the
resistively heated catalyst to operating temperature was
considered to be a drawback of the initial prototype tested.
An improved configuration, the subject of the present report,
was designed to achieve light-off temperature in a
substantially shorter period of heating time than the initial
prototype.
III. Catalytic Converter Description
The catalytic converter evaluated here was a dual-bed
configuration consisting of an unheated metal monolith catalyst
and a smaller resistively heated metal monolith catalyst.
Detailed specifications are provided in Appendix A.
The dimensions of the converter are similar to those of
typical underfloor catalysts on late model compact
automobiles. The amperage draw was comparable to that required
by an automotive starter motor cranking in cold weather. The
rise in mid-bed gas temperature from 70°F to 600°F during
prestart heating as measured by a thermocouple located near the
center of the converter was linear and is presented in Figure
1. The catalyst wall temperature was probably higher than the
measured 600°F after 15 seconds of heating, since the
thermocouple may not have responded fast enough to the quickly
rising temperature and stagnant gas temperature was probably
lower than the resistively heated wall prior to start.
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Drawing 300 to 400 amps at 10 volts is 3 to 4 kilowatts.
Assuming that the use per start is 30 seconds, the energy
required is 0.03 kw/hr, so this device is like a starter
motor: high power drain but low energy consumption due to the
short time it is used.
FIGURE 1
SUBSTRATE TEMPERATURE VERSUS TIME
TEMP (F)
800
700
600
500
400
300
200
100
0
Conditiona-
-10.0 volts (approx)
-300 to 400 ampi
-no flow through the converter
.Temperature Measured by Thermocouple
6 8 10 12 14 18
TIME (SEC)
IV. Vehicle Description
The test vehicle was a 1981 Volkswagen Rabbit 4-door
sedan, equipped with automatic transmission, air conditioning,
and radial tires. The 1.6-liter engine had a rated maximum
power output of 88 horsepower at 5,600 rpm, when using neat
methanol fuel. The vehicle was tested at 2,500 Ibs inertia
weight and 7.7 actual dynamometer horsepower.
A detailed description of the vehicle and special methanol
modifications is provided in Appendix B.
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-3-
V. Test Facilities and Analytical Methods
Emissions testing was conducted on a Clayton Model ECE-5Q
double-roll chassis dynamometer, using a direct-drive variable
inertia flywheel unit and road load power control unit. The
Philco-Ford CVS has a nominal capacity of 350 CFM. Exhaust HC
emissions were measured with a Beckman Model 400 flame
ionization detector (FID). CO was measured using a Bendix
Model 8501-5CA infrared CO analyzer. NOx emissions were
determined by a Beckman Model 951A chemiluminescent NOx
analyzer.
Exhaust formaldehyde was measured using a dinitrophenyl-
hydrazine (DNPH) technique.[4] Exhaust carbonyls including
formaldehyde are reacted with DNPH solution forming hydrazine
derivatives; these derivatives are separated from the DNPH
solution by means of high performance liquid chromatography
(HPLC), and quantization is accomplished by spectrophotometric
analysis of the LC effluent stream.
HC test results in the text and in Appendices C and E are
presented without accounting for FID response to methanol or
the difference in HC composition because of the use of methanol
fuel. The emission values presented in this report were also
calculated using proposed methanol-fueled vehicle test
procedures.[5] Modifications to the proposed test procedures
were required as methanol emissions were not specifically
measured. These modifications are discussed in Appendix D.
VI. Test Procedure
The evaluation program had three separate goals:
1. To evaluate different resistive heating strategies
for the catalyst over the FTP cycle, with emphasis on
elimination of HC and HCHO emissions;
2. To determine the effect of resistive heating on
exhaust gas temperature; and
3. To evaluate the emissions performance of the vehicle
using a specific heating mode, with emphasis on elimination of
HC and HCHO emissions.
Different heating strategies were determined by first
conducting a series of tests consisting of the Bag 1 portion
(first 505 seconds) of the FTP cycle. Emissions of all
regulated pollutants, as well as formaldehyde and methane, were
sampled and measured. The better orientation in the exhaust
train of the catalyst was selected, and a series of tests over
the complete FTP cycle were then conducted to further define
the heating strategy. The various configurations in which the
converter was tested are explained in Figure 2.
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-4-
FIGURE 2
TESTED CONFIGURATIONS
Baseline
No Converter Installed
Engine Out Emissions
Exhaust Flow
Configuration A
Converter Installed
Small Catalyst Brick Upstream
(Unheated)
Configuration B
Converter Installed
Small Catalyst Brick Downstream
(Unheated)
1
|»12v
Configuration C
Converter Installed
Small Catalyst Brick Upstream
(Heated)
1
Configuration 0
Converter Installed
Small Catalyst Brick Downstream
- (Heated)
»12v
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-5-
The catalyst can was fitted with thermocouples to measure
inlet and outlet exhaust gas temperatures. A thermocouple was
also installed in the middle of the heated catalyst brick so
that the gas temperature in the middle of the substrate could
be measured. Data from these thermocouples was translated to
temperature data and recorded on a stripchart recorder during
the heating strategy optimization testing. This, temperature.
data is presented in the Discussion section.
The catalyst's emissions reduction performance was
evaluated by testing it several times over the FTP cycle; the
configurations tested no resistive heating as well as the
optimized heating strategy determined in the first phase of the
project. The results from this testing are also presented in
the Discussion section.
VII. Discussion
A. Different Heating Strategy Evaluation
Two orientations, Configurations C and D of Figure 2, were
possible with the heated converter in the exhaust train.
Configuration C might be considered the more logical
alternative as much of the energy generated during resistive
heating and any exothermic chemical reactions could be
transferred to the relatively cool exhaust gas passing through
the converter immediately after a cold start. This energy
would aid the catalytic processes downstream by warming the
surface of the larger catalyzed but unheated monolith.
Configuration D could not be ignored, however. The upstream
catalyst eventually could be coated with a reducing or 3-way
catalyst and the heated downstream monolith .coated with an
oxidizing formulation.
Several emission tests were conducted over the first 505
seconds of the FTP cycle to determine the preferred
orientation. The results are presented in Figures 3 and 4;
emissions of greatest interest were HCHO and HC. Detailed test
results are given in Table C-l of Appendix C.
The tests of Configuration D, which required heating of
the catalyst for 15 seconds following cold start, produced
substantially lower masses of both HC and HCHO than the tests
which ceased resistive heating upon start. Configuration C,
which placed the heated unit upstream, was almost 20 percent
more efficient in both emission categories than Configuration D
given similar heating strategies. Though the amount of testing
was limited, the results indicated a slightly greater
efficiency for Configuration C over Configuration D, with some
resistive heating after cold start preferred.
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-6-
FIGURE 3
INITIAL CONFIGURATION DETERMINATION
0.6
0.6
0.4
0.3-
0.2-
0.1 -
Bag 1 HC, grams
0.62
Configuration 0
Heat Time (sec) 15/0
0;4T
D
15/0
0
15/15
0.16
C
15/15
FIGURE 4
INITIAL CONFIGURATION DETERMINATION
120
100
Bag 1 HCHO, mga
Configuration D
Heat Time (sec) 15/0
D
15/0
62
\\\\\\\N
D
15/15
C
15/15
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-7-
Figures 5 and 6 present graphically the results of several
tests over the FTP cycle utilizing different strategies for
resistive heating of the catalyst during the early part of Bags
1 and 3 (first 505 seconds and final 505 seconds respectively
of the test cycle). Figures 5 and 6 present grams of HC
produced during Bags 1 and 3. Complete emission results are
given in Table C-2 of Appendix C. Figure 6 shows the trends in
Bag 1 emissions as a function of pre-start heating time for the
data for which the post-start heating time was constant at 15
seconds.
FIGURE 5
REFINEMENT OF HEATING STRATEGY
GRAMS HC
0.8-
0.6-
0.4-
0.2-
ConflQuration C
Bag 1 HMI (••<:) o/16
Bag 3 H«at (••che/16
C C
16/16 0/16
16/16 0/16
!BAG 1 HC
C C
6/16 10/16
6/16 10/16
D BAG 3 HC
FIGURE 6
REFINEMENT OF HEATING STRATEGY
GRAMS HC
6 10
PRE8TART HEATING TIME. SECS
BAG 1 HC
BAG 3HC
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-a-
Lengthening the period of heating time prior to start
generally reduced HC emission levels as shown in Figure 6. The
two highest masses of HC produced during Bag 1, .91 and .75
grams respectively, occurred during tests when resistive
heating commenced with the cold start. The lowest mass
produced during Bag 1, .20 grams, occurred when the catalyst
was resistively heated for 15 seconds prior to start. All
tests included at least a 15-second period of heating following
engine start to ensure that the catalyst experienced a rapid
transition to a stabilized, warm temperature.
Bag 3 results followed Bag 1; generally, extending heating
times prior to engine start produced lower masses of HC
emissions. The lowest masses, .10 and .12 grams respectively,
were produced after 15 seconds of heating prior to engine
start. A 15-second heating period following start was included
on each test.
Figure 7 present levels of HCHO measured under the same
heating schemes as given in Figure 5. Generally, Bag 1 levels
of formaldehyde decreased with increasing periods of resistive
heating prior to start. Because of the lower mass of HCHO
involved under hot start conditions of Bag 3, it is difficult
to determine an optimum heating scheme. Some heating prior to
hot start appears preferable though; 9 milligrams of HCHO were
measured during the 0/15 Configuration C test, compared to 6,
4, and 2 milligrams measured during the three following tests
which utilized short periods of resistive heating prior to the
hot start.
FIGURE 7
REFINEMENT OF HEATING STRATEGY
100
HCHO, MQ3
Configuration C
Bag 1 Heat (a«c) 0/16
Bag 3 Heat (aac) 16/16
100
BAG 1 HCHO i BAG 3 HCHO
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-9-
B. Exhaust Gas Temperature Behavior During Resistive
Heating
The -catalytic converter was modified to accept three
K-type thermocouples. These thermocouples measured inlet and
outlet exhaust gas temperatures as well as gas temperature near
the middle of the heated monolith. Temperature data from these
thermocouples was collected during the tests previously
described.
Figure 8 presents inlet exhaust gas temperature data over
a portion of the FTP commencing at 15 seconds prior to start
and ending with the completion of 120 seconds of this test.
Two modes of catalyst operation are considered here:
1. No resistive heating of the catalyst; and
2. Resistive heating of the catalyst for 15 seconds
prior to and 15 seconds following start, using Configuration C.
Inlet temperatures follow a similar pattern for both
heating modes; resistively heating the catalyst did not
appreciably affect inlet exhaust temperatures. Inlet
temperatures appeared to stabilize at about 650-700°F after 120
seconds of engine operation over the FTP.
FIGURE 8
INLET QAS TEMPERATURES
1200
TEMP. DEGREES F
SECONDS
NO HEAT -I- 16/16 HEATED
120
Outlet exhaust gas temperatures for the conditions
described in the previous paragraphs are given in Figure 9.
Very different temperature patterns are evident here for the
two heating schemes.
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-10-
Outlet gas temperature rose very slowly for the first
40-50 seconds following engine start with the unheated
catalyst. The next 30 seconds was characterized by a greatly
increased-rate of temperature change; during this time period,
exhaust gas temperature rose from less than 200°F to
approximately 650°F. A stabilizing of the exhaust temperature
occurred after that, the temperature reaching a stabilized
value of approximately 650-700°F.
A gradual rise in outlet exhaust gas temperature, from 75
to approximately 110°F, occurred during the 25 seconds
following engine start with the heated catalyst. A very large
change in temperature, from 100° to 800°F, occurred during the
next 20-25 seconds of engine operation. Outlet exhaust gas
temperature appeared to stabilize after approximately 1 minute
of engine operation and the stabilized value was 750°F, or
almost 50°F higher than the stabilized temperature from the
unheated catalyst mode testing.
FIGURE 9
OUTLET GAS TEMPERATURES
TEMP. DEGREES F
1200r
-16
SECONDS
16/16 HEATED — NO HEAT
120
Figure 10 presents gas temperature at the middle of the
catalyst bed for the heating modes and the time periods
mentioned above.
In the unheated mode, the catalyst gas temperature
gradually warmed to 100°F during the first 25 seconds of engine
operation. A 35-40 second period of increased temperature
change then occurred with the catalyst finally warming to 650°F
after a total of 1 minute of engine operation. The mid-bed
temperature then warmed to approximately 750°F after an
additional minute of engine operation.
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-11-
The heated catalyst attained a mid-bed gas temperature of
approximately 650°F immediately before engine start through the
15-second preheat period. This rate of temperature increase
continued after engine start until a maximum temperature of
approximately 1100°F was attained 15 seconds after engine
start. This gas temperature dropped steadily for the next 25
seconds; the decrease in temperature coincided with the
cessation of resistive heating. During the remainder of the
120-second period following engine start the mid-bed gas
temperature moved toward a stabilized value of approximately
750 °F.
FIGURE 10
MIDBED GAS TEMPERATURE
1200-1
TEMP. DEGREES F
-16
SECONDS
16/16 HEATED NO HEAT
120
The primary significance of the data in Figure 10 is that
the gas at the mid-bed point of the converter reaches light-off
temperature at vehicle start. This temperature is defined here
to be greater than 600°F; a near stabilized exhaust gas
temperature of 600°F was obtained with the unheated
configuration only after 1 minute of engine operation. After
start, the gas temperature measured by the mid-bed thermocouple
did not drop below 600°F. Further, at no time during the first
120 seconds of engine operation did the temperature of the
resistively heated catalyst drop below the temperature of the
unheated configuration for the same point in time. If a
light-off temperature of 600°F is all that is necessary, then
the substrate temperature characteristics of the resistively
heated catalyst tested here may be difficult to improve upon.
Configuration C was determined to be the better
orientation of the catalyst in the exhaust. A period of
resistive heating prior to and following cold start was
determined to be necessary. Generally, more extended periods
of heating prior to cold start generated lower emission levels
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-12-
of HC and HCHO than shorter heating periods. A heating
strategy of 10 seconds prior to cold start was chosen as a
guess at a compromise; shorter heating periods may not have
generated the light-off temperatures desired, whereas a longer
period (15 or more seconds) might be considered by some
unacceptable from a vehicle operator's standpoint. This
resistive heating continued for 20 seconds following cold start
to ensure a stabilized catalyst temperature. A 5/15 heating
strategy for Bag 3 was chosen because catalyst light-off is
considerably easier to achieve from hot start conditions.
C. Evaluation of Resistively Heated Catalyst
The resistive heating strategy for further evaluation of
the catalyst was chosen to be:
1. Heating for 10 seconds prior to cold start and 20
seconds following cold start over the Bag 1 (first 505 seconds)
portion of the FTP; and
2. Heating for 5 seconds prior to and 15 seconds
following the hot start of the Bag 3 (final 505 seconds)
portion of the FTP.
This strategy was chosen with a 10-second preheat time to
achieve a timing that might be customer acceptable. The first
diesel engines had glow plug preheat times of up to one
minute. As they were improved, this time was reduced to 10
seconds or less. Since this time seemed to be acceptable to
customers, we chose it as a maximum preheating time for this
test phase.
Four complete FTP tests were conducted using this heating
strategy. Several FTP tests were also conducted utilizing the
unheated catalyst Configurations A and B referred to in Figure
2. Test results are summarized and compared in Tables 1
through 6. Details of individual test results are given in
Appendix E.
Table 1 presents the average mass of emissions over the
Bag l (first 505 seconds) portion of the FTP. The results are
given in grams per test phase except for HCHO, which is
presented in milligrams per test phase. Catalyst efficiencies
over baseline in percent are provided in Table 2; a figure for
percent improvement in emissions reduction by the heated
catalyst over an average of the unheated catalyst configuration
by emissions category is also provided in Table 2.
Unheated catalyst Configurations A and B showed
substantial and similar reductions in mass of emissions
produced for each pollutant category. The two pollutant
categories of particular interest, HC and HCHO, were reduced to
levels of 1.74 grams and 162 milligrams per phase respectively,
when a simple average composite of the unheated configuration
is considered. These levels equate to efficiencies of 74 and
88 percent respectively for these pollutant categories.
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-13-
The resistively heated catalyst configuration reduced
emission levels in almost every pollutant category from
unheated catalyst levels. The heated catalyst reduced Bag 1 HC
mass to 0.50 grams for a 92 percent efficiency; HCHO efficiency
rose to 96 percent over baseline levels. The improvement in
emission levels by the resistively heated catalyst over the
unheated composite configuration was 71 and 67 percent for HC
and HCHO respectively. Reduction of NOx levels was slightly
improved (9 percent) by heating the catalyst versus the
unheated composite.
CO increased to 11.6 grams over Bag 1 when the catalyst
was heated from 8.5 grams with the unheated composite
configuration. The reason for this increase is unknown. The
testing over Bag 1 conducted as part of the heating strategy
optimization indicated that 5.8 to 10.9 grams of CO might be
expected given similar heating strategies. Additional testing
may be necessary to determine the cause of this increase in
emissions.
Table 3 presents the average mass of emissions produced
over the Bag 3 (final 505 seconds) portion of the FTP. Test
results are presented in the same format as that in Table 1.
Table 4 presents catalyst efficiencies over Bag 3 in the same
format as that in Table 2.
Again, the unheated Configurations A and B provided
substantial and similar reductions in emissions from baseline
levels over each pollutant category. HC and HCHO levels were
reduced to .35 grams and 10 milligrams respectively over Bag 3,
when the composite of Configuration A and B emission levels is
considered. Composite unheated converter efficiencies exceeded
90 percent for each pollutant category with the exception of
NOx. HCHO efficiency in particular was 99 percent for both
unheated configurations.
The heated configuration substantially lowered emissions
below levels from unheated catalyst testing in almost every
pollutant category. HC and CO were reduced 29 and 40 percent
respectively from unheated catalyst levels. HCHO mass
emissions increased to 19 milligrams from 10 milligrams over
the composite unheated configuration. The 19 milligram HCHO
emission level corresponds to a greater than 98 percent
decrease in emissions from baseline levels, however.
Table 5 presents FTP results for the catalyst
configurations referred to in Tables 1 through 4. Catalyst
efficiencies are presented in Table 6.
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-14-
Table 1
Average Mass of Emissions
Bag 1 of FTP Cycle
Catalyst Configuration
Baseline (no catalyst)
Configuration A
Configuration B
Average of A and B
HC NMHC* HC** OMHCE**CH30H** CO NOx HCHO
(q) (q) (q) (q) (q) (q) (q) (mq)
6.63 6.58 0.78 9.19 18.01 33.03 8.36 1324
1.85 1.80 0.22 2.45 4.99 9.33 4.56 157
1.62 1.58 0.20 2.18 4.40 7.66 4.10 166
1.74 1.69 0.21 2.32 4.70 8.50 4.33 162
Configuration C-Heated 10/20***0.50 0.44 0.06 0.67 1.35 11.56 3.92
54
Table 2
Catalyst Efficiencies Over Bag 1 of FTP
Catalyst Confiquration
Configuration A
Configuration B
Average of A and B
Heated configuration
HC NMHC HC** OMHCE**CH30H*
(%) (%) (%) (%) (\)
72 73 72 73 72
76 76 74 76 76
74 74 73 75 74
92 93 92 93 93
versus baseline
Heated configuration
versus unheated composite
71
74
71
71
71
72
77
74
65
(36)
NOz HCHO
(*) _tll
45 88
51 87
48 88
53 96
9 67
* Non-methane hydrocarbons.
** Calculated values per proposed rulemaking.
*** Catalyst preheated 10 seconds prior to cold start and 20 seconds
following start.
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-15r
Table 3
Average Mass of Emissions
Bag 3 of FTP Cycle
Catalyst Configuration
Baseline (no catalyst)
Configuration A
Configuration B
Average of A and B
HC NMHC HC* OMHCE* CH3OH* CO NOx HCHO
(g) (g) (g) (g) (g) (g) (g) (mg)
3.71 3.69 0.44 5.31 10.09 21.12 8.26 1095
0.36 0.34 0.02 0.47 0.97 1.26 3.60 8
0.34 0.31 0.04 0.45 0.92 2.96 3.47 12
0.35 0.33 0.03 0.46 0.95 2.11 3.54 10
Configuration C-Heated 5/15** 0.25 0.21 0.03 0.33 0.67 1.27 3.42
19
Table 4
Catalyst Efficiencies Over Bag 3 of FTP
Catalyst Configuration
Configuration A
Configuration B
Average of A and B
Heated configuration versus
HC
(V
90
91
91
93
NMHC
. (*>
91
92
91
94
HC*
(%)
95
91
93
93
OMHCE*
(M
91
92
91
94
CH3OH*
(%)
90
91
91
93
CO
(**>)
94
86
90
94
NOx
(%)
56
58
57
59
HCHO
(%)
99
99
99
98
baseline
Heated configuration versus
unheated composite
29
36
28
29
40
(90)
* Calculated values per proposed rulemaking.
** Catalyst preheated 5 seconds prior to hot start and 15 seconds following
start.
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-16-
Table 5
Emission Levels Over The FTP Cycle
Catalyst Configuration
Baseline (no catalyst)
Untie a ted Configuration A
Unheated Configuration B
Average of A and B
Configuration C-Heated 10/20
Bag 1, 5/15 Bag 3
HC NMHC HC* OMHCE* CH30H* CO NOx HCHO
j/mi g/mi g/mi g/mi g/mi g/mi g/mi mq/mi
1.11 1.10 0.13 1.58 3.00 6.62 1.74 337
0.14 0.13 0.02 0.19 0.38 0.73 0.85 10
0.13 0.12 0.02 0.17 0.36 0.92 0.75 12
0.14 0.13 0.02 0.18 0.37 0.83 0.80 11
0.05 0.04 0.01 0.07 0.14 0.77 0.83 5
Table 6
Catalyst Efficiencies Over The FTP Cycle
Catalyst Configuration
Unheated Configuration A
Unheated Configuration B
Average of A and B
Heated configuration versus
HC
(%)
89
89
89
95
NMHC
(%)
90
90
90
96
HC*
(%)
86
86
86
92
OMHCE*
(%)
90
90
90
96
CH30H*
(%)
89
89
89
95
CO
(%)
89
86
87
88
baseline
Heated configuration
versus unheated composite
64
69
50
61
62
NOx HCHO
55
57
56
52
(4)
97
96
97
99
55
Calculated values per proposed rulemaking.
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-17-
The unheated composite configuration produced HC and HCHO
levels of .14 g/mi and 11 mg/mi respectively over the FTP.
These levels were reduced to .05 g/mi and 5 mg/mi respectively
by resistively heating the catalyst. CO and NOx levels were
relatively unchanged by heating the catalyst versus the
unheated configurations.
Individual FTP HCHO levels in Table E-3 vary from 4 to 7
mg/mi for this heated catalyst testing; Bag 1 levels vary from
42 to 60 mg. These levels substantially exceed those from
testing conducted during the prior phase, reported in Table
C-2. For example, the three tests of Configuration C presented
in Table C-2 that involve preheating the catalyst for 10
seconds or longer prior to Bag 1 cold start produced HCHO Bag 1
levels of 15, 14, and 26 mg. These same tests produced
weighted FTP levels of 3, 1, and 2 mg/mi.
The reason for this increase in HCHO levels between test
sets is unknown. The baseline levels presented in Table E-l
are high when compared to the resistively heated catalyst
levels from either Table C-2 or E-3. Resolution of
chromatograph test results may be difficult at the low emission
levels considered here. Higher levels of HCHO from the later
tests under the same conditions could also mean that
deterioration of the catalyst's activity was occurring.
Additional car and bench testing of the catalyst and of
background levels in the test cell may be necessary to explain
this difference.
VIII.Conclusions
1. Best results were obtained when the resistively
heated portion of the catalyst was located upstream.
2. Generally, lower emissions levels of HC and HCHO
over Bag 1 of the FTP resulted when resistive heating time of
the catalyst prior to cold start was increased. Preheating
periods in excess of 15 seconds were not evaluated.
3. Extending the resistive preheating time prior to the
hot start generally lowered emission levels of HC and HCHO from
Bag 3 of the FTP. Preheating periods in excess of 15 seconds
were not evaluated.
4. A 12-volt DC power source was able to increase gas
temperature in the center of the catalyst from 75° to 650°F.
This temperature rise occurred during 15 seconds of catalyst
preheat prior to engine cold start. Fifteen seconds of
additional heating following cold start raised mid-bed gas
temperature to 1100°F at the end of this period.
5. Resistively heating the catalyst for 10 seconds
prior to and 20 seconds following cold start lowered Bag 1
emissions of HC and HCHO to 0.50 grams and 54 milligrams
respectively. The levels were a 71 and 67 percent improvement
respectively over HC and HCHO levels from a composite of two
unheated configurations of the same catalyst.
-------
-18-
6. Resistively heating the catalyst for 5 seconds prior
to and 15 seconds following start lowered Bag 3 emission levels
of HC and HCHO to 0.25 grams and 19 milligrams, respectively.
These figures represent a 93 and 98 percent reduction in HC and
HCHO emissions from baseline levels over the Bag 3 portion of
the FTP.
7. Weighted FTP emission level averages from testing
the catalyst with the heating strategy utilized were 0.05 g/mi
and 5 mg/mi for HC and HCHO, respectively. These figures
represent a 95 and 99 percent efficiency from baseline HC and
HCHO levels, respectively.
IX. Future Effort
The test vehicle is equipped with an air pump;
modifications to the exhaust system permit testing of
converters as simulated oxidation catalysts. This converter
will be tested as a simulated oxidation catalyst utilizing the
final heating strategy.
A gasoline-powered 1987 Volkswagen Golf has been procured
by CTAB to be used as a test vehicle for this converter. The
catalyst will be emission tested on the vehicle using the final
heating strategy. Emission results from resistively heated
catalyst testing will be compared to engine-out emission levels
and emission levels from the vehicle equipped with a stock
catalytic converter. Because the unburned fuel from this car
will not contain oxygen, in contrast to methanol, we estimate
that some air injection may be necessary for good results.
The success of this effort has prompted us to begin
looking at the background levels of HCHO in our test cell more
closely. We are considering running background tests for each
test in the future and accounting for background in a manner
similar to that done for other pollutants. No allowance for
background levels was made in the results reported in this
report, even though one test (which is being repeated)
indicated that the background levels were roughly equivalent to
1 mg/mi.
At the low levels of HCHO measured (below 5 mg/mi) we
sometimes see results in the DNPH cartridges that are difficult
to understand. For example, the backup cartridge maybe
measured as containing more HCHO than the primary cartridge.
This "shouldn't happen." As a result, we are reexamining the
sampling approach and procedure. We may have to improve the
procedure at the low levels of HCHO measured in each bag of the
test.
-------
-19-
X. Acknowledgments
The catalyst used in this test program was supplied by
Garnet, located in Hiram, Ohio. Garnet is a manufacturer and
sales agent for W. R. Grace and Company.
The authors appreciate the efforts of Ernestine Bulifant,
Robert Moss and Stephen Halfyard of the Test and Evaluation
Branch, Emission Control Technology Division (ECTD), who
conducted the driving cycle tests and prepared the formaldehyde
samples for analysis.
In addition, the authors appreciate the efforts of
Jennifer Criss and Marilyn Alff of the Control Technology and
Applications Branch, ECTD, who typed this manuscript.
XI. References
1. 1975 Federal Test Procedure, Code p_f Federal
Regulations, Title 40, Part 86, Appendix I(a), Urban
Dynamometer Driving Schedule.
2. Improved Control of Formaldehyde by Warmup of
Catalyst Prior to Vehicle Start, Memorandum, Piotrowski, G. K.,
OAR, QMS, ECTD, Ann Arbor, MI, 1985.
3. Evaluation of Electrically Heatable Metal Monolith
Catalytic Converter, EPA Memorandum from David M. Blair to
Charles L. Gray, Jr., Director, ECTD, October 8, 1987.
4. Formaldehyde Measurement In Vehicle Exhaust at MVEL,
Memorandum, Gilkey, R. L., OAR, QMS, EOD, Ann Arbor, MI, 1981.
5. "Proposed Emission Standards and Tests Procedures
for Methanol-Fueled Vehicles, Draft Regulation" U. S. EPA,
Summer 1986.
-------
A-l
APPENDIX A
CAMET RESISTIVELY HEATED CATALYTIC CONVERTER
SPECIFICATIONS AND POWER REQUIREMENTS
Construction
Dual-bed element composed of
two metal monolith catalysts,
a smaller resistively
beatable one and a larger one
with no provisions for
resistive heating
Catalyst material/loadings
Shape
Proprietary
Rectangular
Overall outer dimensions
(excluding mounting flanges)
10-3/4" x 4-1/4" x 2-3/4"
Length: flange to flange
14-3/4'
Heated brick dimensions
3" x 4-1/4" x 2-3/4" (approx)
Unheated brick dimensions
4" x 4-1/4" x 2-3/4" (approx)
Power supply
12-volt automotive battery
Power delivered
300-400 amps at 10-11 volts
Heatup time to 600°F
with no gas flow through
the converter
Less than 20 seconds from 70°F
-------
B-l
APPENDIX B
TEST VEHICLE SPECIFICATIONS
Vehicle type
1980-81 Volkswagen Rabbit
Fuel
M100 (neat methanol)
Engine
Displacement
Bore
Stroke
Compression ratio
1.6 liter
7.95 cm
8.00 cm
12.5 to 1
Fuel System
Cold start injectors
Type Bosch CIS fuel injection
with Lambda feedback control,
calibrated for methanol
operation
Two injectors, valve pulse for
8 seconds after start when
coolant temperature below 0° C
Transmission
Type
Torque converter ratio
Stall speed
Gear ratios
1
2
3
Axle
Production 1981 automatic
three-speed
2.44
2000-2200 rpm
2.55
1.45
1.00
3.57
Curb weight
2822 Ibs
Equivalent test weight
2500 Ibs
Actual dynamometer horsepower 7.7 hp
-------
APPENDIX C
HEATING STRATEGY TESTS
-------
C-l
Table C-l
Heating Strategy Tests
Cold Start Bag 1 Portion of FTP
Test Configuration NMHC* HC HC** OMHCE** CH30H** CO NOx HCHO
Number Heat Strategy (g) (g) (g) (g) (g) (g) (g) (mg)
883951 Configuration D .48 .52 .06 .72 1.43 5.83 4.48 87
15/0***
883952 Configuration D
15/0
.43 .47 .06
,66
1.29 5.50 4.08 95
883953 Configuration D
15/15
.16 .20
,02
,28 0.55 5.30 4.18 52
883956 Configuration C .11 .15 .02
15/15
.22 0.42 5.80 4.40 42
* Non-methane hydrocarbons.
** Calculated values per proposed rulemaking.
*** Notation indicates time of preheating catalyst in seconds prior to
start/time of heating in seconds immediately following start.
-------
C-2
Table C-2
Heating Strategy Tests
FTP Cycle
Test Number/Type
Heating Strategy NMHC HC
883955/Configuration D
Bag 1—15/15***
Bag Kg) .68
Bag 2(g) .02
Bag 3(g) .32
Composite(g/mi) .07
883958/Configuration C
Bag 1—0/15 Bag 3 — 15/15
Bag Kg) .88
Bag 2(g) .02
Bag 3(g) .05
Composite(g/mi) .06
883959/Configuration C
Bag 1—15/15 Bag 3 — 15/15
Bag Kg) .16
Bag 2(g) .02
Bag 3(g) .06
Composite (g/mi) .02
884263/Configuration C
Bag 1—0/15 Bag 3—0/15
Bag Kg) .71
Bag 2(g) .02
Bag 3(g) .29
Composite(g/mi) .07
CO
.73
.07
.35
.08
.91
.08
.10
.07
.20
.07
.12
.03
.75
.07
.32
.08
8.70
3.33
3.80
1.23
8.18
3.32
3.91
1.21
9.13
2.51
4.25
1.18
8.34
4.60
3.62
1.37
3.93
1.82
3.48
0.73
4.71
2.35
4.23
0.90
4.78
2.33
4.39
0.92
4.94
2.28
4.63
0.94
79
11
12
7
64
4
6
5
15
7
9
3
37
6
9
4
NOx HCHO* HC** OMHCE** CH30H**
.09
.01
.04
.01
.11
.01
.01
.01
.02
.01
.01
.01
.09
.01
.04
.01
.98
.10
.46
.11
1.21
0.11
0.14
0.10
.27
.10
.16
.04
.99
.10
.43
.10
1.98
0.21
0.96
0.21
2.48
0.23
0.28
0.20
.55
.20
.32
.08
2.03
0.20
0.89
0.21
* HCHO is given in mg for bag data and mg/mi for composite data.
** Calculated values per proposed rulemaking.
*** Notation indicates preheating catalyst 15 seconds prior to start of
vehicle and 15 seconds into test.
-------
C-3
Table C-2 (conf d)
Heating Strategy Tests
FTP Cycle
Test Number/Type
Heating Strategy NMHC
884418/Configuration C
Bag 1—5/15 Bag 3 — 5/15
Bag Kg)
Bag 2(g)
Bag 3(g)
Composite(g/mi)
884440/Configuration C
Bag 1—10/15 Bag 3 — 10/15
Bag Kg)
Bag 2(g)
Bag 3(g)
Composite(g/mi)
884419/Configuration C
Bag 1 — 10/20 Bag 3 — 5/15
Bag Kg)
Bag 2(g)
Bag 3(g)
Composite(g/mi)
HC
CO
NOx
HCHO* HC** OMHCE** CH30H**
.58
.05
.15
.05
5
.16
.04
.03
.02
.62
.63
.15
.05
.62
.10
.20
.06
.22
.09
.16
.04
.66
.08
.20
.06
8.54
5.07
4.97
1.54
8.68
7.88
4.76
1.91
10.97
4.85
6.10
1.74
5.12
2.44
4.69
0.98
4.89
2.16
4.55
0.91
4.52
2.48
4.09
0.90
45
7
6
4
14
3
4
1
26
3
2
2
.07
.01
.02
.01
.03
.01
.02
.01
.08
.01
.02
.01
.82
.14
.26
.09
.29
.12
.21
,05
.87
.11
.26
.08
1.67
0.28
0.54
0.18
0.59
0.25
0.43
0.10
1.81
0.23
0.54
0.17
* HCHO is given in mg for bag data and mg/mi for composite data.
** Calculated values per proposed rulemaking.
-------
APPENDIX D
MODIFICATION OF THE PROPOSED
METHANOL-FUELED VEHICLE TEST PROCEDURES
As proposed, the regulations in reference 5 require the
measurement of methanol (CH3OH) and formaldehyde (HCHO).
Methanol emissions are especially important since the dilution
factor equation includes CH3OH emissions. At the time the
testing reported on here was conducted, the EPA test cell in
which this program was run was not equipped to measure
CH3OH. Therefore, the results shown here were computed with
a FID response factor of 0.75 and an assumed HC ppm to methanol
ppm factor of xx/.85, where xx is the fraction of methanol in a
methanol gasoline blend. HC results were then computed using
the procedures specified in the draft regulations. [5]
-------
APPENDIX E
CATALYST EVALUATION - DETAILED FTP RESULTS
-------
Test Number/Type
383229/Baseline
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
883231/Baseline
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
FTP (g/mi)
884422/Baseline
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
884423/Baseline
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
E-l
Table E-l
Individual FTP Test Results
Baseline Testing
HC
7.60
3.38
3.90
1.19
7.23
3.45
4.05
1.19
5.46
3.09
3.36
0.98
6.22
3.23
3.54
1.06
NMHC
7.56
3.36
3.88
1.18
7.19
3.42
4.02
1.18
5.42
3.06
3.34
0.97
6.16
3.20
3.51
1.05
HC*
0.90
0.40
0.46
0.14
0.85
0.41
0.48
0.14
0.64
0.36
0.40
0.12
0.73
0.38
0.42
0.12
OMHCE*
10.42
5.08
5.61
1.71
9.86
5.08
5.75
1.68
7.78
4.56
4.83
1.42
8.71
4.78
5.06
1.52
CH30H*
20.66
9.19
10.60
3.23
19.66
9.38
11.01
3.22
14.83
8.41
9.14
2.67
16.90
8.79
9.61
2.87
CO
33.22
23.06
19.81
6.52
31.08
21.94
20.69
6.29
32.47
25.06
22.79
6.93
35.33
23.33
21.18
6.75
NOx
8.47
4.62
8.16
1.73
8.55
4.80
8.52
1.78
8.15
4.54
8.10
1.69
8.27
4.90
8.27
1.76
HCHO**
1256
1525
1205
369
1065
1323
1097
322
1543
1200
1038
327
1433
1275
1038
331
* Calculated values per proposed rulemaking.
** HCHO given in mg and mg/mi.
-------
E-2
Table E-2
Individual FTP Test Results
Unheated Catalyst Mode
Test Number/Type
HC
NMHC
HC* OMHCE* CH30H*
CO
NOx HCHO**
883239/Conf iguration A
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
883240/Configuration A
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
884121/Configuration A
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
884441/Conf iguration A
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
883242/Configuration B
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
883950/Conf iguration B
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
1.53
0.07
0.19
0.11
1.81
0.10
0.29
0.14
2.10
0.01
0.48
0.16
1.90
0.04
0.46
0.15
1.66
0.07
0.33
0.13
1.58
0.07
0.35
0.13
1.50
0.03
0.17
0.10
1.77
0.05
0.26
0.13
2.06
0.01
0.46
0.15
1.86
0.01
0.45
0.14
1.61
0.02
0.30
0.12
1.54 v
0.02
0.32
0.12
0.18
0.01
0.02
0.01
0.21
0.01
0.03
0.02
0.25
0.01
0.06
0.02
0.22
0.01
0.06
0.02
0.20
0.01
0.04
0.02
0.19
0.01
0.04
0.02
2.04
0.10
0.26
0.15
2.42
0.14
0.38
0.19
2.80
0.02
0.62
0.21
2.54
0.06
0.61
0.20
2.23
0.10
0.43
0.17
2.12
0.10
0.46
0.17
* Calculated values per proposed rulemaking.
** HCHO given in mg and mg/mi.
4.16
0.20
0.53
0.31
4.93
0.28
0.79
0.38
5.71
0.04
1.31
0.43
5.15
0.11
1.26
0.41
4.51
0.20
0.89
0.36
4.29
0.20
0.95
0.35
5.40
1.16
1.80
0.60
7.09
1.71
1.99
0.78
13.22
0.02
0.62
0.81
11.60
0.01
0.61
0.71
7.50
1.94
3.03
0.92
7.83
1.89
2.88
0.92
4.35
1.81
3.75
0.78
4.95
1.99
3.51
0.81
4.69
2.88
3.66
0.93
4.25
2.76
3.48
0.88
4.04
1.76
3.51
0.74
4.16
1.94
3.42
0.76
121
3
8
9
157
5
17
11
169
3
2
10
180
1
4
11
165
5
3
10
166
10
22
13
-------
E-3
Table E-3
Individual FTP Test Results
Catalyst
Test Number
884442
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
884443
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
884444
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
884445
Bag 1 (g)
Bag 2 (g)
Bag 3 (g)
Composite (g/mi)
HC
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
82
02
25
07
32
03
22
04
30
03
25
04
54
03
26
05
- Configuration C
Heated 10/20 Bag 1, 5/15 Bag 3
NMHC
0.76
0.01
0.21
0.06
0.28
0.01
0.19
0.03
0.24
0.01
0.23
0.03
0.46
0.01
0.22
0.04
HC*
0.10
0.01
0.03
0.01
0.04
0.01
0.03
0.01
0.04
0.01
0.03
0.01
0.06
0.01
0.03
0.01
OMHCE*
1.09
0.03
0.33
0.09
0.44
0.04
0.29
0.05
0.42
0.04
0.35
0.06
0.73
0.04
0.34
0.07
CH30H*
2.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
1.
0.
0.
0.
24
05
67
19
87
09
60
11
82
07
69
11
47
07
71
15
CO
15
0
1
1
7
0
1
0
10
0
1
0
12
0
1
0
.48
.02
.43
.00
.81
.02
.21
.54
.53
.06
.12
.70
.40
.04
.33
.82
NOx HCHO**
4.17
2.60
3.33
0.84
3.92
2.58
3.35
0.82
3.73
2.75
3.66
0.86
3.86
2.51
3.35
0.81
42
15
17
6
60
1
2
4
57
32
50
7
59
2
7
4
* Calculated values per proposed rulemaking.
** HCHO given in mg and mg/mi.
------- |