17

Table 5

Testing Limited To Current-Generation Catalyst
Bag 1 Of FTP Cycle
Air Assist To Catalyst

NMHC HC*® CH3;0H HCHO OMHCE co NOx
Category g g g ng g g g

Baseline

15/40 Heat/
No Air

30 Sec Air/No
Heat

60 Sec Air/No
Heat

120 Sec
Air/No Heat

15/40 Heat/
30 Sec Air

15/40 Heat/
60 Sec Air

15/40 Heat/
120 Sec Air

* Gasoline-fueled vehicle measurement procedure with a propane
calibrated FID.


11

Figure 5

QLOC Only, No Air Assist
Carbon Monoxide Emissions, Bag 1 of FTP

EHC Resistive Heat Configuration

Baseline 37.3
No Heat
3/90+
5/40
15/20
15/40

15/60

to) 10 20 30 40 50

Exhaust Carbon Monoxide (grams)
* Heat 3 Seconds Prior To Start,
90 Seconds Following Start

Table 3

Testing Limited To Current-Generation Catalyst
Bag 1 Of FTP Cycle
No Air Assist To Catalyst

NMHC HC* CH,0H HCHO OMHCE co Nox
Category g g g ng g g g

Baseline

No Heat/No
Air

3/90 Heat
5/40 Heat
15/20 Heat
15/40 Heat
15/60 Heat

* Gasoline-fueled vehicle measurement procedure with a Propane
calibrated FID.


21

The use of a MC also significantly assisted the conversion of
formaldehyde emissions. Roughly similar levels of formaldehyde
emissions from Bag 1 were measured from the heated/air assisted
QLOcC only (Configuration A) and the unassisted MC, Configuration B;
this data is presented in Figure 10. Substantial successive
decreases in aldehyde emissions were noted with the two-catalyst
configuration (C) when air only, then heat only, and finally
resistive heat/air assist were utilized. While the final two-
catalyst configuration tested yielded a very efficient 34
milligrams of formaldehyde in Bag 1, more additional testing would
have to be conducted to determine a more optimum resistive
heating/air addition strategy.

Figure 10
QLOC & MC, W/WO Air Assist

Formaldehyde Emissions, Bag 1 Of FTP

Catalyst/Heat/Air Configuration

Baseline WU), 1298

A, 15/40, 30 Aire

B, No Heat, No Air++
C, No Heat, No Air
C, No Heat, 100 Air

C, 15/40, No Aires

C, 15/40, 100 Air

0 400 800 1200 1600
Exhaust Formaldehyde (milligrams)
*A (EHC Only), 15/40 Heat, 30 Sec Air
**B (MC Only), No Heat, No Air
**sC (EHC+MC), 15/40 Heat, No Air


2

also reduced, to 34 milligrams over Bag 1 with QLOC resistive
heat/air addition. This was an 85 percent improvement from the 227
milligrams in Bag 1 measured when the two-catalyst system received
no resistive heating or air assist.

The largest increase in catalyst efficiency when resistive
heating/air assist was provided to the two-catalyst system occurred
for CO control, however. Almost 16 grams of CO were measured over
Bag 1 with the two-catalyst system, when the QLOC was not supplied
with resistive heating or additional air. CO was reduced to less
than two grams over Bag 1 with 15/40 resistive heating and 100
second air addition, a 90 percent reduction.

Improvements in Bag 1 emission levels generally caused average
FTP emissions to decrease almost proportionally to the decrease in
Bag 1 levels. With the resistively heated and air assisted two-
catalyst system, OMHCE were reduced to a low 0.07 grams per mile.
Formaldehyde emissions were also very low at only four milligrams
per mile. The greatest percentage increase in efficiency from
unassisted catalyst operation, however, was in the category of CO
emissions. The heated/air assisted two-catalyst system gave
average FTP CO emissions of only 0.2 grams per mile, an increase in
efficiency of 80 percent over unassisted catalyst operation.
Although Bag 1 NOx levels appeared to increase slightly with
increasing air addition times, the level of FTP NOx emissions was
0.7 grams per mile with the two-catalyst system either unassisted
or assisted with both resistive heating/air addition.

II. Introduction

The largest portion of methanol, carbon monoxide (CO), and
formaldehyde exhaust emissions from a catalyst-equipped M100-fueled
vehicle tested over the Federal Test Procedure (FTP) occur during
the cold start and catalyst warm-up phase in Bag 1.[1] The same is
generally true for hydrocarbon exhaust emissions from a catalyst-
equipped gasoline-fueled vehicle emission tested over the FTP. [2]
Emissions of oxides of nitrogen (NOx) at cold start are generally
not as significant as levels of NOx emissions generated later in
the cycle as they are produced at higher concentrations under
greater load after the engine has warmed. Cold start is defined
here as following a vehicle soak of 12-36 hours at 72-86°F.[3]

A catalytic converter is generally ineffective for oxidizing
emissions of methanol and formaldehyde from an M100-fueled vehicle
until the converter has reached catalytically active, or light-off
temperature. Though this temperature varies for the catalyst
considered, light-off temperatures for typical three-way converters
of 350°C have been recently mentioned in the literature[4] when
referring to the performance of an electrically heated catalyst
(EHC). Resistively heating the substrate and thereby the catalyst
to light-off temperature at cold start reduces the time during
which the catalyst remains ineffective because of insufficient


18

Table 6

Testing Limited To Current-Generation Catalyst
FTP Composite Emission Levels

Air Assist To Catalyst

NMHC HC*® CH30H HCHO OMHCE co NOx
Category g/mi g/mi ss g/mi_ mg/mi_ g/mi g/mi g/mi

Baseline

15/40 Heat/
No Air

30 Sec Air/No
Heat

No Heat/60
Sec Air

No Heat/120
Sec Air

15/40 Heat/
30 Sec Air

15/40 Heat/
60 Sec Air

15/40 Heat/
120 Sec Air

* Gasoline-fueled vehicle measurement procedure with a propane
calibrated FID.


24

Table 7

Quick Light-Off And Main Catalyst Testing
Bag 1 Of FTP Cycle

NMHC HC* CH30H HCHO OMHCE co NOx
Category g g g mg g g g

Baseline

15/40 Heat/No
Air/No Main
Catalyst

No Heat/60 Sec
Air/No Main
Catalyst

15/40 Heat/30
Sec Air/No Main
Catalyst

Main Catalyst
Only/No Heat/No
Air

QLc + Main No
Heat/No Air

QLC + Main
No Heat/100 Sec
Air

QLc + Main
15/40 Heat/No
Air

QLC + Main
15/40 Heat/100
Sec Air

* Gasoline-fueled vehicle measurement procedure with a propane
calibrated FID.


20

Figure 9
QLOC & MC, W/WO Air Assist

Methanol Emissions, Bag 1 Of FTP

Catalyst/Heat/Air Configuration

Baseline

A, 15/40, 30 Aire

B, No Heat, No Aire*
G, No Heat, No Air
C, No Heat, 100 Air
C, 15/40, No Airss*

C, 15/40, 100 Air

° 5 10 16 20 25

Exhaust Methanol (grams)
+A (EHC Only), 15/40 Heat, 30 Sec Air
**B (MC Only), No Heat, No Air
***C (EHC+MC), 15/40 Heat, No Air

The QLOC alone, in Configuration "A," provided good methanol
conversion efficiency in spite of its limited size. The simulated
MC alone, however, was not nearly as efficient for methanol
conversion. The Bag 1 emission level of 10.02 grams of methanol
was comparable to the smaller QLOC's performance (10.69 grams,
Figure 3) in the unheated, no air assist mode. Adding the QLOC in
front of the MC did not improve methanol emissions to much below 8
grams/Bag 1. Even with the addition of air for 100 seconds, the
decrease in emissions to 6.08 grams was only a small improvement
from the 7.54 grams noted with the addition of air for 60 seconds
over the QLOC only (Figure 6).

Heating the QLOC + MC configuration, in the absence of excess
air, significantly lowered methanol emissions from levels obtained
with the heated QLOC only. 1.46 grams of methanol in Bag 1 were
noted with the two-catalyst system and the QLOC heated 15/40 in Bag
1. This is a 63 percent decrease from the 3.95 grams measured with
QLOc alone heated over the 15/40 convention (Figure 3). With 100
seconds of excess air added in front of the two-catalyst
configuration, methanol emissions were reduced again very
significantly to 0.37 grams/Bag 1.


15

Figure 7

QLOC Only, With Air Assist
Formaldehyde Emissions, Bag 1 Of FTP

EHC Resistive Heat/Air Addition

Baseline

No Heat, No Air
Heat Only

60 Sec Air Only
Heat, 30 Sec Air
Heat, 60 Sec Air

Heat, 120 Sec Air

1) 400 800 1200 1600
Exhaust Formaldehyde (milligrams)
* Heat 15 Seconds Prior To/40 Seconds
Following Start, 30 Seconds Air
Addition Following Start

Figure 8

QLOC Only, With Air Assist
Carbon Monoxide Emissions, Bag 1 Of FTP

EHC Resistive Heat/Air Addition

Baseline

No Heat, No Air
Heat Only

60 Sec Air Only
Heat, 30 Sec Air+
Heat, 60 Sec Air

Heat, 120 Sec Air

Lo) 10 20 30 40 50
Exhaust Carbon Monoxide (grams)

+ Heat 15 Seconds Prior To/40 Seconds
Following Start, 30 Seconds Air
Addition Following Start


Most of the emission results in this report are computed using
the methods outlined in the "Final Rule For Methanol Fueled Motor
Vehicles And Motor Vehicle Engines," which was published in the
Federal Register on Tuesday, April 11, 1989. Because these
specialized procedures and calculation methods are not in
widespread use, we have also included a hydrocarbon result which is
what would be obtained if the exhaust was treated as if the fuel
were gasoline. This is done as a convenience for the readers and
users of the report who may be more familiar with hydrocarbon
results obtained this way.

vI. Tes ocedures

This program had as its goal the evaluation of a QLOC provided
by Camet Co. for the reduction of unburned fuel, CO and
formaldehyde emissions from a methanol-fueled vehicle.

The evaluation consisted of three distinct phases which are
discussed separately in the following section. The first phase
consisted of a preliminary evaluation of the QLOC on the test
vehicle. All emissions testing was conducted over the FTP cycle,
and resistive heating was limited to different schemes during the
cold start portion of Bag 1. All of the testing in this evaluation
was conducted at 72-73°F conditions.

The next phase of the evaluation involved the addition of air
during resistive heating to assist the oxidation of unburned fuel,
CO and formaldehyde. This air addition allowed the catalyst to
function as an oxidation catalyst; the catalyst formula, however,
was a typical three-way variety. The QLOC alone was evaluated
during this phase. Testing was conducted over the FTP cycle and
resistive heating/air addition was again limited to the cold-start
portion of Bag 1.

The final phase of the evaluation had the QLOC employed as a
true warm-up catalyst. A main catalyst was added underfloor in
series behind the QLOC. The purpose of the main converter was to
provide sufficient catalyst volume and activity to reduce emissions
to very low levels over a wide variety of engine speed and load
conditions following catalyst warm-up.

Air addition in front of the QLOC, as well as resistive
heating, were utilized in Bag 1 during this phase of the
evaluation. Because the QLOC was located upstream from the main
catalyst, any excess air added in front of it would also affect the
operation of the main catalyst. The air assist was utilized for
only limited periods following key-on, however; it was thought that
limiting the addition of air to these brief periods would limit the
effect on any possible increase in oxides of nitrogen due to the
converter.


30

14. Sales Literature, Electrically Heated Catalytic
Converter, Camet Co., Hiram, OH.

15. Formaldehyde Measurement In Vehicle Exhaust At MVEL,
Memorandum, Gilkey, R. L., OAR, OMS, EOD, Ann Arbor, MI, 1981.

16. "Formaldehyde Sampling From Automobile Exhaust: A
Hardware Approach," Pidgeon, W., EPA/AA/TEB/88-01, July 1988.

17. "Sample Preparation Techniques For Evaluating Methanol
and Formaldehyde Emissions From Methanol-Fueled Vehicles and
Engines," Pidgeon, W., and M. Reed, EPA/AA/TEB/88-02, September
1988.

18. "Catalysts for Methanol Vehicles," SAE Paper 872052,
Piotrowski, G. K., and J. D. Murrell, November 1987.


27

addition. This was an 85 percent improvement from the 227
milligrams in Bag 1 measured when the two-catalyst system received
no resistive heating or air assist.

The largest increase in catalyst efficiency when resistive
heating/air assist was provided to the two-catalyst system occurred
for CO control, however. Almost 16 grams of CO were measured over
Bag 1 with the two-catalyst system, when the QLOC was not supplied
with resistive heating or additional air. CO was reduced to less
than two grams over Bag 1 with 15/40 resistive heating and 100
second air addition, a 90 percent reduction.

Improvements in Bag 1 emission levels generally caused average
FTP emissions to decrease roughly proportionally to the decrease in
Bag 1 levels. With the resistively heated and air assisted two-
catalyst system, OMHCE were reduced to a low 0.07 grams per mile.
Formaldehyde emissions were also very low at only four milligrams
per mile. The greatest percentage increase in efficiency from
unassisted catalyst operation, however, was in the category of CO
emissions. The heated/air assisted two-catalyst system gave
average FTP CO emissions of only 0.2 grams per mile, an increase in
efficiency of 80 percent over unassisted catalyst operation.
Although Bag 1 NOx levels appeared to increase slightly with
increasing air addition times, the level of FTP NOx emissions was
0.7 grams per mile with the two-catalyst system either unassisted
or assisted with both resistive heating and air addition.

IX. Future Efforts

Future efforts will be made to quantify the relationship
between catalyst heating/air addition and real time emission rates
of individual pollutants. These efforts will be concerned only
with the period of time during which resistive heating and/or air
addition is occurring.

A Horiba modal analysis system has been installed at the EPA
Motor Vehicle Emissions Laboratory; this analyzer will be used to
map the effects of changes in catalyst resistive heating/air
addition on emissions. While it is not possible to obtain methanol
or formaldehyde analysis, CO, NOx, and FID-measured hydrocarbons
emission levels will be determined.

xX. Acknowledgments

The catalysts evaluated in this test program were supplied by
Camet Co., located in Hiram, Ohio. Camet is a manufacturer and
sales agent for W. R. Grace and Company. The methanol-fueled test
vehicle was supplied by Volkswagen of America.


4

Figure 1

Camet Resistively Heated Catalyst

Table 1

Detailed Specifications Of Quick
Li Of talyst Evaluated

Specification

Camet Model Number 10-15
Catalyst Volume 216 cm?
Rated Power Usage (Camet Data) 2,800 watts
Approx. Heating Time To 650°F 14 seconds
-Substrate Material Stainless steel foil
Back Pressure At 55 mph 230 mm of H,0
Length Between Edges Of End Pipes 107 mn
Catalyst 5:1 Pt:Rh, 1.41 g/liter
Battery Used To Supply Resistive Heating Action Pack, 12V

Deep Cycle/Marine Battery,
115 Amp-Hr


3

warming by the relatively cold exhaust gas. This accelerated
warmup would also have the advantage of occurring when the engine
is cold and producing higher levels of unburned fuel and CO because
of operation under relatively richer conditions.

EPA has been interested in catalyst preheating for some time
and has conducted evaluations of resistively heated catalyst
technologies supplied by Camet Co.[1,5,6,7,8,9] This work has
involved both methanol and gasoline-fueled vehicle applications.
Other sources, both government and industry, have conducted
evaluations of this technology and published test
results. [(4,10,11,12,13] These other efforts have involved
primarily gasoline-fueled test vehicles.

The Camet catalysts previously evaluated by EPA were a
prototype design, consisting of a resistively heated segment and a
slightly larger nonresistively heated main catalyst. These two
segments were placed in close proximity to each other in the same
converter shell. The end of the shell containing the resistively
heated segment was placed upstream in the exhaust during the
previous EPA evaluations. A complete description of these
prototype converters was provided in an earlier report published by
Camet; details are also given here below in the section providing
a description of the catalysts evaluated.

The current generation of EHC now furnished by Camet to
automakers for evaluation consists of a single resistively heated
segment. This unit is designed specifically as a quick light-off
catalyst, to oxidize excess emissions of unburned fuel and CO
following cold start.[14] Camet suggests that a standard
underfloor catalytic converter system may also be necessary to
reduce unburned fuel and CO emissions from most vehicles to very
low levels. Camet supplied EPA with a current-generation EHC for
evaluation on an M100-fueled vehicle. This catalyst was evaluated
by EPA as part of an effort to identify and determine the
effectiveness of novel emission control technologies. The details
of the technology evaluated and the test procedures are given
below. All of the testing referred to here consists of an
evaluation of fresh, unaged catalysts.

III. Description Of Catalytic Converters

The catalytic converter of primary interest in this evaluation
is referred to hereafter as the quick light-off catalyst (QLOC).
The QLOC uses a single-segment, resistively heated stainless steel
foil substrate, configured into a honeycomb (Figure 1). The total
volume of the honeycomb was approximately 200 cm’, and the energy
for heating was supplied from a dedicated 12-volt, 115 amp-hour,
deep cycle battery. The QLOC evaluated here was a fresh, unaged
catalyst. A solid-state power controller, normally supplied by
Camet to regulate the high current involved, was not used in this
evaluation. Instead, a switch and engine starter motor relay were
used to supply energy from the dedicated battery when desired. A
typical three-way catalyst formulation was used; Table 1 contains
more detailed specifications of the QLOC.


16

gasoline-fueled EHC-equipped vehicle when air addition is used. (2]
The addition of air in front of the catalyst evaluated here
provided a very significant enhancement of EHC activity for CO
removal.

Figure 8 provides Bag 1 CO emissions data for the EHC with air
addition. As mentioned above, catalyst heating alone provided
virtually no benefit for CO beyond unheated catalyst emission
levels. Sixty seconds of air addition following start reduced CO
to approximately 12.7 grams, a 33 percent decrease from no-heat/no-
air catalyst operation.

Catalyst heating with increasing lengths of air addition time
provided significant increases in CO conversion efficiency. The
15/40 heating scheme, with 30 seconds of air addition following
start, gave the same level of Bag 1 CO, 12.7 grams, as the addition
of air only for 60 seconds. Increasing the time of air addition to
a full 60 seconds with catalyst heating decreased CO by roughly 50
percent to 5.9 grams. (This convention involved air addition for
approximately 20 seconds following the end of catalyst heating.)
When the period of air addition was increased to 120 seconds, a
further substantial decrease in CO emissions resulted. While it
appears from these tests that catalyst resistive heating may
provide a useful assist to an oxidation catalyst for CO control,
more tests would have to be conducted to quantify the contribution
of the heating. Different heating conventions could also be tried
to determine a scheme that would more effectively complement the
air addition strategy selected.

Bag 1 emissions data is summarized in Table 5. OMHCE trend in
the same general direction as the heaviest organic component by
total weight actually measured (methanol). A slight increase in
NOx emissions was noted as air addition over the three-way catalyst
was increased to 120 seconds. This increase was minimized by the
limitation of catalyst air assist to relatively short periods of
time of excess CO/unburned fuel emissions following cold start.

Table 6 presents the average FTP results for each emissions
category. Because the Bag 1 emissions of the pollutants of
interest here are such a significant component of average FTP
emissions of these pollutants, it was expected that any improvement
in Bag 1 emissions would be manifest in FTP emissions. This indeed
was noted in most cases.

Though it is not possible to select an optimum catalyst
operating strategy based upon the limited testing commented on
here, the 15/40 heating/30 second air addition strategy appears to
be relatively effective. Air addition time is kept to a minimun,
reducing any cooling effect on the heated substrate. Excess


6

Figure 2

Main Catalyst Used in Program

Table 2

Detailed Specifications Of
Main Catalyst*

Simulated

Camet Model
Dimensions:

Frontal Area
Length
cells/cm?
Weight

Catalyst Type/Loading

Unheated segment,

Designed Power Rating

* From Reference 4, no
segment during current testing.

Specifications
Prototype
Model 513

54 cm? heated brick,
57 cm* unheated brick

8.9 cm heated brick,
8.9 cm unheated brick

20, heated segment
50, unheated segment

240 g, heated segment
345 g, unheated segment

Heated segment 3:1 Pt:Pd,

1.06 g/liter
6.7:1 Pt:Rh,
1.41 g/liter

3,000 watts

heat applied to resistively heated


22

Figure 11 presents CO emissions over Bag 1 for Configuration
Cc. Though not shown there, it should be recalled that the QLOC
alone, with 120 seconds air assist, gave very low Bag 1 CO
emissions of only 4.5 grams (Figure 8).

Figure 11

QLOC & MC, W/WO Air Assist
Carbon Monoxide Emissions, Bag 1 Of FTP

Catalyst/Heat/Air Configuration

Baseline

A, 15/40, 30 Aire

B, No Heat, No Aires
C, No Heat, No Air
C, No Heat, 100 Air

C, 15/40, No Airees

C, 15/40, 100 Air

° 10 20 30 40 50
Exhaust Carbon Monoxide (grams)
*A (EHC Only), 15/40 Heat, 30 Sec Air
**B (MC Only), No Heat, No Air
***C (EHC*MC), 15/40 Heat, No Air

CO emissions rose slightly above MC only levels, when the QLOC
was placed in front of it in the exhaust stream (no resistive heat
or air assist utilized). No reason for this unexpected occurrence
is given here. No unusual driving conditions or engine problems
were noted during this testing that might have contributed
substantially to this unexpected result.

The addition of air and the use of QLOC resistive heating
separately had a beneficial effect on catalyst performance. The
use of 100 seconds of air addition alone reduced Bag 1 CO emissions
by 50 percent to 7.4 grams, over no heat/no air emission levels
with the two-catalyst system. QLOoc heating in the absence of
additional air also reduced CO, to approximately 10 grams/Bag 1.
This was a 35 percent improvement from _ the two-catalyst
configuration which did not rely on QLOC resistive heating. This
improvement was not noted when the QLOC was heated in the absence
of a MC (Figure 5).


EPA/AA/CTAB/91-03

Technical Report

Evaluation Of Camet Resistively Heated
Metal Monolith Catalytic Converters
On An M100 Neat Methanol-Fueled Vehicle

Part III

by

Gregory K. Piotrowski
Ronald M. Schaefer

duly 1991

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, MI 48105


Figure 3
QLOC Only, No Air Assist
Methanol Emissions, Bag 1 Of FTP

EHC Resistive Heating

Baseline

No Heat

3/90°

5/40

15/20

15/40

15/60

to) 5 10 15 20 25

Exhaust Methanol (grams)
+ Heat 3 Seconds Prior To Start,
90 Seconds Following Start

Figure 4

QLOC Only, No Air Assist
Formaldehyde Emissions, Bag 1 of FTP

EHC Resistive Heating

Baseline

No Heat

3/90*

5/40

15/20

15/40

15/60

0 200 400 600 800 1000 1200 1400 1600
Exhaust Formaldehyde (milligrams)
* Heat 3 Seconds Prior To Start,
90 Seconds Following Start


VII. Discussion Of Test Results

A. QLoc Only, Without Air Assist

This evaluation consisted of three separate phases. The first
phase, commented on in this section, consisted of a brief
evaluation of the QLOC without the benefit of air assist or a
larger main catalyst.

During all phases of this evaluation, resistive heating and
air assist were restricted to the cold-start portion of Bag 1 of
the FTP. The first 505 seconds of the FTP is commonly referred to
as Bag 1; the cold-start portion consists of the initial minutes of
Bag 1 during which the engine and exhaust system heat to a
relatively steady-state temperature. The following discussion
comments on differences in exhaust emission levels which may be
related to oxidation catalyst operation, catalyst resistive heating
or both. Bag 1 emission levels are given in grams of emissions
over the test segment (Bag 1) except for formaldehyde, which are
presented in milligrams over Bag 1. Composite FTP emissions are
given in tabular form in grams per mile except for formaldehyde,
which are presented in milligrams per mile.

Figure 3 presents Bag 1 methanol emission levels during the
first phase of the evaluation. Several catalyst heating
conventions were tried to gauge the effectiveness of changes in
heating strategy. The notation used in Figure 3 and thereafter to
denote the heating convention utilizes two numbers separated by a
slash. The first number refers to the number of seconds of
catalyst resistive heating applied prior to key-on (start) in Bag
1; the second number refers to the number of seconds of resistive
heating applied immediately following cold start. All heating
conventions involved 3-15 seconds of heating prior to start.
Fifteen seconds of heating prior to key-on may be impractical in
order to accommodate the driver's desire for a quick start/drive
sequence, as well as for possible catalyst durability concerns. A
15-second heating period prior to start, however, ensured a warmed
substrate and surroundings for these laboratory experiments.

Bag 1 emissions of methanol were reduced almost 50 percent
from baseline levels by the small QLOC, without the aid of
resistive heating. Resistive heating, even in the absence of
additional air to promote oxidation, increased the efficiency of
the catalyst significantly. Heating the catalyst for 90 seconds
following start reduced methanol emissions from unheated catalyst
levels almost 50 percent. It is less clear, however, how changes
in the catalyst heating convention affected emissions when compared
to levels from 3/90 catalyst heating. Increasing the time interval
of resistive heating prior to key-on appeared to increase the
heated catalyst's effectiveness. The three conventions which had
15-second heat periods prior to key-on had Bag 1 emission levels of
methanol roughly 20 percent lower than the 3/90 heating
configuration. Extending catalyst heating after key-on for modes
utilizing 15-second heating periods prior to start gave mixed


29

XI. References

1. “Evaluation of Resistively Heated Metal Monolith
Catalytic Converters On An M100 Neat Methanol-Fueled Vehicle, Part
II," Piotrowski, Gregory K., EPA/AA/CTAB/89-09, December 1989.

2. Air Injection To An Electrically-Heated Catalyst For
Reducing Cold Start Benzene Emissions From Gasoline Vehicles," SAE
Paper 902115, Heimrich, Martin J., 1990.

3. 1975 Federal Test Procedure, Code of Federal Regulations,
Title 40, Part 86.

4. "Recent Developments In Electrically Heated Metal
Monoliths," SAE Paper 900503, Whittenberger, W. A. and J. E. Kubsh,
February 1990.

5. "Resistive Materials Applied To Quick Light-off
Catalysts," SAE Paper 890799, Hellman, Karl H., et al., March 1989.

6. "Recent Results From Prototype Vehicle And Emission
Control Technology Evaluation Using Methanol Fuel," SAE Paper
901112, Hellman, Karl H., and G. K. Piotrowski, May 1990.

7. "A Resistively Heated Catalytic Converter With Air
Injection For Oxidation Of Carbon Monoxide And Hydrocarbons At
Reduced Ambient Temperatures," Piotrowski, Gregory K.,

EPA/AA/CTAB/89-06, September 1989.

8. "Evaluation Of A Resistively-Heated Metal Monolith
Catalytic Converter On A Gasoline-Fueled Vehicle," Piotrowski,
Gregory K., EPA/AA/CTAB/88-12, December 1988.

9. "Evaluation of A Resistively-Heated Metal Monolith
Catalytic Converter On A M100 Neat Methanol-Fueled Vehicle," Blair,
D. M., and G. K. Piotrowski, EPA/AA/CTAB/88-08, August 1988.

10. "Evaluation of Metallic And Electrically Heated Metallic
Catalysts On A Gasoline Fueled Vehicle," SAE Paper 900504, R. G.
Hurley, et al., February 1990.

11. “Electrically Heated Metal Substrate Durability," SAE
Paper 910613, Whittenberger, W. A., and J. E. Kubsh, February 1991.

12. “Electrically Heated Catalyst System Conversions On Two
Current-Technology Vehicles," SAE Paper 910612, Heimrich, M. J., et
al., February 1991.

13. “Formaldehyde Emission Control Technology For Methanol-
Fueled Vehicles," SAE Paper 902118, L. R. Smith, et al., 1990.


28

The authors appreciate the efforts of James Garvey, Steven
Halfyard, Robert Moss, Rodney Branham, and Ray Ouillette of the
Test and Evaluation Branch, ECTD, who conducted the driving cycle
test and prepared the methanol and formaldehyde samples for
analysis. The authors also appreciate the efforts of Jennifer

Criss and Leslie Cribbins of CTAB, ECTD, for word processing and
editing support.


5

The Camet QLOC tested here may not be a substitute for a
larger volume main catalyst (MC). A MC was added in series with
the QLOC in order to reduce emission levels over the remainder of
the FTP to the low levels experienced with a conventional three-way
catalyst. The simulated MC was a two-segment Camet EHC prototype
previously evaluated by EPA.

This simulated MC (Figure 2) consisted of resistively heated
and nonresistively heated segments canned in very close proximity
to each other in a common shell. No resistive heating was applied
to the EHC portion of this simulated main catalyst during any of
the testing conducted as part of the current evaluation. Table 2
contains detailed specifications of this catalyst.

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 lbs inertia weight and 7.7 actual
dynamometer horsepower. This vehicle was loaned to the U. S. EPA
by Volkswagen of America.

A detailed description of the vehicle and special methanol
modifications were provided in an earlier report. [9]

v. Test Facilities And Analytical Methods

Emissions testing at EPA was conducted on a Clayton Model ECE-
50 double-roll chassis dynamometer, using a direct-drive variable
inertia flywheel unit and road load power control unit. The Philco
Ford constant volume sampler 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.(15,16] 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
Le effluent stream.

The procedure developed for methanol sampling and presently
in-use employs water-filled impingers through which are pumped a
sample of the dilute exhaust or evaporative emissions. The
methanol in the sample gas dissolves in water. After the sampling
period is complete, the solution in the impingers is analyzed using
gas chromatographic (GC) analysis.[{17]


19

formaldehyde and NOx formation are also minimized by reducing the
air addition time, and the lowest rates of methanol and
formaldehyde emissions were noted with this catalyst operating
procedure. It should be recalled, however, that this QLOC has a
small volume and it requires the assistance of a larger main
catalyst, according to the manufacturer, Camet Inc. Therefore,
although the small QLOC was generally more efficient when
resistively heated and operated in the oxidation catalyst mode, it
would still be necessary to use a larger main catalyst to ensure
better performance. The lowest formaldehyde emission level noted
here, 50 milligrams/mile far exceeded the California standard of 15
milligrams/mile over the FTP, even at low mileage.

Cc. QLOc + Main Catalyst, With/Without Air Assist

The QLOC evaluated here used a small substrate in order to
minimize the power requirements for catalyst heating. The smaller
volume also ensures ease of location, wherever desired, in the
exhaust system. According to Camet, it is necessary to equip
vehicles with a larger, nonresistively heated catalyst in order to
reduce pollutant emissions to very low levels over the entire FTP.

A metal monolith catalyst, described earlier in Section III,
was installed immediately following the QLOC underfloor to simulate
a QLOC assisted by a main catalyst. The larger main catalyst also
had the capability of being resistively heated, however, at no time
during the testing commented upon here was any resistive heating
applied to the main catalyst. Catalyst heating of the QLOC was
limited to the 15/40 convention, and air addition occurred over
100-second intervals.

Three separate catalyst configurations are referred to in the
remaining Figures. Configuration "A" refers to the electrically
heated catalyst only, without benefit of a main catalyst in the
exhaust. This data is from the catalyst testing with 15/40 heating
and air addition for 30 seconds. Configuration "B" refers to
testing conducted with the main catalyst only present in the
exhaust stream. No resistive heating or air addition was used
during this testing. Configuration "C" is the QLOC with the main
catalyst close coupled downstream. Resistive heating here was
limited to 15/40, and air addition occurred in front of the QLOC.
This additional air was added for intervals of 100 seconds
following start in Bag 1. Because the MC was coupled immediately
downstream of the QLOC, the activity of the MC would also be
affected by the supplemental air.

Figure 9 presents emissions data from the QLOC + MC testing,
compared with other selected test results of single converter
systems. The catalyst system denoted "A" is a mode of QLOC
operation discussed previously that appeared more efficient with
respect to other QLOC operating conventions evaluated. Catalyst
system "B" refers to the evaluation of the MC without the QLOC in
the exhaust.


25

Table 8

Quick Light-Off And Main Catalyst Testing
FIP Composite Emission Levels

Category

Baseline

NMHC
g/mi

HC*®
g/mi

CH,0H
g/mi

HCHO OMHCE

mg/mi__g/mi

co
g/mi

NOx
g/mi

15/40 Heat/No
Air/No Main
Catalyst

No Heat/60 Sec
Air/No Main
Catalyst

15/40 Heat/30 Sec
Air/No Main
Catalyst

0.30

50

Main Catalyst
Only/No Heat/No
Air

0.26

0.73

22

0.35

QLC + Main No
Heat/No Air

16

QLC + Main
No Heat/100 Sec
Air

13

QLC + Main 15/40
Heat/No Air

QLC + Main 15/40
Heat/100 Sec Air

* Gasoline-fueled vehicle measurement procedure with a propane

calibrated FID.



I. Summary

A low mileage resistively heated catalytic converter of a type
currently furnished by the Camet Co. to automakers was evaluated on
a methanol fueled vehicle. This converter was smaller in volume
than typical three-way catalytic converters used on current model
year vehicles of comparable engine displacement, and is designed
specifically as a quick light-off catalyst (QLOC) by Camet.

The QLOC was evaluated in three separate modes. First, the
QLOoc was placed in the exhaust stream of the test vehicle and
evaluated without the benefit of catalyst air assist (simulated
oxidation catalyst) or a larger main catalyst (MC) also present
downstream. Next, the QLOC was tested with resistive heating and
simulated air assist, but without a MC in the exhaust. Finally, a
low mileage nonresistively heated MC was added immediately
downstream of the QLOC. This two-catalyst system was then
evaluated with resistive heating applied to the QLOC and catalyst
air assist. Because the additional air was added in front of the
QLoc, this air assist also affected the operation of the larger MC
positioned downstream.

With the QLOC alone and resistive heating applied for 15-
seconds prior to and 40 seconds following cold start (15/40
resistive heating), Bag 1 emissions from the Federal Test Procedure
(FTP) cycle were reduced 50 percent from unheated catalyst levels.
Only a slight reduction in formaldehyde, and no change in carbon
monoxide (CO) Bag 1 emission levels were noted when this catalyst
was resistively heated.

Air was added in front of the catalyst at an average rate of
5 SCFM for short intervals following start in Bag 1. The addition
of air for 30 seconds to the 15/40 resistively heated catalyst
decreased Bag 1 methanol emissions a further 54 percent from heated
catalyst only levels, to 1.83 grams. Bag 1 formaldehyde levels
were reduced 30 percent when air assist was provided for 30 seconds
to the resistively heated catalyst. CO levels decreased as the
time period of air addition was increased. CO was reduced to 12.7
grams over Bag 1 with air addition for 30 seconds to the heated
catalyst, a 33 percent decrease from heated-catalyst-only levels.
cO emissions continued to decrease, to 4.5 grams in Bag 1 as the
air assist period was extended to 120 seconds following start in
Bag 1.

The addition of the MC behind the QLOC had the effect of
reducing Bag 1 emissions of methanol, CO and formaldehyde to very
low levels, while contributing to only a slight reduction in Nox
emission levels. The most efficient configuration of the two-
catalyst system modes evaluated utilized the 15/40 resistive
heating schedule mentioned above and air addition for 100 seconds
following cold start in Bag 1. The simultaneous use of these two
assists decreased Bag 1 methanol emissions to 0.37 grams. This was
down from 7.95 grams measured with no resistive heat or air assist
provided to the two-catalyst system. Formaldehyde emissions were


12

Table 4
Testing Limited To Current-Generation Catalyst

FTP Composite Emission Levels
No Air Assist To Catalyst

NMHC HC* CH30H HCHO OMHCE co NOx

Category g/mi g/mig/mi_ se mg/mi_g/mi g/mi g/mi
Baseline 0.28 1.17 2.93 323 1.63 7.3 1.6
No Heat/No 0.04 0.31 0.80 61 0.42 1.7 0.8
Air
3/90 Heat 0.03 0.18 0.46 47 0.26 1.4
5/40 Heat 0.04 0.21 0.49 59 0.29
15/20 Heat 0.02 0.17 0.43 57 0.24
15/40 Heat 0.03 0.16 0.36 51 0.22
15/60 Heat 0.01 0.18 0.51 66 0.27
* Gasoline-fueled vehicle measurement procedure with a propane

calibrated FID.

In summary, even without air assist to the QLOC, resistive
heating significantly decreased emission levels of methanol over
the FTP. Only marginal improvement in average FTP formaldehyde
emissions was noted with resistive heating, and no substantial
lowering of CO levels was noted with resistive heating alone. NOx
emissions over the FTP were relatively unaffected by resistive
heating.

B. QLoc Only, With Air Assist

Even if a catalyst is resistively heated during cold start,
its effectiveness may be lessened by the absence of sufficient
oxygen in the exhaust to bring the desired oxidation reactions to
completion. In some cases, a lack of oxygen may promote partial
combustion to undesired intermediate products. Air addition before
the catalyst may supply sufficient oxygen to the relatively rich
exhaust to promote the desired oxidation of unburned fuel and
intermediate products (formaldehyde and CO). Alternatively, a flow
of ambient air through an EHC may have the undesirable effect of
hindering NOx reduction activity and cooling the resistively heated
substrate.


14

As previously shown in Figure 3, resistive heating alone over
the 15/40 heating convention provided better than a 60 percent
reduction in unburned fuel emissions from unheated catalyst levels.
The addition of air for 60 seconds following start in Bag i also
reduced methanol emissions, yet these levels were almost twice as
high as those noted when the catalyst was resistively heated. Air
flowrate over the catalyst did not vary much because of changes in
the flowrate of exhaust; fluctuations of only 0.1-0.2 £t?/minute of
air were noted.

The combination of air addition and resistive heating appeared
to improve the efficiency of the EHC substantially with respect to
methanol emissions. This improvement did not continue as the
length of time the air addition occurred was lengthened, however.
A roughly 50 percent improvement in efficiency was noted when air
was added for 30 seconds to the heated catalyst (15/40 heating).
The level of methanol emissions rose slightly when air addition
time was increased to 60 seconds; a similar increase in the level
of methanol emissions was noted at 120 seconds of air addition.
Additional testing would have to be conducted to determine the
statistical significance of the rise in methanol emissions noted
when the length of air addition was increased to 60 seconds.

Figure 7 presents the levels of formaldehyde emissions noted
when air assist was used. The addition of air, in the absence of
catalyst heating, caused formaldehyde levels to increase above
nonresistively-heated catalyst levels. In this first case, air was
added for 60 seconds following start in Bag 1. When the catalyst
was resistively heated, and air was added for only 30 seconds
following start, Bag 1 formaldehyde emissions were reduced to 286
milligrams. As the air flow was extended over longer time periods,
up to 120 seconds following start, formaldehyde levels increased.
At the level of 2 minutes of air addition, in spite of 15/40
catalyst heating, formaldehyde levels increased to exceed levels
from no heat/no air catalyst testing.

It is interesting to note that the single heat/air scheme at
which formaldehyde levels were lower than heated catalyst only
levels involved air addition for only 30 seconds following start.
The heating scheme used here, 15/40 involved resistive heating for
40 seconds following start. The other two heat/air configurations
had air addition times that exceeded the period of catalyst heating
(40 seconds). It is not known how significant the period of air
addition in the absence of catalyst heat is to the production of
aldehydes during Bag 1. Given the 15/40 heating scheme, more
testing, preferably using modal analysis, would have to be
conducted to determine a more optimum air flowrate and addition
period.

In previous testing on a gasoline-fueled vehicle at lower
temperatures, a significant decrease in CO emissions was noted when
air addition was used with a resistively heated catalyst.[(7] Other
researchers have noted an improvement in CO efficiency from a


I.

Il.

III. Description of Catalytic Converters

Iv.

v.

VI.

Table of Contents

Summary ........

Introduction. .....

Description of Test Vehicle .

Test Facilities and Analytical Methods.

Test Procedures ....

VII. Discussion of Test Results.

A. QLOc Only, Without Air Assist.

B. QLOoc Only, With Air Assist .

Cc. QLOoc + Main Catalyst, With/Without

VIII.Evaluation Highlights .

Ix.

xX.

XI.

Future Efforts. ....
Acknowledgments ....

References. .....-.

Air Assist.

Page
Number


23

A very big assist for CO control to Configuration Cc was
provided by combined QLOC resistive heating and the addition of
excess air. Bag 1 emissions of CO were reduced to 1.7 grams, a
very significant decrease from levels measured when either
resistive heating or excess air was employed alone. Again, more
testing would have to be conducted, however, to obtain an optimum
resistive heating/air addition strategy for CO.

A summary of Bag 1 emissions from the two-catalyst system
testing is given below in Table 7. Although much of the data there
has been discussed above, one new observation which may be made is
that the addition of the main catalyst did not cause a significant
decrease in NOx emissions in Bag 1. The MC by itself was effective
as a NOx removal catalyst, yet its additional catalyzed surface
area did not substantially lower Bag 1 NOx emissions when added
behind the QLOC. Slight trends toward increased NOx efficiency
with catalyst heating and decreased NOx efficiency with air
addition were noted with the QLOC + MC configuration. Reduced
levels of other emissions, caused by the increased conversion
efficiency of the heated/air assisted QLOC, may play a significant
role in the ability of the MC to reduce NOx emissions. More
detailed work would have to be conducted to quantify the effects of
the reduction of other emission levels caused by catalyst
heating/air assist on NOx conversion efficiency, however.

Table 8 presents FTP average emissions from the QLOC + MC
evaluation. The very low Bag 1 CO levels from the two-catalyst
system using both resistive heating and air addition significantly
lowered CO over the FTP. The configuration utilizing 15/40
resistive heating and 100 seconds of air addition was the most
effective configuration tested overall. While the CO levels of 0.2
grams per mile were very low, emissions of formaldehyde were also
measured at only four milligrams per mile with this configuration,
well under the level of California standard of 15 milligrams per
mile. It must be pointed out that these 4 mg/mi emission levels
were achieved at low mileage.

In the configuration suggested by Camet (QLOC assisting a
larger main catalyst) the addition of air and the use of resistive
heating appeared to be successful strategies to improve the overall
efficiency of the catalysts. When the no-heat/no-air assist
configuration is compared with the heated/air assisted
configuration, every FTP emission level except NOx is substantially
lower with the assisted catalysts. OMHCE, formaldehyde, and CO
were lowered by approximately 75 percent. NOx emissions over the
FTP were essentially unchanged, in spite of the addition of air.
Further lowering of emission levels could depend upon a refinement
and better integration of resistive heat/air addition strategies,
as well as a more appropriate selection of active catalysts for the
application.


EO St,

SJ

"ey

qn0dinny

oe 4% UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
e ANN ARBOR, MICHIGAN 48105
aes
4 part

AL 30 {991 OFFICE OF

AIR AND RADIATION

MEMORANDUM
SUBJECT: Exemption From Peer and Administrative Review

FROM: Karl H. Hellman, Chief Fd.
Control Technology and Applications Branch

TO: Charles L. Gray, Jr., Director
Emission Control Technology Division

The attached report entitled "Evaluation Of Camet Resistively
Heated Metal Monolith Catalytic Converters On An M100 Neat
Methanol-Fueled Vehicle - Part III" (EPA/AA/CTAB/91-03) describes
the evaluation of the most current generation of quick light-off
catalytic converters now being furnished by the Camet Co. to
automobile manufacturers. This evaluation was conducted on a
methanol-fueled (M100) vehicle.

Since this report is concerned only with the presentation of
data and its analysis and does not involve matters of policy or
regulation, your concurrence is requested to waive administrative
review according to the policy outlined in your directive of April
22, 1982.

Concurrence: LA 4 i Date:_7- 2-2/
Charles L. Gray, KY Dir., ECTD

Nonconcurrence: Date:
Charles L. Gray, Jr., Dir., ECTD

cc: E. Burger, ECTD


26

VIII. Evaluation Highlights

1. Catalyst resistive heating alone reduced Bag 1 methanol
emissions by 50 percent from unheated catalyst levels with the QLoc
only in the exhaust. (Several heating conventions were evaluated;
the most efficient convention was 15/40 heating. This convention
was only slightly more efficient than the others evaluated,
however.)

Only a slight reduction in Bag 1 formaldehyde levels was
gained by resistively heating the QLOC in the absence of additional
air. Bag 1 CO was unaffected by catalyst resistive heating without
air assist.

2. Adding air in front of the resistively heated QLoc
significantly improved its efficiency of methanol conversion. Air
was added at an average rate of 5.0 SCFM; Bag 1 methanol emissions
were reduced approximately 50 percent to two grams when air was
added for 30 seconds after start. Formaldehyde emissions were
reduced approximately 30 percent from heated catalyst levels when
air was added for only 30 seconds in front of the heated catalyst.
Extending the time of air addition past 30 seconds caused
substantial increases in formaldehyde emissions. Formaldehyde more
than doubled to 673 milligrams when air addition was increased to
120 seconds from the 286 milligrams in Bag 1 with air addition for
only 30 seconds.

Bag 1 CO emissions steadily decreased as the time of air
addition was increased at a constant rate of catalyst resistive
heating. At 60 seconds of air addition following start, without
catalyst heating, CO was measured at almost 13 milligrams in Bag 1.
This emission level was reduced by more than half, to 5.9
milligrams when 15/40 catalyst resistive heating and 60 seconds of
air assist were used. co emissions appeared to decrease at a
slower rate as the time of air addition was extended beyond 60
seconds.

3. Very low Bag 1 emissions of methanol, formaldehyde and CO
were measured when a main catalyst was added to the exhaust system
immediately following the QLOC. Overall, the lowest emissions of
all three pollutants were obtained when resistive heating and air
assist to the QLOC were used simultaneously. The main catalyst was
not resistively heated.

The QLOC resistive heating/air addition convention used during
the two-catalyst system evaluation was 15/40 heating and air assist
for 100 seconds following start in Bag 1. The simultaneous use of
these two assists decreased Bag 1 methanol emissions to 0.37 grams.
This was down from 7.95 grams measured with no resistive heat or
air assist provided to the two-catalyst system. Formaldehyde
emissions were likewise affected; formaldehyde emissions were
reduced to 34 milligrams over Bag 1 with QLOC resistive heat/air


10

results. The methanol emissions from the 60-second post-start
heating period, 4.34 grams over Bag 1, were slightly higher than
levels obtained with 20- and 40-second post-start heating periods.
Although three tests were conducted in each mode, it may be
necessary to conduct more tests, using modal analysis, to correlate
average Bag 1 emissions with catalyst resistive heating time
intervals.

Figure 4 presents Bag 1 formaldehyde emissions when the
catalyst heating conventions referred to in Figure 3 were used.
Resistive heating in the absence of any excess air assist to the
catalyst appeared to increase catalyst efficiency, though not to
the extent noted with unburned fuel (methanol) emissions. The most
efficient scheme was 3/90 heating, which provided an approximately
30 percent decrease in formaldehyde emissions from unheated
catalyst levels. Catalyst efficiency improved very slightly over
the modes using 15-second prestart heating, when post-start heating
times were increased. The decrease in formaldehyde emissions was
only 8 percent as post-start heating was increased from 20 seconds
to 60 seconds.

Figure 5 contains Bag 1 data from the FTP on CO levels with
the QLOC over the same resistive heating modes. Generally no
change in emissions of CO of the magnitude experienced with
unburned fuel was noted when the catalyst was resistively heated.
cO emissions from the 15/20 and 15/40 heating schemes were similar
to levels obtained without catalyst heating. CO was measured at a
higher level when the catalyst was tested using the 5/40 heating
sequence than without any catalyst resistive heating. Although
slightly lower CO emissions were noted with the 3/90 heating
convention, other heating modes which involved significant amounts
of resistive heating did not substantially reduce CO from unheated
catalyst levels, in the absence of air assist.

Table 3 is a summary of Bag 1 levels for other emission
categories as well as the three previously discussed here. NOx
emissions did not appear to be significantly affected by catalyst
resistive heating possibly because the heating occurred during the
period of engine warmup to hotter, near steady-state temperature
conditions.

Because Bag 1 emissions of unburned fuel, CO, and formaldehyde
are comparatively greater than those from other segments of the FTP
for a typical three-way catalyst equipped M100 vehicle,
improvements in Bag 1 emissions due to catalyst resistive heating
should also be seen in FTP composite emission averages. Table 4 is
a summary of FTP weighted average emissions over the first phase of
this evaluation. Generally, the weighted average emissions reflect
Bag 1 emissions trends noted above. For example, FTP average
methanol emissions were approximately 21 percent lower with the
15/40 catalyst heating convention than the 3/90 mode; the
difference in Bag 1 emissions between tests with the same two
resistive heating modes was 25 percent.


13

Catalyst air assist was used in a previous effort by EPA to
reduce CO levels from a gasoline-fueled vehicle at lower ambient
temperatures with an EHC.(7] In this case, additional air proved
useful as an assist for EHC performance. Other EPA work with
methanol-fueled vehicles has indicated, however, that air assist to
contemporary platinum:rhodium catalysts caused a significant
increase in Bag 1 emissions of formaldehyde. [18]

Air assist before the EHC was tried here as a strategy to
improve catalyst efficiency. The air was added only during the
initial portions of Bag 1 following key-on, in order to minimize
any production of formaldehyde or increases in oxides of nitrogen.

Air was added from a shop air hose, rather than from a belt or
electrically driven air pump. A regulator was placed in the air
line to decrease the air flowrate to approximately 5.0 ft3/minute.
An airflow meter was also added to determine the effect of changes
in exhaust flowrate on the flowrate of air in to the exhaust. The
air addition began with key-on, and continued for intervals of 30
to 120 seconds.

Figure 6 contains unburned fuel emissions data in grams over
Bag 1, when air assist is provided to the electrically heated
catalyst. Baseline (no catalyst) and no-heat/no-air emissions data
are also given in Figure 6 for comparison. All catalyst heating
conducted during this phase of the evaluation utilized the 15/40
heating strategy.

Figure 6

QLOC Only, With Air Assist
Methanol Emissions, Bag 1 Of FTP

EHC Resistive Heat/Air Addition

Baseline

VIA 19.14
No Heat, No Air
Heat Only

60 Sec Air Only
Heat, 30 Sec Air+

Heat, 60 Sec Air

Heat, 120 Sec Air

° 5 10 158 20 25
Exhaust Methanol (grams)
* Heat 15 Seconds Prior To/40 Seconds
Following Start, 30 Seconds Air
Addition Following Start