-17-

The improvements in HC efficiency caused by resistively
heating the Pd:Ce catalyst in Bags 1 and 3 also substantially
decreased weighted average HC emissions. Measured HC emissions
were reduced to 0.06 grams/mile with the resistively heated
Pd:Ce catalyst; this data is displayed in Figure 11. The base
metal catalyst showed some improvement with resistive heating,
but this improvement was minimal. Weighted FTP HC emissions
were reduced to 0.26 grams/mile with the base metal catalyst
resistively heated, an improvement of only 10 percent from the
non-resistively heated configuration. Overall, the lowest
measured HC level was obtained with the Pd:Ce catalyst in the
resistively heated mode.

Figure 12 shows average CO levels over the FTP for the
various configurations tested. Resistive heating did not
increase CO efficiency for either catalyst in the manner in
which each was tested here. Average CO over the FTP rose
slightly, to 2.0 grams/mile, with the base metal catalyst
resistively heated. Because both catalysts had slightly higher
Bag 1 CO efficiencies, it may not be accurate to conclude that
resistive heating contributed to increases in CO, however. It
may be necessary to add air in front of the catalyst during the
initial portion of Bag 1, even at 70°F ambient conditions, in
order to substantially increase CO efficiency with resistive
catalyst heating.[6]

NOx emissions over the FTP also did not substantially
change when the catalysts were resistively heated; Figure 13
contains NOx emission averages over the FTP for all
configurations tested. The Pd:Ce catalyst reduced average NOx
emissions by half, while NOx was unaffected by the base metal
catalyst. While the Pd:Ce catalyst reduced NOx emissions below
1.0 gram/mile, additional work would have to be done with this
configuration to ensure attainment of 0.4 or 0.2 grams/mile
levels.

Resistive heating greatly assisted the light-off of the
noble metal catalyst for HCHO oxidation. Figure 14 shows FTP
HCHO emission averages for the catalyst configurations tested.
The Pd:Ce catalyst had substantial increases in HCHO efficiency
in both Bags 1 and 3 with resistive heating, leading to a low
weighted average of 2.0 milligrams/mile HCHO measured over the
FTP. This level of HCHO from an M100-fueled vehicle is low
with respect to many methanol vehicle catalysts which have been
evaluated at low mileage by EPA.[3,4,7,8,13]


-ll-

Table 2

Average Mass of Emissions
Bag 3 of FIP Cycle

Catalyst HC® CHa HCe*® OMHCE CH30H co NOx HCHO
Configuration (q) (q) (gq) (gq) (g) (gq) (gq) (mg)
Baseline 3.39 0.03 0.64 4.85 9.56 20.9 6.6 989.0
(no catalyst)

Pd:Ce (no heat) 0.321 0.02 0.16 0.38 0.45 0.7 2.7 60.0
Pd:Ce (resistive 0.16 0.05 0.13 0.19 0.19 1.2 2.9 3.0
heat)

Base metal 1.08 0.03 0.01 1.47 3.31 4.9 6.9 70.1
(no heat)

Base metal 1.03 0.03 0.17 1.35 2.66 5.9 6.5 68.2
(resistive

heat)

* Measured as hydrocarbons with a propane-calibrated FID.

** Calculated per "Final Rule for Methanol Fueled Motor Vehicles and Motor
Vehicle Engines.”


-21-

xX. References

1. 1975 Federal Test Procedure, Code of 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, OMS, ECTD, Ann Arbor, MI, 1985.

3. "Resistive Materials Applied To Quick Light-Off
Catalysts," SAE Paper 890799, Hellman, K. H., et al., March
1989.

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

. 5. "Evaluation of a Resistively Heated Metal Monolith
Catalytic Converter on a Gasoline-Fueled Vehicle," Piotrowski,
G. K., EPA/AA/CTAB/88-12, December 1988.

6. "A Resistively Heated Catalytic Converter With Air
Injection For Oxidation of Carbon Monoxide and Hydrocarbons At
Reduced Ambient Temperatures," Piotrowski, G. K., EPA/AA/CTAB/
89-06, September 1989.

7. “Uses of Palladium in Automotive Emission Control
Catalysts," SAE Paper 880281, Summers, J. C., et al., March
1988.

8. “Durability of Palladium Only Three-Way Automotive

Emission Control Catalysts," SAE Paper 890794, Summers, J. C.,
et al., March 1989.

9. "Low Mileage Catalysts Evaluation with a
Methanol-Fueled Rabbit - Second Interim Report," Wagner, R. D.
and L. C. Landman, EPA/AA/CTAB/TA/84-3, June 1984.

10. “Evaluation of Emissions from Low Mileage Catalysts
on a Light-Duty Methanol-Fueled Vehicle," Piotrowski, G. K.,
EPA/AA/CTAB/87-05.

11. “Process For Making Metal Substrate Catalytic
Converter Cores," Cornelison, R. C. and W. B. Retallick, U.S.
Patent 4,711,009, December 8, 1987.

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


II. Introduction

The major portion of emissions measured as hydrocarbons
(HC) and formaldehyde (HCHO) emissions from a catalyst-equipped
methanol-fueled vehicle over the FTP cycle are generated during
cold start and warm-up 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.

Heating parts of the engine or the catalytic converter at
cold start may provide an emissions reduction benefit over the
FTP cycle.[3] However, even if parts of the engine were hot
enough to allow an engine's cold-start emissions to be as low
as its hot-start emissions, Bag 1 emissions would still be
higher because the catalyst would not light-off (come to
operating temperature) until some time after cold start.
Heating a large mass of engine metal at cold start may be
costly from an economic standpoint also. Resistively heating a
catalytic converter at cold start may be a feasible concept if
the electrical power requirement for heating is not excessive
and resistive heating is required for only a limited period of
time while the vehicle is operated.

Resistively heated metal monolith catalytic converters
have been previously evaluated by EPA.(3,4,5,6] Earlier
testing of this technology [4] on a methanol-fueled vehicle
utilized a  platinum/palladium/rhodium mixture similar to
conventional three-way automotive catalysts. FTP Bag 1 levels
of emissions measured as hydrocarbons and formaldehyde were
0.50 and 0.054 grams respectively when the catalytic converter
was resistively heated for 30 seconds at cold start. These
were improvements of 71 and 67 percent respectively over HC and
HCHO levels from the same catalyst in the absence of resistive
heating. The lower Bag 1 emissions translated into weighted
average FTP levels of 0.05 grams per mile for emissions
measured as HC and 5 milligrams per mile for HCHO.

One way to improve upon this technology would be changing
the active catalyst mix to provide greater efficiency at the
same economic cost or the same efficiency at lower cost.
Palladium (Pd) is of great interest as a gasoline vehicle
catalyst because of its lower cost with respect to platinum
(Pt) and rhodium (Rh) as well as its increased availability due
to its wide distribution throughout the earth's crust.[{7,8] Pd
is less resistant to poisoning from fuel contaminants such as
lead, phosphorus, and sulfur;{7] as neat methanol contains no
additives, catalyst deactivation through poisoning is
unlikely. Pd, then, may be a useful alternative to a
conventional three-way catalyst for a vehicle fueled with M100.


-18-

Figure 11

Weighted Average CVS 75 (FTP)
Emissions Measured as HC

Catalyst Configurations

(WO/ resistive heat)
(W/ resistive heat)

(WO/ resistive heat)
(W/ resistive heat)

*Measured as HC with a propane

calibrated FID.

Catalyst Configurations

(WO/ resistive heat)
(W/ resistive heat)

(WO/ resistive heat)
(W/ resistive heat)

Baseline -
(No catalyst) iT 1.07
L
1
Pace |
WE 0.2
Hi 0.06 :
[ |
Base Metal ~
EE «20
EE «0.26 ; |
° 0.2 0.4 0.6 0.8 1.2
HC (Grams/Mile)
Figure 12
Weighted Average CVS 75 (FTP)
CO Emissions
Baseline f |
(No catalyst) 68 |
F |
Pace + H
he
0.6 |
i
|
Base Metal |
Ha 1c
|_.
o 1 2 3 4 5 6 7 8

CO (Grams/Mile)


-20-

VIII.Highlights From Testing

1. The resistively heated Pd:Ce converter had the
highest emission control efficiencies of the configurations
tested here.

2. Emissions measured as HC from a propane-calibrated
FID were reduced to 0.06 grams/mile over the FTP with the
resistively heated Pd:Ce converter. This was a 70 percent
decrease in emissions from the level with the unheated Pd:Ce
configuration; CH;OH emissions were reduced by almost the
same proportion. CH,OH emissions were measured at an average
of 0.20 grams/mile over the FTP with the resistively heated
Pd:Ce catalyst.

3. HCHO emissions were reduced to a very low 2
milligrams/mile over the FTP with the resistively heated Pd:Ce
catalyst.. This decrease is primarily attributable to the 81
percent increase in efficiency in Bag 1 caused by resistive
heating. ,

4. Average CO and NOx emissions over the FTP were not
substantially affected by resistively heating either the Pd:Ce
or base metal catalysts.

5. Emissions measured as HC and CH;0H over the Bag 1
portion of the FTP were measured at similar levels with both
the Pd:Ce and the base metal catalysts. Resistive heating was
not as successful with the base metal catalyst; however, HC and
CH;OH were reduced an average 24 percent below nonresistively
heated catalyst levels when the base metal catalyst was heated.

6. HCHO emissions were reduced to an average 19.1
milligrams/mile over the FTP with the resistively heated base
metal catalyst. While this represents an efficiency of greater
than 93 percent from baseline levels, the average HCHO level of
2.0 milligrams/mile with the heated Pd:Ce catalyst was much
lower.

IX. Acknowledgments

The catalysts evaluated in this test program were supplied
by Camet, 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.

The author appreciates the efforts of Ernestine Bulifant,
Robert Moss, and Rodney Branham of the Test and Evaluation
Branch, ECTD, who conducted the driving cycle tests and
prepared the methanol and formaldehyde samples for analysis.
The author also appreciates the efforts of Jennifer Criss and
Diane Descavish of CTAB, ECTD, for word processing and editing
support.


Bag 3 of CVS 75 (FTP) Cycle

Catalyst Configurations

Baseline
(No catalyst)

Pd:Ce
(WO/ resistive heat)
(W/ resistive heat)

Base Metal
(WO/ resistive heat)
(W/ resistive heat)

Bag 3 of CVS 75 (FTP) Cycle
Formaldehyde (HCHO) Emissions

Catalyst Configurations

Baseline
(No catalyst)

Pd:Ce
(WO/ resistive heat)

(W/ resistive heat)

Base Metal
(WO/ resistive heat)
(W/ resistive heat)

-15-

Figure 9

NOx Emissions

oe | gy
rs)
yoN
©
ad
o o
©

 <:

°

1

2 3

4

5 6 7 8

NOx (Grams/Bag 3)

Figure 10

|

60
3

f
HB 70.1
h

HB ce.2

te)

200

400

600

800 1000 1200

HCHO (Milligrams/Bag 3)


-7-

The baseline (no catalyst) configuration used a straight
pipe in the place of the underfloor converter. "No heat"
refers to the evaluated catalyst tested without resistive
heating applied to the _ substrate. Two hydrocarbon (HC)
emission categories are listed in Table 1. The first category
refers to emissions measured as HC with a FID calibrated with
propane; a FID response factor for methanol is not used. The
second HC figure is calculated per the requirements of the
methanol vehicle emissions rulemaking.

Bag 1 HC emission test results are displayed graphically
in Figure 1. HC emissions in Bag 1 with the propane calibrated
FID were approximately 3 grams with both the Pd:Ce and base
metal catalysts. While these emissions with both catalysts
were substantially reduced when the substrates were resistively
heated, a greater assist was provided to the Pd:Ce catalyst.

Emissions measured as HC were reduced to 0.86 grams/Bag 1,
a reduction of 85 percent from baseline levels, with the
resistively heated Pd:Ce catalyst. The base metal catalyst in
the heated mode reduced HC to 2.38 grams/Bag 1, a reduction of
60 percent from baseline levels.

Methanol (CH;0H) emission levels, displayed graphically
in Figure 2, decreased substantially with resistive heating for
both catalysts, yet the decrease with the Pd:Ce catalyst was
greater. CH;:OH emissions were approximately 8.6 grams/Bag 1
with either catalyst in the non resistively heated mode.
Heating the Pd:Ce catalyst caused CH;OH emissions to drop to
2.94 grams/Bag 1, an efficiency of 79 percent from baseline
levels. Average CH;0H emissions decreased to 6.32 grams/Bag
1, a 54 percent efficiency from baseline levels, when the base
metal converter was resistively heated.

cO emission levels over Bag 1 are given in Figure 3.
Resistively heating each catalyst did not cause CO levels to be
reduced below non-resistively heated catalyst levels with
efficiencies as great as those experienced with HC and CH;0H
missions. CO was reduced to 9.7 grams/Bag 1 with the
non-resistively heated Pd:Ce configuration, an efficiency of 68
percent from baseline levels. Resistively heating the catalyst
reduced CO further, to 9.1 grams/Bag 1, an incremental increase
in efficiency of only 2 percent. The base metal catalyst
reduced CO to 16.2 grams/Bag 1 without resistive heating for an
efficiency from baseline of 47 percent. Resistively heating
the catalyst lowered CO to 14.6 grams/Bag 1; this represents an
incremental increase in efficiency of 5 percent from baseline
levels.

Average Bag 1 NOx levels, depicted in Figure 4, decreased
slightly with catalyst resistive heating for the Pd:Ce
catalyst; the base metal catalyst did not appear effective for
NOx conversion. From a baseline level of 6.5 grams/Bag 1, NOx


~4-

The catalysts evaluated here were two separate
compositions:

1. Pd, with Ce promoter; and
2. A base metal composition.

The exact specifications of the catalyst compositions are
considered proprietary to Camet and W. R. Grace.

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 was provided in an earlier report.[4]

Vv. 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.[12,13] 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.

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.[14]


-3-

Base metal catalysts are also attractive for a methanol
vehicle application because of their low cost and the absence
of poisons like those mentioned above in the exhaust.[9] Base
metal catalysts have been evaluated by the Control Technology
and Applications Branch ‘as methanol vehicle catalysts.{10] An
efficient base metal catalyst utilizing the resistively heated
substrate technology might provide a lower cost alternative to
a conventional noble metal catalyst for the methanol vehicle
application.

The manufacturers of the resistively heated substrate,
Camet and W. R. Grace, agreed to supply EPA with substrates
coated with two active catalysts not previously evaluated with
this technology on a methanol-fueled vehicle:

1. A Pd, Cerium (Ce)-promoted configuration; and

2. A base metal configuration.

The evaluation of these catalysts described in this report
involved the use of the same methanol-fueled test vehicle
mentioned in reference 4.

III. Catalytic Converter Description

The catalytic converters evaluated here were dual-bed
configurations, consisting of an unheated metal monolith
substrate and a smaller resistively heated metal monolith
catalyst. This is the same substrate configuration that was
evaluated on a methanol-fueled vehicle in reference 4.

The metal monoliths were resistively heated using a single
12-volt DC battery capable of providing 500-600 cold cranking
amps. Voltage measured across the converter during heating was

typically 9.5-9.9 volts. Current to the converter was
typically measured at 350 and 250 amps at the start and after 1
minute of resistive heating, respectively. The period of

resistive heating was limited to 10 seconds prior to and 50
seconds following cold start, and 5 seconds prior to and 30
seconds following hot start in the FIP cycle at 72°F soak
conditions.

The dimensions of the converter are similar to those of
typical underfloor catalysts on late model compact
automobiles. The amperage draw was comparable to the maximum
required by an automotive starter cranking in cold weather,
although starter motors generally do not draw this high level
of current for as long as the resistively heated catalyst does.

A description of the process for making the folded metal
substrate may be found in a patent filed by Camet.{11] A
detailed description of the substrate and its quick light-off
characteristics have been published in an earlier report.[4]


-16-

Tat .e 3

Emissions Leveis ver The FIP Cycle

Catalyst —~ HC® CHa HC**  OMHCE  CH30H co NOx HCHO
Configuration (q/mi) (g/mi) (q/mi) (g/mi) (g/mi) (g/mi) (g/mi) (mg/mi)

Baseline 1.07 0.01 0.20 1.48 2.65 6.6 1.4 293.0
(no catalyst)

Pd:Ce (no heat) 0.20 0.01 0.03 0.27 0.54 0.6 0.7 19.4
Pd:Ce (resistive 0.06 0.01 0.02 0.08 0.20 0.6 0.7 2.0
heat)

Base metal 0.29 0.01 0.03 0.37 0.76 1.6 1.5 22.0
(no heat)

Base metal 0.26 0.01 0.06 0.33 0.62 2.0 1.4 19.1
(resistive

(heat)

* Measured as hydrocarbons with a propane-calibrated FID.

** Calculated per "Final Rule for Methanol Fueled Motor Vehicles and Motor
Vehicle Engines."


Table 1

Average Mass of Emissions
Bag _1 of FTP Cycle

Catalyst HC® CHa HC#* OMHCE CH30H co NOx HCHO
Configuration (q) (gq) (q) (gq) (gq) (gq) (q) (mq)
Baseline 5.90 0.05 1.23 7.89 13.78 30.6 6.5 1159.0
(no catalyst)

Pd:Ce (no heat) 3.02 0.05 0.21 4.02 8.63 9.7 3.6 160.8
Pd:Ce (resistive 0.86 0.06 0.10 1.19 2.94 9.1 3.3 29.5
heat)

Base metal 3.08 0.04 0.31 4.12 8.56 16.2 6.5 242.2
(no heat)

Base metal 2.38 0.06 0.33 3.14 6.32 14.6 6.4 167.8
(resistive

heat)

* Measured as hydrocarbons with a propane-calibrated FID.

ae Calculated per “Final Rule for Methanol Fueled Motor Vehicles and Motor
Vehicle Engines."


-22-

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

14. "Sample Preparation Techniques For Evaluating"
Methanol and Formaldehyde Emissions From Methanol-Fueled
Vehicles and ~ Engines," Pidgeon, WwW. and M. Reed,

EPA/AA/TEB/88-02, September 1988.


EPA/AA/CTAB/89-09

Technical Report

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

Part II

by

Gregory K. Piotrowski

December 1989

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


Figure 3
Bag 1 of CVS 75 (FTP) Cycle
CO Emissions

Catalyst Configurations

Baseline -

(No catalyst) TS 30.5

i
H
Pd:ce |
(WO/ resistive heat) [NN 0.7
(W/ resistive heat) [MMMM 0.1

Base Metal r
(WO/ resistive heat) NS 16.2
(W/ resistive heat) [MII 13.6

0 5 10 15 20 25 30
CO (Grams/Bag 1)

Figure 4
Bag 1 of CVS 75 (FTP) Cycle
NOx Emissions

Catalyst Configurations

35

Baseline

(No catalyst) 6.5

Pace

(WO/ resistive heat) i  3.c

(W/ resistive heat) —— 3.3

Base Metal 7

(WO/ resistive heat) i  c.s
(W/ resistive heat) in 6.4

ce) 1 2 3 4 5 6 7
NOx (Grams/Bag 1)


-8-

Figure 1
Bag 1 of CVS 75 (FTP) Cycle
Emissions Measured as HC*

Catalyst Configurations

Baseline -

(No catalyst) i 5.0

Pd:Ce -

(WO/ resistive heat) —S 3.02 '

(W/ resistive heat) [IE 0.86

Base Metal

[
I
(WO/ resistive heat) I 3.05
(W/ resistive heat) [J 2.39 .

° 1 2 38 4 § 6 7
HC (Grams/Bag 1)

*Measured as HC with a propane
calibrated FID.

Figure 2
Bag 1 of CVS 75 (FTP) Cycle
Emissions of Methanol (CH3OH)

Catalyst Configurations

Baseline + i

(No catalyst) i 13.72

Pace; i

(WO resistive heat) IE s.c3 |

(W/ resistive heat) || 2.94

Base Metal -

(WO resistive heat) I 2.5 |
(W/ resistive heat) [MIN 6.32

o 2 4 6 8 10 12 14 16
CH30OH (Grams/Bag 1)



-5-

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, wé 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. Test Procedure

This program had as its goal the reduction of unburned
fuel and HCHO emissions from the test vehicle using two
different active catalysts and a specific resistive heating
strategy.

The test vehicle was emission tested in the baseline
(no-catalyst) mode twice over the FTP cycle. The Pd:Ce
catalyst was then placed in the exhaust stream and again tested
twice over the FTP; no resistive heating was applied to the
catalyst during this testing. The catalyst was then
resistively heated and emission tested six times over the FTP.
The substrate was resistively heated for 10 seconds prior to
cold start in Bag 1; the heating was continued for 50 seconds
following cold start for a total heating time of 1 minute. The
catalyst was also heated for 5 seconds prior to and 30 seconds
following hot start in Bag 3, for a total time that heat was
applied of 35 seconds. No resistive heating was applied during
the Bag 2 portion of the test.

The Pd:Ce catalyst was then replaced with the base metal
configuration provided by Camet. Two tests over the FTP were
conducted without catalyst heating. The catalyst was then
resistively heated using the scheme referred to above; three
emission tests were conducted in this heated catalyst mode.
The base metal catalyst was then removed from the exhaust and
replaced with a straight pipe. Two additional baseline
emission tests were conducted to conclude the data gathering
phase of this report.

VII. Discussion of Test Results

Average Bag 1 (cold transient phase) emissions over the
FTP for the various catalyst configurations tested are given in
Table 1. Emission levels are described as grams per Bag 1
(grams/test phase) for all pollutants except HCHO; emissions of
HCHO are reported as milligrams/Bag 1.


-19-

Figure 13
Weighted Average CVS 75 (FTP)
NOx Emissions

Catalyst Configurations

Baseline | |

i ;
(No catalyst) iy +

Pd:Ce
(WO/ resistive heat)

(W/ resistive heat) [J 0.7
i

| .
2
q

Base Metal L |
(WO/ resistive heat) I 15
W/ resistive hoot) I

0 02 04 06 08 1 1.2 1.4 16 18
NOx (Grams/Mile)

Figure 14
Weighted Average CVS 75 (FTP)
HCHO Emissions

Catalyst Configurations

Baseline f
(No catalyst) 293

Pd:Ce
(WO/ resistive heat) 19.4
(W/ resistive heat) | 2

Base Metal r
(WO/ resistive heat) [J 22
(W/ resistive heat) J 19.1 ,

0 §0 100 150 200 250 300 350
HCHO (Milligrams/Mile)



I. Summar 4

Two catalyst formulations using resistively heated metal
monolith substrates were evaluated for the application of
exhaust emission catalysts on an M100 neat methanol-fueled
vehicle. The active catalyst formulations were
palladium:cerium (Pd:Ce) and a base metal formulation. The
catalysts were evaluated at low mileage in two modes:

1. Resistive heating applied to the substrate during
initial portions of the cold-start and hot-start transient
segments of the test cycle (the Federal test procedure (FTP));
(1] and

2. No resistive heating applied to the substrate during
the driving cycle.

The test vehicle was also driven in the baseline, or
no-catalyst mode, to obtain engine-out emission levels for
comparison.

Resistively heating the Pd:Ce catalyst provided a
substantial emissions control benefit over the non-resistively
heated catalyst mode, for emissions measured as hydrocarbons
(HC), methanol (CH3;0H), and formaldehyde (HCHO).
Efficiencies from baseline levels for these pollutants with the
resistively heated Pd:Ce converter over the FIP were 94, 92,
and 99 percent, respectively. The HCHO levels measured, 2.0
milligrams/mile over the FTP, were low compared with other
catalysts previously evaluated at low mileage by EPA.

The base metal catalyst showed a slight improvement in
emissions of HC, CH3;OH, and HCHO when the catalyst was
resistively heated. Generally, the base metal catalyst was not
as efficient as the Pd:Ce catalyst in either the resistively
heated or non-resistively heated modes.

The catalysts and resistively heated metal monolith
substrates evaluated were provided by Camet, Inc., a subsidiary
of W. R. Grace. The Ml00-fueled test vehicle was provided by
Volkswagen of America.


-12-

Figure 5
Bag 1 of CVS 75 (FTP) Cycle
Formaldehyde (HCHO) Emissions

Catalyst Configurations

Baseline r

(No catalyst) EE 1159

Pa:Ce i

(WO/ resistive heat) [EM 160.8 |
(W/ resistive heat) [J 29.5
Base Metal — |

(WO/ resistive heat) [NMI 242.2 |
(W/ resistive heat) MM 167.8 |

, 0 200 400 600 800 1000 1200 1400
HCHO (Milligrams/Bag 1)

Figure 6
Bag 3 of CVS 75 (FTP) Cycle
Emissions Measured as HC

Catalyst Configurations

(No catalyst) — 3.99 |

Baseline |
|

Pd:Ce
(WO/ resistive heat)
(W/ resistive heat)

Le i

0.31

°
P

Base Metal
(WO/ resistive heat) — 1.08
(W/ resistive heat) MMMM 4.03,

0 05 1 #15 2 265 3 35 4
HC (Grams/Bag 3)

|
|

*Measured as HC with a propane
calibrated FID.


-14-

catalyst configurations tested. CO decreased to 0.7 grams/Bag
3 with the Pd:Ce catalyst, for an efficiency from baseline
levels greater than 96 percent. CO increased slightly, to 1.2
grams/Bag 3, when resistive heating was applied to the Pd:Ce
catalyst. The level of CO was also slightly increased when the
base metal converter was heated. CO was measured at 5.9
grams/Bag 3 when resistive heating was applied, up from 4.9
grams/Bag 3 without resistive heating.

Recent testing of this resistively heated converter
technology on a gasoline-fueled vehicle [6] at lower ambient
temperatures suggested that reductions in CO following cold
start were possible only with the addition of air in front of
the converter. This excess air during catalyst resistive
heating was supplied by an air pump in [6].

The testing reported on here involved a methanol, rather
than a gasoline-fueled, vehicle. Also, the testing discussed
in [6] was conducted at 20°F ambient, rather than 72°F
ambient conditions. The gasoline-fueled vehicle may have been
operating under significantly richer conditions during catalyst
resistive heating than the methanol fueled test vehicle.
Nevertheless, more work should be done to determine whether
some excess air addition, even at 70°F conditions, is
necessary to improve resistively heated catalyst CO efficiency
with an M100 fueled engine.

Bag 3 NOx levels are given in Figure 9. Resistive heating
did not noticeably improve the performance of the Pd:Ce
catalyst for NOx control. Nox levels were essentially
unchanged, approximately 2.8 grams over Bag 3, for both heated
and unheated Pd:Ce configurations. The base metal converter,
unheated or in the resistively heated mode, did not appear: to
be effective for NOx reduction.

Figure 10 displays HCHO levels over Bag 3 for the
evaluated configurations. Bag 3 HCHO conversion efficiency of
the Pd:Ce catalyst was greatly improved by resistive heating.
HCHO emissions were reduced to 60 milligrams/bag with the
unheated Pd:Ce converter; resistive heating lowered emissions
from this configuration to 3 milligrams, an efficiency
approaching virtually 100 percent from baseline levels. HCHO
was reduced to 70 milligrams/Bag 3 for the base metal catalyst
in the unheated mode, an efficiency of almost 93 percent from
baseline levels. Resistively heating this catalyst, however,
did not appreciably reduce Bag 3 HCHO below unheated catalyst
levels.

Weighted average FTP emissions in units of mass/distance
driven, for the various pollutant categories, are given in
Table 3.


vI.
VIL.
VIII.

IX.

Table of Contents

Summary .

Introduction

. Catalytic Converter Description .

Vehicle Description...

Test Facilities and Analytical Methods
Test Procedure

Discussion of Test Results

Highlights From Testing ......
Acknowledgments ........

References .........46.4

Page
Number

1

2

20
20

21


ED Stay,
~ &

2 a UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
3

a

ANN ARBOR, MICHIGAN 48105

Pa peor
VAN [Bo OFFICE OF
AIR AND RADIATION

MEMORANDUM

SUBJECT: Exemption From Peer and Administrative Review

. “i
FROM: Karl H. Hellman, Chieté [KY
Control Technology and Applications Branch
TO: Charles L. Gray, Jr., Director

Emission Control Technology Division

The attached report entitled "Evaluation of Resistively
Heated Metal Monolith Catalytic Converters On An M100 Neat
Methanol-Fueled Vehicle - Part II" (EPA/AA/CTAB/89-09),
describes the evaluation of palladium/cerium and base metal
catalysts on resistively heated metal monolith substrates. The
test vehicle was an M100-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: Lhe Date://“4,-70

Cal
Charles L. Gray, Meyotr., ECTD

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

cc: E. Burger, ECTD


-10-

was reduced to 3.3 grams/Bag 1 with the resistively heated
Pd:Ce catalyst. The improvement attributed to resistive
heating was only 0.3 grams/Bag 1 (non-resistively heated
catalyst emissions less resistively heated catalyst
emissions). The level of baseline emissions of NOx, 6.5
grams/Bag 1, did not change with the base metal converter, even
when resistively heated; this catalyst appeared to be
ineffective for NOx reduction in the manner in which it was
evaluated here.

Bag 1 HCHO oxidation efficiency with either catalyst was
greatly improved by resistive heating; HCHO levels over Bag 1
are given in Figure 5. The heated Pd:Ce catalyst had average
Bag 1 HCHO emissions of 29.5 milligrams/Bag 1, an improvement
of almost 82 percent from non resistively heated catalyst
levels. HCHO efficiency was almost 98 percent from baseline
with the heated Pd:Ce catalyst. Again, the base metal catalyst
did not exhibit HCHO efficiencies as high as those from the
Pd:Ce catalyst; the improvement caused by resistive heating was
approximately 30 percent from non-resistively heated catalyst
levels. HCHO emissions from the heated base metal catalyst
were 167.8 milligrams/Bag 1, an efficiency of approximately 85
percent from baseline levels.

Table 2 contains emission averages over the Bag 3 (hot
transient) portion of the FIP for the catalyst configurations
evaluated. Resistive heating was applied for a period of 5
seconds preceding and 30 seconds following hot start for a
total heating period of 35 seconds in Bag 3.

The Pd:Ce catalyst provided very high HC and CH,0OH
efficiencies in Bag 3; a graphical summary of this data is
given in Figures 6 and 7. In the unheated mode, emissions
measured as HC and CH;0H were reduced to 0.31 and 0.45
grams/Bag 1, respectively. These were efficiencies of 91 and
95 percent from baseline. Resistively heating this catalyst
reduced these emission levels by half, to 0.16 and 0.19
grams/Bag 1, respectively. The base metal catalyst was not as
effective in the unheated mode, and resistive heating did not
improve the catalyst's performance to an efficiency equal to
that of the noble metal catalyst. Bag 3 HC with the base metal
catalyst was 1.08 grams, an efficiency from baseline of 68
percent; this level was essentially unchanged by resistive
heating. Without resistive heating, the base metal catalyst
reduced CH;OH to 3.31 grams/Bag 3, an efficiency from
baseline of 65 percent. Heating the base metal catalyst
reduced CH;OH further, to 2.66 grams/Bag 3, an efficiency of
72 percent.

Resistively heating either catalyst in Bag 3 appeared to
reduce converter efficiency slightly for CO control. Figure 8
presents graphically CO levels obtained over Bag 3 for the


Catalyst Configurations

Baseline

(No catalyst)

Pa:Ce
(WO/ resistive heat)
(W/ resistive heat)

Base Metal
(WO/ resistive heat)
(W/ resistive heat)

Bag 3

Catalyst Configurations

Baseline
(No catalyst)

Pa:Ce
(WO/ resistive heat)
(W/ resistive heat)

Base Metal
(WO/ resistive heat)
(W/ resistive heat)

Figure 7
Bag 3 of CVS 75 (FTP) Cycle
Emissions of Methanol (CH30H)

4 6 8 10

CH3OH (Grams/Bag 3)

Figure 8
of CVS 75 (FTP) Cycle
CO Emissions

12

:

w °

a «>

0.7
1.2

49

=

20.9

°o

10 15 20
CO (Grams/Bag 3)

5

25