EPA/AA/CTAB/88-10
Technical Report
Methanol Vehicle Catalyst Evaluation:
Phase III
by
Gregory K. Piotrowski
November 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
-------
\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
/ ANN ARBOR. MICHIGAN 48105
OFFICE OF
AIR AND RADIATION
"FC 1 9 1989
•1BMORANDUM
SUBJECT: Exemption From Peer and Administrative Review
FROM
TO:
Karl H. Kellman, Chief
Control Technology and Applications Branch
Charles L. Gray, Jr., Director
Emission Control Technology Division
The attached report entitled "Methanol Vehicle Catalyst
Evaluation: Phase III," (EPA/AA/CTAB/88-10) describes the
evaluation of several noble and base metal catalyst
technologies for their use as neat methanol-fueled vehicle
catalysts.
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
Caa-fles L. Gray, xJr/, Dir., ECTD
Nonconcurrence:
Date:
Charles L. Gray, Jr., Dir., ECTD
cc: E. Burger, ECTD
-------
I. Summary
The methanol catalyst testing reported on here was
conducted as a follow-up to an earlier EPA catalyst evaluation
program.[1,2,3,4] The purpose of the testing described here in
Part 1, Section V was to evaluate noble metal catalysts
suggested by researchers to be particularly effective for
methanol-vehicle applications.[5,6] The purpose of the testing
described in Part 2, Section V was to evaluate selected base
metals and other specific catalyst technologies for use as
methanol-vehicle catalysts.
Both of the configurations tested in Part 1, Ag:Pd(50) and
Pt(50), were effective when tested as three-way catalysts over
the Federal test procedure (FTP). The formaldehyde emission
level was only 5.9 milligrams per mile over the FTP in the
three-way mode with the Pt(50) catalyst. The simulated
oxidation catalyst mode was not preferred to the three-way mode
because of considerably higher NOx and formaldehyde emissions.
Both catalysts had good HC, CO, and formaldehyde conversion
efficiencies over the highway fuel economy test (HFET) cycle.
The base metal/palladium and platinum/palladium/unique
washcoat configurations discussed in Part 2 had HC efficiencies
greater than 90 percent over the FTP. CO emissions from the
test vehicle were low, only 0.73 grams per mile over the FTP,
when the base metal/palladium catalyst was used. NOx emissions
with these catalysts were relatively unchanged from baseline
levels. Both base metal-containing catalysts also had
formaldehyde conversion efficiencies greater than 90 percent
over the FTP.
II. Introduction
Section 211 of the Clean Air Act [7] requires the U.S.
Environmental Protection Agency (EPA) to play a key role in the
introduction of new motor vehicle fuels. EPA studies [8] have
suggested that methanol stands out from other alternative
transportation fuels from an environmental perspective. The
use of alcohol fuels can also play a significant role in the
reduction of the foreign trade deficit and aid the security
interests of the United States by reducing U.S. dependence on
imported petroleum.[9]
The use of methanol fuel rather than gasoline may be
expected to benefit the performance of a catalytic converter in
two ways. First, pure methanol contains low levels of
substances such as sulfur and lead which act as catalyst
poisons. Second, reduced exhaust gas temperatures at the
catalyst inlet should reduce thermal degradation over an
extended period of vehicle operation.
-------
Table of Contents
Page
Number
I. Summary 1
II. Introduction 1
III. Vehicle Descriptions 2
IV. Test Facilities and Analytical Methods 3
V. Part 1: Noble Metal Catalyst Screening 4
A. Program Design 4
B. Catalysts Tested 4
C. FTP Test Discussion 4
D. HFET Test Discussion 8
VI. Part 2: Base Metal/Alternative Technology
Catalyst Screening 9
A. Program Design 9
B. Catalysts Tested 9
C. FTP Test Discussion 10
D. HFET Test Discussion 12
VII.Test Highlights 13
A. Part 1 13
B. Part 2 13
VIII.Acknowledgments 14
IX. References 15
APPENDIX A - Specifications For Volkswagen Test Vehicle. A-l
APPENDIX B - Specifications For Toyota Test Vehicle . . B-l
-------
-3-
The emission control system was modified by EPA to include
an air injection pump which can inject air into the exhaust at
a location approximately 1 foot downstream from the oxygen
sensor. A manually adjustable valve was installed in the line
between the diverter valve and the exhaust inlet. The valve
permits the oxygen concentration over the catalyst to be varied
while operating the engine in the closed-loop mode.
A detailed description of the vehicle and special methanol
modifications is provided in Appendix A.
The test vehicle referred to in Part 2, Section V was a
1986 Toyota Carina, a vehicle sold in Japan but currently not
exported to the United States. The powerplant is a 1587 cc
displacement, 4-cylinder, single-overhead camshaft engine. The
engine has been modified for operation on methanol in a lean
burn mode, incorporating the lean mixture sensor, swirl control
valve and timed sequential fuel injection found on the Toyota
lean combustion system (T-LCS). Modifications to the fuel
system included the substitution of parts resistant to methanol
corrosion for stock parts.
A detailed description of the vehicle and special methanol
modifications is provided in Appendix B.
IV. 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 CVS used has a nominal capacity of 350
cfm.
Exhaust HC emissions were measured by flame ionization
detection (FID) using a Beckman Model 400. This FID was
calibrated with propane; no attempt was made to adjust for FID
response factor to methanol. No corrections were made for the
difference in hydrocarbon composition due to the use of
methanol rather than unleaded gasoline for fuel. NOx emissions
were measured by chemiluminescent technique utilizing a Beckman
Model 8501-5CA.
Exhaust formaldehyde is measured using a dinitrophenyl-
hydrazine (DNPH) technique.[12,13] Exhaust carbonyls including
formaldehyde are reacted with DNPH solution forming hydrazone
derivatives. These derivatives are separated from the DNPH
solution by means of high performance liquid chromatography
(HPLC). Quantization is accomplished by spectrophotometric
analysis of the LC effluent stream.
HC test results in the text 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.
-------
-2-
The Emission Control Technology Division (ECTD) of the
Office of Mobile Sources, EPA, assesses technology that could
be used to reduce mobile source emissions. One part of this
assessment has been a program to evaluate various exhaust
catalysts at low mileage on neat methanol-fueled (M100)
vehicles. Test results from this program have been published
in a variety of EPA and other professional literature
sources.[1,2,3,4]
The testing discussed in this report has been divided into
two separate sections. The first section discusses the
evaluation of two noble metal catalysts: 1) Platinum, at 50
grams per cubic foot of substrate volume, and 2) a
silver/palladium mixture, also at 50 grams per cubic foot of
substrate volume. These catalysts were supplied to EPA by
Engelhard Industries; specifications are provided in Section V
of this report.
Two different catalyst operating modes were chosen for
Part 1. The catalysts were first tested as three-way
converters, to oxidize unburned fuel, aldehydes, and CO as well
as to reduce NOx emissions. An air pump which supplied air to
the exhaust ahead of the catalyst but downstream of the exhaust
oxygen sensor was then used to evaluate the catalysts in a
simulated oxidation mode. The driving cycles tested were the
Federal test procedure (FTP) [10] and the highway fuel economy
test (HFET) [11] cycles.
Part 2 of Section V in this report discusses the
evaluation of three catalysts obtained from Automotive Catalyst
Company, a subsidiary of Allied-Signal. These catalysts
utilized in turn:
l. A base-metal only technology;
2. A mixture of base metal and palladium; and
3. A platinum-palladium mixture utilizing a unique
washeoat.
The details of the catalyst formulation and application
are proprietary to Allied-Signal.
III. Vehicle Descriptions
The vehicle used for the noble metal catalyst screening
described in Part l, Section V was a 1981 Volkswagen Rabbit
4-door sedan, equipped with automatic transmission, air
conditioning, and radial tires. The 1.6-liter engine is rated
at maximum power output of 88 horsepower at 5,600 rpm. The
vehicle was tested at 2,500 Ibs inertia weight and 7.3 actual
dynamometer horsepower.
-------
-4-
V. Part 1: Noble Metal Catalyst Screening
A. Program Design
The evaluation of a catalyst during this phase was a
three-step process. First, the test vehicle was
emission-tested on a chassis dynamometer without the catalytic
converter present in the exhaust stream and with the air pump
rendered inoperable. The driving cycles tested were the FTP
and HFET.
Following these baseline tests, the catalyst to be
evaluated was attached under the vehicle in the exhaust
stream. The catalyst was evaluated in an underfloor location.
The second step of the process was to repeat the series of
tests described above with the air pump still disabled. The
catalyst was evaluated in the "three-way" mode in this test.
In the third step, the air pump was enabled and air was
added at a predetermined rate to the exhaust directly in front
of the catalyst but downstream of the oxygen sensor. This
action simulated the operation of the catalyst as an oxidation
catalyst. The amount of air supplied by the air pump during
testing was the amount of necessary makeup air to obtain 3
percent oxygen in the vehicle exhaust (at the catalyst inlet)
at 30 MPH steady-state conditions as measured with a Sun oxygen
analyzer. The car was then tested over the FTP and HFET cycles
in this configuration. Following this oxidation catalyst mode
testing the converter was removed from the exhaust stream, the
air pump was disabled, and the car was again baseline tested.
B. Catalysts Tested: Part 1
The catalysts reported on here used ceramic monolithic
substrates which contained 400 square cells per square inch.
The substrates were cylindrically shaped, 4.0 inches in
diameter and 6.0 inches in length.
The catalyst descriptions indicate the ratio of the
constituents by weight, and the number in parentheses at the
end of the description gives the catalyst loading in grams per
cubic foot. Constituents are identified by their chemical
abbreviations.
Other details of catalyst formulation, application and
structure are considered proprietary to Engelhard Industries.
C. FTP Test Discussion
FTP test results are presented and analyzed here in two
formats. Table 1 details emission levels from the evaluated
converters obtained over two catalyst operating modes,
three-way and oxidation catalyst, respectively. Baseline (no
catalyst) results with the air pump disabled are also presented
for each pollutant category. The discussion below includes a
determination of the most effective operating mode for these
catalysts.
-------
-5-
Table 1
Emissions Test Results
VW Rabbit Vehicle, M100 Fuel, FTP Cvcle
Number HC HC* CO NOx CH30H* OMHCE* Aide.
Configuration of Tests (q/mi) (g/mi) (g/mi) (g/mi) (g/mi) (g/mi) (mg/mi)
Baseline 3
Ag:Pd(50) 3-way 3
Ag:Pd(50) Oxid. 3
Pt(50) 3-way 3
Pt(50) Oxid. 2
1.02 0.12 6.45 1.67 2.78 1.47 302.0
0.18 0.02 0.68 0.96 0.48 0.24 17.6
0.25 0.03 0.48 1.82 0.68 0.38 115.0
0.18 0.02 0.45 0.95 0.49 0.24 5.9
0.16 0.02 0.34 1.84 0.42 0.21 8.9
Calculated values per proposed rulemaking.
HC and CO emissions were 0.18 and 0.68 grams per mile
respectively over the FTP with the Ag:Pd (50) catalyst in the
three-way mode. HC increased to 0.25 grams per mile when the
catalyst was tested in the oxidation mode. The addition of air
assisted the oxidation of CO, however; CO dropped to 0.48 grams
per mile over the FTP with the air pump on. HC emissions from
the Pt(50) converter were a similar 0.18 and 0.16 grams per
mile respectively over the three-way and oxidation catalyst
modes. The addition of air appeared to assist the conversion
of CO with the Pt(50) converter, as was the case with the
Ag:Pd(50) catalyst; CO dropped to 0.34 grams per mile with the
air pump on, versus 0.45 grams per mile in the three-way mode.
NOx emission levels were similar for both catalysts in the
three-way mode over the FTP, approximately 0.95 grams per
mile. The addition of air caused NOx emissions from both
catalysts to rise to similar levels of approximately 1.8 grams
per mile. The Pt(50) catalyst reduced emissions of
formaldehyde to 5.9 milligrams per mile over the FTP in the
three-way mode; formaldehyde emissions were 17.6 milligrams per
mile with the Ag:Pd(50) catalyst in the same mode. The use of
additional air caused formaldehyde levels to increase
substantially with both catalysts; formaldehyde levels of 115
milligrams per mile over the FTP were noted with the Ag:Pd(50)
catalyst in the oxidation mode. The increase in formaldehyde
emissions from the Pt(50) catalyst, from 5.9 (three-way) to 8.9
milligrams per mile when tested in the oxidation mode was
substantial; however, the efficiency of the Pt(50) catalyst
exceeded 97 percent in the oxidation mode.
-------
-6-
The three-way catalyst mode appears to be the preferred
operating mode when all pollutants are considered to be of
equal concern. HC levels were determined to be approximately
0.16 to 0.18 grams per mile for each configuration with the
exception of 0.25 grams per mile from the Ag:Pd(50) catalyst in
the oxidation mode. The oxidation mode was preferred for CO
conversion, increasing conversion efficiency by 25 to 30
percent for the catalysts evaluated. The three-way mode was
clearly preferred for NOx and formaldehyde, however. Overall,
despite the suggestion that CO conversion is assisted by the
addition of excess air, the three-way mode, because of its
simplicity and superiority in reducing formaldehyde and NOx
emissions and the lack of convincing evidence that HC
efficiency was significantly improved by the addition of excess
air, was preferred.
Figures 1 and 2 compare the results from the evaluated
catalysts over the three-way mode to heavily loaded noble metal
catalyst test results obtained [4] with this vehicle. The
catalysts used for this comparison were 5Pt:Rh(80) and
Ag:Rh(300) coated ceramic monoliths of the same physical size
and exhaust stream location as the catalysts evaluated here.
CATALYST EFFICIENCIES
FTP CYCLE
CATALYST COMPOSITION
5PT:RH(80)
10AG:RH(300)
AG:PD(50)
PT(50)
HC EFFICIENCY
CO EFFICIENCY
40 60 80
% EFFICIENCY
100 120
FIGURE 1
-------
-7-
CATALYST EFFICIENCIES
FTP CYCLE
I NOx EFFICIENCY MS ALDY. EFFICIENCY
CATALYST COMPOSITION
5PT:RH(80)
10AG:RH(300)
AG:PD(50)
PT(50)
98.2
93.6
94.2
20 40 60 80 100 120
% EFFICIENCY
FIGURE 2
Both of the evaluated catalysts had HC efficiencies of
82.4 percent, slightly lower than the 89.2 percent efficiency
obtained with the more heavily loaded 5Pt:Rh(80) catalyst. The
use of palladium rather than rhodium, at least in the
proportions tested here, appeared to be preferred when used
with silver for HC conversion. The evaluated catalysts also
had CO conversion efficiencies slightly higher than that
previously experienced with the 5Pt:Rh(80) catalyst. The
increase in efficiencies was marginal, however; Ag:Pd(50) had a
89.6 percent efficiency compared with 89.3 percent for 5
Pt:Rh(80).
NOx efficiencies for the evaluated catalysts were similar,
42.5 and 43.1 percent respectively for the Ag:Pd(50) and Pt(50)
catalysts. These were slightly lower than the 50.9 percent
efficiency from the 5Pt:Rh(80) catalyst, yet a substantial
improvement from the 28.1 percent from the 10Ag:Rh(300)
catalyst. Both evaluated catalysts had NOx levels which
approximated the current 1 gram per mile light-duty vehicle NOx
standard.
-------
-8-
Forraaldehyde efficiencies for all catalysts referred to
here were uniformly high; however, the silver-containing
catalysts performed less efficiently than the platinum-
containing catalysts. Silver-containing catalysts had
formaldehyde conversion efficiencies of 94 percent; these
efficiencies were consistent despite the widely varying
formulations between the catalysts because of the addition of
other noble metals. The platinum-containing catalysts had a
consistent 98 percent formaldehyde efficiency; platinum appears
to be a very good catalyst for conversion of formaldehyde in
vehicle exhaust.
The three-way operating mode was preferable to the
oxidation mode for the catalysts evaluated, when the pollutants
measured are considered to be equally undesirable. Similar
catalyst efficiencies were noted for HC and NOx conversion for
both the Ag:Pd(50) and Pt(50) catalysts. The Pt(50) catalyst
was slightly more efficient than * Ag:Pd(50) at controlling
formaldehyde and CO emissions.
D. HFET Test Discussion
HFET results are presented in Table 2. The same format
that was used in Table 1, FTP Results, is used here.
Table 2
Emissions Test Results
VW Rabbit Vehicle. M100 Fuel, HFET Cycle
Number HC HC* CO NOx CH30H* OMHCE* Aide.
Configuration of Tests (q/mi) (q/mi) (q/mi) (q/mi) (q/mi) (q/mi) (mq/mi)
Baseline 1 0.56 .07 5.30 2.81 1.53 0.79 128.0
Aq:Pd(50) 3-way 3 0.01 -- 0.01 1.53 0.03 0.02 3.6
Ag:Pd(50) Oxid. 3 0.01 -- -- 2.78 0.04 0.02 9.4
Pt(50) 3-way 3 0.01 — -- 1.43 0.02 0.01 1.9
Pt(50) Oxid. 2 0.01 -- -- 2.91 0.03 0.01 1.6
* Calculated values per proposed rulemaking.
No detectable levels.
-------
-9-
All of the catalysts tested reduced HC emissions to very
low levels over both operating modes. This was not unexpected
due to the high speed driving characteristics of the cycle
which caused catalysts to light-off very early. The oxidation
reactions which produced lower aldehyde and CO emissions were
similarly affected. The Ag:Pd(50) catalyst had a substantially
lower formaldehyde conversion efficiency in the oxidation mode
than in the three-way mode. NOx levels from both evaluated
catalysts approximated baseline levels when tested in the
oxidation mode. NOx efficiencies approximated 47 percent from
both catalysts when tested in the three-way mode.
VI. Part 2: Base Metal/Alternative Technology Catalyst
Screening
A. Program Design
The evaluation of the catalysts during this phase was a
three-step process. First, the car was emission tested on a
chassis dynamometer with an uncatalyzed substrate present in
the stock catalytic converter can on the vehicle. This testing
was defined as baseline testing for this report. The original
equipment (OEM) converter for the MIOO-fueled Toyota Carina
vehicle used in this testing is close-coupled to the exhaust
manifold, rather than located underfloor. The driving cycles
were the FTP and HFET cycles.
Following these baseline tests, the uncatalyzed substrate
was replaced with the OEM Pt:Rh catalyzed substrate and the
vehicle was tested over FTP and HFET cycles. This testing is
referred to later in the discussion as OEM manifold converter
testing.
The candidate catalysts were then mounted in the exhaust
stream in an underfloor location and separately evaluated over
FTP and HFET cycles. The uncatalyzed substrate was placed in
the exhaust at the exhaust manifold location during the
separate underfloor catalyst evaluations.
The catalysts were not evaluated here in the oxidation
mode for two reasons. First, we believed that the three-way
mode was preferable for the reasons given in Section V, Part 1
of this report. Second, the test vehicle operates lean of
stoichiometric by design.[14]
B. Catalysts Tested: Part 2
The catalysts reported on here used ceramic monolithic
substrates of the same dimensions as the substrates described
in Part 1. The three catalysts reported on in this section
made use of:
-------
-10-
1. Base-metal-only technology;
2. A mixture of base metal and palladium; and
3. A platinum-palladium mixture utilizing a unique
washcoat.
The third technology is referred to as Pt/Pd/coat in
Figures 3 and 4.
The details of the catalyst formulations are proprietary
to Allied-Signal.
C. FTP Test Discussion
Results of testing over the FTP cycle are presented in
Table 3 and Figures 3 and 4.
Table 3
Emissions Test Results
Toyota Carina, M100 Fuel, FTP Cycle
Number HC HC* CO NOx CH30H* OMHCE* Aide.
Configuration o£ Tests (q/mi) (q/mi) (q/mi) (q/mi) (q/mi) (q/mi) (mq/tni)
Baseline 4 1.67 0.200 4.26 1.11 4.55 2.36 419.
OEM manifold 3 0.07 0.008 1.84 0.73 0.19 0.09 11.
converter
Base metal 3 0.38 0.044 1.08 1.24 1.02 0.50 34.
converter
Base metal 3 0.14 0.017 0.73 1.16 0.39 0.20 30.
and Pd
Pt/Pd, unique 2 0.13 0.016 1.62 1.01 0.36 0.19 56.
washcoat
Calculated values per proposed rulemaking.
HC levels from the OEM manifold converter were 0.07 grams
per mile for an efficiency of almost 96 percent. The noble
metal-containing catalysts had similar efficiencies exceeding
90 percent, yet the weight per mile of HC allowed by these
catalysts was almost twice the level from the OEM converter.
The efficiency of the base metal converter was considerably
lower at 77 percent.
-------
-11-
CO levels from the OEM converter exceeded those from each
underfloor catalyst tested. The base metal and palladium
configuration had a CO efficiency at 82.9 percent, considerably
higher than the OEM converter. The base metal converter
reduced CO emissions by almost 75 percent, better than the 62
percent decrease in CO with the platinum/palladium catalyst.
NOx levels in some cases exceeded baseline emissions. The
OEM converter had the lowest NOx levels, 0.73 grams per mile
over the FTP for an efficiency of 34 percent. Each of the
evaluated converters had NOx emissions in excess of the current
1 gram per mile light-duty vehicle standard, though the
platinum/palladium catalyst came close to meeting the standard
at 1.01 grams per mile NOx. The base metal containing
catalysts each had NOx levels exceeding baseline levels; Figure
4 does not reflect this negative efficiency, however.
Aldehyde efficiencies from each of the evaluated catalysts
were uniformly high, exceeding 85 percent. The OEM manifold
close-coupled converter had the highest efficiency though, 97.4
percent. This high efficiency was probably the result of the
catalysts' location close to the engine, allowing for a very
fast warmup and hence, guick light off. Both base
metal-containing catalysts tested here had formaldehyde
efficiencies greater than 90 percent; even at these high
conversion efficiencies, however, these catalysts allowed
almost three times the mass of formaldehyde emitted over the
FTP when compared to the manifold close-coupled converter.
CATALYST EFFICIENCIES
FTP CYCLE
I HC EFFICIENCY Sffl CO EFFICIENCY
CATALYST COMPOSITION
OEM
BASE METAL
PT/PD/COAT
BASE METAL + PD
20 40 60 80 100 120
% EFFICIENCY
FIGURE 3
-------
-12-
CAT;
CATALYST COMPOSITION
OEM
BASE METAL
PT/PD/COAT
BASE METAL * PD
C
ILYST EFFICIENCIES
FTP CYCLE
•1 NOx EFFICIENCY Sffl ALDY. EFFICIENCY
MMIM! 34.2
^^^^^^•^^•^•BB^BBJ .97.4
^•^^•JSBSBBSB^^^H 91.9
[
SJiiMtaBK^^^ 86.6
^•^•••MSS^MMMBB^ 92.8
' - ; i l
|
) 20 40 60 80 100 120
% EFFICIENCY
FIGURE 4
D. HFET Test Discussion
HFET test results are given in Table 4.
Table 4
Emissions Test Results
Toyota Carina, M100 Fuel, HFET Cycle
Number HC HC* CO NOx CH30H* OMHCE* Aide.
Configuration of Tests (g/mi) (g/mi) (g/mi) (g/mi) (g/mi) (g/mi) (mg/mi)
Baseline
OEM manifold
converter
Base metal
converter
Base metal
and Pd
Pt/Pd, unique
washcoat
0.94 0.11 1.65 0.83 2.57 1.29 134.
0.005 0.001 0.13 0.83 0.01 0.01 8.
0.007 0.001 0.01 1.05 0.02 0.01 3.
0.003
1.05 0.01 0.01 3.
0.003 0.001 0.09 0.94 0.01 0.01 6.
* Calculated values per proposed rulemaking.
No detectable levels.
-------
-13-
HC, CO and formaldehyde emission levels were uniformly low
when compared to baseline levels. The base metal-containing
catalyst had higher CO and formaldehyde efficiencies than the
manifold close-coupled and platinum/palladium underfloor
catalysts. The base metal-containing catalysts had NOx levels
of 1.05 grams per mile, however, which exceeded baseline levels.
VII. Test Highlights
A. Part 1
1. Both Ag:Pd(50) and Pt(50) configurations in the
three-way mode had similar HC and NOx efficiencies from
baseline levels over the FTP of 82 and 43 percent,
respectively. A more heavily loaded platinum/rhodium converter
had HC and NOx efficiencies from baseline of 89 and 51 percent,
respectively, in the same mode.
2. Formaldehyde levels over the FTP were lowest (5.9
mg/mi) from the Pt(50) catalyst in the three-way
configuration. Formaldehyde and NOx levels generally increased
from all catalysts when the oxidation mode was used.
3. CO levels over the FTP were generally lower in
oxidation mode testing. In the three-way mode, the CO
emissions from the Ag:Pd(50) and Pt(50) catalysts of 0.68 and
0.45 grams per mile approximated levels from the more heavily
loaded 5Pt:Rh(80) converter.
4. The three-way catalyst mode is the preferred
operating configuration when all measured pollutants are
considered to be of equal concern.
5. HC, CO, and formaldehyde efficiencies over the HFET
cycle were generally very high from both catalysts in the
three-way mode. NOx efficiencies approximated 47 percent from
both catalyts in the three-way mode; NOx emissions rose to
baseline levels from both catalysts when tested in the
oxidation mode, however.
B. Part 2
1. The lowest HC emissions over the FTP, approximately
0.13 grams per mile, were obtained from the two noble
metal-containing catalysts. The OEM converter had an HC
emission level of 0.07 grams per mile; the difference may be
due to quicker light-off of the OEM converter, which is located
closer to the engine.
2. All three evaluated catalysts had higher CO
efficiencies over the FTP than the manifold closed-coupled
converter.
-------
-14-
3. All three evaluated catalysts had lower NOx
efficiencies than the manifold close-coupled converter. NOx
levels with each evaluated catalyst slightly exceeded the
current 1 gram per mile light-duty vehicle standard for NOx.
4. The base metal-containing catalysts had formaldehyde
efficiencies exceeding 90 percent over the FTP. The levels of
formaldehyde emissions were approximately 30-34 grams per mile
over the FTP for these two catalysts.
5. HC, CO, and formaldehyde levels from each evaluated
catalyst were low over the HFET cycle. NOx levels from each
catalyst exceeded baseline amounts over the HFET, however.
VIII.Acknowledgment s
The catalysts described in Section V, Part 1 of this
report were provided by Engelhard Industries. The
methanol-fueled vehicle used for this testing was supplied to
EPA by Volkswagen AG. The catalysts described in Section V,
Part 2 were provided by Automotive Catalyst Company, a
subsidiary of Allied-Signal. These catalysts were evaluated on
a methanol-fueled vehicle supplied by the Toyota Motor
Corporation.
The author appreciates the efforts of Ernestine Buiifant,
Robert Moss, and Stephen Halfyard of the Test and Evaluation
Branch, Emission Control Technology Division, who conducted the
driving cycle tests and prepared the formaldehyde samples for
analysis.
In addition, the author appreciates the efforts of
Jennifer Criss and Marilyn Alff of the Control Technology and
Applications Branch, ECTD, whose attention to detail during the
typing of the text and the tables was greatly appreciated.
-------
-15-
IX. References
1. "Low Mileage Catalyst Evaluation With a
Methanol-Fueled Rabbit - Interim Report," Wagner, R. and L.
Landman, EPA-AA-CTAB-83/05, May 1983.
2. "Low Mileage Catalyst Evaluation With a
Methanol-Fueled Rabbit - Second Interim Report," Wagner, R. and
L. Landman, EPA-AA-CTAB-84/03, June 1984.
3. "Evaluation of Catalyst for Methanol-Fueled Vehicles
Using a Volkswagen Rabbit Test Vehicle," presented at the Joint
Conference On the Introduction and Development of Methanol As
An Alternate Fuel, Columbus, OH, June 26-27, 1986, ASME.
4. "Catalysts for Methanol Vehicles", Piotrowski, G. K.
and J. D. Murrell, SAE Paper 872052, November, 1987.
5. "Kinetics and Reaction Pathways of Methanol
Oxidation on Platinum," McCabe, R. W. and D. F. McCready,
Journal of Physical Chemistry, 1986, Vol. 90, pp. 1428-1435.
6. "Exhaust-Catalyst Development For Methanol-Fueled
Vehicles: A Comparative Study of Methanol Oxidation Over
Alumina-Supported Catalysts Containing Group 9, 10, and 11
Metals," McCabe, R. W. and P.J. Mitchell, Applied Catalysis,
Vol. 27, 1986, pp. 83-98.
7. The Clean Air Act As Amended Through July 1981,
Section 211(c)(l).
8. Speech by Charles L. Gray, Jr., EPA, QMS, OAR, to
1983 Midyear Refining Meeting of the API, May 11, 1983.
9. Policy Statement to Vice President of the U.S.A.,
George Bush, March 6, 1987.
10. 1975 Federal Test Procedure, Code of Federal
Regulations, Title 40, Part 86, Appendix l(a), Urban
Dynamometer Driving Schedule.
11. Highway Fuel Economy Driving Schedule, Federal
Register, Vol. 41, No. 100, May 21, 1976, Appendix l.
12. Formaldehyde Measurement In Vehicle Exhaust At MVEL,
Memorandum, Gilkey, R. L., OAR, OMS, EOD, Ann Arbor, MI, 1981.
13. "Formaldehyde Sampling From Automobile Exhaust: A
Hardware Approach," Pigeon, W., EPA-AA-TEB-88/01, July, 1988.
14. "Development of Methanol Lean Burn System," Katoh,
K., Y. Imamura and T. Inoue, SAE Paper 860247, February, 1986.
-------
APPENDIX A (conr'd)
Methanol-Powered Volkswagen Test Vehicle
Soecifications and Chanaes To Accommodate Methanol Fuel
Vehicle Item
Idle Setting
PCV:
Ignition:
Distributor
Spark Plugs
Transmission:
General
Torque Converter Ratio
Stall Speed
Gear Ratios:
1
2
3
Axle
Fuel Tank:
Material
Coating
Seams and Fittings
Cap
Fuel
Specification/Change
Specific to methanol
calibration.
PCV valve with calibrated
plunger—no orifice.
Slightly reduced maximum
centrifugal advance and
slightly modified vacuum
advance/retard characteristics
Bosch W260T2
1981 production automatic
3-speed.
2.44
2000-2200 RPM
2.55
1.45
1.00
3.57
Steel
Phosphated steel
Brazed
European neck and locking cap
Neat methanol (M100)
-------
APPENDIX A
Methanol-Powered Volkswagen Test Vehicle
Specifications and Changes To Accommodate Methanol Fuel
Vehicle Item
Engine:
Displacement
Bore
Stroke
Compression Ratio
Valvetrain
Basic Engine
Fuel System:
General
Pump Life
Accumulator-Maximum Holding
Pressure
Fuel Filter
Fuel Distributor
Specification/Change
Air Sensor
Fuel Injectors
Cold Start Injectors
Fuel Injection Wiring
1.6 liter
7.95 cm
8.00 cm
12.5:1
Overhead camshaft
GTI basic engine - European
high performance engine to
withstand higher loads - U.S.
cylinder head
Bosch CIS fuel injection with
Lambda feedback control, cali-
brated for methanol operation
1 year due to corrosiveness of
methanol. Improved insulation
on wiring exposed to fuel
3.0 Bar
One-way check valve deleted
because of fuel incompatibility
5.0-5.3 bar system pressure,
calibration optimized for
methanol, material changes for
fuel compatibility
Modified air flow
characteristics.
Material changes for fuel
compatibility, plastic screen
replaced by metal screen
2 injectors, valves pulse for 8
seconds beyond start mode below
zero degrees centrigrade
Modified for cold start pulse
function and to accommodate
relays and thermo switch
-------
APPENDIX B (cont'd)
Description of Toyota LCS-M Test Vehicle
Ignition Timing
Engine Oil
Fuel Injectors
Fuel Pump
Fuel Lines and Filter
Catalytic Converter
With check connector shorted,
ignition timing should be set
to 10°BTDC at idle. With check
connector unshorted, ignition
timing advance should be set to
15°BTDC at idle. Idle speed is
approximately 550-700 rpm
10W-30(SF). Toyota recommends
oil change interval of 3,000
miles
Fuel injectors (main and cold
start) capable of high fuel
flow rates. The fuel injector
bodies have been nickel-plated,
and the adjusting pipes are
stainless steel.
In-tank electric fuel pump with
brushless motor to prevent
corrosion. The body is nickel
plated and its capacity to
deliver fuel (flow rate) has
been increased.
The tube running from the fuel
tank to the fuel filter has
been nickel plated. The fuel
filter, located in the engine
compartment, has also been
nickel plated. The fuel
delivery rail has been plated
with nickel-phosphorus.
1 liter total volume, Pt:Rh
loaded. Catalyst is close
coupled to the exhaust manifold.
-------
APPENDIX B
Description of Toyota LCS-M Test Vehicle
Vehicle Identification Number:
Curb Weight
Inertia Weight
Odometer at Delivery
Transmission
Shift Speed Code
Dynamometer Horsepower
Engine:
Fuel
Number of Cylinders
Displacement
Camshaft
Compression Ratio
Combustion Chamber
Fuel Metering
Bore
Stroke
Fuel tank
Ignition
AT15102264700000
2015 Ibs
2250 Ibs
1358 miles
Manual, 5 speed
15-25-40-45 mph
8 HP
M100 neat methanol
4, in-line
97 cubic inches
Single, overhead camshaft
11.5, pistons with flat heads
are used
Wedge shape
Electronic port fuel injection
3.19 inches
3.03 inches
Stainless steel construction,
capacity 14.5 gallons
Spark ignition; spark plugs are
NDW27ESR-U, gapped at .8 mm,
torqued to 13 ft-lb. Toyota
recommends changing spark plugs
after 9,000 miles of vehicle
operation
------- |