EPA/AA/CTAB/86-01
Technical Report
Durability Evaluation of
Aftermarket Catalysts
by
Robert I. Bruetsch
John Shelton
March 1986
NOTICE
Technical Reports do not necessarily represent final EPA de-
cisions 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
-------
EPA/AA/CTAB/86-01
Technical Report
Durability Evaluation of
Aftermarket Catalysts
by
Robert I. Bruetsch
John Shelton
March 1986
NOTICE
Technical Reports do not necessarily represent final EPA de-
cisions 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
-------
I. Introduction
Recently, aftermarket catalysts have been introduced into
commerce by several companies. These catalysts appear to be
different than OEM catalysts in one or more design features.
These catalysts are also considerably less expensive than
replacement OEM catalysts. The purpose of this project was to
evaluate the efficiency of a group of aftermarket catalysts as
a function of accumulated miles and to evaluate a single OEM
catalyst at a single mileage point (83,161 miles) for
comparison. Nine aftermarket catalysts were evaluated on one
vehicle, which was provided by EPA. Catalyst evaluation was
performed at Automotive Testing Laboratories, Inc. (ATL) in
East Liberty, Ohio. Mileage was accumulated using other
vehicles (five Impalas) by Hercules, Inc. of Cumberland, MD.
The catalysts were evaluated for exhaust emissions conversion
efficiencies and backpressure at each test point. This project
was performed under Technical Directive No. 6 of EPA Contract
No. 68-03-3230.
II. Test Vehicle
The test vehicle, which was supplied by EPA, was used for
all emissions testing of all ten catalysts. The vehicle is a
1980 Oldsmobile Delta 88 four-door sedan with vehicle
identification number (VIN) 3Y69YAM169068. It is equipped with
power steering and power brakes, a 305 cubic-inch engine,and a
3-speed automatic transmission. Its emission control system
includes air injection, oxidation catalyst, backpressure
exhaust gas recirculation and early fuel evaporation (engine
family 03L4F).
III. Catalysts Evaluated
Ten catalysts were tested. All ten are oxidation
catalysts supplied by EPA. These include the OEM catalyst on
the test vehicle supplied by EPA. The other nine catalysts
include three nominally identical catalysts from three
different aftermarket catalyst suppliers. EPA labeled each
catalyst with a two-digit code, such as 1-2. This means the
catalyst is from supplier number 1 (Walker) and is catalyst
number 2 of 3 supplied by Walker. Catalyst 3-1 therefore is
the first of three Brown catalysts. Catalysts are identified
by this two-digit code in all documentation of this project,
including this report. The converter suppliers and the
catalyst code numbers are as follows:
Converter/Type Code Numbers
1. Walker/monolith 1-1,1-2,1-3
2. Echlin/pellet 2-1,2-2,2-3
3. Brown/monolith 3-1,3-2,3-3
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IV. Test Sequences
A.
Phase I:
Testing
-2-
Baseline Emissions and Evaluation of Modal
Catalyst conversion efficiency comparisons were generated
two different ways. In the first method, conversion efficiency
was calculated from a single test using the modal analyzer to
measure engine-out and catalyst-out emissions. Bag data to
measure tailpipe emissions was also generated. Catalyst-out
emissions, as measured with the modal analyzer, were compared
to the bag data. These measures were within 1.1 percent of
each other based on a carbon balance analysis. In the second
method, conversion efficiency was calculated from two separate
tests; one run with the catalyst to yield tailpipe emissions,
and the other run with a straight pipe installed in place of
the catalyst to yield engine-out emissions. To achieve this
objective, the test sequence shown in Table 1 was used.
Cycle
1. FTP
2. Idle
(5-min sample)
3. 20 MPH SS
(5-min sample)
4. 40 MPH SS
(5-min sample)
5. 60 MPH SS
(5-min sample)
Table 1
Baseline Test Sequence
Measure
HC, CO, NOx, CO2
catalyst temperature
(in & out), backpressure
(catalyst in & out)
HC, CO, NOx, CO2
catalyst temperature
(in & out), backpressure
(catalyst in & out)
HC, CO, NOx, CO2
catalyst temperature
(in & out), backpressure
(catalyst in & out)
HC, CO, NOx, CO2
catalyst temperature
(in & out) backpressure
(catalyst in & out)
HC, CO, NOx, CO2
catalyst temperature
(in & out) backpressure
(catalyst in & out)
Calculate
MPG, emissions
(g/mi) by bag and
for total test,
pressure drop over
catalyst
Emissions (g/mim)
pressure drop,
fuel consumption
(gal/min)
Emissions (g/mi)
pressure drop, MPG
Emissions (g/mi)
pressure drop, MPG
Emissions (g/mi),
pressure drop, MPG
-------
The test sequence in Table l was run three times with the
the test vehicle (Delta 88) using the OEM catlyst catalyst with
the modal analyzer. Each time the modal analyzer was used,
engine-out and tailpipe emissions were measured. The actual
dynamometer horsepower (ADHP) was increased to 18.3 and the
test sequence, less the FTP and idle cycles, was repeated twice
using the OEM catalyst with the modal analyzer. Three more
test sequences were then run with the OEM catalyst without the
modal analyzer. The OEM catalyst was then removed and the test
sequence was repeated three more times without the modal
analyzer. The dynamometer horsepower settings were then
increased and two more test sequences, less the FTPs and idles,
were then run without the modal analyzer. This phase of
testing is summarized as follows:
Number of Use Modal
Test Sequences ETW/ADHP Catalyst Analyzer?
3 4000/12.2 OEM Yes
2 less FTPs 4000/18.3 OEM Yes
and idles
3 4000/12.2 OEM No
2 less FTPs 4000/18.3 OEM No
and idles
3 4000/12.2 Straight Pipe No
2 less FTPs 4000/18.3 Straight Pipe No
and idles
The results of these tests showed that the modal testing
is preferable to the test sequences with the straight pipe.
This decision was based on cost (one FTP per test with modal
analyzer versus two FTPs per test; one with catalyst and one
with straight pipe) and the fact that the pipe did not
accurately represent backpressure caused by a catalyst thereby
influencing imputed catalyst efficiency. EPA evaluated the
data and informed the contractor to use the modal analysis
method of generating data for subsequent phases of testing.
B. Phase 2: Zero-Mile Testing of Aftertnarket Catalysts
The first aftermarket catalyst was installed on the test
vehicle without mileage accumulation. After the exhaust system
was checked and found free of leaks, the contractor completed
two valid test sequences as shown previously in Table 1. The
first catalyst was removed and the second aftermarket catalyst
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-4-
from the same manufacturer (Walker) was installed. Again the
exhaust system was checked for leaks. Two additional valid
test sequences were conducted. This catalyst was removed and
the third Walker catalyst was installed. Two valid test
sequences were then conducted with this catalyst. After all
three Walker catalysts were tested at the zero mile test point,
the same procedure was performed on the three Echlin and Brown
catalysts. The vehicle odometer readings were recorded when
each catalyst was installed or removed and at the start of each
test cycle in the test sequence. Two test sequences, less FTPs
and idles, were run on one catalyst from each manufacturer at
the increased dynamometer horsepower setting (18.3 actual HP).
The resulting summary of testing for Phase 2: Zero-Mile
Testing of Aftermarket Catalysts, is shown in Table 2. These
sequences, as will be shown later, are exactly the same as
those-that were run at the 25K mileage point.
Table 2
Summary of Phase 2 Testing
No. of Sequences (less
Catalyst Catalyst Number of FTPs and idles) With
Manufacturer Number Sequences Increased Dyno. HP
112 2
122 2
132 2
21 2 2
222 2
2 32 2
31 2 2
322 2
332 2
C. Phase 3; Mileage Accumulation and Testing at Higher
Mileage Intervals
The aftermarket catalysts, which were removed from the
test vehicle in Phase 2, were installed on other vehicles to
accumulate mileage on the catalysts. The converters were
installed on one of five nominally identical 1985 Chevrolet
Impalas, equipped with V-8, 5.O-liter/305-CID engines and 700R4
automatic tranmissions. Mileage was accumulated over three of
Hercules' standard test routes. These road routes are
routinely used by Hercules for tire-wear testing, and are
described below.
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-5-
l. Route W-4
Route W-4 is characterized as a "slow wear" route. Its
course consists entirely of dual-lane interstate expressways,
about 15 percent in West Virginia and 85 percent in Maryland.
2. Route W-10-H
Route W-10-H is rated for what the tire industry considers
as "medium wear." It consists almost entirely of interstate
expressways, about 50 percent in Maryland and 50 percent in
West Virginia. Compared to the slow wear route, this route's
more extensive driving in mountainous terrain adds more turns
and grades to the vehicle's duty cycle.
3. Route M-101
Route M-101 is a "high wear" route developed to simulate
European driving. It splits about 60/40 percent Maryland/West
Virginia and includes 250 miles of interstate expressway
driving and 250 miles of mountainous driving which includes
hard turns and grades up to 20 percent.
These three different routes can have potentially
different effects on catalyst performance. Prior to the
aftermarket catalyst aging on these routes, an instrumented
Impala (one of the cars used later with the aftermarket
catalysts) was used to profile the three routes. Engine rpm
and the inlet and outlet temperatures of the vehicle's OEM
catalysts were measured every 10 seconds. The catalyst
temperature results obtained were as follows:
Average OEM Catalyst Temperature, °F
Inlet Outlet
Route W-4 941 939
Route W-10-H 965 1008
Route M-101 945 1004
Plots of the distributions of the catalyst inlet and
outlet temperatures are shown in Figures 1 and 2, respectively.
The three different routes did not result in significantly
different catalyst temperatures. The catalyst outlet
temperature distributions are more similar to each other than
are the inlet temperature distributions. Note that the
"hardest" route in terms of tire wear did not produce the
highest catalyst temperatures.
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i
28
-6-
Figure 1 - Inlet Temperature Distributions
of Durability Routes
TIME AT TEMPERATURE
ROUTE W4 (t SHIFT)
26 -
24 -
22 -
20 -
18 -
12 -
a -
6 -
4
..ll.lll
ll—
290 900 790 1000 1290 1900 1790 2000
INLET TEMPERATURE DEGREES (F)
14
13
12 -
1 1 -
10 -
9 -
8 -
7 -
6 -
S -
4 -
3 -
2 -
1 -
0
TIME AT TEMPERATURE
POUTE WtOH (1 SHIFT)
ll,
290 900 790 1000 1290 1900
INLET TEMPERATURE DECREES (F)
17SO
:ooo
TIME AT TEMPERATURE
ROUTE Ml 01 (1 SHIFT)
Ul
5
tt
Ul
a.
2
Ul
r-
5
Ul
a
*~
z
Ul
K
U
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-7-
Figure 2 - Outlet Temperature Distributions
of Durability Routes
TIME AT TEMPERATURE
ROUTE W4 (1 SHIFT)
4O -
39 •
w
| 30-
oc
jjj 29 •
5 20-
a
p 19 -
z
K 10 -
0.
9 -
0 -
L.
0 290 900 790 1000 1290 1900 1790 2CC
OUTLET TEMPERATURE DECREES (F)
TIME AT TEMPERATURE
2* -
22 -
20 -
w
3 18 -
5
2 16 -
a.
2 14-
5 12-
Ul
3 10 -
1—
5 8-
2' 6-
hi
a.
2 -
0 -
ROUTE W10H (1 SHIFT)
• _ -..ill
L
0 290 900 790 1000 1290 1900 1790 :"
OUTLET TEMPERATURE DECREES (F)
TIME AT TEMPERATURE
22 -
20 -
u "
a
? 16 -
(t
£ 14-
2
" 12 -
u 10 -
a
£ 8-
0 6 -
It
"" 4 -
2 -
a -
ROUTE M101 (1 SHIFT)
.Lull
1.
290 900 790 1000 1230 1900
OUTLET TEMPERATURE DECREES (F)
1790
2000
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-8-
The catalysts were removed from the Impalas for testing on
the test vehicle at the following mileage points (plus or minus
250 miles):
4,000 miles
15,000 miles
25,000 miles
The referenced mileage intervals are miles accumulated on
the catalyst, not the vehicle, and include miles accumulated on
the test vehicle. Testing at the 25,000-mile point was
identical to that done in Phase 2: the zero-mile testing.
Testing at the 4,000- and 15,000-mile points was also identical
to the testing in Phase 2, except that three converters, l-i,
2-1, -and 3-1, accumulated 25,000 miles without intermediate
emissions testing. The remaining converters were removed at
4,000 and 15,000 accumulated miles for emissions testing at
ATL's facilities. A breakdown by converter, vehicle, mileage
and route is shown in Table 3.
V. Aged Aftermarket Versus OEM Catalyst Efficiency Results
A log book of vehicle maintenance and malfunctions was
kept for both the test vehicle and the five durability
vehicles. However, no vehicle was reported to have had any
incidences of poor driveability or operational problems. There
were also no reported incidences involving misfires or other
combustion problems.
Converter 1-3 was reported as being clogged with debris
prior to 15,000-mile testing. Further inspection revealed a
meltdown of substrate material on the downstream end of the
converter. The mileage accumulation contractor was contacted
with regard to the condition of the vehicle used for the 4,000-
to 15,000-mileage increment. No problems were noted on the
driver's comment sheets during this, period, or during a
mechanic's inspection of the vehicle at the 15,000-mile point.
The meltdown was unusual in that the damage was at the outlet
(downstream) end of the converter. Approximately 25 percent of
the honeycomb had broken away and was missing. The exposed
ragged ends had melted down, but did not clog the converter.
Steady-state measurements indicated backpressure was reduced.
The converter was returned for the final 10,000 miles of
service. No problems were experienced with subseguent
converters installed on this vehicle.
-------
Converter
#1-2
#1-3
#2-1
#2-2
#2-3
#3-1
#3-2
#3-3
-9-
Table 3
Schedule of Durability Mileage Accumulation
of Aftermarket Catalytic Converters
Vehicle
TC-361
TC-363
TC-362
TC-369
TC-360
TC-361
TC-362
TC-361
TC-363
TC-362
TC-369
TC-361
TC-360
TC-360
INTERNAL
TC-362
TC-363
TC-362
TC-361
TC-369
INTERNAL
TC-360
TC-369
TC-363
Installed
10-04-85
10-25-85
09-19-85
10-25-85
12-30-85
09-19-85
10-28-85
12-30-85
11-09-85
10-16-85
11-13-85
01-24-86
10-16-85
11-13-85
MATERIAL BROKE
11-13-85
01-07-86
10-21-85
11-26-85
01-24-86
MATERIAL BROKE
10-21-85
12-06-85
01-24-86
Removed
10-25-85
11-08-85
09-28-85
11-13-85
01-12-86
10-02-85
11-13-85
01-20-86
1-06-86
10-21-85
12-06-85
02-13-86
10-21-85
12-09-85
APART . TEST
01-05-86
01-13-86
10-28-85
12-18-85
02-10-86
APART.
10-28-85
01-02-86
02-13-86
Test
Miles
14,000
25,000
COMPLETE
4,000
15,000
25,000
COMPLETE
4,000
15,000
25,000
COMPLETE
25,000
COMPLETE
4,000
15,000
25,000
COMPLETE
Route
W-10-H
W-10-H
M101
W-10-H
W4
M101
W-10-H
W-10-H
W-10-H
W-10-H
M101
W4
4,000 W-10-H
15,000 W4
TERMINATED
19,500
25,000
COMPLETE
4,000
15,000
25,000
COMPLETE
4,000
15,000
25,000
COMPLETE
M101
W-10-H
W-10-H
W-10-H
M101
W-10-H
M101
W4
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-10-
Converter 2-3 testing was terminated prior to the
15,000-mile tests due to loss of the converter's pelleted
catalyst material. Further mileage accumulation on 2-3 was
canceled and the converter was returned to EPA.
Ten to twenty small fragments of bead were noted inside
the inlet pipe of converter 2-2 at the 15,000-mile test point.
However, this converter completed 25,000 miles of aging, though
efficiency dropped substantially.
Converter 3-2 had developed a crack at the 4,000-mile test
point. However, no significant deterioration in efficiency was
noted through the 15,000-mile testing. Converter 3-2
fractured, however, during the final 10,000 miles of driving.
A clear path was formed for exhaust gases to bypass the
converter element. This represented approximately 20 percent
of the surface area of the converter. All of the small pieces
of substrate and liner were removed from the shell. One piece
larger than the outlet of the converter remained at the
25,000-mile test point. Three tests were run on converter 3-2
at the 25,000-test point, instead of two, because the first two
cycles of the modal analysis were missing from the first test.
Summaries of the aged aftermarket catalyst HC and CO
conversion efficiencies compared to baseline OEM catalyst
efficiencies are shown in Tables 4 and 5, respectively. A
possible EPA regulatory requirement of 70 percent conversion
efficiency for both HC and CO can be compared to these data.
As can be seen in Tables 4 and 5, most catalysts' efficiencies
are in line with the possible EPA regulatory requirement with
the exceptions of the previously mentioned problem catalysts,
i.e., Walker tt3 after 15,000 miles, Echlin tt3 after 15,000
miles, and Brown #2 after 25,000 miles. Converter 1-1 was
tested a third time at 25,000 miles because it was so near the
70 percent conversion goal for HC.
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-11-
Table 4
Aftermacket Catalyst HC Conversion Efficiency*
Mileage
Test 81
Converter
Walker 81 87
Walker 82 87
Walker 83 83
Echlin 81 77
Echlin 82 79
Schlin 83 74
Brown 81 83
Brown 82 82
Brown 83 84
Mileage
Summary
Walker Avg.
Min.
Max.
Echlin Avg.
Min.
Max.
Brown Avg .
Min.
Max.
OK
82
.0 85.5
.9 84.5
.9 82.3
.3 76.8
.4 79.5
.9 73.8
.7 82.0
.4 81.9
.4 82.0
OK
85.2
82.3
87.9
77.0
73.8
79.5
82.7
81.9
84.4
4K
81 82
—.— -
81.6 81.5
76.4 74.7
— —
64.2 60.7
64.4 63.4
— —
80.9 79.4
76.9 76.0
4K
78.6
74.7
81.6
63.2
60.7
64.4
78.3
76.0
80.9
15K
81 82
^__ —
75.9 76.3
36.2 36.9
— —
50.5 51.7
25K
81 82
83
66.2 70
69.5
66.5 67
29.7 27
47.8 49
47.9 48
.1
.0
.9
.3
.4
TESTING TERMINATED
— —
69.0 66.9
72.1 71.0
15K
56.3
36.2
76.3
51.1
50.5
51.7
69.8
66.9
72.1
68.6 67
34.2 31
33.3
67.5 62
25K
54.7
27.9
70.1
48.4
47.8
49.3
55.4
31.6
68.6
.8
.6
. 7
OEM baseline HC conversion efficiency = 65.9 percent
83,161 miles.
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-12-
Table 5
Aftermarket Catalyst CO Conversion Efficiency*
Mileaqe
Test ttl
Converter
Walker ttl 96
Walker K2 97
Walker #3 96
Echlin ttl 87
Echlin tt2 91
Echlin tt3 88
Brown ttl 94
Brown #2 93
Brown tt3 95
Mileage
Summary
Walker Avg.
Min.
Max.
Echlin Avg.
Min.
Max.
Brown Avg.
Min.
Max.
OK
tt2
.3 95.4
.3 94.5
.4 93.4
.9 89.9
.3 92.0
.6 86.4
.8 92.5
.0 93.6
.8 93.5
OK
95.6
93.4
97.3
89.4
86.4
92.0
93.9
92.5
95.8
4K
ttl #2
__
95.2 96.7
94.1 92.0
— —
78.7 74.5
76.9 78.2
— —
94.1 92.2
90.7 90. 1
4K
94.5
92.0
96.7
77.1
74.5
78.7
91.8
90.1
94.1
15K
#1 #2
__
93.4 94.1
48.1 50.6
— —
61.8 62.7
25K
ttl #2
K3
87.9 88
89.8
90.1 89
37.2 35
56.7 58
58.0 56
.5
.6
.0
.3
.9
TESTING TERMINATED
• — . —
86.2 84.0
86.3 86.3
15K
71.6
48.1
94.1
62.2
61.8
62.7
85.7
84.0
86.3
85.1 85
30.2 30
31.9
81.4 79
25K
71.6
35.0
90.1
57.5
56.7
58.3
65.5
30.2
85.2
.2
.9
.4
OEM baseline CO conversion efficiency = 79.0 percent @
83,161 miles.
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