EPA/AA/CTAB/87-01 Technical Report Durability of Low Cost Catalysts For Methanol-Fueled Vehicles By Robert M. Heavenrich Robert I. Bruetsch Gregory K. Piotrowski October 1987 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 December 14, 1987 MEMORANDUM SUBJECT: Exemption From Peer and Administrative Review FROM: Karl H. Hellman, Chief Control Technology and Applications Branch TO: Charles L. Gray, Jr., Director Emission Control Technology Division The attached report entitled "Durability of Low Cost Catalysts for Methanol-Fueled Vehicles," (EPA-AA-CTAB-87-01) describes catalysts tested at MVEL for efficiency at zero miles and then aged 12,000-14,000 miles in Los Angeles, California as part of a California Energy Commission sponsored program in cooperation with Ford, Toyota, and EPA. This report compares FTP and HWY test results at the 12,000-14,000 mile point with the zero-mileage results. 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. Approved: : Date Charles L. Gray, Jr.", Dir., ECTD Attachment ------- Background The objective of the project was to evaluate the efficiency durability of low cost catalysts operated on- methanol-fueled vehicles in fleet service. The catalysts were first tested at EPA for efficiency at zero miles. [1]* The catalysts were then operated on cars in Los Angeles, California. After 12,000-14,000 miles were accumulated on the catalysts, they were removed from the cars and shipped back to EPA for further testing. This report compares the tests at the 12,000-14,000 mile point with the zero-mileage results. The California Energy Commission, Engelhard Specialty Chemical Division, Johnson Matthey Catalytic Systems Division, Ford and Toyota cooperated with EPA in this effort. Description of Catalysts Two catalyst types were tested in this program. Both catalyst types were monoliths with substrates of 400 cells per inch and a 6-mil wall thickness. Both were composed of two separate biscuits in a single container. Each biscuit has an oval cross section measuring 3.15 by 4.75 inches. The front biscuit is 2.98 inches long and the rear biscuit 4.3 inches long for a total substrate volume of 92.8 cubic inches. Both catalyst types had loadings of 20 grams of noble metal per cubic foot. One catalyst type contained only palladium (Pd); the other contained platinum (Pt) and palladium in a ratio of 3:2. Using standard CTA3 notation, these are denoted Pd(20) and 3Pt:2Pd(20), respectively. A total of eight catalysts (four of each type) were prepared for this project. Three of the four units of each type were shipped to California in January 1984 without any testing at EPA. One catalyst of each type was zero-mileage tested at EPA before being shipped to California in April 1984.** Table 1 gives a listing of the catalysts that were installed on the fleet vehicles for mileage accumulation: the catalyst type, formula, catalyst serial number, vehicle identification number (VIN), fleet vehicles, license plate, and odometer reading when the catalyst was removed from the car. * Numbers in brackets denote references listed at the end of the report. ** The two catalysts zero-mileage tested at EPA had serial numbers NPN 7-16 (PD(20» and 9K-8579, EPA 2648 (3Pt:2Pd(20)). The catalysts were installed on the aging vehicles in January 1984 by Bill Stroppe & Son, Long Beach, CA, but the initial odometer readings were not recorded. ------- -2- Table 1 Sample Numbers of Catalysts Aged on Fleet Vehicles Sample Catalyst Number Type Formula 1 OX Pd(20) 2 TWC* Pd(20) 3 TWC* 3Pt:2Pd (20) 4 OX 3Pt : 2Pd (20) 5 OX 3Pt : 2Pd (20) 6 OX Pd(20) Serial No. NPN 6-15 NPN 8-17 9K-8583 EPA2650 9K-8580 EPA2649 9K-8584 EPA2651 NPN 3-12 Vehicle License Ident . No. Plate No. 1FABP137 0868571 XDW237350 1FABP137 0868573 XDW237378 1FABP137 0868572 6DW237359 1FABP137 0868570 3DW237349 1FABP137 0868575 9DW237405 1FABP137 0868574 9DW237386 Odometer Reading 13306 .3 12732.0 14249 . 2 12493.8 11809.4 13247.9 No thermactor belt. ------- -3- For each catalyst used as an oxidizing catalysts, the downstream air tube was flush mounted with the exhaust pipe to put air (from the air pump) into the exhaust at least six inches upstream of the catalyst. For each catalyst used as a three-way catalyst, the belt to the air pump was removed, and the downstream air tube was capped. EPA Test Vehicle The catalysts were tested at EPA on a 1982 Toyota Cressida described in Table 2. This vehicle was modified by Toyota to operate on methanol fuel. Additional modifications were made to the Cressida's exhaust system to facilitate installation of the catalysts and to allow for the installation of thermocouples before and after the catalyst. Fuel injectors were changed by Toyota in March 1984, April 1984, May 1984, June 1984, July 1984, August 1986, and August 1987. Zero Mileage Test Procedure The initial plan called for testing of the catalysts over the following sequence: 1975 Federal Test Procedure (FTP) Highway Test Procedure (HWY) 10 mph steady state 20 mph steady state 30 mph steady state After baselining the test car without a catalyst, the sequence was performed three times for each catalyst at each of two exhaust oxygen levels. The higher of the two exhaust oxygen levels was measured at the catalyst inlet using a Sun oxygen analyzer and was obtained at 30 mph steady state. The two oxygen levels were stoichiometry (or near 0 percent) and about 6 percent. The air pump was installed (March 1984) in order to provide the 6 percent oxygen level. By testing at different exhaust oxygen levels we could, therefore, evaluate each catalyst as a three-way catalyst and also as an oxidation catalyst. As the project proceeded, steady-state test points were deleted in order to speed up the testing. HC, CO, NOx, MPG, methane, and aldehydes were initially measured over each test in the sequence. Measurement for aldehydes was deleted for some of the steady-state tests. The apparatus used to measure HC, CO, NOx, and aldehyde emissions is described in references 2 and 3. The test fuel used in this program was pure methanol. Five batches of methanol were consumed in this phase of the project; one was analyzed, and described in reference 2. The gasoline used in the cold-start system of the Toyota is Indolene clear (unleaded) and meets the EPA specifications for that fuel (40 CFR 86.307-82). ------- Table 2 Emission Test Vehicle Description 1982 Toyota Cressida (methanol-fueled) Vehicle Identification Number: MX62-083780 Engine: Type Bore x Stroke Displacement Compression Ratio Fuel Metering Drive Train: Transmission Type Axle Ratio Chassis: Type Tires Curb Weight Test weight (ETW) Actual Dynamometer Horsepower 4-stroke Otto cycle, in-line 6 83 . 0 x 85.0 mm 2759 cc (168 CID) 10.0: 1 Two separate fuel injection systems. (The main fuel injection system uses pure methanol; a separate cold-start fuel injection system uses pure gasoline. 4-speed automatic with overdrive 3.73 4-door sedan Dunlop 185/70SR14 steel belted radials 2,855 pounds 3,000 pounds 10.3 ------- -5- Zero Mileage Test Results Tables 3 and 4 present average zero-mile FTP emissions and efficiencies. (More detailed data on these tests is presented in reference 2.) Due to the substantial shift in engine-out emissions following the replacement of the fuel injectors, the data in these tables is limited to those tests after the change in injectors. Tables 5 and 6 present zero-mileage highway emissions and efficiencies* for the two catalysts. Table 7 contains zero-mile efficiencies for each bag of the FTP. Mileage Accumulation Vehicles Mileage accumulation was performed on six model year 1983 methanol-fueled Escorts (Tables 8 and 9). These cars were part of a fleet based at the Los Angeles airport and driven by State of California employees. Initial maintenance on the vehicles was performed under contract by Thrifty Rent-A-Car. After January 1, 1986, the maintenance was performed by Dollar Rent-A-Car. Mileage accumulation on the Escorts was very uneven. Some selected cars were signed out almost continuously, while some were utilized only on those occasions when a great number of cars were needed. The level of maintenance of these cars apparently dropped off appreciably before January 1986. Appendix A gives a summary of the maintenance performed on each of the Escorts used in this project. A Ford Motor Company engineer examined 17 of the fleet Escorts- in June 1985 and observed a number of maintenance problems with these vehicles. Commonly observed problems were: 1. Carburetors had been adjusted to very rich idle mixtures; and 2. Ignition timing which should have been maintained at 14° BTDC had been retarded to approximately 8°. Thus, the cars were operated by a number of drivers, on a number of unknown routes, under a number of different driving conditions, often under conditions of maintenance different from those recommended by the manufacturer. Catalyst efficiency is defined as the percent difference between the emissions measured with and without a catalyst. ------- -6- Table 3 Summary of Average Zero-Mile at Different Oxygen Catalyst None 3Pt:2Pd(20 Pd(20) HC (g/mi) Oxygen 0% 6+% .99 ) .24 .27 .29 .28 Aid. (mg/mi) Oxygen 0% 6+% 283.6 37.3 264.6 41.0 236.5 Table 4 FTP Emissions Levels CO (g/mi) Oxygen 0% 6% 8.85 2.80 0.34 1.97 0.72 NOx (g/mi) Oxygen 0% 6% 2.08 0.51 1.35 0.32 1.32 Zero-Mile FTP Catalyst Efficiency (percent) at Different Oxyqen Levels Catalyst 3Pt:2Pd(20 Pd(20) HC (g/mi) Oxygen 0% 6+% ) 76 73 71 72 Aid. (mg/mi) Oxygen 0% 6+% 87 7 86 17 Table 5 Summary of Average Zero-Mile at Different Oxyqen Catalyst None 3Pt:2Pd(20 Pd(20) HC (g/mi) Oxyqen 0% 6+% .42 ) .01 .01 .01 .01 Aid. (mg/mi) Oxygen 0% 6+% 167.2 5.4 40 . 4 7.3 31.9 CO (g/mi) Oxygen 0% 6% 68 96 78 92 HWY Emissions Levels CO (g/mi) Oxyqen 0% 6% 6.33 . 0 . 74 0 . 00 0.74 0.02 NOx (g/mi) Oxygen 0% 6% 75 35 85 36 NOx (g/mi) Oxygen 0% 6% 1.88 0.26 1.06 0.06 1.06 ------- -7- Table 6 Zero-Mile Catalyst Efficiency (percent) Over HWY at Different Oxygen Levels* HC (g/mi) Oxygen Catalyst 3Pt:2Pd(20) Pd(20) 0% 98 98 6+% 97 97 Aid. (mg/mi) Oxygen 0% 97 96 6+% 76 81 CO (g/mi) Oxygen 0% 88 88 6% 99 + 99+ NOx ( g/mi) Oxygen 0% 86 97 6% 44 43 Table 7 Zero-Mile Catalyst Efficiency (percent) Over FTP By Bag at Different Oxygen Levels* HC Effic. Run As : TWC OX Aid. Effic. Run As : TWC OX CO Effic. Run As : TWC OX NOx Effic. Run As : TWC OX 3Pt:2Pd(20): Bag 1 49 48 67 8 54 87 65 19 Bag 2 97 94 96 5 73. 100 82 50 Bag 3 88 78 90 8 74 98 77 31 Pd(20): Bag Bag Bag 1 2 3 38 97 84 44 97 81 65 96 85 1 39 -24 54 90 78 77 99 93 72 92 87 18 53 34 "TWC" denotes a three-way catalyst (0 percent oxygen level), and "OX" denotes an oxidizing catalyst (6+ percent oxygen level). ------- -8- Table 8 Mileage Accumulation Vehicle Description 1983 Methanol-Fueled Ford Escorts Engine: Type Bore x Stroke Displacement Compression Ratio Fuel Metering Drive Train: Transmission Type Chassis: Type Vehicle Identification Numbers 4-stroke Otto cycle, in-line 4 80.0 x 79.5 mm 1.6 liters (98 CID) 11.8:1 2-barrel carburetor 3-speed automatic transaxle 4-door station wagon or 4-door sedan 1FABP1373DW237349 1FABP137XDW237350 1FABP1376DW237359 1FABP137XDW237378 1FABP1379DW237386 1FABP1379DW237405 ------- -9- Table 9 Modifications Made to the Model Year 1983 Gasoline-Fueled Escorts to Convert Them to Methanol-Fueled Fuel System Fuel Tank: Same design as gasoline-fueled Escort, but it is made of stainless steel for corrosion protection. Fuel Tank Sending Unit: Same design as standard unit, but it is nickel plated to prevent corrosion and has nickel plated brass float. Fuel Tank Straps: Same design as standard model, but the straps are coated with nylon to prevent dissimilar metal corrosion of the stainless steel methanol fuel tank. Fuel Lines: Same routing as standard Escort, but the lines are fabricated from stainless steel to prevent corrosion. Fuel Pump: Same design as standard unit, but all metallic parts have been made corrosion resistant through nickel plating, and all plastic and rubber parts are made from a material which will withstand methanol. Carburetor: The carburetor is stock, modified and recalibrated to meet the higher fuel-flow requirements of the methanol engine. All parts have been nickel plated or manufactured from a material which is compatible with fuel methanol. For example, idle adjusting needles and throttle shafts are made of stainless steel. The float unit is an acetal hollow design and replaces the standard unit. Carburetor Spacer : A rectangular spacer plate is installed between the carburet jr base and intake manifold. This plate uses a round electrical heating unit which replaces the square heating unit used on the gasoline-fueled engine. ------- -10- Table 9 (cont'd) Modifications Made to the Model Year 1983 Gasoline-Fueled Escorts to Convert Them to Methanol-Fueled Engine Basic Engine: The engine that powers the methanol vehicle is the same basic design as the Escort's gasoline-fueled l.6L high-output (HO) engine. The compression ratio has been increased from 8.8:1 to 11.8:1. This was accomplished by installing the piston from a European 1.3L Ford engine in the 1.6L block. Each piston has been fitted with a special top compression ring which is barrel faced and hard chromed steel. Piston rings two and three are standard. A 1984 head gasket that will withstand higher compression pressures is used to replace the standard gasoline head gasket. This head gasket uses a stainless steel fire ring and special backing material. The base 1.6L camshaft (pink color code) is used in place of the HO camshaft (yellow color code). Engine Oil: A unique engine oil containing a special additive must be used with methanol-fueled engines. The recommended oil is marked for methanol engines only. Ignition Distributor: The distributor is a modified, solid-state unit. Its operation is the same as the standard unit; the advance curves have been modified. The major difference is less mechanical advance. Spark Plugs: The spark plugs used in the methanol-fueled engine are two heat ranges colder than the spark plugs in the gasoline powered 1. 6L engine. This is necessary to prevent engine damage due to preignition. ------- -11- Tests on Aged Catalysts Baseline (i.e., without a catalyst) FTP and HWY tests were first run on the Toyota Cressida to compare to the zero-mile vehicle baseline emissions measured in 1984. The Toyota Cressida was then used to test the aged catalyst efficiency of the six catalysts returned from California. FTP and HWY tests were performed for each catalyst with HC, CO, NOx, MPG, and aldehydes measured over each test in the sequence. The need to replace fuel injectors in the Cressida continued. Table 10 gives a listing of the dates unscheduled, non-routine maintenance was performed on the Toyota Cressida for the period July 1, 1984 to September 30, 1987. New injectors were installed twice during this phase of the project in July 1984 and again in August 1986. Bag-by-bag FTP and highway baseline results for the period August 8, 1986 to September 23, 1987 are presented in Appendix B. The data for HC in this appendix show that the average baseline FTP emissions for HC for the tests run November 7 to 14, 1986 are essentially double what they were for the period August 8 to October 28, 1986. At this point Toyota replaced the fuel injectors. Baseline HC emissions with this set of injectors were about the same as those for the period August 8 to October 28, 1986, but CO was lower and NOx higher. Test results for the aged catalysts are presented in Tables 11 and 12. Table 11 gives FTP results for the catalysts; Table 12 gives the HWY results. Comparison of New and Aged Catalyst Efficiencies Tables 13 and 14 compare percent conversion efficiency for the new and aged catalysts for the -FTP and HWY tests respectively. Because of the shifting of the baseline emission data, percent conversion gives a better indication . of the ^.erformance of the catalyst than the actual emission levels achieved by the catalyst. The zero-mileage (i.e., new) efficiencies in this table are the same as presented previously. Emission levels as measured on the Cressida are likely to differ from those in-the Escorts for two reasons: 1. Zngine-out emissions from the Cressida for HC and CO are low; and 2. The two cars have different engine-out emission and exhaust gas temperature characteristics. ------- -12- Table 10 Unscheduled Maintenance on the Toyota Cressida* July l, 1984 to September 30, 1987 Date Comments July 3, 1984 November 27, 1984 August 4, 1986 August 18, 1986 August 19, 1986 August 29, 1986 September 10, 1986 November 13, 1986 November 14, 1986 August 8, 1987 September 24, 1987 September 28, 1987 Toyota installed new injectors and a new pulsating damper valve New battery installed New battery installed Car stalled when put into gear when started cold for LA-4 Toyota representative observes test and agrees car needs repair Toyota installed new fuel injectors Stalling problem only marginally improved, caution must be exercised to keep car from stalling shortly into the FTP Several stalls at idle Engine seems to be running rough at cruise Toyota replaced fuel filter and fuel injectors. Car stalled 22 times during FTP preparation. Car returned to Toyota. Unscheduled maintenance on the Toyota for the period February 1, 1984 to June 30, 1984 was previously reported in Reference 2. ------- -13- Table 11 Aged Oxidation Catalyst FTP Emissions Catalyst Sample Formula No. 3Pt:2Pd(20) 4 3Pt:2Pd(20) 5 Pd(20) 6 Pd(20) 1 Pd(20) 1 Test No. 864996* 864998 865000 870165 870167 870177 870451 875295* 879453* 870506* 871339 871340 871341 Date 08/19/86 09/10/86 09/12/86 10/09/86 10/10/86 10/29/86 10/30/86 09/24/87 10/31/86 11/04/86 09/15/87 09/16/87 09/17/87 0 0 0 0 0 0 0 0 0 0 0 0 0 HC .35 .54 .55 .53 .54 .39 .36 .24 .51 . 47 .40 .36 .41 CO (g/mi; 3.9 4.8 4.7 5.5 5.5 5.5 5.4 0.49 5.7 7.0 .50 .64 .73 CO 2 ) 387 370 369 376 377 377 379 3d7 387 397 383 381 380 0 0 0 0 0 0 0 2 0 0 1 2 2 NOx .83 .89 .88 .97 .90 .73 .71 .31 .89 .80 .92 .03 . 10 MPG 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 4 9 9 7 6 6 6 6 4 1 6 7 7 HCHO (jng/mi) 152.8 124.6 83.8 94.5 140.8 366.7 164.4 400.7 187.8 125.4 521.0 611. 5 632.7 Aged Three-Way Catalyst FTP Emissions Catalyst Sample Formula No. 3Pt:2Pd(20) 3 Pd(20) 2 Pd(20) 2 Test No. 870169 870171 870535 870527 871334 871335 871336 Date 10/16/86 10/21/86 11/05/86 11/06/86 08/25/87 09/04/87 09/09/87 0 0 0 0 0 0 0 HC .32 .32 .31 .36 .33 .23 .31 CO (g/mi; 4.6 4 . 7 5.9 6.9 2.9 2.8 2.9 C02 380 385 391 421 388 391 381 0 0 0 0 1 1 1 NOx .57 .57 .59 , 54 .36 .59 .29 MPG 10. 10. 10. 9. 10. 10. 10. 6 5 3 5 4 4 6 HCHO (mg/mi) 68.9 53.6 51 . 5 53.6 156.7 105.8 103 .3 Essentially a void test, not used in data analysis (injectors changed). ------- -14- Table 12 Aged Oxidation Catalyst HWY Emissions Catalyst Sample Formula No. 3Pt:2Pd(20) 4 3Pt:2Pd(20) 5 Pd(20) 6 Pd(20) 1 Test No. 864997* 864999 865001 870166 870168 870438 870452 870454* 870507* Date 08/10/86 09/10/86 09/12/86 10/09/86 10/10/86 10/29/86 10/30/86 10/31/86 11/04/86 HC CO C02 NOx (g/mi) 0 0 0 0 0 0 0 0 0 .02 . 04 .04 .05 .05 .02 .02 .04 .03 2 5 5 5 5 5 5 6 6 Aged Three-Way Catalyst HWY Catalyst Sample Formula No. 3Pt:2Pd(20) 3 Pd(20) 2 Test No. 870170 870172 870536 870528 Date 10/16/86 10/21/86 11/05/86 11/06/86 HC .9 . r .1 .8 .4 .2 .4 . 1 .2 334 322 321 334 331 329 333 341 322 0.51 0 .38 0.37 0.42 0.40 0.34 0 .36 0.43 0.34 MPG 12.2 12.5 12.5 12.0 12. 1 12.2 12.1 11.7 12.4 HCHO (mg/mi) 4.3 4 .9 2.3 3.4 0 .0 4 .7 VOID 3.5 2.3 Emissions CO CO z NOx (g/mi) 0 0 0 0 .02 .01 . 02 .02 3 2 5 5 . 1 . 6 .2 .6 . 332 333 348 359 0.27 0.27 0.26 0.26 MPG 12. 12. 11. 11. HCHO (mg/mi) 2 0 . 2 0. 6 1 . 2 2. 2 0 0 4 Essentially a void test, but used in data analysis (injectors changed). ------- -15- Table 13 Comparison of Percent New and Aqed Catalyst Catalyst Formula Aging and Testing Mode Sample Number 3Pt TWC 3 :2Pd(20 OX 4 Conversion for s on FTP Test ) OX 5 TWC 2 Pd(20) OX 1 OX 6 Efficiency for: HC CO NOx Aid. Aged New Difference* Aged New Difference Aged New Difference Aged New Difference 78 76 +2 63 68 -5 70 75 -5 82 87 -5 57 73 -16 66 96 -30 51 35 + 16 67 7 + 60 63 73 -10 57 96 -39 50 35 + 15 65 7 + 58 77 71 -6 62 78 -16 45 85 -40 71 86 -15 70 72 +4 92 92 0 17 36 -19 N/A 17 N/A 82 72 + 10 73 92 -19 58 36 +22 30 17 + 13 Table 14 Comparison of Percent Conversion for New and Aged Catalysts on HWY Test Catalyst Formula Efficiency for: HC CO Aged New Difference* Aged New Difference NOx Aged New Difference Aid. Aged New Difference 3Pt:2Pd(20) Aging and Testing Mode TWC Sample Number 3 OX 97 98 -1 76 88 -12 83 86 -3 100 97 3 90 97 -7 60 99 -39 73 44 29 98 76 22 OX 91 97 -6 52 99 -47 74 44 30 99 76 23 TWC 97 98 -1 69 88 -19 82 97 -15 99 96 3 Pd(20) OX OX 95 97 -2 65 99 -34 74 43 +31 99 81 18 97 97 0 70 99 -29 76 43 +23 98 81 17 Difference is aged minus new. ------- -16- The percent conversion for the aged catalysts were determined by calculating the average emissions for each catalyst on the FTP and HWY tests, and then comparing these values with the average of the baselines immediately before and immediately following the tests for that catalyst. For example, the HWY tests for sample 4 run on September 10 and September 12, 1986 and compared to the "before" tests run August 8 and August 12, 1986 and also to the "after" runs on October 3 and October 8, 1986. Appendix C shows the effect of the shifts in the baseline data on the percent conversion date of the aged catalysts. For some cases, this effect is relatively small. For example, sample 3 on the FTP test had a percent conversion range for HC of 76 to 80. For many cases, the effect is much larger (e.g., 58 to 71 for CO on sample 3 on the FTP test). The highest tailpipe formaldehyde emission levels (and lowest percent conversions) occurred on the FTP zero-mileage runs in the oxidation mode (17 and 7 percent compared to TWC mode results of 86 and 87 percent for the Pd(20) and 3Pt:2Pd(20) catalysts, respectively). When operated as oxidation catalysts, the aged Pd(20) catalysts perform somewhat better than their counterparts with the 3Pt:2Pd(20) formula, particularly on the FTP. The differences between the results for the two formulas are smaller when the catalysts are operated in the TWC mode. Deterioration Factors To further compare the catalysts, deterioration factors were calculated for each of them. Table 15 gives DF* for each of the six catalysts for HC, CO, NOx, and HCHO, and compares these values with the actual DF for HC, CO, and NOx for gasoline-powered light-duty vehicles. In calculating DF* several assumptuions were made: 1. Differences between the mileage accumulation in California and the AMA mileage accumulation route were ignored; 2. Maintenance differences were not accounted for; 3. Engine-out emissions were assumed to be constant over 50,000 miles; and 4. An expodential extrapolation of the form: Efficiencyt = Efficiency0 EXP (k miles/1000) was used to calculate emissions at 4,000 and 50,000 miles. This is the same extrapolation method as was used in reference 4. ------- -17- 5. Because the exact number of miles each catalyst was aged was unavailable, the odometer readings when the catalysts were removed for shipment to Ann Arbor were used as an assumed number of miles aged. This represents a "best case" scenario. Under these assumptions, the formula for DF* becomes: (1 - EFF5o) DF* = (1 - EFF4) Where, EFFSO and EFF4 are the extrapolated catalyst efficiencies at 4,000 and 50,000 miles, respectively. A value of "1" was used in Table 15 for those cases where no deterioration in catalyst efficiency occurred. The data in this table shows relatively good agreement between catalyst types and modes. For example the 3Pt:2Pd catalyst, when operated in Oxcat mode (samples 4 and 5), had DF* values of 2.2 and 2.0 for HC, and 5.3 and 4.6 for CO. The agreement between DF* and DF for a gasoline car is of order of magnitude quality. Analysis of this data is complicated by three factors: 1. The number of samples is small; 2. Little is known about how, when, and where the fleet vehicles were driven; and 3. The condition of the EPA test vehicle varied greatly despite the relatively small number of • miles it was driven during the test period. Conclusions After 12,000 to 14,000 miles of fleet use on the road aging: 1. Both catalyst types tested showed evidence of deterioration in their ability to convert CO in both three-way and oxidation modes; 2. There is little evidence of any change in the ability of either catalyst type to convert HC; and 3. When tested in the three-way mode, both catalyst types show degradation in their ability to convert NOx. ------- -18- Table 15 FTP Deterioration Factors By Catalyst Sample Number Formula 3 3Pt:2PD(20) 4 5 2 Pd(20) 1 6 Mode TWC OX ox TWC OX ox HC 1 2. 2. 1 1 . 1. 2 0 2 3 CO 1 . 5. 4 . 2. 1 . 4 . NOx 4 3 6 5 0 3 1 1 1 3 1 1 .6 . 1 .4 . 1 HCHO 2 1 1 3 1 .0 . 1 NA Gasoline car: DF 1.3 1.2 1.1 NA ------- -19- References 1. "Low Mileage Catalyst Evaluation With a Methanol-Fueled Rabbit - Second Interim Report," Wagner, R. and L. Landman, EPA/OAR/OMS/ECTD/CTAB/84-3, May 1984. 2. "Interim Report on Durability Testing of Low Cost Catalysts for Methanol-Fueled Vehicles," Wagner, R. and L. Landman, EPA/OAR/OMS/ECTD/CTAB-84-4, August 1984. 3. "Evaluation of Catalysts for Methanol-Fueled Vehicles Using a Volkswagen Rabbit Test Vehicle," Piotrowski, G., J. D. Murrell, and K. Hellman, Proceedings from Methanol: An Alternate Fuel, ASME Joint Conference on the Introduction and Development of Methanol as an Alternate Fuel, pp. 90-95, Columbus, OH, June 1986. 4. "Aftermarket Catalyst Durability Evaluation," Bruetsch, R., J. P. Cheng, and K. Hellman, SAE Paper 861555. ------- A-l APPENDIX A Maintenance of Escort/License Plate Number 0868570 Date 06/24/84** 08/09/84 08/22/84 01/14/85 04/05/85 05/22/85 09/11/85 03/12/86 VIN Odometer Reading 3144 3493 3632 6222 9233 10058 12087 12493 .8 1FABP137XDW237349* Comments Lube, oil, filter Tow in (mechanical) Air conditioning water leak Lube, oil, filter, add antifreeze Lube, oil, filter, add antifreeze Tow in (no reason given) 12,000-mile service Catalyst removed for shipment Ann Arbor to * This vehicle was used to age sample 4, a 3Pt:Pd(20) catalyst, in oxidation mode. ** First entry in maintenance records. ------- A-2 APPENDIX A (cont'd) Maintenance of Escort/License Plate Number 0868571 Date 06/27/83 02/21/84 05/03/84** 12/26/84 03/11/85 04/30/85 07/11/85 08/19/85 10/15/85 11/08/85 11/26/85 03/12/86 VIN Odometer Reading N/A N/A 3126 6579 9242 9801 9811 10798 12345 12937 ~ N/A 13306.3 1FABP137XDW237350* Comments Accepted for delivery Tow in (no reason given) Lube and oil change Lube, oil, filter, checked brakes, wipers Add antifreeze Replace fuel filter Replace fuel pump Fix flat tire 12,000-mile service Detail and check body fenders, glass wipers, decals, upholstery Detail exterior. Catalyst removed for shipment to Ann Arbor * This vehicle was used to age sample 1, a Pd(20) catalyst, in oxidation mode. ** First entry in maintenance records with mileage recorded. ------- A-3 APPENDIX A (cont'd) Maintenance of Escort/License Plate Number 0868572 Date 06/20/83 06/27/83 02/16/84 05/24/84 06/12/84 09/24/84 12/17/84 04/11/85 07/27/85 08/06/85 10/11/85 03/12/86 . VIN Odometer Reading N/A 03 439 2899 3365 4431 6018 9061 11833 11833 13088 14249 . 2 1FABP137XDW237359* Comments Predelivery inspection Accepted for delivery Inspected Lube, oil, filter Inspected Fix driver ' s door Lube, oil, filter Lube, oil, filter, clean air filter 12,000-mile service Change locks ( key lost) Replace ash tray Catalyst removed for shipment to Ann Arbor This vehicle was used to age sample 3, a 3Pt:2Pd(20) catalyst, in three-way mode. ------- A-4 APPENDIX A (cont'd) Maintenance of Escort/License Plate Number 0868573 Date 12/14/84** 02/02/85 05/09/85 05/24/85 10/01/85 03/12/86 VIN Odometer Reading 6762 7956 9645 10089 N/A ' 12732.0 1FABP137XDW237378* Comments Add antifreeze Tow in — out of gas Lube, oil, filter, change oil filter Tow in — mechanical 12,000-mile service Catalyst removed for shipment to Ann Arbor * This vehicle was used to age sample 2, a Pd(20) catalyst, in three-way mode. ** First entry in maintenance records with mileage recorded. ------- A-5 APPENDIX A (cont'd) Maintenance of Escort/License Plate Number 0868574 VIN 1FABP137XDW237386* Date 06/27/83 01/31/84 05/15/84 05/16/84 05/30/84 06/06/84 12/10/84 05/04/85 09/20/85 03/12/86 Odometer Reading 4 73 3073 3079 9344(?) N/A 6143 9221 12009 13247.9 Comments Accepted for delivery Inspected Inspected Lube, oil, filter 4,000-mile service, lube, oil, filter remove front wheels Vehicle in accident, but not damaged Lube, oil, filter, add transmission fluid, antifreeze Lube, oil, filter, add antifreeze, clean air filter 12,000-mile service Catalyst removed for shipment to Ann Arbor This vehicle was used to age sample 6, a Pd(20) catalyst, in oxidation mode. ------- A-6 APPENDIX A (cont'd) Maintenance of Escort/License Plate Number 0868575 Date 06/27/83 04/03/84 04/18/84 05/22/84 06/07/84 07/03/84 02/15/85 07/18/85 08/26/85 08/26/85 09/20/85 03/12/86 VIN Odometer Reading 3 N/A 1330 1968 N/A 2545 5823 9331 10171 10171 10172 11809 . 4 1FABP1370DW237405* Comments Accepted for delivery Vehicle misfueled with gasoline; clean, drain, and flush gasoline from tank Fix arm rest Inspect Accident — fender, hood, frame damaged Lube, oil, filter Lube, oil, filter, clean air filter, adjust brakes Lube, oil, filter Needs fuel pump Replace fuel filter Replace electric fuel pump Catalyst removed for shipment to Ann Arbor This vehicle was used to age sample 5, a 3Pt:2Pd(20) catalyst, in oxidation mode. ------- B-l APPENDIX B Toyota Cressida Baseline (No Catalyst) Date (ODO KM) 8/8/86 (5314.7) 8/12/86 (5376.3) 10/3/86 (5832.7) 10/8/86 (5905.6) 10/23/86 (6273.4) 10/28/86 (6368.5) 11/7/86 (6800.3) 11/13/86 (6862.9) Test 864992 Bag 1 Bag 2 Bag 3 Average 864994 Bag 1 Bag 2 Bag 3 Average 865003 Bag 1 Bag 2 Bag 3 Average 865005 Bag 1 Bag 2 Bag 3 Average 870173 Bag 1 Bag 2 Bag 3 Average 870175 Bag 1 Bag 2 Bag 3 Average 870529 Bag 1 Bag 2 Bag 3 Average 870531 Bag 1 Bag 2 Bag 3 Average FTP Results Odometer (km) 5314.7 5376.3 5832.7 5905.6 6273.4 6368.5 6800.3 6862 .9 HC (g/mi) 2.00 1.01 0.85 1.17 2.33 1.09 .96 1.31 2.42 1.06 .97 1.31 . 2.38 1.08 .99 1.32 2.56 1.33 1.20 1.54 2.84 1.42 1.23 1.66 3.31 2.49 1.82 2.46 3.49 2.69 1.81 2.61 CO (g/mi) 17.7 15.4 13.0 15.2 20.0 17.2 14.8 17.2 14.0 ' 10.4 10.1 11.0 14.5 11.3 10.2 11.7 17.2 13.2 12.2 13.7 18.3 13.6 12.3 14.2 24.8 28.2 22. 1 25.8 26.7 28.8 22.6 26.7 C02 (g/mi) 419 351 345 363 432 351 343 366 415 . 340 341 356 418 344 342 358 426 349 346 . 364 421 346 342 360 419 347 342 360 416 342 336 355 NOx (g/mi) 2.59 1.23 1.98 1.72 2.66 1.27 1.94 1.74 2.74 1.41 2.16 1.89 2.84 1.37 2.11 1.88 2.73 1.44 2.11 1.89 2.71 1.43 2.09 1.87 2.42 1.20 1.86 1.63 2.38 1.09 1.84 1.56 HCHO (g/mi) 395.7 321.2 261.4 312.4 392.8 374.0 200.9 324.5 435.9 288.1 241.3 305.7 467.5 273.0 246.8 303.9 437.4 315.2 500.6 391. 5 344.0 362.1 235.3 323.0 338.6 436.7 431.9 415.3 504.9 360.1 338.8 393.6 MPG 10.5 10.4 10.9 10.8 10.5 10.6 10.1 10.2 ------- Date 11/14/86 (6924.5) 08/18/87 (7137.0) 08/19/87 (7200.7) 08/20/87 (7211.7) 09/10/87 (7415.9) 09/11/87 09/22/87 (7569.7) 09/23/87 (7592.0) Test 870533 Bag 1 Bag 2 Bag 3 Average 871328 Bag 1 Bag 2 Bag 3 Average 871330 Bag 1 Bag 2 Bag 3 Average 871332 Bag 1 Bag 2 Bag 3 Average 871337 Bag 1 Bag 2 Bag 3 Average 871338 Bag 1 Bag 2 Bag 3 Average 871342 Bag 1 Bag 2 Bag 3 Average 871343 Bag 1 Bag 2 Bag 3 -.verage B-2 APPENDIX B (cont'd) Toyota Cressida Baseline (No Catalyst) FTP Odometer (km) (g 6924.5 3 2 1 2 2 0 1 1 2 1 0 1 2 1 0 1 2 1 0 1 2 0 0 1 2 1 0 1 2 1 0 1 Test HC /mi) .45 .59 .77 .52 .31 .66 .08 .12 .34 .15 .97 .35 .25 .08 .94 .28 .37 .11 .93 . 31 .24 .1 .92 .29 . 17 .13 .94 .29 .24 .15 .95 .32 Results CO (g/mi) ( 26 28 22 26 7 7 6 7 9 7 6 7 10 7 6 7 10 6 r^ 7 10 7 6 7 10 7 5 7 10 7 6 8 .2 .6 .0 .3 .69 .25 .33 .69 .99 .31 .75 .71 .15 .33 .43 .66 .79 .97 .24 .56 . 6 .4 .2 .7 .6 .6 . 6 .9 .3 .9 .6 . 1 CO 2 Lg/mi ) 414 341 340 356 404 375 347 373 406 379 348 376 403 373 345 372 398 360' 338 362 397 359 337 361 394 362 331 360 394 362 330 360 NOx (q/mi) 2 1 1 1 3 3 2 3 3 1 3 2 3 1 2 2 3 1 2 2 3 1 2 2 3 1 2 2 3 1 2 2 .29 .03 .81 .51 .22 .28 .92 . 17 .16 .19 .15 .48 .34 .81 .96 .43 .45 .83 .90 .45 .35 .81 .83 .42 .39 .81 .89 .43 .46 .74 .85 .40 HCHO (q/mi) 470 379 331 390 590 636 392 560 523 480 380 462 1798 577 399 778 219 307 271 279 235 305 4 209 604 509 445 511 445 448 382 430 .7 .7 .4 .0 .5 .1 .3 .9 .0 .4 .6 .0 .2 . 1 .4 .8 .9 .2 .4 .2 . 6 .3 .4 1 .0 .2 . 6 . 5 .5 .4 .2 .3 MPG 10.2 10.6 10.5 10.6 10.9 10.9 10.9 10.9 ------- Date 08/08/86 08/12/86 10/03/86 10/08/86 10/23/86 10/28/86 11/7/86 11/13/86 11/14/86 08/18/87 08/19/87 08/20/87 B-3 APPENDIX B (cont'd) Toyota Cressida Baseline (No Catalyst) Highway Test Results Test No. 864993 864995 865004 870164 870174 870176 870530 870532 870534 871329 871331 871333 HC (q/mi) 0.31 0 .37 •0 .47 0 .51 0.61 0. 60 0.88 0.80 0 .91 0 .62 0.61 0 . 59 CO (q/mi) 14.1 15.7 10.4 11.1 12.9 12.8 22.5 22.5 21.7 5.5 5.9 5.8 CO 2 (q/mi) 318 317 315 316 321 318 322 324 317 292 305 298 NOX (q/mi) 1.24 1.23 1.54 1.51 1.61 1.54 1.36 1.42 1.28 2.69 2.89 2.81 MPG 12. 1 12.0 12.4 12.3 12.0 12.1 11.4 11.4 11.6 13.6 13\0 13.3 HCHO (mq/mi) 191.6 181.8 181.8 182.3 203.1 210 .0 251.0 285.2 270.8 52.7 172. 7 N/A ------- C-l APPENDIX C Effect of Baseline Changes On Percent Conversion On HWY Test Catalyst Formula Pd(20) Pd(20) 3Pt:2Pd(20 3Pt:2Pd(20 Pd(20) 3Pt:2Pd(20 Sample Number 1 6 ) 4 ) 5 2 ) 3 Test and Aqinq Mode OX OX OX OX TWC TWC Baseline Comparison Before* After** Before After Before After Before After Before After Before After Percent Conversion HC 70 70 77 85 56 59 59 67 77 77 76 80 CO 92 92 61 79 71 58 52 61 63 62 59 67 NOx 17 17 62 54 49 53 50 50 48 42 70 70 Aid. -141 -25 25 34 67 66 61 67 80 50 80 83 * Compared to baseline tests made before catalyst was tested ** Compared to- baseline tests made after catalyst was tested. ------- C-2 APPENDIX C (cont'd) Effect of Baseline Changes On Percent Conversion On FTP Test Catalyst Sample Formula Number Pd(20) 1 Pd(20) 6 3Pt:2Pd(20) 4 3Pt:2Pd(20) 5 Pd(20) 2 3Pt:2Pd(20) 3 Test and Baseline Aqinq Mode Comparison OX Before* After** OX Before After OX Before After OX Before After TWC Before After TWC Before After Percent Conversion HC 94 96 97 98 89 92 90 92 97 98 97 98 CO 52 72 59 76 66 53 48 56 58 76 74 78 NOx 75 72 78 74 70 75 73 74 84 81 82 83 Aid. 99 99 98 98 98 98 99 99 99 99 100 100 * Compared to baseline tests made before catalyst was tested ** Compared to baseline tests made after catalyst was tested. ------- |