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AssigneeGM Global Technology Operations LLC
InventorsChang H. Kim, Janean E. Kowalkowski, David N. Belton, Steven J. Schmieg
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The capacity of a platinum-containing diesel oxidation catalyst (DOC) to simultaneously convert NO to NO2, CO to carbon dioxide, and remaining hydrocarbons to carbon dioxide and water in the exhaust system of a vehicle diesel engine may be evaluated and diagnosed using measured DOC exhaust inlet temperatures and outlet temperatures at a relatively high exhaust temperature and, soon thereafter, at a relatively low exhaust inlet temperature. Values of the platinum-containing DOC exotherms at the high and low DOC inlet temperatures are found to provide a basis for evaluation of both NO conversion and the HC and CO conversion capabilities of the DOC. The process may be repeated as the catalyzed DOC conversion efficiency changes with use. The practice may also be used to evaluate the performance of oxidation catalysts used in a like way in treating the exhaust from a lean-burn gasoline engine.
A method of evaluating the nitrogen oxide (NO) oxidation performance of a platinum-containing diesel oxidation catalyst (DOC) in the exhaust stream of a vehicle diesel engine where the DOC is intended to simultaneously convert nitrogen monoxide (NO) to nitrogen dioxide (NO2), carbon monoxide to carbon dioxide, and unburned hydrocarbons to carbon dioxide and water, the method comprising:
A method of determining the capability of a platinum-based diesel oxidation catalyst to oxidize NO to NO2 in the exhaust conduit of a vehicle diesel engine, the diesel oxidation catalyst being coupled to the exhaust manifold of the engine and employed to oxidize residual hydrocarbons, carbon monoxide, and NO in the exhaust stream from the engine preparatory to the exhaust stream being subjected to selective catalytic reduction of NO and NO2 and filtration and periodic burning of particulates in the exhaust, the platinum-based catalyst comprising particles of platinum and palladium dispersed on alumina support particles in a diesel oxidation catalyst reactor vessel (DOC) with a DOC inlet and DOC outlet with respect to the flow of the exhaust gas, the platinum-based oxidation catalyst having a pre-determined composition with aging characteristics as predetermined by heating specimens of the platinum-based catalyst in a catalyst-aging gas stream comprising carbon dioxide, water, oxygen, and nitrogen at temperatures above the specified operating temperatures of the DOC, the vehicle having a computer-based exhaust stream control system operable in combination with a diesel engine operation control system, that comprises means for periodically tracking engine exhaust gas temperatures at the DOC reactor exhaust inlet and exhaust outlet;
Dependencies are inferred from the claim text.