Operation of diesel engine produces toxic particulate matter that have significant impact on human health. Therefore, in 2020 India sets an automotive emission standard Bharat stage (BS) VI. Under the BS VI a diesel vehicle will have to reduce their emission of hydrocarbon and nitrogen oxides by 43%, their NOx levels by 68% and particulate matter levels by 82%. Hence, various solutions are implemented by the automotive sector to reduce the pollution from diesel engine vehicles. One of such solution is the use of diesel oxidation catalyst.
A diesel oxidation catalyst (DOC) is an aftertreatment component that is built to convert carbon monoxide and hydrocarbons into carbon dioxide and water. A typical DOC consist of a canister and a substrate. The substrate will be coated with the catalytic metals which helps in oxidation of the exhaust gas produced from the engine. The DOC is installed along with Diesel particulate filters (DPM) and Selective catalytic reduction (SCR) as a part of exhaust system of a vehicle. Over the years many researches are undertaken to improve the operation of DOC. The below paragraphs details about the three recent patents filed by BASF in the field of DOC.
Patent application titled Emissiontreatment catalysts, systems and methods teaches about the zoned oxidation catalysts comprise two different slurries made up of platinum and palladium. The inlet zone of the substrate is coated with first slurry made by mixing Platinum and palladium and the outlet zone coated with slurry of only palladium. Loading of slurry in the inlet zone is made higher than the loading in the outlet zone of DOC. Further the axial length of the inlet zone is made less than or equal to the axial length of the outlet zone. Therefore, this design helps in reducing the platinum loading on the DOC and in turn lowering the overall cost. In addition, thermal durability of the DOC is improved by increasing the palladium to platinum ratio.
Patent application titled Diesel oxidation catalyst containing platinum group metal nanoparticles details about the use of platinum group nanoparticles in a reduced form along with refractory metal oxide material as a Diesel oxidation catalyst to control the polluting emission. These two materials can be combined within the same substrate or can be coated sequentially on a substrate. The catalyst compositions containing PGM materials in reduced nanoparticulate form yield higher conversions of NO to NO2 than comparative catalyst compositions prepared using standard PGM bodies.
Patent application titled Palladium diesel oxidation catalyst discusses the method of reducing the exhaust gas emission from a lean burn engine using the diesel oxidation catalyst. The catalysts comprise two layers. The first layer further comprises two different components. The first component is made of ceria impregnated with palladium compound and the second component is made of one or more of Magnesium, Rhodium and Platinum. The second layer has refractory metal oxide impregnated with Platinum and Palladium. This new composition improves the light-off performance by lowering the light-off temperature of the catalyst, as well as enhances the catalyst resistance to sulfur poisoning.
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