Recently, the demand for fuel efficiency provokes the widespread application of diesel engines. However, the control of NOx from diesel emission is regarded as a great challenge, since NOx cannot be reduced effectively with Three-Way-Catalysts (TWC). Although NOx Storage Reduction (NSR) and Selective Catalytic Reduction (SCR) catalysts are being applied, both catalysts reduce the NOx at only high temperature (above 200 °C). As the exhaust regulation on NOx emission is getting more stringent, the removal of NOx during cold start, in other words, at low temperature becomes more crucial. It is known that Pd based catalysts can adsorb NOx at low temperature. Hence, those materials have potential to be applied as a cold start catalyst which has the function of removing NOx during start-up by adsorbing NOx at low temperature and releasing them at higher temperature, where SCR catalyst operates. In this work, we aimed at investigating several Pd supported catalysts with respect to the NOx adsorption/desorption behavior and the role of Pd and supports by using the combination of NOx adsorption/desorption measurements and DRIFT experiments, which are of importance to develop novel cold start catalyst. Especially, two types of supports such as CeO2 and zeolite were compared in terms of intrinsic NO adsorption/desorption behavior and chemistry, and the resistance to SO2 poisoning.

Low temperature NO adsorption over Pd based catalysts for cold start application

2019 Spring National Meeting

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