Ce Mn mixed oxides for low temperature catalytic after treatment applications

Manganese oxides molecular sieves (OMS) materials have a mixed valency of Mn3+ and Mn4+ cations that contributes to its highly active redox properties, which make it particularly interesting for emission control applications. Cryptomelane is an OMS-2 mateiral which has a microporous, nano-tunnel structure composed of edge shared MnO6 octahedra that form a 2 x 2 arrangement, with a K+ cation positioned within the framework [1]. The structural incorporation of various dopants and tunnel cations can further enhance the functionality of OMS-2 [2]. Other synthesis routes can be used for the incorporation of a high concentration of dopants, can also lead to the inhibition of the crystalline[3]. In this work we have synthesized a range of manganese oxide based supports doped with Ce and tested for applications in automotive emission abatement. Due to the high emissions of lean burn diesel engines operating at low temperatures and during cold start, and issues with catalyst deactivation, the requirement for a catalyst which is active at low temperature is one of the main challenges in automotive emission control [4]. In particular, we have investigated the use of manganese oxide hybrid catalyst supports for their applicable use in automotive after treatment. We have studied their activity in the oxidation reactions of CO and C3H6, before comparing their activity with a commercial diesel oxidation catalyst.