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Acidic zirconia materials have been tested as catalysts for the Selective Catalytic Reduction of nitrogen oxides (NOx) by ammonia (NH3-SCR). This paper focuses on the promotion of acidic zirconia by ceria. The introduction of ceria increases the NOx conversion, the selectivity to N2 and the durability and makes acidic zirconia materials attractive for Diesel after treatment systems.

Acidic doped zirconia catalyst supports with high thermal stability and high SOx resistance have been tested in Diesel exhaust. This paper focuses on the optimization of these materials to get the best trade-off between acidity and thermal stability. These materials were tested as a Platinum support for Diesel Oxidation Catalysts (DOC). Preliminary data are also discussed concerning their ammonia adsorption properties for the Selective Catalytic Reduction of NOx by ammonia (SCR).

A ceria stabilised zirconia supported Pd/Zn catalyst (Pd/Zn ratio=1:2) has demonstrated its ability to perform as a three-way catalyst (TWC) and to give conversions of up to 99% of a stoichiometric mixture of carbon monoxide/npropane/nitric oxide/dioxygen in dinitrogen carrier at a WHSV of 44,000 h-1. The catalyst also exhibits excellent thermal stability inoxidising conditions. Characterisation of the catalyst has been performed using XRD, XPS, BET,and DSC. From this it has emerged that the palladium is in a highly dispersed state, closely associated with the zinc phase. In situ kinetic studies have also been conducted under continuous flow conditions.