The effect of Al and Cu content on the performance of CuZSM5 catalysts at the exhaust of high efficiency spark ignition engines.

Catalytic performance of copper catalysts based on ZSM5 structure (MFI) were investigated at the exhaust of a lean-burn engine for the NOx reduction. The presence of both Cu and Al resulted indispensable to have catalyst activity in real conditions. While activity remained unchanged for the over-exchanged catalysts, the durability always increased with copper content. Al enhanced both activity and durability. Fast deactivation rate resulted correlated to segregation of small CuO particles dispersed into zeolite channels, as evidenced by characterisation of deactivated catalysts.