Ir/ZSM-5/cordierite monolith for catalytic NOx reduction from automobile exhaust

Ir/ZSM-5/cordierite was studied as promising catalyst for the reduction of nitrogen oxides from automobile exhaust under both stoichiometric combustion and lean conditions. ZSM-5 was in situ synthesized on the surface of honeycomb cordierite substrate and iridium was introduced to ZSM-5/cordierite by wet impregnation. Under stoichiometric combustion, Ir/ZSM-5/cordierite exhibited good catalytic activity approaching commercial three-way catalysts, and the three main pollutants nitrogen oxides, carbon monoxide and unburned hydrocarbons could be purified simultaneously. Under lean conditions, Ir/ZSM-5/cordierite also exhibited quite good deNOx activities though excess oxygen showed inhibition effect on NOx reduction.