NH3–SCR of NOx on Silicoaluminophosphate Molecular Sieves Based Catalysts: A Comparative Study

Abstract

In this study, copper aluminophosphate catalysts were prepared from home made and commercial zeolites. Various formulations were prepared, and several parameters such as the type of structure, the crystal size, the copper and the silicon content were varied. The catalysts were tested in selective catalytic reduction of NO or NO/NO2 by NH3 after calcination at 550 °C and hydrothermal treatment at 850 °C. The efficiency and stability depended mainly on a good correlation between copper and silicon contents. A higher mean crystal size of the starting zeolite could also be beneficial. Thus, a copper catalyst with a copper content of 1.25 wt%, prepared from a Chabazite zeolite furnished by Clariant (Si content = 3 wt%), was the most efficient catalyst after hydrothermal treatment at 850 °C in NO reduction by NH3.