Ammonia selective catalytic reduction of NO over Ce–Fe/Cu–SSZ-13 catalysts

Abstract

A series of CHA-type trimetallic composite zeolites of Ce_x–Fe_y/Cu–SSZ-13 catalysts were prepared using Cu–SSZ-13, synthesized in a one-pot procedure, and subsequent ion-exchange with Fe³⁺ and Ce³⁺. The catalysts were characterized including TEM, XRD, XPS, SEM and BET. Their catalytic performances for selective catalytic reduction of NO with NH₃ were investigated. The results of XRD revealed that the crystal structure of zeolite Ce–Fe/Cu–SSZ-13 is the same as Cu–SSZ-13. It is known from the results of BET and catalytic performance tests that larger specific surface areas and smaller pore size favor a catalytic reaction. Among the prepared Ce_x–Fe_y/Cu–SSZ-13 catalysts, Ce_0.017–Fe_0.017/Cu–SSZ-13 displayed the best SCR performance. The NO conversion was more than 90% between 200 and 500 °C. N₂ selectivity was above 98% within the wider temperature range of 150–550 °C. In addition, the catalyst demonstrated sulfur–water tolerance and effective resistance against high space velocity. The phenomena suggest that synergistic effects of Cu, Fe and Ce species improve the SCR performances and make the Ce–Fe/Cu–SSZ-13 catalyst a promising candidate for NH₃–SCR technology.