Non-precious metal catalysts supported on high Zr loaded-SBA-15 for lean NO reduction

Abstract

Various non-precious metal (M=Co, Ni, Cu, and Ag) catalysts supported on high Zr-loaded SBA-15 were developed for lean NO reduction. Several properties such as mesoporous structure, high specific area, moderate surface acidity, homogenous dispersion of Zr and M species, and strong interaction between support and doped metals were investigated by various techniques. The NO reduction efficiency of the developed catalysts in the propene selective reduction of NO was in the order of Co-2.5-Zr-SBADP>Ni-2.5-Zr-SBADP>Cu-2.5-Zr-SBADP>Ag-2.5-Zr-SBADP in the temperature range of 250–450°C. Amongst, Co-2.5-Zr-SBADP displayed 42%, 55% and 46% N2 yield at 300, 350 and 400°C, respectively, in the dry feed whereas a slight decrease was observed in the wet feed. The catalyst activity improved significantly when a higher ratio of hydrocarbon to NO (CN=8) with the minimum fuel penalty (1%) was applied. The catalyst activity increased to 68% and 71% of NO conversion to N2 at 350 and 400°C, respectively, in the presence of water vapor. The catalyst showed excellent hydrothermal stability and durability during prolonged reaction so that 68% of N2 yield was achieved in the extreme condition in the presence of 5.3 vol% of water vapor at 400°Cfor 96h.