Enhanced Resistance to Pb Poisoning of the Co-modified Mn/Fe-pillared Clay Catalysts for NH3-SCR at Low Temperatures

摘要

Lead (Pb) is a heavy metal commonly found in industrial exhaust gases, which can reduce catalytic activity of a catalyst for the NH3-SCR reaction. In this study, 4.0 wt Mn-loaded Fepillared interlayer clay (4Mn/Fe-PILC) and its Co-modified catalyst (2Co-4Mn/Fe-PILC) were prepared, in the meanwhile the 4Mn/Fe-PILC-Pb and 2Co-4Mn/Fe-PILC-Pb samples were also obtained using the impregnation method with a Pb- (CH3COO)2 aqueous solution. It was found that the addition of 2.0 wt cobalt could significantly enhance Pb resistance of the 4Mn/Fe-PILC catalyst. The characterization results revealed that the doping of Co to Mn/Fe-PILC increased the surface Mn4+ species concentration, reducibility, and acid site amount, thereby improving Pb resistance of the catalyst. Furthermore, the in situ DRIFTS results demonstrated that Co modification enhanced the adsorption capacity of NH3 or NO, especially influenced formation of the NH3 intermediates and bridging nitrate species, which were also conducive to the improvement in Pb resistance of the catalyst.