Investigation of the effect of bimetallic Zn-Mg modified Al2O3 carriers modulating Ag species on the performance of H2-assisted C3H6-SCR and the mechanism

The effects of Zn and Mg on selective catalytic reduction (SCR) of NO with C3H6 were studied by introducing Zn and Mg into Ag/Al2O3 catalysts with the rotary evaporation method. The effects of Zn and Mg on the microstructure and denitrification performance were characterized by N2 adsorption–desorption, XRD, UV–vis spectroscopy, H2-TPR, NO + O2-TPD, XPS and HR-TEM. The results showed that bimetallic Zn and Mg modification increased the proportion of ZnAl2O4 and MgAl2O4 spinels in Ag/Al2O3 catalysts, regulated the dispersion of Ag on the Al2O3 support, and promoted the conversion of Ag0 to active Ag+ and Agδn+, which enhanced the NO adsorption capacity and optimized denitrification performance at low temperature. Furthermore, in-situ DRIFTS suggested that enol and acetate generated by C3H6 in the presence of H2 will react with NO + O2 to form more –NCO and –CN intermediate species, which facilitated the formation of N2 and improved N2 selectivity. Specially, Ag2.5Zn2.5MgAl exhibited more than 95 % NOx conversion, excellent water resistance and sulfur resistance at 300 °C with GHSV = 100 000 h−1. This process promotes the development of efficient vehicle exhaust treatment technology and the application of related products.