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 micro-structure and denitrification performance were characterized by N2 adsorption-desorption, XRD, UV-vis spec-troscopy, 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 Ag delta n+, 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 degrees C with GHSV = 100 000 h-1. This process promotes the development of efficient vehicle exhaust treatment technology and the application of related products.

Automated summary

The effects of Zn and Mg on the selective catalytic reduction (SCR) of NO with C3H6 were investigated. The bimetallic Zn and Mg modification increased the proportion of ZnAl2O4 and MgAl2O4 spinels in the catalysts, regulated the dispersion of Ag on the support, and promoted the conversion of Ag0 to active Ag+ and Ag delta n+. This enhanced the NO adsorption capacity and optimized denitrification performance. In addition, it was found that the presence of H2 facilitated the formation of N2 and improved N2 selectivity.