Layered Double Hydroxides Derived ZnO-Al2O3 Supported Pd-Ag Catalysts for Selective Hydrogenation of Acetylene

Abstract

ZnO-Al2O3 derived from layered double hydroxides (ZnAl-LDH) was successfully applied for dispersion of Pd-Ag bimetallic catalysts for the selective hydrogenation of acetylene to ethylene and the Pd-Ag/ZnO-Al2O3 catalyst showed the best catalytic performance among the prepared samples. It was found that the catalyst carrier of ZnO-Al2O3 metal-oxides derived form ZnAl-LDH could significantly suppress the over-hydrogenation of acetylene to obtain the relatively higher selectivity of ethylene. The introduction of Ag restricted efficiently the formation of coke because of the oligomerization reaction, which was further evidenced by thermal gravimetric analysis. The selectivity towards ethylene was in the order of Pd-Ag/ZnO-Al2O3>Pd/ZnO-Al2O3>Pd-Ag/Al2O3>Pd/Al2O3 at a high conversion level. As the thermal gravimetric and differential temperature analysis (TG-DTA) revealed, Pd-Ag intermetallic catalyst on the ZnO-Al2O3 support showed less coke formation.