Preparation and structure-property relationships of supported trimetallic PdAuAg catalysts for the selective hydrogenation of acetylene.

To simultaneously achieve thorough purification of acetylene and maximum ethene increment, a sea urchinlike trimetallic PdAuAg mesocrystal catalyst as targeting sample and cuboctahedral trimetallic PdAuAg x and bimetallic catalyst as control samples were prepared by a co-reduction method, immobilized on MgAl hydrotalcite. Compared with bimetallic PdAu and PdAg catalysts, trimetallic PdAuAg x catalyst gave prior selectivity due to the positive synergetic effect. Significantly, PdAuAg 2 mesocrystal catalyst exhibited a turnover frequency of 0.063 s −1 , 46.5% higher than that of cuboctahedral PdAuAg 2 catalyst. A 76.2% ethene selectivity was achieved for the thorough purification of acetylene over PdAuAg mesocrystal catalyst with H 2 :C 2 H 2 of 2:1. Further improving H 2 :C 2 H 2 to 3, 76.5% yield can be maintained at 140 °C. Enhanced activity of the mesocrystal catalyst could be attributed to a high concentration of defect sites and a low activation barrier. Improved ethene selectivity could be ascribed to the increase in the (1 1 1)/(1 0 0) facets ratio and the formation of a Pd-C phase. [ABSTRACT FROM AUTHOR]