No abstract

Cu-alloyed Pd single-atom catalysts exhibit excellent catalytic performance for the semi-hydrogenation of acetylene; however, the limit of the Cu/Pd atomic ratio for forming the alloyed Pd single-atom catalyst is ambiguous. Herein, silica-supported Cu-Pd bimetallic catalysts with fixed Pd content and varied Cu loadings were synthesized using an incipient wetness co-impregnation method. The X-ray absorption spectroscopy results indicated that Pd formed an alloy with Cu after reduction at 250 °C and that the Pd atoms were completely isolated by Cu for Cu/Pd atomic ratios ≥ 40/1. Notably, increasing the reduction temperature from 250 to 400 °C hardly affected the catalytic performances of the Cu-Pd/SiO2 catalysts. This finding can be attributed to the similar chemical environments of Pd demonstrated by the X-ray absorption spectroscopy results.