Selective hydrogenation of acetylene over Pd/CeO2

Five hundred ppm Pd/CeO2 catalyst was prepared and evaluated in selective hydrogenation of acetylene in large excess of ethylene since ceria has been recently found to be a reasonable stand-alone catalyst for this reaction.Pd/CeO2 catalyst could be activated in situ by the feed gas during reactions and the catalyst without reduction showed much better ethylene selectivity than the reduced one in the high temperature range due to the formation of oxygen vacancies by reduction.Excellent ethylene selectivity of〜100%was obtained in the whole reaction temperature range of 50℃-200℃ for samples calcined at temperatures of 600℃ and 800℃.This could be ascribed to the formation of PdX-Ce1-xO2-y or Pd-O-Ce surface species based on the X-ray diffiaction and X-ray photoelectron spectroscopy results,indicating the strong interaction between palladium and ceria.