Ionic liquid and plasma effects on SiO2 supported Pd for selective hydrogenation of acetylene

摘要

SiO2 supported ionic liquid with Pd systems are investigated for the first time for the selective hydrogenation of acetylene and with the assistance of RF non-thermal plasma procedures to assist/replace the traditional reduction procedure in this study. Supported Pd catalysts loaded with ionic liquids are effective for selective hydrogenation of acetylene in ethylene. The results also suggest that the catalysts with ionic liquids of [BF4] anion usually achieve higher conversion but lower selectivity, and those catalysts with [PF6] anion lower conversion but higher selectivity. Pd/BmimBF4/SiO2 shows a stable yield of ethylene from acetylene during the stability test, however, it decreases slightly after 6 h. On the other hand, although the ethylene yield of Pd/EmimBF4/SiO2is higher than that of Pd/BmimBF4/SiO2 in the first 3 h, large decrease in selectivity after 3 h results in decrease in overall ethylene yield and with significant activity fluctuations. The selectivity and the overall yield of Pd/EmimBF4/SiO2 with Ar plasma+H2 procedures are more stable than the one with the conventional reduction which shows significant fluctuation throughout the stability testing period. It is apparent that the Ar plasma treatment followed by hydrogen reduction can minimize the fluctuation phenomena of Pd/IL/SiO2 and stabilize their catalytic activity effective for selective hydrogenation of acetylene in ethylene.