Dehydrochlorination of 1,2-dichloroethane over a tetraphenylphosphonium chloride-supported carbon catalyst

摘要

Aiming to explore promising catalysts with superior anti-coking properties for the 1,2-dichloroethane (EDC) dehydrochlorination reaction, we prepared several activated carbon (AC)-supported high-melting-point quaternary phosphonium salt (QPS/AC) catalysts through the incipient wetness impregnation technique. After comparing the catalytic activities of these QPS/AC catalysts for EDC dehydrochlorination, we selected the activated carbon-supported tetraphenylphosphonium chloride catalyst (TPPC/AC) as the research subject because it had the highest catalytic activity. Activity evaluation results demonstrate that the optimum catalyst loading of 15%TPPC exhibits outstanding catalytic activity (acetylene conversion of 85.9%) and stability (deactivation rate of 0.014% h(-1)). Through BET, TG and TPD characterizations, it is shown that 15%TPPC/AC can promote the desorption of C2H3Cl and retard the desorption of HCl. These special adsorption and desorption properties of 15%TPPC/AC can be attributed to its excellent anti-coking capacity, which ensures its long-term stability in the EDC dehydrochlorination process. In combination with density functional theory (DFT) calculations, it is indicated that the TPPC can activate the C-H bonds of EDC molecules and dramatically decrease the activation energy of the reaction, consequently enhancing the EDC dehydrochlorination reaction.