Selective Hydrogenation of Acetylene to Ethylene Over Nanosized Gold and Palladium Supported Catalysts.

Ethylene, the main raw material for polyethylene production, is a by-product produced by thermally decomposing naphtha and it contains a small amount of acetylene. The acetylene reacts as a permanent catalyst poison for the ethylene polymerization catalyst. In this study, we wanted to improve the acetylene conversion and the ethylene selectivity by selective hydrogenation of acetylene for removing acetylene contained in ethylene. Catalyst was prepared by loading nanosized gold (Au) and palladium (Pd) particles on support (Al₂O₃, TiO₂). Deposition order Au and Pd particles was changed. The activity of the catalyst was investigated using a flow-typed fixed bed reactor under atmospheric pressure. Au and Pd particles deposited on TiO₂ were oxidized to Au₂O₃ and PdO due to strong metal support interaction (SMSI). It was considered that the Au/Pd/Al₂O₃ catalyst was more active than the Pd/Au/Al₂O₃ catalyst due to the formation of the interface between Au particles and Pd particles (or support). But Pd/Au/Al₂O₃ catalyst is considered to have poor activity because Pd particles cover part of the interface between Au and the support. Au/Pd/Al₂O₃ catalyst showed the best catalytic activity, and acetylene conversion and ethylene selectivity were 100% and about 80% at 40 °C, respectively.