The Study Of Acetylene Selective Hydrogenation On Supported Ni-Cu Catalyst

In the early days of20th century, with the development of petroleum industry, an increasing number of ethylene obtained through the course of thermal cracking of hydrocarbons. For trace amounts of acetylene, propyne, butadiene in the output of cracking furnace, the production of polyolefine, Ziegler-Natta catalyst deactivate because of acetylene polymerization and coke formation which leads to deactivation by pore plugging. So it calls for a more excellent catalyst for trace acetylene removal. Palladium based catalysts express a high acetylene conversion and ethylene selectivity, but its active centers are also easily blocked by high-carbon compounds and green oil.In our early work, supported Pd-Cu catalysts for a small amount of acetylene removal received good results. With the space velocity of1.54×106cm3/g·h, the catalysis shows a100%acetylene conversion and ethylene selectivity can reach99%. Therefore, this paper continues to investigate the performance of supported Ⅷ nickel-family metal with copper loading on silicon dioxide which prepared by co-impregnation method.The introduction of Nickel to Cu/SiO2catalyst can lead to the formation of nickel-copper alloy, coke deposition can be reduced for this alloy effect and catalyst life was prolonged. At the same time, acetylene conversion and ethylene selectivity maintained at a high level. With nickel-copper ratio of1.1, space velocity of4.1×101cm3/g·h, acetylene hydrogen ratio of1:10, the catalysis showed an acetylene conversion rate of100%, and the ethylene selectivity is80%. Compared with the expensive Pd-Ag catalyst, Ni-Cu catalysts are worth looking in to.We also examined the acetylene hydrogenation performance of platinum and palladium. The experimental results show that:mono component platinum or palladium metal catalyst gave much vitality in acetylene hydrogenation activity with low ethylene selectivity which almost over-hydrogenated to ethane. When carried out ethylene hydrogenation reaction on Pt-Cu bimetallic catalysts, ethylene conversion rate reached100%at first but this rate dropped significantly after catalyzed the acetylene hydrogenation reaction for several hours, indicating that the catalyst surface had been undergone some changes. If this took place on Pd-Cu bimetallic catalyst, the situation was different. Pd-Cu/SiO2with low Pd loading showed almost no activity to ethylene; but to acetylene hydrogenation reaction, the acetylene conversion rate reached100%and had a up to98%ethylene selectivity. when the Pd loading was high, ethylene could convert to ethane either, this meant the higher Pd loading could not always get better effect.