Stability of Pd/Sibunit and Pd-M/Sibunit (M: Zn, Ag) catalysts for gas-phase acetylene hydrogenation

摘要

Pd/Sibunit and Pd-M/Sibunit (M: Zn, Ag) catalysts were investigated in the selective gas-phase acetylene hydrogenation. It was found that modified Pd-Zn/Sibunit and Pd-Ag/Sibunit catalysts have stable properties for 10 hours at 85°C, while the activity of monometallic Pd/Sibunit sample is gradually decreased from 791 to 717 ml(C_2H_4)/g min. Using the DTA method, it was shown that light carbonaceous deposits, based on acetylene oligomerization products, form on the surface of Pd/Sibunit and Pd-M/Sibunit catalysts during the reaction. It was found by the NMR method that the oligomers trapped by Pd/Sibunit surface is C_8 hydrocarbons. It is assumed that the differences in the resistance to deactivation of Pd/Sibunit and modified systems can be associated with different localization of carbon deposits on the surface of studied catalysts.