Effect of Reductive Treatment Duration on the Structure and Properties of Pd−Zn/C Catalysts for Liquid‐Phase Acetylene Hydrogenation

Abstract

Structural features of bimetallic PdÀ Zn catalysts supported on Sibunit carbon material were studied by EXAFS, TEM, XRD and XPS methods, depending on the heat treatment conditions in hydrogen. It was found that supported particles of PdZn intermetallic compound of tetragonal structure are formed in all samples. An increase in the duration of catalyst reduction in H 2 at 500 °C from 1 to 20 hours leads to an increase in the amount of PdZn intermetallic particles (d av = 2-3 nm), which is confirmed by the increasing of the PdÀ Zn coordination number from 2.4 to 4.3 and by the decreasing of the surface Pd 0 /PdZn ratio from 0.63 to 0.18. The observed changes in the nature and structure of active sites provide an increase in the ethylene selectivity of PdÀ Zn/C catalysts in liquid-phase acetylene hydrogenation.

Selective Hydrogenation of Acetylene over Pd-Co/C Catalysts: The Modifying Effect of Cobalt

“…Catalysts based on Sibunit have been successfully used earlier in the processes of selective hydrogenation [24][25][26]. We have also previously shown that bimetallic Pd-Ga [4,27], Pd-Ag [28,29], and Pd-Zn [30,31] catalysts supported on Sibunit (C) exhibit high selectivity in the reaction of acetylene hydrogenation to ethylene, both in the liquid and gas phases.…”

Synthetic Strategies of Supported Pd-Based Bimetallic Catalysts for Selective Semi-Hydrogenation of Acetylene: A Review and Perspectives

“…In consideration of the strong exothermicity of the gas-phase catalytic hydrogenation of acetylene, liquid-phase catalytic hydrogenation is definitely a safe option, which was firstly reported by Edvinsson et al [ 20 ] in 1995. Simply speaking, for the liquid-phase hydrogenation process, the key equipment is typically a semi-batch reactor with a certain amount of pre-added solvent and catalyst; the feed steam continuously passes through this system at a given flow rate, and reaction occurs in the liquid [ 21 , 22 , 23 , 24 , 25 ]. In comparison with gas-phase catalytic hydrogenation of acetylene, solvent involvement in liquid-phase hydrogenation makes the heat transfer better; moreover, by selecting a suitable solvent, better catalyst stability and/or selectivity to ethylene can also be obtained [ 1 , 14 , 20 ].…”