Influence of Active Metal Precursors on the Structure and Catalytic Behavior of Pd/Al2O3 Catalysts for Selective Acetylene Hydrogenation

Choosing an appropriate metal precursor is a basic step in the preparation of catalysts. In this paper, PdCl42−, PdSO4 and Pd(acac)2 were selected as the metal precursor, which was supported on α-Al2O3 commonly used in industry to explore the impact of palladium precursor on the structure and catalytic behavior for selective acetylene hydrogenation. The activity for the three catalysts is similar, while the ethylene selectivity of Pd(acac)2 can outclass the other two catalysts at the fixed conversion. The different catalytic performance is mainly ascribed to the influence of non-metal residua distribution on valence state structure and size effect determined by HRTEM, CO chemisorption, XPS and in situ CO-IR. More importantly, the catalyst prepared by Pd(acac)2 perform better stability due to the formation of the Pd carbide species after 24 h reaction. The catalytic deactivation with time-on-stream for other two catalysts was attributed to the sintering of Pd particles and carbon deposition under reaction conditions.