Competition of C‐C bond formation and C‐H bond formation For acetylene hydrogenation on transition metals: A density functional theory study

Abstract

Selective hydrogenation of acetylene is an important reaction for production of polymer grade ethylene. The green oil formation has great influence on the selectivity and activity of acetylene selective hydrogenation. This article describes a density functional theory study on the C + H hydrogenation reaction and C + C coupling reaction on the (111) surface of Ag, Cu, Pd, Pt, Rh, and Ir. The activity of acetylene selective hydrogenation is examined by the effective barrier for ethylene formation. A comparison between the reaction barrier of ethylene hydrogenation and desorption is used to identify the selectivity for ethylene formation. The barriers of three pathways for 1,3‐butadiene formation suggest that acetylene and vinyl coupling reaction is the favorable pathway. The stability of catalysts is evaluated by the selectivity of 1,3‐butadiene, which follows the order of Pt(111) > Ir(111) > Rh(111) > Pd(111) > Cu(111) > Ag(111). Furthermore, the relationship between acetylene adsorption energy and effective barrier of ethylene formation and 1,3‐butadiene formation has been established to well understand the catalytic properties of different metals. © 2018 American Institute of Chemical Engineers AIChE J, 65: 1059–1066, 2019