Theoretical Studies of the Formation and Reactivity of C2 Hydrocarbon Species on the Fe(100) Surface

Abstract

The adsorption and reactions of organic fragments containing C2 unit on the iron surface have been investigated employing periodic density functional theory with a plane-wave basis set and pseudopotentials, as well as a slab model representing the p(2 × 2) Fe(100) surface topology. The calculations demonstrate that the most favorable C2 species on the Fe(100) surface are those containing the acetylenic carbon at the α position (i.e., C−CH, C−CH2, and C−CH3). Both the hydrogenation reactions and C−C bond coupling that are responsible for the chain growth process have been explored; it is observed that the most likely mechanism of C−C bond propagation involves the recombination of adsorbed C and CH2/CH3 followed by the migratory insertion of hydrogen at the α C atom. The subsequent β-hydride or reductive elimination results respectively in the evolution of ethylene or ethane. The present computational study indicates that the production of ethane is preferred over ethylene, which agrees with the product sel...