Selectivity of zeolite supported rhodium and iridium catalysts for the hydrogenation of alkenes and alkynes

Abstract

Alkene and alkyne hydrogenation reactions are currently one of the most common industrial procedures for reducing unsaturated organic compounds to a variety of useful chemicals. In the catalytic hydrogenation of alkenes and alkynes under both homogeneous and heterogeneous conditions, several metal-based catalysts have been used. Metals in supported catalysts are usually cationic and chemically bonded to the supports when they are atomically distributed. The study of noble metals in this class is continually expanding, resulting in the discovery of novel catalysts with unique features. In this study, the selectivity of zeolite supported Rh and Ir catalysts for the hydrogenation of alkenes and alkynes is investigated by using Density Functional Theory (DFT). The reaction pathways for the hydrogenation have been modeled to monitor which pathway is energetically more favorable by comparing the activation barriers between the states. The results have shown that ethylene production is selective with zeolite supported Rh(C2H2)2 catalyst. Moreover, the ethylene selectivity for the hydrogenation is more favorable when the metal is Ir. However, the regeneration of the catalyst is facile with Rh metal. This outcome is elucidated by analyzing geometric parameters, ligand bond dissociation energies and potential energy surfaces. This study contributes to a better understanding of ethylene selectivity along the hydrogenation of acetylene. This study is expected to shed light on the synthesis and usage of single atom catalysts for the hydrogenation of acetylene and ethylene.