Theoretical catalytic performance of single-atom catalysts M <sub>1</sub>/PW <sub>12</sub>O <sub>40</sub> for alkyne hydrogenation materials
Shamraiz Hussain Talib, Xue‐Lian Jiang, Shixiang Feng, Mengdie Zhao, Qi Yu
Abstract
Single-atom catalysts (SACs) have provoked significant curiosity in heterogeneous catalysis due to the benefits of maximum metal atoms usage, robust metal-support interaction, single-metal-atom active sites, and high catalytic efficiency. In this study, the electronic structures and catalytic mechanism of ethyne hydrogenation of SACs with the group-9 metal atoms M<sub>1</sub> (M<sub>1</sub>= Co, Rh, Ir) anchored on PTA (phosphotungstic acid) cluster have been explored by using first-principles quantum calculations. It is found that the catalytic activity of ethyne (C<sub>2</sub>H<sub>2</sub>) hydrogenation is determined by two critical parameters: the adsorption energies of the adsorbate (H<sub>2</sub>, C<sub>2</sub>H<sub>2</sub>) and the activation energy barrier of ethyne hydrogenation. We have shown that the reaction pathway of ethyne hydrogenation reaction on the experimentally characterized Rh<sub>1</sub>/PTA at room temperature consists of three steps: C<sub>2</sub>H<sub>2</sub> and H<sub>2</sub> coadsorption on Rh<sub>1</sub>/PTA, H<sub>2</sub> attacking C<sub>2</sub>H<sub>2</sub> to form C<sub>2</sub>H<sub>4</sub>, then C<sub>2</sub>H<sub>4</sub> desorbing or further reacting with H<sub>2</sub> to produce C<sub>2</sub>H<sub>6</sub> and completing the catalytic cycle. The Rh<sub>1</sub>/PTA possesses fair catalytic activity with a C<sub>2</sub>H<sub>4</sub> desorption energy of 1.46 eV and a 2.59 eV barrier for ethylene hydrogenation. Moreover, micro-kinetics analysis is also carried out to understand the mechanism and catalytic performance further. The work reveals that the PTA-supported SACs can be a promising catalyst for alkyne hydrogenation.