González-Navarrete Patricio, Andrés Juan, Calatayud Monica
Departament de Química Física i Analítica, Universitat Jaume I , Av. Sos Baynat S/N, 12071 Castelló, Spain.
Laboratoire de Chimie Théorique CC 137, Sorbonne Universités, UPMC Univ Paris 06, CNRS , 4, place Jussieu F, 75252 Paris Cedex 05, France.
J Phys Chem A. 2018 Feb 1;122(4):1104-1113. doi: 10.1021/acs.jpca.7b11264. Epub 2018 Jan 19.
A detailed density functional theory study is presented to clarify the mechanistic aspects of the methanol (CHOH) dehydrogenation process to yield hydrogen (H) and formaldehyde (CHO). A gas-phase vanadium oxide cluster is used as a model system to represent reduced V(III) oxides supported on TiO catalyst. The theoretical results provide a complete scenario, involving several reaction pathways in which different methanol adsorption sites are considered, with presence of hydride and methoxide intermediates. Methanol dissociative adsorption process is both kinetically and thermodynamically feasible on V-O-Ti and V═O sites, and it might lead to form hydride species with interesting catalytic reactivity. The formation of H and CHO on reduced vanadium sites, V(III), is found to be more favorable than for oxidized vanadium species, V(V), taking place along energy barriers of 29.9 and 41.0 kcal/mol, respectively.
本文提出了一项详细的密度泛函理论研究，以阐明甲醇（CH₃OH）脱氢生成氢气（H₂）和甲醛（CH₂O）过程的机理。使用气相钒氧化物簇作为模型体系来代表负载在TiO催化剂上的还原态V(III)氧化物。理论结果提供了一个完整的情况，涉及考虑不同甲醇吸附位点的几种反应途径，存在氢化物和甲醇盐中间体。甲醇的解离吸附过程在V-O-Ti和V═O位点上在动力学和热力学上都是可行的，并且可能导致形成具有有趣催化活性的氢化物物种。发现在还原的钒位点V(III)上形成H₂和CH₂O比在氧化的钒物种V(V)上更有利，分别沿着29.9和41.0 kcal/mol的能垒发生。
