Zhang Shujie, Lv Xiaojing, Wang Junkai, Wang Tianqi, Shan Jingyi
Henan Key Laboratory of Materials On Deep-Earth Engineering, School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo, 454003, China.
J Mol Model. 2021 Nov 8;27(12):346. doi: 10.1007/s00894-021-04971-2.
Methanol is a promising source that can replace non-renewable petroleum energy. Therefore, it is of great importance to oxidize the methane into methanol because methane is not easy to transport although its huge reserves. The stability between TM (Ti, V) atoms and CN is firstly studied through DFT calculations. The results show that the binding energy between TM and CN(Ti@CN = - 9.0 eV, V@CN = - 8.0 eV) is more negative than its cohesive energy (Ti = - 5.6 eV, V = - 5.6 eV), indicating TM@CN possess good stability. On this basis, the oxidation process of methane to methanol is further studied on the TM@CN single-atom catalysis using NO as the oxidant. The results show that NO is firstly adsorbed on TM@CN, and then directly decomposed into N and O. N is released and only O is adsorbed on CN as active oxygen for the following catalytic methane oxidation to methanol process. The process includes two steps: (1) CH + O → CH* + OH*, the reaction barriers in this process are 1.2 eV (Ti) and 1.5 eV (V); (2) CH* + OH* → CHOH, the reaction barriers are 1.8 eV (Ti) and 1.8 eV (V) in this step. Finally, the obtained CHOH molecule will leave the surface of TM@CN single-atom catalyst and the energy required for this step is 1.4 eV (Ti) and 1.0 eV (V), respectively. These findings provide theoretical guidance for the catalytic oxidation of CH to CHOH using TM (Ti,V)@CN single-atom catalysts.
甲醇是一种很有前景的可替代不可再生石油能源的来源。因此，将甲烷氧化成甲醇非常重要，因为尽管甲烷储量巨大，但它不易运输。首先通过密度泛函理论（DFT）计算研究了过渡金属（TM，即Ti、V）原子与碳氮化物（CN）之间的稳定性。结果表明，TM与CN之间的结合能（Ti@CN = -9.0 eV，V@CN = -8.0 eV）比其内聚能（Ti = -5.6 eV，V = -5.6 eV）更负，这表明TM@CN具有良好的稳定性。在此基础上，进一步研究了以NO为氧化剂，在TM@CN单原子催化作用下甲烷氧化为甲醇的过程。结果表明，NO首先吸附在TM@CN上，然后直接分解为N和O。N释放出来，只有O作为活性氧吸附在CN上，用于后续催化甲烷氧化为甲醇的过程。该过程包括两个步骤：（1）CH + O → CH* + OH*，此过程中的反应势垒为1.2 eV（Ti）和1.5 eV（V）；（2）CH* + OH* → CHOH，此步骤中的反应势垒为1.8 eV（Ti）和1.8 eV（V）。最后，生成的CHOH分子将离开TM@CN单原子催化剂表面，此步骤所需能量分别为1.4 eV（Ti）和1.0 eV（V）。这些发现为使用TM（Ti，V）@CN单原子催化剂将CH催化氧化为CHOH提供了理论指导。
