The density functional theory method is employed to systematically explore the mechanism of syngas methanation on the Ni4/MCM-41 catalyst surface. The calculation results show that the optimal pathway of CH4 formation is CO + H → CHO + H → CH2O + H → CH3O → CH3 + H → CH4 with the rate-determining step of CH3O direct dissociation. Because the activation energy for the direct dissociation of CH3O species is much lower than that for the CH3OH formation (198.6 vs 264.8 kJ mol−1), there is almost no by-product CH3OH that appeared in the products of the syngas methanation over the Ni4/MCM-41 catalyst. Compared with other conventional nickel-based methanation catalysts, Ni4/MCM-41 catalyst is an excellent methanation catalyst with high selectivity of CH4.

中文翻译：

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基于密度泛函理论的Ni4/MCM-41催化剂合成气甲烷化机理研究

采用密度泛函理论方法系统地探索了Ni4/MCM-41催化剂表面合成气甲烷化的机理。计算结果表明，CH4形成的最佳途径为CO+H→CHO+H→CH2O+H→CH3O→CH3+H→CH4，其中CH3O直接解离为定速步骤。由于 CH3O 物质直接解离的活化能远低于 CH3OH 形成的活化能（198.6 vs 264.8 kJ mol-1），因此在 Ni4 上的合成气甲烷化产物中几乎没有出现副产物 CH3OH。 /MCM-41 催化剂。与其他传统的镍基甲烷化催化剂相比，Ni4/MCM-41催化剂是一种优异的甲烷化催化剂，具有高CH4选择性。