钴配合物催化CO_(2)氢化为甲醇的“氢质子和氢负离子”同时转移机理  

Simultaneous transfer mechanism of“a hydroxyl proton and hydride”for the hydrogenation of CO_(2)to methanol catalyzed by cobalt complexes

作　　者：闫秀丽 赵雪乔 石博[3] 郝勇静 YAN Xiu-li;ZHAO Xue-qiao;SHI Bo;HAO Yong-jing(College of Material Science and Engineering,Hebei University of Engineering,Handan 056038,Hebei,China;College of Architecture and Art,Hebei University of Engineering,Handan 056038,Hebei,China;College of Chemistry and Material Science,Hebei Normal University,Shijiazhuang 050024,Hebei,China)

机构地区：[1]河北工程大学材料科学与工程学院,河北邯郸056038 [2]河北工程大学建筑与艺术学院,河北邯郸056038 [3]河北师范大学化学与材料科学学院,河北石家庄050024

出　　处：《西北师范大学学报（自然科学版）》2024年第2期58-64,共7页Journal of Northwest Normal University(Natural Science)

基　　金：河北省自然科学基金资助项目(B2021402012;E2021402017)。

摘　　要：全球二氧化碳(CO_(2))过度排放,由此引发的温室效应日益严峻.将CO_(2)选择性加氢为甲醇,可以将丰富、安全的碳源转化为有价值的化学品和燃料.文中采用密度泛函理论对半三明治结构钴配合物催化CO_(2)加氢制甲醇的反应机理及新型催化剂的设计进行计算研究.计算结果表明,形成甲二醇分子时金属Co上的氢负离子和吡啶配体中的氢质子同时转移至甲酸分子上的过程是该反应的决速步,总反应能垒为122.2 kJ·mol^(-1)(2→TS 8,11).此外,通过不同的取代基取代酰胺氮原子和吡啶配体上的氢原子,设计了6种钴配合物,计算预测了它们催化CO_(2)加氢到甲醇的活性.在所有新提出的钴配合物中,1a,1b,1c有潜力在温和条件下高效催化CO_(2)加氢到甲醇,它们的总自由能垒分别为107.5,109.2和111.7 kJ·mol^(-1).The greenhouse effect caused by excessive global carbon dioxide(CO_(2))emissions is becoming more and more serious.Selective hydrogenation of CO_(2)to methanol can convert abundant and safe carbon sources into valuable chemicals and fuels.A computational study using density functional theory is conducted to investigate the reaction mechanism of CO_(2)hydrogenation to methanol catalyzed by a half-sandwich cobalt complex,as well as the design of new catalysts.The calculated results show that the formation of methanediol via the simultaneous transfer of a hydroxyl proton in the pyridine ligand and the hydride on the metal Co to the formic acid is the rate-determining step with a total barrier of 122.2 kJ·mol^(-1)(2→TS 8,11).Furthermore,six cobalt complexes are designed by replacing the hydrogen atom on the amide nitrogen atom and pyridine ligand with different substituents.Among all newly proposed cobalt complexes,1a,1b,and 1c are the promising catalyst candidates for hydrogenation of CO_(2)to methanol with low total free energy barriers of 107.5,109.2,and 111.7 kJ·mol^(-1),respectively.

关 键 词：二氧化碳 催化加氢 密度泛函理论 反应机理 催化剂设计 

分 类 号：O643.36[理学—物理化学] TQ223.121[理学—化学]