C_(18)环基过渡金属(Os,Ir)单原子对甲烷C—H的活化  

Methane C—H Activation by Cyclo[18]Carbon-based Single-atom Transition Metal(Os,Ir)

作　　者：张海平 孔雪 夏文生[1] 张庆红[1] 万惠霖[1] ZHANG Haiping;KONG Xue;XIA Wensheng;ZHANG Qinghong;WAN Huilin(State Key Laboratory of Physical Chemistry of Solid State Surface,National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters,Fujian Province Key Laboratory of Theoretical and Computational Chemistry,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学化学化工学院,固体表面物理化学国家重点实验室,醇醚酯化工清洁生产国家工程实验室,福建省理论与计算化学重点实验室,厦门361005

出　　处：《高等学校化学学报》2023年第11期120-127,共8页Chemical Journal of Chinese Universities

基　　金：国家重点研发计划“政府间国际科技创新合作/港澳台科技创新合作”重点专项项目(批准号:2019YFE04400);教育部创新团队发展计划项目(批准号:IRT1036)资助。

摘　　要：由于高度的化学稳定性,作为天然气主要成分的甲烷分子的转化和利用极富挑战性和研究意义.然而,这一问题的突破有赖于甲烷C—H的活化,特别是温和条件下活化催化剂的研发.本文采用密度泛函理论方法计算考察了过渡金属TM(Os, Ir)单原子-碳18环(TMC_(18))对甲烷C—H的活化.结果表明,相对于TM单原子,TM单原子键合在碳18环上后,显著降低了甲烷C—H的活化能垒;而相较于TM单价阳离子,则削弱了C—H键裂解物种CH_(3)与TM的结合力.结合力较弱的TM-CH_(3),对物种CH_(3)的脱附或进一步转化为附加值高的化学品有利.对TM-碳18环间的作用进行分析发现,碳18环通过与TM的d-π共轭,呈现良好的储存和吸电子的作用,进而可以促进甲烷C—H活化能垒的降低.碳18环基TM单原子具有温和条件下高效活化甲烷C—H的潜力.It is of great significance and challenge for the conversion and utilization of methane(the main component of natural gases)due to its high stability in chemistry.In order to breakthrough out it,the key is to develop the catalysts for methane C—H activation under mild conditions.Here,we investigated methane C—H activation over cyclo[18]carbon-based single-atom transition metal(TM=Os,Ir)(TMC18)by means of density functional theory(DFT).The results show that the activation barrier of methane C—H over TMC18 is significantly lower than TM itself,and the species CH_(3) resulted from methane C—H cleavage tends to bind more weakly with TMC18 than TM+ions.The weakened interaction between CH_(3) and TMC18 favors to the CH_(3) desorption or further transformation into value-added chemicals.Thus,cyclo[18]carbon-based single-atom TM exhibits its promising ability to high-efficiently activate C—H of methane at mild conditions.The detailed analysis on the interaction of TM with cyclo[18]carbon indicate that cyclo[18]carbon is good in electron-storage/attraction by d-πconjugation of TM-cyclo[18]carbon,which leads to the decrease in barrier of methane C—H activation over cyclo[18]carbon-based TM.

关 键 词：甲烷 C—H活化 碳18环 单原子 密度泛函理论 

分 类 号：O643[理学—物理化学]