ZnCr_(2)O_(4)(111)-OV表面活性氢的产生及其在CO加氢中的应用  

Generation of Active Hydrogen and Its Application to CO Hydrogenation on the ZnCr_(2)O_(4)(111)-OV Surface

作　　者：刘慧慧[1] 来壮壮 魏呵呵 王志强 胡培君 LIU Huihui;LAI Zhuangzhuang;WEI Hehe;WANG ZhiQiang;HU Peijun(Centre for Computational Chemistry,Research Institute of Industrial Catalysis,State Key Laboratory of Green Chemical Engineering and Industrial Catalysis,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China;School of Physical Science and Technology,Shanghai Tech University,Shanghai 201210,China)

机构地区：[1]华东理工大学化学与分子工程学院,绿色化学工程与工业催化国家重点实验室,工业催化研究所,计算化学中心,上海200237 [2]上海科技大学物质科学与技术学院,上海201210

出　　处：《华东理工大学学报(自然科学版)》2025年第2期147-157,共11页Journal of East China University of Science and Technology

基　　金：国家自然科学基金青年基金(22203030)。

摘　　要：ZnCr_(2)O_(4)(111)-O_(V)作为CO选择性加氢反应的重要催化材料,其表面活性氢物种的产生机制及其对CO加氢反应的作用一直备受争议。本文研究了ZnCr_(2)O_(4)(111)-O_(V)表面活性氢的产生及其在CO加氢中的应用,结果表明:H2分子在ZnCr_(2)O_(4)(111)-O_(V)表面异裂解离为O_(V)-H-和O-H物种是最佳活化路径,这主要归因于ZnCr_(2)O_(4)(111)-O_(V)表面Zn物种灵活的Zn 3d轨道;当O_(V)-H-/O-H物种进攻CO分子的C^(δ+)/O^(δ-)时,动力学上更支持形成HCO物种而非COH物种;当以O-H作为氢源进行CO选择性加氢反应时,氢物种在反应过程中会优先转化为自由基,相反,若以O_(V)-H-物种参与反应,其可直接作为氢源实现CO高选择性加氢。本文可为Zn-基合成气选择性加氢催化材料的理性设计提供潜在的理论指导。The reduced ZnCr_(2)O_(4)(111)surface is an important catalytic material for CO hydrogenation,but the mechanism underlying the generation of active hydrogen species and its role for CO hydrogenation on this surface are controversial.In this work,we systematically calculate the activation of the most stable H2 species on the ZnCr_(2)O_(4)(111)-O_(V)surface,and the calculated results show that the heterolytic H2 dissociation producing O_(V)-H−and O-H species on the ZnCr_(2)O_(4)(111)-O_(V)surface is the optimal activation pathway.The heterolytic H2 dissociation can form the highly active and stable O_(V)-H−species,which is mainly attributed to the flexible 3d orbitals of the Zn species on the ZnCr_(2)O_(4)(111)-O_(V)surface,which favours the stabilization of hydride species due to the high symmetry of the Zn 3d orbitals.Moreover,we systematically investigate the reaction mechanism of CO-selective hydrogenation on the ZnCr_(2)O_(4)(111)surface,and the results show the energy barriers of the O_(V)-H−/O-H species attacking with the C^(δ+)/Oδ−of CO to generate HCO species are lower than those generating COH species.When the O-H species is used as a hydrogen source to initiate the CO hydrogenation reaction,the H-species is converted into radicals during the reaction;whereas,when the O_(V)-H−species is used as an H-source,the hydride species can be directly used as a hydrogen source to participate in the highly selective hydrogenation of CO.We also find that the O_(V)-H−species activates CO to produce HCO species with the lowest energy barriers,indicating that O_(V)-H−species also possesses high activity and selectivity.This work can provide some theoretical guidance for the rational design of Zn-based catalytic materials for selective hydrogenation of syngas.

关 键 词：ZnCr_(2)O_(4)(111)还原表面 活性氢物种 CO 选择性加氢 密度泛函理论 

分 类 号：O643.38[理学—物理化学]