物理化学学报2017，Vol.33Issue(7)：1310-1323,14.DOI:10.3866/PKU.WHXB201704172
镍族金属团簇在催化加氢过程中的应用
Nickel Family Metal Clusters for Catalytic Hydrogenation Processes
摘要
Abstract
Nanoparticles of precious metals play an important role in many heterogeneous catalytic reactions due to their excellent catalytic performance.As an idealized model,gas phase metal clusters have been extensively utilized to understand catalytic mechanisms at a molecular level.Here we provide an overview of our recent studies on H2 dissociative chemisorption on nickel family clusters.The structure evolution and the stability of the metal clusters were first compared.H2 dissociation on the clusters was then carefully addressed to understand the capability of metal clusters to break the H-H bond.Two key parameters,the dissociative chemisorption energy (AEcE) and the H sequential desorption energy (AEDE),were employed to characterize the catalytic activity of metal clusters.Our results show that both △EcE and △EDE decline significantly as the H coverage increases.Since the catalyst is in general covered entirely by H atoms and H2 molecules in a typical hydrogenation process,and maintained at a pre-determined pressure of H2 gas,we can rationally use the calculated △EcE and AEDE values at full H saturation to address the activity of metal clusters.Our results suggest that at full H coverage,each Pt atom is essentially capable of adsorbing 4 H atoms,while each Ni or Pd atom can only accommodate 2 H atoms.Considering the similar values of H desorption energies on Pt and Pd clusters,the higher average H capacity per Pt atom could probably lead to a faster reaction rate because more active H atoms are produced on the Pt catalyst particles in the hydrogenation process.Finally,the charge sensitivity of the key catalytic properties of Pt clusters for hydrogenation was systematically evaluated.The results show that the dissociation of H2 and H desorption are strongly correlated to the charge state of the Pt clusters at low H coverage.However,at high H-capacities,both AEcE and △EDE fall into a narrow range,suggesting that the charge can be readily dispersed and that the Pt-H bonds average the interaction between clusters and H atoms.As a result,the H-capacities on charged clusters were found to be similar as the cluster size increased;in case of sufficiently large clusters,the reactivity of a fully saturated cluster was no longer sensitive to its charge state.关键词
团簇/过渡金属/催化加氢/饱和氢吸附/带电状态/密度泛函理论Key words
Clusters/Transition metal/Catalytic hydrogenation/Full H saturation/Charge state/Density functional theory分类
化学化工引用本文复制引用
韩波,程寒松..镍族金属团簇在催化加氢过程中的应用[J].物理化学学报,2017,33(7):1310-1323,14.基金项目
The project was supported by the National Natural Science Foundation of China (21473164,21203169,21233006) and the Fundamental Research Funds for the Central Universities,China University of Geosciences,China,and Air Products and Chemicals,Inc.国家自然科学基金(21473164,21203169,21233006),中国地质大学(武汉)中央高校基本科研业务费以及空气与化学品公司资助项目 （21473164,21203169,21233006）
