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Study on catalytic properties of metal-supported ZIF-8 with computational chemistry

BO Xiaofan1, WU Pingyi2, LIU Dahuan1, YANG Qingyuan1, MA Qintian1, LAN Ling2, WANG Shaohua3, ZHANG Yi3, ZHONG Chongli1   

  1. 1 State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China;
    2 Petrochemical Research Institute, PetroChina, Beijing 100195, China;
    3 China Kunlun Contracting Engineering Corporation Liaoning Company, Liaoyang 111003, Liaoning, China
  • Received:2013-12-26 Revised:2014-01-28 Online:2014-05-05 Published:2014-05-05
  • Supported by:

    supported by the National Basic Research Program of China (2013CB733503) and the National Natural Science Foundation of China (21136001,21276008).

负载金属的ZIF-8催化活性的计算化学研究

薄晓帆1, 吴平易2, 刘大欢1, 阳庆元1, 麻沁甜1, 兰玲2, 王少华3, 张轶3, 仲崇立1   

  1. 1 北京化工大学有机无机复合材料国家重点实验室, 北京 100029;
    2 中国石油化工研究院, 北京 100195;
    3 中国昆仑工程公司辽宁分公司, 辽宁 辽阳 111003
  • 通讯作者: 兰玲,张轶
  • 基金资助:

    国家重点基础研究发展计划项目(2013CB733503);国家自然科学基金重点项目(21136001,21276008)。

Abstract: Metal-organic frameworks (MOFs) are a new family of nanoporous functional materials that have shown potential applications in catalysis, due to their unique structural features. In this work, a combination of molecular simulation and density functional theory (DFT) calculation were employed to investigate the catalytic properties of metal-supported ZIF-8 with different metals (Pd, Ag, Pt and Au). First, the radial distribution function between these metal particles and the different atoms in ZIF-8 was analyzed from Monte Carlo (MC) and molecular dynamics (MD) simulations in order to determine the possible locations of the metal particles. Then, DFT calculations were performed at the generalized gradient corrected approximation (GGA) level with PW91 functional and the double numerical plus polarization (DNP) basis set. The binding energy was calculated to evaluate the relative stability of the metal particles (Pd, Ag, Pt and Au) in each site of the framework. The results showed that there were three types of interaction modes between the metals and the framework: carbon-metal-carbon (C-M-C), metal-carbon (M-C) and metal-bond (M-bond) modes, where the first type was the most stable one. For the same interaction type, the order of the stability of ZIF-8 with different metals was: Pd > Ag > Pt > Au. At the same time, the catalytic activity of the metal-supported materials was also investigated using CO as probe molecule. The analysis of the Mulliken population and the electrostatic potential distributions of metals indicated that metal particles were the Lewis acid sites which were related to their capabilities of accepting an electron. The order of their catalytic activities was: Pd > Pt > Ag > Au. The results obtained in this work may provide useful information for the catalytic application of MOFs loaded with metals.

Key words: metal-organic frameworks, nanoscale, density functional theory, metal particles, catalysis, stability, model

摘要: 金属-有机骨架材料(metal-organic frameworks,MOFs)是一类新型纳米多孔功能材料。由于其独特的结构特征,在催化方面展现出潜在的应用价值。采用分子模拟结合密度泛函理论的计算方法系统地研究了ZIF-8在负载金属Pd、Ag、Pt、Au后的催化活性。结果表明,金属与材料之间主要有3种作用方式,其中以“碳-金属-碳”(C-M-C)形式最为稳定。并且对于同一种方式,ZIF-8负载金属后的稳定性顺序为:Pd >Ag >Pt >Au。同时,利用CO作为探针分子,系统地研究了负载金属后ZIF-8的催化活性,发现这些金属原子的Lewis酸性强弱与其电子接受能力有关,其催化活性顺序为:Pd >Pt >Ag >Au。这为研究利用MOF材料负载金属用于催化提供了参考信息。

关键词: 金属-有机骨架材料, 纳微尺度, 密度泛函理论, 金属粒子, 催化, 稳定性, 模型

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