催化学报 ›› 2024, Vol. 61: 226-236.DOI: 10.1016/S1872-2067(24)60055-0

• 论文 • 上一篇    下一篇

晶相设计钌基纳米催化剂提高CO2甲烷化活性

杨冲亚a,c,1, 王玮珏a,c,1, 卓红英a, 沈铮a, 张天雨b,*(), 杨小峰a,*(), 黄延强a   

  1. a中国科学院大连化学物理研究所, 中国科学院航天催化材料重点实验室, 辽宁大连 116023
    b北京林业大学环境科学与工程学院, 北京 100083
    c中国科学院大学, 北京 100049
  • 收稿日期:2024-03-22 接受日期:2024-05-04 出版日期:2024-06-18 发布日期:2024-06-20
  • 通讯作者: * 电子信箱: tzhang@bjfu.edu.cn (张天雨), yangxf2003@dicp.ac.cn (杨小峰).
  • 作者简介:

    1共同第一作者.

  • 基金资助:
    国家重点研究与发展计划(2022YFA1506200);中国科学院青年基础研究项目(YSBR-022);中国科学院战略重点研究项目(XDB36030200);国家自然科学基金(22208021);国家自然科学基金(21978286);国家自然科学基金(21925803);国家自然科学基金(U19A2015);中国科学院青年创新促进会(Y2022061);辽宁省青年拔尖人才(XLYC2203108);辽宁省青年拔尖人才(2007082);辽宁省青年拔尖人才(1907170)

Phase engineering of Ru-based nanocatalysts for enhanced activity toward CO2 methanation

Chongya Yanga,c,1, Weijue Wanga,c,1, Hongying Zhuoa, Zheng Shena, Tianyu Zhangb,*(), Xiaofeng Yanga,*(), Yanqiang Huanga   

  1. aCAS Key Laboratory of Science and Technology on Applied Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
    bCollege of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
    cUniversity of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2024-03-22 Accepted:2024-05-04 Online:2024-06-18 Published:2024-06-20
  • Contact: * E-mail: tzhang@bjfu.edu.cn (T. Zhang),yangxf2003@dicp.ac.cn (X. Yang).
  • About author:

    1Contributed to this work equally.

  • Supported by:
    National Key Research and Development program of China(2022YFA1506200);CAS Project for Young Scientists in Basic Research(YSBR-022);Strategic Priority Research Program of the Chinese Academy of Sciences(XDB36030200);National Natural Science Foundation of China(22208021);National Natural Science Foundation of China(21978286);National Natural Science Foundation of China(21925803);National Natural Science Foundation of China(U19A2015);Youth Innovation Promotion Association CAS(Y2022061);Young Top-notch Talents of Liaoning Province(XLYC2203108);Young Top-notch Talents of Liaoning Province(2007082);Young Top-notch Talents of Liaoning Province(1907170)

摘要:

金属纳米颗粒在许多化学反应中表现出优异的催化性能, 因而广泛用于能源和环境等催化领域. 形貌是影响其催化行为的关键因素之一, 它通过改变金属纳米颗粒表层原子排列结构, 进而调控化学反应过程中的物质吸附、催化机理和反应动力学. 此外, 由于金属存在多种晶相结构, 其纳米颗粒暴露的表面结构也可通过改变晶相得以实现. 该调控策略可使得纳米颗粒具有独特的表面结构, 并展现出不同的催化性能. 因此, 金属纳米颗粒的晶相设计为优化金属催化剂的催化性能提供了一种有效方式. Ru基纳米催化剂对CO2甲烷化反应具有较好的活性和选择性, 且密堆积的Ru(0001)晶面被证明是hcp相Ru纳米催化剂的活性中心, 而(10-11)面对CO2甲烷化反应的贡献较小. 因此, 开发具有更丰富密堆积fcc-(111)表面的Ru基纳米催化剂, 有望大幅提高CO2甲烷化的活性.
本文首先通过密度泛函理论计算和微观动力学模拟, 研究了fcc相Ru纳米催化剂的密堆积(111)晶面上CO2加氢反应的催化机理. 结果表明, 与hcp-(0001)相比, 该密堆积的fcc-(111)表面因能促进CO2的吸附活化, 而具有更好的CO2甲烷化反应活性. 制备了具有完全暴露fcc-(111)晶面的二十面体Ru金属纳米颗粒, 并将其负载于惰性载体氧化铝上, 结果表明, CO2甲烷化活性比传统六方密堆积相(hcp)的钌基催化剂高5‒8倍, 证实了fcc相催化剂具有更高的甲烷化催化性能. 同时, 在较高的反应温度下, fcc-晶相的Ru基催化剂在初始反应阶段甲烷化反应活性逐渐下降, 但其CO2甲烷化活性仍远高于hcp-相催化剂. 原位X射线衍射和环境透射电镜等结果表明, 在反应温度高于250 °C条件下, fcc-晶相的金属催化剂发生部分晶相转变. 该相变主要发生于Ru金属纳米颗粒的聚集体, 并伴随着金属粒子的团聚和粒径的增长; 然而, 单颗粒分散的Ru纳米粒子在相同条件下仍能维持其fcc-晶相, 从而确保了其较高的甲烷化活性. 此外, 原位红外结果进一步证实了CO2甲烷化在Ru基纳米催化剂上通过氢化生成HCOO*中间体的反应路径, 以及Ru纳米颗粒在反应过程中的动态结构演化.
综上, 金属纳米颗粒的晶相设计是调控表面原子结构及其催化反应性能的有效手段. 通过对Ru基纳米催化剂的晶相设计, 可以显著提升其在CO2甲烷化反应中的催化活性. 然而, 潜在的高温晶相转变可导致催化剂活性的部分失活. 总之, 晶相设计通过对金属纳米粒子表面原子结构的调变, 为高效催化剂的设计开发和反应机理的深入研究提供了新的机遇.

关键词: 晶相设计, 面心立方相, 钌纳米催化剂, 二氧化碳甲烷化, 相变

Abstract:

The catalytic behavior of metal nanocatalysts is intrinsically contingent on the diversity of their exposed surfaces, which can be substantially regulated through the phase engineering of metal nanoparticles. In this study, it is demonstrated that the face-centered cubic (fcc) phase Ru with a close-packed (111) surface presents superior catalytic activity towards CO2 methanation. This behavior is attributed to its enhanced capability toward CO2 chemisorption derived from its inherently high surface reactivity. Complete exposure of such surfaces was successfully achieved experimentally by the synthesis of icosahedral Ru metal nanoparticles, which exhibited remarkable performance for CO2 methanation with 5-8 times higher activity than its conventional hexagonal close-packed (hcp) counterpart when supported on inert supports. However, for the joined fcc-Ru nanoparticles in the fresh catalyst, an fcc- to hcp-phase transformation was observed at a relatively high temperature with the in situ characterizations, which resulted in metal agglomeration and led to catalyst deactivation. However, the CO2 conversion was still much higher than that of the hcp-phase Ru nanocatalysts, as the monodispersed particles could maintain their fcc phase. Our results demonstrate that phase engineering of Ru nanocatalysts is an effective strategy for a catalyst design with improved catalytic performance. However, the phase transformation could represent a latent instability of the catalysts, which should be considered for the further development of robust catalysts.

Key words: Phase engineering, Face-centered cubic, Ru nanocatalyst, CO2 methanation, Phase transformation