催化学报

催化学报 ›› 2016, Vol. 37 ›› Issue (10): 1702-1711.DOI: 10.1016/S1872-2067(16)62468-3

• 论文 • 上一篇    下一篇

金催化一氧化碳氧化反应中锌锡复合氧化物的载体效应

李威a, 杜林颖b, 贾春江b, 司锐a   

  1. a 中国科学院上海应用物理研究所微观界面物理与探测重点实验室, 上海光源, 上海 201204;
    b 山东大学化学与化工学院胶体与界面化学教育部重点实验室, 特种功能聚集体材料教育部重点实验室, 山东济南 250100
  • 收稿日期:2016-04-18 修回日期:2016-05-23 出版日期:2016-10-21 发布日期:2016-10-22
  • 通讯作者: Chunjiang Jia, Rui Si
  • 基金资助:

    国家自然科学基金（21373259，21301107）；中国科学院“百人计划”；中国科学院战略性先导科技专项（A类，XDA09030102）；山东大学基础研究基金（2014JC005）；山东省“泰山学者”计划；中国科学院微观界面物理与探测重点实验室开放基金.

Support effect of zinc tin oxide on gold catalyst for CO oxidation reaction

Wei Lia, Linying Dub, Chunjiang Jiab, Rui Sia   

  1. a Key Laboratory of Interfacial Physics and Technology, Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China;
    b Key Laboratory for Colloid and Interface Chemistry, Key Laboratory of Special Aggregated Materials, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, Shandong, China
  • Received:2016-04-18 Revised:2016-05-23 Online:2016-10-21 Published:2016-10-22
  • Contact: Chunjiang Jia, Rui Si
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21373259, 21301107), the Hundred Talents Project of the Chinese Academy of Sciences, the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA09030102), the Fundamental Research Funding of Shandong University (2014JC005), the Taishan Scholar Project of Shandong Province (China), and the Open Funding from Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences.

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摘要：

氧化物负载的纳米金催化剂对CO氧化反应具有极高的活性，这不仅依赖于金的结构特性，也取决于氧化物载体的结构.近年来，除了氧化硅、氧化铝等惰性载体以及氧化钛、氧化铈、氧化铁等可还原性载体外，人们还致力于探索各类新型氧化物载体.另一方面，锡酸锌是具有反尖晶石结构的化合物，并且在透明导电氧化物、锂离子电池阳极材料、光电转换装置以及传感器等方面应用广泛.然而，迄今为止，锡酸锌仍未被用于负载纳米金催化剂，因此相关的构效关系作用研究也十分有限.基于此，本文采用氮气吸附-脱附实验、电感耦合等离子体原子发射光谱（ICP-AES）、X射线衍射（XRD）、X射线光电子能谱（XPS）、透射电子显微镜（TEM）和高分辨电镜（HRTEM）、高角环形暗场像-扫描透射电子显微镜（HAADF-STEM）、X射线吸收精细结构谱（XAFS）和氢气程序升温脱附（H2-TPD）等手段，系统研究了锡酸锌负载的纳米金催化剂在CO氧化反应中催化性能差异的原因.
首先，利用水热法制备了锡酸锌（ZTO）载体，而其织构性质可由碱（N2H4·H2O）与金属离子（Zn2+）的比例在4/1（ZTO_1）、8/1（ZTO_2）和16/1（ZTO_3）之间进行调节.结果发现，ZTO_2具有最大的孔体积（0.223 cm3/g）和最窄的孔径分布.再采用沉积沉淀法将0.7 wt% Au负载于其上，得到金-锡酸锌（Au_ZTO）催化剂.ICP-AES测得样品中Au含量在0.57-0.59 wt%，与投料比接近.CO氧化反应结果显示，Au_ZTO_1和Au_ZTO_2的表观活化能相同，但后者的活性更高；而Au_ZTO_3在220℃以下没有活性，催化性能最差，与纯锡酸锌载体相当.
XRD结果显示，反应过程中ZTO晶相、晶胞参数及晶粒尺寸变化不明显；TEM和HRTEM分析表明，载体ZTO在反应前后均为多面体形貌，平均颗粒尺寸在12-16 nm；XPS结果验证了Zn2+和Sn4+离子是新鲜和反应后样品中载体金属的存在形式；HAADF-STEM探测到所有样品中均含有1-2 nm的Au粒子；XAFS结果表明，Au以Au0形式存在，并且在Au_ZTO_3中Au平均粒径大于4 nm，而其它两样品约为2 nm.H2-TPR结果表明，金的引入对ZTO载体耗氢量影响不大，但还原峰温度向低温移动；金属-载体相互作用强弱与催化活性高低具有正相关性，即Au_ZTO_2 > Au_ZTO_1 >> Au_ZTO_3.这是由于不同织构性质的锡酸锌载体对于纳米金活性物种的稳定作用不同所致，具有最大孔体积和最窄孔径分布的ZTO_2负载的金纳米颗粒表现出最高活性.

关键词: 金催化剂, 锌锡复合氧化物, 一氧化碳氧化, X射线吸收精细结构谱, 构效关系

Abstract:

Nanostructured gold catalyst supported on metal oxide is highly active for the CO oxidation reaction. In this work, a new type of oxide support, zinc tin oxide, has been used to deposit 0.7 wt% Au via a deposition-precipitation method. The textural properties of Zn2SnO4 support have been tuned by varying the molar ratio between base (N2H4·H2O) and metal ion (Zn2+) to be 4/1, 8/1 and 16/1. The catalytic tests for CO oxidation reaction revealed that the reactivity on Au-Zn2SnO4 with N2H4·H2O/Zn2+=8/1 was the highest, while the reactivity on Au-Zn2SnO4 with N2H4·H2O/Zn2+=16/1 was almost identical to that of the pure support. Both fresh and used catalysts have been characterized by multiple techniques including nitrogen adsorption-desorption, X-ray diffraction, transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray adsorption fine structure, and temperature-programmed reduction by hydrogen. These demonstrated that the textural properties, especially pore volume and pore size distribution, of Zn2SnO4 play crucial roles in the averaged size of gold nanoparticles, and thus determine the catalytic activity of Au-Zn2SnO4 for CO oxidation.

Key words: Gold catalyst, Zinc tin oxide, Carbon monoxide oxidation, X-ray absorption fine structure, Structure-activity relationship