催化学报 ›› 2016, Vol. 37 ›› Issue (12): 2053-2058.DOI: 10.1016/S1872-2067(16)62538-X

• 论文 • 上一篇    下一篇

Au/CeO2催化剂上CO2选择加氢为CO反应及其中间物种研究

朱晓兵, 曲新, 李小松, 刘景林, 刘剑豪, 朱斌, 石川   

  1. 大连理工大学氢能与液体燃料研究中心;等离子体物理化学实验室, 辽宁大连 116024
  • 收稿日期:2016-08-23 修回日期:2016-09-29 出版日期:2016-12-27 发布日期:2016-12-27
  • 通讯作者: Chuan Shi
  • 基金资助:

    国家自然科学基金(11475041,11175036,21373037),中央高校基本科研业务费(DUT16QY49).

Selective reduction of carbon dioxide to carbon monoxide over Au/CeO2 catalyst and identification of reaction intermediate

Xiaobing Zhu, Xin Qu, Xiaosong Li, Jinglin Liu, Jianhao Liu, Bin Zhu, Chuan Shi   

  1. Center for Hydrogen Energy and Liquid Fuels;Laboratory of Plasma Physical Chemistry, Dalian University of Technology, Dalian 116024, Liaoning, China
  • Received:2016-08-23 Revised:2016-09-29 Online:2016-12-27 Published:2016-12-27
  • Contact: Chuan Shi
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (11475041, 11175036, 21373037), and the Fundamental Research Funds for the Central Universities (DUT16QY49).

摘要:

CO2的化学转化具有环境及科学双重研究意义.CO2具有很高的化学稳定性,加氢还原是一种有效的转化途径.其中将CO2选择性还原为CO,即逆水汽变换(RWGS)反应(CO2+H2→ CO+H2O),具有重要的理论意义和应用价值:(1)CO作为合成气的重要原料,可以通过F-T合成生产更有价值的液体燃料;(2)H2可通过可再生能源电解水制取,实现了全过程的零排放碳循环利用.
从热力学角度分析,RWGS反应是一个吸热反应,高温有利于平衡转化率的提高.从动力学角度,一个对正反应有活性的催化剂可同时催化逆反应进行.可还原性载体负载贵金属催化剂,如Pt/CeO2,Au/FeOx,Au/CeO2等,具有很好的低温WGS催化活性,但它们在RWGS反应上的研究较少.我们制备了CeO2负载纳米Au催化剂(HRTEM表征结果表明金高度分散于CeO2载体表面,粒径为4-5 nm),其在常压CO2加氢还原为CO反应中表现出优异的低温活性,分别在450℃,CO2/H2=1,WHSV=12000 mL/(h·g),及400℃,H2/CO2=1,WHSV=6000 mL/(h·g)条件下,CO2转化率接近平衡转化率,且CO的选择性为100%.随着H2/CO2比例增加,CO2转化率明显提高,且维持H2/CO2为1的化学计量比反应.通过原位漫反射红外光谱与质谱相结合的技术,研究了Au/CeO2催化剂上的RWGS反应路径:Au/CeO2催化剂表面形成了甲酸盐中间物种,它的消耗伴随着CO和H2O产物的生成.说明Au/CeO2催化剂遵循中间体机理,这应该是其具有优异低温RWGS反应性能的微观机制.

关键词: 二氧化碳还原, Au/CeO2催化剂, 一氧化碳, 甲酸盐中间物种, 原位红外漫反射光谱

Abstract:

CO2 selective reduction to CO with H2 over a CeO2-supported nano-Au catalyst at atmospheric pressure was investigated. A high CO2 conversion, approaching the thermodynamic equilibrium value, and nearly 100% CO selectivity were obtained. The surface formate intermediates generated during the reverse water-gas shift reaction at 400℃ were identified using in situ diffuse-reflectance infrared Fourier-transform spectroscopy. The formate consumption to give CO and H2O, determined using mass spectrometry, indicated that the reaction proceeded via an associative formate mechanism; this contributes to the high Au/CeO2 catalytic activity at low temperatures.

Key words: CO2 reduction, Au/CeO2 catalyst, Carbon monoxide, Formate intermediate, In situ DRIFT spectroscopy