物理化学学报 >> 2010, Vol. 26 >> Issue (12): 3263-3272.doi: 10.3866/PKU.WHXB20101223

催化和表面结构 上一篇    下一篇

氧化铝载体和氧化钡助剂对钌基氨合成催化剂结构和性能的影响

杨晓龙1,2, 夏春谷1, 唐立平1,2, 熊绪茂1, 慕新元1, 胡斌1   

  1. 1. 中国科学院兰州化学物理研究所, 兰州730000;
    2. 中国科学院研究生院, 北京100049
  • 收稿日期:2010-09-01 修回日期:2010-09-29 发布日期:2010-12-01
  • 通讯作者: 胡斌 E-mail:hcom@lzb.ac.cn
  • 基金资助:

    国家杰出青年科学基金(20625308)资助项目

Effect of Alumina Support and Barium Oxide on the Structure and Catalytic Activity of Ruthenium Catalysts for Ammonia Synthesis

YANG Xiao-Long1,2, XIA Chun-Gu1, TANG Li-Ping1,2, XIONG Xu-Mao1, MU Xin-Yuan1, HU Bin1   

  1. 1. Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, P. R. China;
    2. Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2010-09-01 Revised:2010-09-29 Published:2010-12-01
  • Contact: HU Bin E-mail:hcom@lzb.ac.cn
  • Supported by:

    The project was supported by the National Science Foundation for Distinguished Young Scholars of China (20625308).

摘要:

采用不同来源γ-Al2O3(市售Al2O3-1, 合成Al2O3-2)作为钌基氨合成催化剂载体, 利用浸渍法制备了一系列添加不同BaO助剂含量的Ba-Ru/Al2O3催化剂. 通过X射线衍射(XRD)、N2-低温物理吸附、X射线荧光光谱(XRF)、透射电镜(TEM)、H2程序升温还原(H2-TPR)、NH3程序升温脱附(NH3-TPD)和X射线光电子能谱(XPS)等方法研究了不同来源的Al2O3以及BaO助剂含量对负载型钌基催化剂的物相结构、织构性质、微观形貌、表面性质和催化剂的氨合成活性等方面的影响. 结果表明, 载体的物理化学性质对制备的钌基氨合成催化剂的结构以及活性有较大影响. BaO助剂对催化剂的影响主要表现在两个方面: 添加量不同导致BaO与γ-Al2O3的作用力不同, 从而进一步影响催化体系的比表面积和孔结构性质; BaO助剂会对体系的Ru物种还原性质以及催化剂表面酸碱性质进行调节, 适量BaO的加入能够极大提高反应活性, 而这种最佳量与载体性质密切相关.

关键词: 氨合成, γ-Al2O3, 载体, Ru, 还原, 酸性

Abstract:

A series of Ba-Ru/Al2O3 catalysts were prepared by the impregnation method using industrial alumina (Al2O3-1) and synthesized alumina (Al2O3-2) as supports. The catalysts were characterized by X-ray diffraction, N2 adsorption-desorption, X-ray fluorescence spectroscopy, transmission electron microscopy, H2 temperature-programmed reduction, NH3 temperature-programmed desorption, and X-ray photoelectron spectroscopy. The effect of Al2O3 and the BaO promoter on the phase structure, texture properties, morphology, surface properties, and catalytic activity in ammonia synthesis were investigated. The results indicate that the physical and chemical properties of Al2O3 have a strong impact on the structure and activity of the ruthenium catalysts. The BaO promoter has a strong impact on the ruthenium catalyst in two ways: first, the amount of BaO added leads to a difference in the interaction between BaO and γ-Al2O3, which further influences the specific area and the porous structure of the catalysts; second, the addition of BaO influences the reduction process and the surface acidity and alkaline properties of the ruthenium catalysts. A proper amount of BaO promotes the activity and the optimal amount of BaO depends on the properties of the supports.

Key words: Ammonia synthesis, γ-Al2O3, Support, Ruthenium, Reduce, Acidity

MSC2000: 

  • O643.3