物理化学学报 >> 2011, Vol. 27 >> Issue (10): 2416-2420.doi: 10.3866/PKU.WHXB20110934

催化和表面科学 上一篇    下一篇

Nb2O5在t-ZrO2表面的分散状态与Brønsted 酸特征

何杰1,2, 范以宁2   

  1. 1. 安徽理工大学化学工程学院, 安徽淮南 232001;
    2. 介观化学教育部重点实验室, 南京大学化学化工学院, 南京 210093
  • 收稿日期:2011-05-16 修回日期:2011-07-07 发布日期:2011-09-27
  • 通讯作者: 何杰 E-mail:jhe@aust.edu.cn
  • 基金资助:

    国家重点基础研究发展计划项目(G1999022400)和国家自然科学基金(21071004)资助

Dispersion States and Brønsted Acidity Feature of Nb2O5on t-ZrO2

HE Jie1,2, FAN Yi-Ning2   

  1. 1. School of Chemical Engineering, Anhui University of Science and Technology, Huainan 232001, Anhui Province, P. R. China;
    2. Key Laboratory of Mesoscopic Chemistry of MEO, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
  • Received:2011-05-16 Revised:2011-07-07 Published:2011-09-27
  • Contact: HE Jie E-mail:jhe@aust.edu.cn
  • Supported by:

    The project was supported by the National Key Basic Research Program of China (G1999022400) and National Natural Science Foundation of China (21071004).

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摘要： 以草酸铌为前驱物, 四方相氧化锆(t-ZrO2)为载体, 通过浸渍法制备不同负载量的Nb2O5/t-ZrO2催化剂.采用粉末X 射线衍射(XRD)、激光拉曼光谱(LRS)、紫外-可见漫反射光谱(UV-Vis DRS)等技术对t-ZrO2表面Nb2O5分散状态进行表征; 采用异丁烯(IB)与异丁醛(IBA)缩合生成2,5-二甲基-2,4-己二烯(DMHD)反应评价不同负载量的Nb2O5/t-ZrO2的催化性能，采用吡啶吸附红外(Py-IR)光谱表征催化剂Brønsted 酸中心特征. 结果表明, 由XRD定量相分析方法测定的Nb2O5在t-ZrO2表面单层分散容量与"嵌入模型"预测值接近. Nb2O5/t-ZrO2表面Brønsted 酸中心特征与Nb2O5聚集状态密切相关.

关键词: Nb2O5, t-ZrO2, 表面分散状态, 酸性特征, 烯醛缩合反应

Abstract: Nb2O5/t-ZrO2 catalysts with different loadings were prepared by aqueous solution impregnation using niobium oxalate as a precursor on tetragonal ZrO2 (t-ZrO2). The dispersion states with respect to niobia species on t-ZrO2 were characterized by powder X-ray diffraction (XRD), laser Raman spectroscopy (LRS), and UV visible diffuse reflectance spectroscopy (UV-Vis DRS). The catalytic activity was evaluated by the condensation reaction of iso-butene (IB) and iso-butyraldehyde (IBA) to 2,5-dimethyl-2,4-hexadiene (DMHD) and the Brønsted acidity was evaluated by the Fourier-transform infrared spectroscopy of pyridine adsorption (Py-IR). The results reveal that the dispersion capacity ΓNb of Nb2O5 on t-ZrO2, which was determined by XRD quantitative phase analysis, is almost identical to the value predicted by the "incorporated model". The results also show that the Brønsted acid sites are strongly related to the states of Nb2O5 on Nb2O5/t-ZrO2.

Key words: Nb2O5, t-ZrO2, Surface dispersion state, Surface acidity feature, Olefin-aldehyde condensation