物理化学学报 >> 2010, Vol. 26 >> Issue (09): 2417-2421.doi: 10.3866/PKU.WHXB20100915

催化和表面结构 上一篇    下一篇

V2O5/CeO2催化剂固相反应的Raman光谱研究

伍燕妮1, 郭明1, 陈芳2, 罗孟飞1   

  1. 1. 浙江师范大学物理化学研究所,先进催化材料省部共建教育部重点实验室, 浙江金华321004;
    2. 浙江大学催化研究所,杭州310028
  • 收稿日期:2010-03-31 修回日期:2010-05-19 发布日期:2010-09-02
  • 通讯作者: 罗孟飞 E-mail:mengfeiluo@zjnu.cn
  • 基金资助:

    国家自然科学基金(20873125)资助项目

Raman Spectroscopic Study on the Solid-State Reaction of V2O5/CeO2 Catalyst

WU Yan-Ni1, GUO Ming1, CHEN Fang2, LUO Meng-Fei1   

  1. 1. Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang Province, P. R. China;
    2. Institute of Catalysis, Zhejiang University, Hangzhou 310028, P. R. China
  • Received:2010-03-31 Revised:2010-05-19 Published:2010-09-02
  • Contact: LUO Meng-Fei E-mail:mengfeiluo@zjnu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20873125).

摘要:

采用浸渍法制备了不同V2O5负载量(分别为5%和15%)的V2O5/CeO2催化剂. 利用不同激发波长(514 和325 nm)的Raman 光谱, 结合X 射线衍射(XRD)、紫外-可见漫反射(UV-Vis DRS)和N2 物理吸附技术, 考察了V2O5/CeO2催化剂中V2O5和载体CeO2之间的固相反应. 结果表明: 催化剂在300 ℃焙烧时, V2O5与CeO2反应生成CeVO4,升高温度有利于固相反应的发生. 样品对325 nm 光的吸收明显大于对514 nm 光的吸收, 因此325nm激发波长的Raman光谱对催化剂的表层信息更为敏感. 当焙烧温度较低时, 由于受到表层CeVO4的阻碍, 未反应的V2O5残留在载体CeO2孔道或粒子堆积孔道内部, 因此514 nm 激发波长下能观察到V2O5的Raman 峰,而表面灵敏的325 nm激发波长下观察不到此现象.

关键词: Raman 光谱, V2O5/CeO2, CeVO4, 相变, 吸光度

Abstract:

We prepared V2O5 /CeO2 catalysts with different V2O5 loadings (5% and 15%) by incipient wetness impregnation. Raman spectroscopy (514 and 325 nmexcitation laser lines), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), and N2 adsorption were used to study the solid-state reaction between V2O5 and CeO2. We found that the vanadium oxidation species reacted with ceria and formed a CeVO4 phase on the surface of the sample that was calcined at 300 ℃, and the reaction was promoted at higher temperature. In addition, the absorption at 325 nm is stronger than that at 514 nm for the sample, therefore, 325 nm Raman spectroscopy is more sensitive to surface information than 514 nm Raman spectroscopy. Calcination at low temperature leads to unreacted V2O5 in the pores of CeO2 but this is hindered by CeVO4 on the sample surface. Therefore, the Raman band of V2O5 is present when using the 514 nmexcitation laser line and absent when using the 325 nmexcitation laser line.

Key words: Raman spectrum, V2O5 /CeO2, CeVO4, Phase transformation, Absorbance

MSC2000: 

  • O643