物理化学学报 >> 2013, Vol. 29 >> Issue (05): 1055-1062.doi: 10.3866/PKU.WHXB201301181

催化和表面科学 上一篇    下一篇

Pt/TiO2催化剂上CO氧化反应动力学研究

李娜, 陈秋艳, 罗孟飞, 鲁继青   

  1. 浙江师范大学物理化学研究所, 先进催化材料教育部重点实验室, 浙江 金华 321004
  • 收稿日期:2012-10-31 修回日期:2013-01-17 发布日期:2013-04-24
  • 通讯作者: 鲁继青 E-mail:Jiqinglu@zjnu.cn
  • 基金资助:

    国家自然科学基金(21173195)资助项目

Kinetics Study of CO Oxidation Reaction over Pt/TiO2 Catalysts

LI Na, CHEN Qiu-Yan, LUO Meng-Fei, LU Ji-Qing   

  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
  • Received:2012-10-31 Revised:2013-01-17 Published:2013-04-24
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21173195).

摘要:

利用沉积沉淀法制备了Pt/TiO2催化剂, 将其在不同温度下焙烧, 以得到不同颗粒尺寸的Pt. 并将这些样品用于CO催化氧化反应以及反应动力学研究. 结果表明: 焙烧温度对催化剂有明显影响, Pt 颗粒尺寸随着焙烧温度的升高而增加; 与此同时, CO催化活性随焙烧温度的升高呈先增加后降低的趋势, 其中, 400℃焙烧的样品表现出最高的催化活性. 反应动力学结果表明, 催化剂上CO氧化反应表观速率方程为r=5.4×10-7pCO0.17pO20.36,说明在该催化剂上CO氧化遵循Langmuir-Hinshelwood机理. 同时, 对催化剂进行了CO化学吸附红外光谱和O2化学吸附表征. 结果表明, 随着焙烧温度的升高, 催化剂上CO和O2吸附量均呈现先升高后降低的趋势, 这与反应结果和反应动力学方程一致, 说明反应受到催化剂表面上CO和O2吸附浓度的影响. 而在400℃焙烧的催化剂上, CO和O2吸附量均最高, 因此其反应活性也最好. 这可能是焙烧过程影响了Pt 和TiO2之间的相互作用引起的.

关键词: 一氧化碳氧化, 铂/二氧化钛, 金属-载体相互作用, 反应动力学, 化学吸附

Abstract:

A series of Pt/TiO2 catalysts were prepared using a deposition-precipitation method and calcined at different temperatures to obtain various Pt particle sizes. The catalysts were tested for catalytic CO oxidation and the kinetics of the reaction was studied. The results showed that the Pt particle size increased with calcination temperature, and that their reactivity for CO oxidation first increased and then decreased with increasing calcination temperature, with the catalyst calcined at 400℃ possessing the highest reactivity. The kinetic investigation revealed that the reaction rate could be described by r=5.4×10-7p CO0.17pO20.36, suggesting that the reaction followed a Langmuir-Hinshelwood mechanism. Meanwhile, O2 chemisorption and infrared (IR) spectroscopy of CO chemisorption on the catalysts were conducted to reveal the relationship between the catalyst structure and its catalytic behavior. It was found that the amount of O2 chemisorption and the intensity of CO chemisorption by IR on the catalysts first increased and then decreased with increasing calcination temperature, which was consistent with the catalytic results and the kinetic equation. This could explain the catalytic behaviors of the catalysts. For example, the highest amounts of chemisorbed O2 and CO were obtained over the Pt/TiO2 calcined at 400℃, which resulted in the highest reactivity. Such an enhancement in reactivity was probably due to the strong interaction between Pt and TiO2 induced by the calcination process.

Key words: CO oxidation, Pt/TiO2, Metal-support interaction, Reaction kinetics, Chemisorption

MSC2000: 

  • O643