催化学报

催化学报 ›› 2014, Vol. 35 ›› Issue (3): 430-436.DOI: 10.1016/S1872-2067(14)60007-3

• 研究论文 • 上一篇    下一篇

混合气体中SAPO-34上单个物种的表面浓度

Ysukzu Koyshi, 李玉新, 王垚, 王德峥   

  1. 清华大学化学工程系, 北京100084
  • 收稿日期:2013-10-26 修回日期:2013-12-23 出版日期:2014-02-26 发布日期:2014-02-26
  • 通讯作者: 王德峥
  • 基金资助:

    国家自然科学基金（21173125）.

Species surface concentrations on a SAPO-34 catalyst exposed to a gas mixture

Yasukazu Kobayashi, Yuxin Li, Yao Wang, Dezheng Wang   

  1. Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
  • Received:2013-10-26 Revised:2013-12-23 Online:2014-02-26 Published:2014-02-26
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21173125).

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475

被引次数

6

摘要：

运用Langmuir等温线方程和理想吸附溶液理论（IAST）两种方法计算了SAPO-34在混合气体中的单个物种表面浓度，并对比了计算值与实验值的吻合程度. 考察了两个二元混合体系，分别为80 ℃的甲醇和二甲醚以及25 ℃的二甲醚和乙烯混合气，发现IAST计算值在实验压力范围内均与实验结果吻合；但是Langmuir理论计算值仅在酸性位覆盖率低于1/3时与实验值吻合较好，随着压力增加严重偏离实验值，而且Langmuir理论不能描述随压力增加低饱和吸附量物种覆盖率降低的现象. 因此，针对包含不同饱和吸附量组分的混合气，Langmuir理论仅适用于描述表面浓度低时的反应动力学，当表面浓度高时应该采用IAST方法.

关键词: 理想吸附溶液理论, 吸附等温线, 混合气体吸附, SAPO-34

Abstract:

The use of the Langmuir isotherm for competitive adsorption and the use of ideal adsorbed solution theory (IAST) for calculating the surface concentrations of adsorbed species on a SAPO-34 catalyst exposed to a gas mixture were compared with experimental measurements. Two binary mixtures, namely, methanol and dimethyl ether (DME) at 80 ℃ and DME and ethene at 25 ℃ were used. IAST gave good agreement in the whole range of experimental concentrations, while Langmuir theory only gave good agreement up to when one-third of the acid sites were covered and then showed increasingly large deviations with increased pressure, and it failed to capture the phenomenon that the concentration of an adsorbed species with a smaller saturation adsorption capacity would decrease with increased pressure. Thus, for reactions of gas mixtures whose components have different saturation adsorption capacities, Langmuir theory can only be used for the reaction kinetics when the surface concentrations are quite low, and IAST should be used when the surface concentrations are high.

Key words: Ideal adsorbed solution theory (IAST), Adsorption isotherm, Mixed gas adsorption, SAPO-34 catalyst