混合气体中SAPO-34上单个物种的表面浓度简

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.

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

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.