Measurement of Intracrystalline Diffusion in Molecular SieveZeolites by the Tracer-Pulse Method - Renewal

气体在微孔固体中的平衡和扩散参数的测量对于许多分离和催化过程的设计是非常重要的。这些性质是用脉冲色谱法测量的，这种方法的独特之处在于它是在平衡条件下操作的宏观方法。将示踪脉冲结果与先前公布的核磁共振扩散系数进行比较，用于确定两种技术之间通常观察到的差异的来源。在不同温度和负载下测量乙烷-硅石体系的平衡等温线和扩散数据，从而研究吸附相浓度对微孔扩散系数的影响。通过对原始示踪脉冲技术的改进，研究了共吸附分子对乙烷在理想和非理想吸附混合物中的扩散行为的影响。二元混合物各组分的平衡等温线也用“浓度示踪脉冲”法测量。由于工业应用总是涉及多组分系统，因此研究混合物中的扩散是非常有趣的。最后，采用两种微扰色谱法（示踪法和浓度脉冲法）考察了在不同吸附浓度下Darken方程的有效性。示踪脉冲色谱仪在这方面是独一无二的，因为其他实验技术不能同时测量输运和自扩散系数。

The measurements of equilibrium and diffusional parameters of gases in microporous solids is very important for the design of many separation and catalytic processes. These properties are measured by use of the pulse chromatography method, which is unique in that it is a macroscopic method that operates under equilibrium conditions. Comparison of the tracer pulse results with previously published NMR diffusion coefficients is used to determine the origin of discrepancies commonly observed between the two techniques. Equilibrium isotherms and diffusion data for the ethane-silicalite system are measured at various temperatures and loadings, allowing investigation of the effect of adsorbed phase concentration on the micropore diffusion coefficient. The effect of co-adsorbed molecules on the diffusional behavior of ethane in ideal and nonideal adsorbed mixtures is investigated by a modification of the original tracer pulse technique. Equilibrium isotherms for each component of the binary mixtures are also measured by the 'concentration-tracer pulse' method. Since industrial applications always involve multicomponent systems, a study if diffusion in mixtures is of great interest. Finally, two variations of perturbation chromatography (tracer and concentration pulse) are used to investigate the validity of the Darken equation at various adsorbed concentrations. The tracer-pulse chromatography apparatus is unique in this respect, since other experimental techniques are not able to measure both the transport and self diffusion coefficients.