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

用示踪脉冲法测量分子筛沸石中的晶内扩散 - 更新

• 批准号: 9101620
• 负责人: Ronald Danner
• 金额: $ 3.49万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-04-15 至 1992-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9101620&HistoricalAwards=false
• 关键词: Measurement; Intracrystalline; Diffusion; Molecular; SieveZeolites

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.

微孔固体中气体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非常重要。 这些特性是通过使用脉冲色谱法来测量的，该方法的独特之处在于它是一种在平衡条件下操作的宏观方法。 将示踪脉冲结果与先前发布的 NMR 扩散系数进行比较，用于确定两种技术之间常见差异的根源。 在不同温度和负载下测量乙烷-硅沸石系统的平衡等温线和扩散数据，从而可以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修改，研究了共吸附分子对理想和非理想吸附混合物中乙烷扩散行为的影响。 二元混合物的每种成分的平衡等温线也通过“浓度示踪脉冲”方法测量。 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引起了人们的极大兴趣。 最后，使用微扰色谱的两种变体（示踪剂和浓度脉冲）来研究达肯方程在不同吸附浓度下的有效性。 示踪脉冲色谱装置在这方面是独特的，因为其他实验技术无法同时测量传输系数和自扩散系数。