Intracrystalline Diffusion in Molecular Sieve Zeolites by the Tracer-Pulse Method

扩散系数是设计吸附分离系统、气体净化和催化转化过程的重要性质。多孔沸石系统通常用于执行传输过程。分子筛沸石中扩散系数的测量导致吸附技术和核磁共振（NMR）方法测定的值之间存在巨大的，无法解释的差异。对这些差异的可能解释是：(1)未能考虑热效应，(2)未能考虑传质阻力，(3)未能考虑晶体表面的表面阻挡阻力，(4)吸附剂晶体结构的差异，以及(5)吸附剂再生的差异。现在有了用三种独立的方法同时测量相同系统中的扩散率的独特可能性。对结果的分析将对文献中报道的巨大差异的困境产生重要的见解，并且本研究可能为涉及微孔介质中气体扩散的传质过程提供改进的设计能力。

Diffusivity is an important property for the design of adsorption separation systems, gas purification, and catalytic conversion processes. Porous zeolite systems are often used to perform the transport processes. The measurement of diffusivities in molecular sieve zeolites has resulted in large, unexplained differences between values determined by adsorption techniques and the nuclear magnetic resonance (NMR) method. The possible explanations for these differences are (1) failure to account for thermal effects, (2) failure to account for mass transfer resistance, (3) failure to account for a surface barrier resistance at the crystal surface, (4) differences in the crystal structure of the adsorbent, and (5) differences in the regeneration of the adsorbent. There is now the unique possibility of simultaneously measuring the diffusivities in identical systems by three independent methods. Analysis of the results will yield significant insights into the dilemma of the large differences reported in the literature, and this study may provide improved design capabilities for mass transfer processes involving gas diffusion in microporous media.