Comparison of nuclear magnetic resonance tracer exchange and molecular uptake of benzene on pentasils
Comparison of nuclear magnetic resonance tracer exchange and molecular uptake of benzene on pentasils
复制标题
核磁共振示踪剂交换和苯在五元硅上的分子摄取的比较
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
A. Zikánová
中科院分区：
文献类型：
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作者：
C. Förste;J. Kärger;H. Pfeifer;L. Riekert;M. Bülow;A. Zikánová
传统的核磁共振波谱法用于研究吸附-吸附体系中示踪剂的交换。在提出的实验过程中，完全排除了热效应，并且由于气相扩散和晶间扩散而可能产生的输运阻力降至最低。估计了吸附剂颗粒偏离球形以及晶内扩散可能的各向异性对示踪剂交换曲线的影响。所得的关系同样适用于摄取研究。对苯在不同ZSM-5样品上的示踪交换数据与吸附测量结果进行了比较。虽然这些实验是用不同的技术和不同的标本独立进行的，但却提供了一致的结果。特别是，在示踪剂实验中获得的自扩散系数与从摄取研究中得到的扩散系数之间的比值，似乎确实是由吸附质浓度与吸附质压力的对数导数给出的，就像在比较自扩散和摄取测量时通常假设的那样。
Conventional NMR spectroscopy is applied to study tracer exchange in adsorbate–adsorbent systems. In the proposed experimental procedure, heat effects are completely excluded and possible transport resistances due to gas-phase diffusion and intercrystalline diffusion are reduced to a minimum. The influence of deviations from the spherical shape of the adsorbent particles as well as possible anisotropy of intracrystalline diffusion on tracer exchange curves is estimated. The obtained relations are likewise applicable to uptake studies. For benzene on different ZSM-5 specimens, the tracer exchange data are compared with the results of uptake measurements. Though carried out independently from each other with different techniques and different specimens, the experiments provide coinciding results. In particular, it appears that the ratio between the self-diffusion coefficient obtained in the tracer experiments and the diffusion coefficient resulting from uptake studies is indeed given by the logarithmic derivative of the adsorbate concentration versus the adsorbate pressure as conventionally assumed on comparing self-diffusion and uptake measurements.