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Diffusion phenomena of propane and propylene in colloidal zeolitic imidazolate Framework-8 particles
Journal of the Taiwan Institute of Chemical Engineers ( IF 5.7 ) Pub Date : 2017-10-10 , DOI: 10.1016/j.jtice.2017.09.034
Shuji Ohsaki , Yuki Morimoto , Satoshi Watanabe , Hideki Tanaka , Minoru T. Miyahara

Zeolitic imidazolate framework-8 (ZIF-8) enables a kinetic separation of propane and propylene with high efficiency, although the detailed mechanism has not yet been clarified. In the present study, we measure the adsorption rates of propane and propylene in ZIF-8 particles and in-situ X-ray diffraction patterns of ZIF-8 during the gas adsorption process to investigate the effect of the gas pressure and the flexibility of ZIF-8 framework on the diffusion process of propane and propylene in ZIF-8 particles. The adsorption rates of propane and propylene depend on the gas pressure, which would be due to the enlargement of the pore window diameter of the ZIF-8 framework during the gas adsorption as suggested by in-situ XRD measurements. This result is also supported by the calculation of interaction potential profiles between a gas molecule and the ZIF-8 framework, in which an energy barrier at the pore window limits the gas diffusion and the height of the barrier decreases with the increase in the pore window diameter. Furthermore, we find that the adsorption rates of propane and propylene depend on the particle size of ZIF-8, and the selectivity of propylene over propane increases with the particle size.



中文翻译:

丙烷和丙烯在胶态沸石咪唑盐Framework-8颗粒中的扩散现象

沸石咪唑啉骨架8(ZIF-8)能够高效分离丙烷和丙烯,尽管尚未阐明其详细机理。在本研究中,我们测量在气体吸附过程中ZIF-8颗粒中丙烷和丙烯的吸附速率以及ZIF-8的原位X射线衍射图,以研究气体压力和ZIF柔韧性的影响-8构架说明丙烷和丙烯在ZIF-8颗粒中的扩散过程。丙烷和丙烯的吸附速率取决于气体压力,这是由于原位吸附表明,气体吸附过程中ZIF-8骨架的孔径窗口直径增大XRD测量。气体分子与ZIF-8骨架之间的相互作用势分布的计算也支持该结果,其中孔窗口处的能垒限制了气体的扩散,并且随着孔窗口的增加,势垒的高度减小直径。此外,我们发现丙烷和丙烯的吸附速率取决于ZIF-8的粒径,并且丙烯对丙烷的选择性随粒径的增加而增加。

更新日期:2017-10-10
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