Nanoporous ZSM-5 Crystals Coated with Silicalite-1 for Enhanced p-Xylene Separation
Nanoporous ZSM-5 Crystals Coated with Silicalite-1 for Enhanced p-Xylene Separation
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DOI：
10.1021/acsanm.9b00037
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发表时间：
2019-05-01
影响因子：
5.9
通讯作者：
Denayer, Joeri F. M.
中科院分区：
文献类型：
--
作者：
Miyamoto, Manabu;Ono, Shumpei;Denayer, Joeri F. M.
在ZSM-5沸石晶体上生长silicalite-1涂层是允许改善其催化对二甲苯选择性的表面改性方法之一。为了理解对二甲苯选择性的这种增加，研究了silicalite-1涂层对ZSM-5吸附性能的影响。脉冲色谱实验表明，silicalite-1涂层改善了对二甲苯相对于邻二甲苯和间二甲苯的分离因子，导致与在母体ZSM-5上相比，在silicalite/ZSM-5上对二甲苯相对于间二甲苯的更好的色谱分离。此外，通过重量吸附测量也证实了与ZSM-5相比，间二甲苯在硅质岩/ZSM-5上的较慢的吸附动力学。可以得出结论，增强的对二甲苯选择性是通过空间位阻效应实现的，该空间位阻效应导致在外部silicalite-1层中更明显地排除间二甲苯并且减少表面吸附位点的数量。
The growth of a silicalite-1 coating on ZSM-5 zeolite crystals is one of the surface modification methods allowing to improve its catalytic p-xylene selectivity. Aiming to understand this increase in p-xylene selectivity, the effect of silicalite-1 coating on the adsorptive properties of ZSM-5 was investigated. Pulse chromatographic experiments revealed the silicalite-1 coating improved the separation factors of p-xylene over o-xylene and m-xylene, resulting in a better chromatographic separation of p-xylene over m-xylene on silicalite/ZSM-5 compared to that on parent ZSM-5. Additionally, slower adsorption kinetics of m-xylene on silicalite/ZSM-5 compared to ZSM-5 was also confirmed by gravimetric adsorption measurements. It is concluded that the enhanced p-xylene selectivity is achieved by steric effects leading to a more pronounced exclusion of m-xylene in the outer silicalite-1 layer and a reduction in number of surface adsorption sites.