Competitive adsorption mechanism of thiophene with benzene in FAU zeolite: The role of displacement
Competitive adsorption mechanism of thiophene with benzene in FAU zeolite: The role of displacement
复制标题
FAU沸石中噻吩与苯的竞争吸附机理：置换作用
DOI：
10.1016/j.cej.2017.07.011
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发表时间：
2017
影响因子：
15.1
通讯作者：
Xu Chunming
中科院分区：
文献类型：
--
作者：
Dang Shanqing;Zhao Liang;Yang Qing;Zheng Meng;Zhang Jingjing;Gao Jinsen;Xu Chunming
为探索苯/噻吩竞争吸附关系随吸附量增加而变化的全过程，首次采用巨正则系综Monte Carlo模拟方法，研究了苯/噻吩在硅质八面沸石（FAU）中从无限稀释到饱和吸附的竞争吸附机理.结果表明，随着苯和噻吩总负载量的增加，竞争吸附机制由“理想-置换吸附”转变为“插入-置换吸附”，拐点为40 molecule/UC。在“理想置换吸附”阶段，苯和噻吩分子都理想地吸附在S和W位上。同时，当总负载量接近40 molecule/UC时，有利S吸附位上的噻吩被苯置换并迁移到W位。在“插入-置换吸附”阶段，随着吸附量的增加，苯继续置换吸附在S位上的噻吩。取代的噻吩插入超笼的中心附近。这种竞争吸附机制的转变是由于相互作用能。此外，噻吩浓度、吸附温度和Si/Al比的提高也在一定程度上提高了噻吩的选择性。
To explore the whole process of competitive relationship changing with increasing adsorption amount, the competitive adsorption mechanism of benzene/thiophene in siliceous faujasite (FAU) zeolite from infinite dilution to saturation adsorption was analyzed through grand canonical ensemble Monte Carlo simulations for the first time. Results showed that the competitive adsorption mechanism transferred from “ideal-displacement adsorption” to “insertion-displacement adsorption” with an inflection point of 40 molecule/UC, as the total loading amount of benzene and thiophene grew. At “ideal-displacement adsorption” stage, both benzene and thiophene molecules adsorbed ideally on S and W sites. Meanwhile, as the total loading closed to 40 molecule/UC, increasing amount of thiophene on favorable S adsorption sites was displaced by benzene and migrated to W sites. Comparatively, at “insertion-displacement adsorption” stage, benzene molecules continued displacing some thiophene adsorbed on S sites when the total loading increased. The displaced thiophene inserted near the center of the supercage. The transformation in this competitive adsorption mechanism was due to the interaction energy. Besides, higher thiophene concentration, adsorption temperatures and ratios of Si/Al to some extent contributed to the increase in the selectivity for thiophene.