Mechanism transformation of cyclohexene-thiophene competitive adsorption in FAU zeolite  

作　　者：Pei Xue Meng Zheng Longwei Wang Liyuan Cao Liang Zhao Jinsen Gao Chunming Xu 

机构地区：[1]State Key Laboratory of Heavy Oil Processing,China University of Petroleum(Beijing),Beijing 102249,China

出　　处：《Chinese Journal of Chemical Engineering》2021年第11期68-78,共11页中国化学工程学报（英文版）

基　　金：the National Natural Science Foundation of China(21822810,21838011);the National Key Research and Development Program(2018YFC1902603).

摘　　要：Competition of hydrocarbon compounds with sulfides in gasoline has caused a not very high selectivity of sulfides in adsorption desulfurization so far,resulting in a reduction of catalyst lifetime as well as more sulfur oxide emissions.Tostudy the whole competitive process changing with the increase of the loading,the dynamic competition adsorption mechanism of cyclohexene and thiophene in siliceous faujasite(FAU)zeolite was analyzed by the Monte Carlo simulation.The results showed that with the increase of the loading,thiophene and cyclohexene had different performances before and after the inflection point of 40 molecule/UC.The adsorbates were distributed ideally at optimal sites during the stage that occurred before the inflection point,which is called the“optimal-displacement adsorption”stage.When approaching the inflection point,the competition became apparent and the displacement appeared accordingly,some thiophene molecules at S sites(refers to the sites inside the supercages)were displaced by cyclohexene.After the inflection point,the concentration of adsorbates at W sites(refers to the 12-membered ring connecting the supercages)was significantly reduced,whereas the adsorbates at S sites got more concentrated.The stage some cyclohexene molecules displaced by thiophene and inserted into the center of the supercage can be named as the“insertion-displacement adsorption”stage,and both the adsorption behavior and the competitive relationship became localized when the adsorption amount became saturated.This shift in the competitive adsorption mechanism was due to the sharp increase of interaction energy between the adsorbates.Besides,the increase in temperature and ratio of Si/Al will allow the adsorbates,especially thiophene molecules to occupy more adsorption sites,and it is beneficial to improve the desulfurization selectivity.

关 键 词：Competitive adsorption mechanism CYCLOHEXENE THIOPHENE FAU zeolite Molecular simulation SELECTIVITY 

分 类 号：TE624.55[石油与天然气工程—油气加工工程]