Intensified shape selectivity and alkylation reaction for the two-step conversion of methanol aromatization to p-xylene  

作　　者：Tingjun Fu Ran Wang Kun Ren Liangliang Zhang Zhong Li 

机构地区：[1]State Key Laboratory of Clean and Efficient Coal Utilization,College of Chemical Engineering and Technology,Taiyuan University of Technology,Taiyuan 030024,China

出　　处：《Chinese Journal of Chemical Engineering》2023年第7期240-250,共11页中国化学工程学报（英文版）

基　　金：financial support from the National Natural Science Foundation of China(21978191 and 22278292);Key Research and Development Project of Shanxi Province(International Science and Technology Cooperation Program)(201803D421011)。

摘　　要：Two-step conversion of methanol to aromatics via light hydrocarbons can significantly improve the conversion stability compared with direct aromatization of methanol,but it remains a challenge to achieve a high p-xylene(PX)selectivity.Herein,silica coating was firstly used to passivate external acid sites of ZSM-5 catalyst for the aromatization of light hydrocarbons by the chemical liquid deposition method.With the increase of SiO_(2) deposition,the density of the external acid sites of the catalyst was decreased from 0.1 to 0.03 mmol·g^(-1),which inhibited the surface secondary reactions and increased the PX/X from 34.6% to 60.0%.In view of the fact that the aromatization process in the second step was partly inhibited as methanol was consumed in advance in the upper methanol-to-light hydrocarbons catalyst layer,part of methanol was directly introduced into the lower aromatization catalyst layer to promote the alkylation process during the aromatization,which decreased the toluene selectivity from 34.5% to 14.3% but increased the xylene selectivity from 40.0%to 55.3%.It was also found that an appropriate external acid density was needed for aromatization catalyst to strengthen the alkylation process and improve the selectivity of xylene under the conditions of methanol introduction.

关 键 词：Methanol to aromatics Two-step conversion PARA-XYLENE Zeolite Silica Catalysis 

分 类 号：TQ241.13[化学工程—有机化工]