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Selective synthesis of p-xylene by alkylation of toluene
with dimethyl carbonate

LI Yongxin,DENG Lijun,XUE Bing   

  1. Department of Chemical Engineering,Jiangsu Polytechnic University
  • Online:2010-04-05 Published:2010-04-05

甲苯与碳酸二甲酯择形烷基化合成对二甲苯

李永昕,邓丽君,薛 冰   

  1. 江苏工业学院化学化工学院

Abstract: Selective synthesis of p-xylene by alkylation of toluene with dimethyl carbonate (DMC) was carried out in a continuous flow fixed-bed reactor over MgO-modified MCM-22 molecular sieves.The MgO/MCM-22 catalysts were characterized by means of XRD,N2 adsorption-desorption and pyridine-IR.Effects of MgO loading and reaction conditions were investigated.Results indicated that a high toluene conversion can be achieved along with an obvious increase in the selectivity for p-xylene over MgO modified MCM-22 using Mg(AC)2 as precursor.The influence of various reaction conditions was studied over a 12% MgO/MCM-22 catalyst.Under the optimal conditions,i.e. reaction temperature of 653 K,n (toluene) :n (DMC) of 4 and WHSV of 1 h-1,the conversion of toluene and the selectivity to p-xylene were 31.01% and 55.61%,respectively.

摘要: 在气相连续流动固定床反应器上,以改性的MCM-22为催化剂,对甲苯与碳酸二甲酯(DMC)的择形烷基化合成对二甲苯(PX)进行了研究。以乙酸镁为前体,采用等体积浸渍法制备了一系列MgO改性的MCM-22催化剂,并通过X射线衍射、低温N2吸附-脱附和吡啶红外光谱等手段对催化剂进行了表征。考察了MgO负载量、反应温度、甲苯与DMC摩尔配比及重时空速对甲苯与DMC烷基化反应的影响。结果显示,采用乙酸镁为前体盐,催化剂能在保持较高甲苯转化率的同时显著提高对二甲苯选择性。采用12% MgO/MCM-22为催化剂,在反应温度653 K、n(甲苯)∶n(DMC)= 4∶1,重时空速(WHSV)为1 h-1条件下,甲苯转化率为31.01%,对二甲苯选择性达55.61%。

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