甲苯甲醇烷基化制对二甲苯催化剂中试反应性能研究

经过多步改性制备了负载二氧化硅（SiO₂）、氧化镁（MgO）、五氧化二磷（P₂O₅）、贵金属铂（Pt）的纳米ZSM-5分子筛催化剂,并在六段固定床反应器上分段装填该催化剂720 g进行甲苯、甲醇烷基化制对二甲苯反应活性评价。实验结果表明,通过调变甲醇和甲苯物质的量比可以使甲苯转化率在22%~30%可调,烷基化液相产物中二甲苯选择性保持在95%以上,二甲苯中对二甲苯选择性保持在95%以上;催化剂单程寿命达到1 300 h,随着反应时间延长催化剂的活性有所下降。通过X射线衍射（XRD）、热重分析（TG-DTG）和氮气吸附-脱附等手段对参加反应前后的催化剂进行了表征,结果表明反应中生成的积炭堵塞了分子筛的孔道或覆盖了催化剂的活性位;经过在反应器内原位再生,催化剂的反应活性基本恢复到新鲜催化剂水平。

Study on pilot catalytic performance of the modified catalyst for alkylation of toluene with methanol to p-xylene

A composite-modified nano ZSM-5 zeolite catalyst was prepared through multi-step impregnation with the precursor of SiO₂,MgO,P₂O₅and Pt.The catalytic performance for alkylation of toluene with methanol was investigated in a six-stage fixed bed reactor,which is filled with more than 720 g of the catalyst.The result shows that the conversion rate of toluene was controllably adjusted in the range of 22%~30%by adjusting the amount-of-substance ratio of toluene to methanol,as well as the selectivity to xylene in liquid products of alkylation and selectivity to p-xylene in xylene(o-xylene,m-xylene and p-xylene)both simultaneously stabilized above 95%.The life of the catalyst reaches 1300 h in alkylation reaction and the catalytic activity decreased after 1200 h.The fresh and deactivated catalysts were characterized by XRD,TG-DTG and N2 adsorptiondesorption.It is indicated that the generated coke blocked the pores of ZSM-5 zeolite or deposited on the active sites of catalyst,leading to the catalytic deactivation.The catalytic activity of deactivated catalyst almost can be restored after in-situ regeneration.