过渡金属改性对MgO/ZSM-5催化剂苯-甲醇烷基化性能的影响

采用过渡金属对2.5%Mg O/ZSM-5催化剂进行负载改性,考察其苯-甲醇烷基化性能,结果表明,Ni和Fe改性催化剂因改性后弱酸量大幅增加,苯转化率提高,分别为56.6%和55.8%;W和Mn改性催化剂二甲苯选择性较高,约为35%;与其他改性催化剂相比,Co和Mo改性催化剂上的苯转化率和二甲苯选择性没有明显优势。选择改性效果较好的双金属催化剂进行苯-甲醇烷基化高空速(15 h-1)长时间运转实验,催化剂初始活性均大于57%,反应20 h时,苯转化率约50%,20 h后烷基化活性迅速下降,是由于催化剂积炭失活所致。

Effects of transition metal modification on alkylation of benzene with methanol over MgO/ZSM-5 catalyst

Alkylation performance of benzene with methanol on 2.5%MgO/ZSM-5 catalyst modified by transition metal was investigated.The results showed that benzene conversion increased to 56.6% and 55.8% respectively on catalysts modified by Ni and Fe,due to significant increase of weak acid content after modification.The catalysts had a higher selectivity to xylene about 35% when W,Mn were loaded.For Co,Mo modified catalysts,alkylation reaction activity and selectivity to xylene were not significantly superior to other modified catalysts.Long-term operation experiment was carried out over preferred bimetal catalysts for benzene-methanol alkylation under high liquid hourly space velocity(15 h^-1).It was showed that the initial catalytic activity was over 57%,benzene conversion was approximately 50% at 20 h,then the alkylation activity decreased rapidly because of coke deposition.