MgO/MCM-22催化苯与草酸二乙酯烷基化合成乙苯的研究

实验以MgO/MCM-22为催化剂,在气相连续流动固定床反应器上催化苯与草酸二乙酯(DEO)烷基化,合成乙苯(EB)。考察了MgO负载量变化和工艺条件的影响。以硝酸镁为前驱体通过等体积浸渍法制备了MgO/MCM-22催化剂,并以低温N_2吸附脱附、X射线衍射、NH_3-TPD、吡啶吸附IR等,对催化剂进行了表征。实验结果表明:随MgO负载量的增加,苯的转化率逐渐下降,而乙苯的选择性明显提高,这主要是由于负载MgO后催化剂的酸性位数量下降引起的。以MCM-22为催化剂,在最佳反应条件下:温度653 K,空速为2 h~(-1),原料配比n(苯):n(DEO)=4:1,苯的转化率为37.5%,乙苯选择性为80.3%。

SELECTIVE SYNTHESIS OF ETHYLBENZENE BY THE ALKYLATION OF BENZENE WITH DIETHYL OXALATE OVER MgO-MODIFIED MCM-22

Selective synthesis of ethylbenzene by the alkylation of benzene with diethyl oxalate (DEO) was carried out in a continuous flow fixed-bed reactor over MgO-modified MCM-22 catalysts prepared through impregnating magnesium nitrate on MCM-22. The effects of MgO loadings and reaction conditions were investigated. The physicochemical properties of MgO/MCM-22 catalysts were characterized by XRD, N_2 adsorption-desorption, NH_3-TPD and pyridine-IR. The results indicated that with increasing MgO loadings, a sharp decrease in benzene conversion was detected, but the selectivity for ethylbenzene was appreciably improved, which can be ascribed to the reduction of the acid sites on the catalyst after MgO modification. Under the optimal conditions: reaction temperature 653 K, n(benzene) : n(DEO) = 4 : 1, WHSV= 2 h~(-1), the conversion of benzene and the selectivity to ethylbenzene were 37.5% and 80.3%, respectively.