Study On The Transalkylation Of Diethylbenzene With Benzene

The effects of catalyst acidity and reaction conditions on the liquid-phase transalkylation of benzene with diethylbenzene (DEB) were studied in a small fixed bed reactor. The activity, stability and regeneration performance of the catalysts on the gas-liquid phase transalkylation was investigated in this paper. The charactered ammonia temperature-programmed desorption (NH3-TPD), nitrogen physical adsorption and pyridine-adsorption infrared spectroscopy (Py-IR) technologies were used to character the catalysts. The following results were obtained:(1) The liquid-phase transalkylation of benzene with diethylbenzene (DEB) were occurred on the weak acid of catalyst, the weaker acid and greater specific surface area of catalyst, the better catalytic activity. The order of catalytic activity of was DLEB-4>MCM-22>ITQ-2. Hydrothermal treatment and Cl and F halogen elements mdified could lead to decrease of weak acid content. The catalytic activity of the catalyst was disappeared when hydrothermal temperature higher than 550℃and the reductiong of weak acid content and catalytic activity modified by F halogen elements were weaker than that of Cl.(2) The optimized reaction conditions of the liquid-phase transalkylation of benzene with DEB were:the temperature,260～270℃; the pressure,3.0MPa; the WHSV,4～6 h-1 and the molar ratio of benzene to DEB,4～6; the conversion of DEB, ethylbenzene selectivity and yield of ethylbenzene were 65%,94% and19%, respectively. Benzene and DEB was liquid-gas diphasic phase at 280℃and 3.0MPa, the conversion rate of DEB, ethylbenzene selectivity and yield of ethylbenzene were 75.3%,92.3% and 23.6%, respectively, was gained under such phase.(3)The comparison of DLEB-4 and DLEB-1 industrial catalysts was studied; the conversion of DEB and yield of ethylbenzene was higher than that of the latter under the optimized reaction conditions, respectively. Ethylbenzene selectivity of DLEB-4 was the same as that of DLEB-1 catalyst, the catalytic activity of regenerated catalyst was the same as that of fresh catalyst, and therefore the DLEB-4 zeolite had well regeneration performance and was an excellent catalyst for industrial application.