Research On The Production Of1,3,5-trimethylbenzene By The Isomerization Of1,2,4-trimethylbenzene

The production of1,3,5-trimethylbenzene by the isomerization of1,2,4-trimethylbenzene was studied in this paper. In the experiment, the commercialhydrogen mordenite (HM) was used as the catalyst support. Ni/Mo and Ni/La wereused as metal components in retarding the coke formation. Catalysts Ni-Mo/HM andNi-La/HM were prepared by the incipient impregnation method. The synthesis werecarried out in the pressurized fixed-bed reactor.Firstly, the effects of Mo contents, reaction temperature, pressure, weight hourlyspace velocity (WHSV), hydrogen-oil ratio and the catalyst life on the isomerizationof1,2,4-trimethylbenzene over catalyst Ni-Mo/HM were studied. The results showedthat the Mo content is1.25%is the best condition for the isomerization of1,2,4-trimethylbenzene. And the optimal reaction conditions were obtained, whichwere the reaction temperature260℃~270℃, pressure1.2MPa~1.4MPa, WHSV0.9h-1~1.1h-1, and hydrogen-oil ratio5~6. Under the conditions of reactiontemperature260℃, reaction pressure1.2MPa, WHSV1.0h-1and hydrogen-oil ratio5, the Ni-Mo/HM catalyst had been reacted for200h, the catalyst kept good activityand stability and no catalyst deactivation sign had been found.Secondly, analytic technique, such as XRD and Py-FTIR, was used tocharacterize the structure and acidity of catalysts Ni-La/HM. Ctalytic performationof catalysts C1, C2, C3, C4and C5with La loading0,0.63%,1.25%,1.88%and2.50%respectively, were evaluated by the isomerization of1,2,4-trimethylbenzene atdifferent temperatures. The results showed that under the conditions of reactiontemperature240℃, reaction pressure1.2MPa, WHSV1.0h-1and hydrogen-oil ratio5, the Ni-La/HM catalyst had the best catalytic activity.The metal-loaded HM including catalyst Ni-Mo/HM and Ni-La/HM bothpossessed excellent catalytic activity and selectivity. The stability of them are betterthan the pure HM zeolite and the life of the catalysts was greately extended.