Research On Durene Synthesis Technology And Its Catalyst

HZSM-5 was prepared by ion-exchanging with hydrochloric acid under certain conditions and modified with NH₄F, Ce(NO₃)₃, KNO₃, Mg(NO₃)₂, Ca(NO₃)₂. The alkylation of 1,2,4-trimethylbenzene with methanol to synthesize durene was studied by gas-solid phase fixed bed reactor with modified HZSM-5, and the catalytic effects of modified solutions density, Si/Al ratio of the catalysts, calcination temperatures, reaction temperatures, methanol/1,2,4–trimethyl-benzen e ratio, flow rate of carrier gas and the conditions of ion-exchanging were investigated. The catalysts were characterized on isotherms, pore volume and pore size with Micromeritics ASAP 2020M.The results show that: the catalyst modified with NH₄F was better than those treated with Ce(NO₃)₃ and KNO3, and the optimal concentration of NH4F solution was 15wt%. The catalyst modified with 15wt% Mg(NO₃)₂ was better than the catalysts modified with 15wt% Ca(NO3)2 or 15wt% NH4F. The best ion- exchanging condition was taken at 80℃, 60 mins per treatment for three times.High calcination temperature will lead to high selectivity of durene, but low conversion of 1,2,4-trimethylbenzene, and it was observed that the optimal calcination temperature was 500℃. The results of experiment exhibited that 38 Si/Al ratio could promote the reaction with optimal reaction temperature of 350℃, carrier gas flow rates of 25ml/min, methanol/1,2,4-tri methylbenzene ratio of 2.