Modification Of IM-5and ZSM-5Zeolites For Toluene Alkylation With Methanol

P-xylene is an important organic chemical raw material, mainly for theproduction of terephthalic acid (PTA) and dimethyl terephthalate (DMT). Thetraditional way of producing P-xylene has been challenged. Starting from the non-oilroute to produce P-xylene by using relative excess toluene and methanol whichderived from coal chemical industry as material is a very worthful process route.In this paper, a series of modified ZSM-5and IM-5catalysts were prepared bytraditional impregnation method and complexation-impregnation method. Theircatalytic properties were investigated for the alkylation of toluene with methanol. Theinfluence of the pore structure and surface acidity on the shape-selectivity of thecatalysts was discussed.Research has shown that HZSM-5modified magnesium in two steps, which cangreatly improve the selectivity of P-xylene. Under the optimized reaction conditionsof435℃, toluene/methanol=2(molar ratio), WHSV=4h-1(toluene and methanol asfeed), H2as the carrier gas, the toluene conversion (Cont) was22.4%and theselectivity of P-xylene (SPX) kept at96%. And the properties of the regeneration ofthis catalyst was favorable.IM-5zeolite catalyst for the reaction showed high catalytic activity, but lowxylene selectivity (24.1%). The modified IM-5zeolites catalysts toluene conversionrate decreased, P-xylene selectivity is somewhat elevated. Among them, after steamtreatment of IM-5zeolite as the carrier prepared SiO2-st-HIM-5catalyst exhibitsgood catalytic properties of the catalyst p-xylene selectivity of55.2%.NH3-TPD characterizations showed oxide modified molecular sieve could coverthe surface acid centers, which improved the selectivity of p-xylene. From the aboveresults it can be found IM-5and modified IM-5zeolite catalysts have good catalyticperformance in the alkylation of toluene with methanol.