Regioselective Nitration of Toluene with Nitric Acid in the Presence of Solid Super Strong Acid ZrO_2-TiO_2/SO_4~(2-) Catalysts

The solid super strong acid catalysts of ZrO_2/SO_4~(2-) and TiO_2/SO_4~(2-)and a series of ZrO_2-TiO_2/SO_4~(2-) with different atom ratios of Zr/Ti were prepared.The optimum conditions of preparing the catalysts were investigated.The effect of all kinds of factors,just like different atom ratios of Zr/Ti of catalysts,calcinations temperature of catalysts,nitrated reaction time,nitrated reaction temperature and recovered catalyst,etc.on the regioselectivities of toluene in mononitration with these catalysts was researched by gas chromatography(GC).The results show that,when the nitrated reaction temperature was controlled at 40℃,and the nitrated reaction time is 60min,nitration of toluene by using 65% nitric acid as nitrating reagent in the presence of acetic anhydride,ZrO_2-TiO_2/SO_4~(2-)(atom ratio of Zr/Ti 1∶1) solid super strong acid catalyst calcinated at 500℃ for 3h,show high regioselectivity,up to ortho-paro isomer ratio of 0.90 in product distribution of toluene nitration,greatly below 1.67 as sulfonitric acid as catalyst,and gave a yield of 92.9%.The catalyst could be reutilized up to five times with little decrease in activity and is a clean nitrated reaction catalyst which has vast prospects.