固体超强酸ZrO_2-TiO_2/SO_4^(2-)催化下甲苯的区域选择性硝化

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

制备了Z rO2/SO42-、T iO2/SO42-和一系列不同Z r/T i原子数比的Z rO2-T iO2/SO42-固体超强酸催化剂。通过气相色谱研究了诸如催化剂的Z r/T i原子数比、催化剂的焙烧温度、硝化反应时间、硝化反应温度及催化剂的重复使用等因素对甲苯硝酸硝化区域选择性的影响。结果表明,在醋酐存在条件下,以硝酸(质量分数为65%)为硝化剂,反应温度控制在40℃,反应进行60m in,经500℃焙烧3 h后的Z rO2-T iO2/SO42-(Z r/T i原子数比为1∶1)固体超强酸催化剂,对甲苯表现出了强的区域选择性,甲苯硝化产物邻对位比达0.90,较硝硫混酸的1.67显著降低,产物得率达到92.9%。该催化剂可循环使用5次,催化活性基本不变,是一种具有应用前景的绿色硝化反应催化剂。

The solid super strong acid catalysts of ZrOz/SO4^2- and TiO2/SO4^2 and a series of ZrO2^-TiO2/SO4^2- 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, ZrO2^-TiO2/SO4^2- （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.