SO_4^(2-)/SiO_2-ZrO_2复合固体超强酸催化α-蒎烯水合反应

Study of Catalytic Hydration of α -Pinene on SO_4^(2-)/SiO_2-ZrO_2 Composite Solid Super Acid

以硫酸锆和硅胶为主要原料在水热条件下合成了SiO2 ZrO2复合体,晶化温度150℃,晶化时间24h。用c(H2SO4)=0 25mol/L水溶液处理焙烧过的SiO2 ZrO2复合体,经焙烧后制得SO2-4/SiO2 ZrO2复合固体超强酸。用FTIR、XRD、BET及NH3-TPD等技术表征了其结构。结果表明,该催化剂存在超强酸中心,比表面积高达203 7m2/g,孔径为16 6nm,孔容为0 8cm3/g,但不具有中孔分子筛的特征结构。将SO2-4/SiO2 ZrO2复合固体超强酸用于催化α 蒎烯水合反应,α 蒎烯的转化率接近100%,对α 松油醇的选择性达50%;该催化剂重复使用5次后,α 蒎烯的转化率由开始的100%变为83 5%,对α 松油醇的选择性仍为50%,表明该催化剂具有良好的重复使用性能。

SiO_2-ZrO_2 composite was synthesized using Zr(SO_4)_2 and silica gel as starting materials in hydrothermal system at crystallization temperature of 150 ℃ for 24 h.Composite super acid SO^(2-)_4/SiO_2-ZrO_2 was prepared by infusing the calcined SiO_2-ZrO_2 with 0.25 mol/L H_2SO_4 and calcinating again.The structure of SO^(2-)_4/SiO_2-ZrO_2 was characterized by FTIR,XRD,BET and NH_3-TPD.It is shown that the obtained SO^(2-)_4/SiO_2-ZrO_2 has super acid sites,high specific surface area and large pore size,yet does not have the structural characteristics of mesoporous molecular sieves.Using SO^(2-)_4/SiO_2-ZrO_2 to catalyze the hydration of α -pinene,the conversion is almost 100% and the selectivity for α -terpineol is 50%.Moreover,the composite catalyst is of good reusability.