摘要
采用溶胶凝胶法制备了固体超强酸SO_4^(2-)/TiO_2-SiO_2催化剂,用XRD,XPS和NH_3-TPD对其结构进行表征与分析,结果表明:该催化剂为非晶态结构,具有超强酸位。以α-蒎烯,草酸的酯化皂化反应为探针,首先研究了Ti/Si摩尔比、硫酸浸渍浓度对SO_4^(2-)/TiO_2-SiO_2催化性能的影响,得到适宜的SO_4^(2-)/TiO_2-SiO_2催化剂制备条件为:Ti/Si摩尔比1∶3,硫酸浸渍浓度1.5 mol/L。以适宜条件下制备的SO_4^(2-)/TiO_2-SiO_2为催化剂,研究了工艺条件对合成龙脑的反应的影响,得到适宜的工艺条件为反应时间7 h,反应温度75℃,催化剂用量为α-蒎烯的6%,n(α-蒎烯)∶n(草酸)=1∶0.4。在此条件下,α-蒎烯的转化率达到100%,龙脑的收率可达58.14%。该催化剂重复使用5次后,催化活性无明显下降。SO_4^(2-)/TiO_2-SiO_2固体超强酸显示出良好的催化活性和稳定性。
Solid superacid SO4^2-/TiO2-SiO2 catalyst was prepared by sol-gel. The SO4^2-/TiO2-SiO2 catalysts were characterized by XRD, XPS and NH3-TPD. The results showed that the catalyst was amorphous and had superacid site. The esterification-sapnifications reactions of α-pinene with oxalic acid were used as probe reactions to investigate the catalytic performance. Firstly, the influence of the molar ratio of Ti to Si and impregnation concentration on catalytic activity was studied. The results showed that the catalytic activity of SO4^2 -/TiO2 -SiO2 prepared by molar ratio of Ti to Si （ 1 ： 3 ） and impregnation concentration （ 1.5 mol/L） was better. The influence of reaction conditions on synthesis of borneol was studied using the SO4^2 -/TiO2 -SiO2 catalyst. The suitable reaction conditions were obtained as follows： reaction time 7 h, reaction temperature 75 ℃ , the dosage of level of catalyst 6% , molar ratio of α-pinene to oxalic acid 1 ： 0.4. Under the above conditions, the conversion of α-pinene was 100% and the yield of borneol was 58. 14%.SO4^2 -/TiO2 -SiO2 solid superacid could be reused for 5 recycles without losing its activity significantly, and which indicated that the SO4^2 -/TiO2 -SiO2 solid acid catalyst exhibited great stability.
出处
《化学工程》
CAS
CSCD
北大核心
2017年第11期7-11,28,共6页
Chemical Engineering(China)
基金
国家自然科学基金资助项目(U1202265)
