Preparation Of Solid Super Acid Catalyst And Catalysis Of α-pinene Synthesis Of Borneol

Borneol is an major industrial material for the perfume and pharmaceutical industry.And borneol functions in inducing resuscitation,clearing heat,and alleviating pain,and has been mainly used to treat cardiovascular and cerebrovascular diseases.In addition,borneol also has the ability of anti-corrosion and insect repellent.It is widely used in pharmaceutical and perfume industry Borneol can be prepared by esterification-saponification of a-pinene,which is the main component of turpentine.Turpentine resources are extremely rich and low prices in China,therefore,borneol synthesized by catalyzing α-pinene has an important practical significance on the deep processing of resin.Solid super acid SO₄^2-/TiO₂-SiO₂,SO₄^2-/TiO₂-Al2O3 and SO₄^2-/TiO₂-La³⁺catalysts were prepared,and synthesis of borneol from a-pinene catalyzed by these solid superacid catalysts firstly.The following several aspects were researched:（1）Synthesis of borneol from a-pinene catalyzed by solid superacid SO₄^2-/TiO₂-SiO₂Solid super acid SO₄^2-/TiO₂-SiO₂ catalyst was prepared by sol-gel.The resulting catalysts were characterized by means of XRD,XPS,NH3-TPD,Py-IR and TEM analysis methods.The esterification-sapnifications reactions of a-pinene with oxalic acid were used as probe reactions to investigate the catalytic performance.The effects of the molar ratio of Ti to Si and impregnation concentration on catalytic properties were optimized in details,and the catalytic use of SO₄^2-/TiO₂-SiO₂ was measured as well.The experimental results show that when molar ratio of Ti to Si was 1:3,concentration of impregnation was 1.5mol/L,reaction temperature was 70 ℃,reaction time was 7h,the dosage of level of catalyst was 7%and molar ratio of a-pinene to oxalic acid was 1:0.4,α-pinene completely converted,and borneol had high selectivity by more than 56%and the SO₄^2-/TiO₂-SiO₂ solid acid maintains high activities with 100%conversion and the yield of borneol could be up to 53.60%after being used for five times,and which indicated that the SO₄^2-/TiO₂-SiO₂ solid acid catalyst exhibited great stability.（2）Preparation of SO₄^2-/TiO₂-Al2O3 soild superacid catalyst and its catalytic activity in borneol synthesisA series of sulphated TiO₂-Al2O3 mixed oxides were prepared by sol-gel and dipping process and used as catalysts in synthesis of borneol.The structure and properties of solid superacid SO₄^2-/TiO₂-Al2O3 catalysts were characterized by SEM,XPS,XRD,NH3-TPD,FT-IR.Py-IR,techniques,and relationship between the catalytic performance and the structure was explored.The optimal condition for the preparation of the catalyst was obtained as follows:n（TiO₂）:（Al2O3）=1:2,concentration of impregnation lmol/L,calcination temperature of the catalysts 500℃.Meanwhile,the effects of the dosage of level of catalyst,molar ratio of a-pinene to oxalic acid,reaction time investigated by synthesis of borneol.The results showed that the dosage of level of catalyst was 6%and molar ratio of α-pinene to oxalic acid was 1:0.4,used program temperature heating method（65℃ 1h、750C4h、90℃ 1h）,respectively.Under these conditions,solid superacid SO₄^2-/TiO₂-Al2O3 catalyst has the best the catalytic performance,α-pinene completely converted,and borneol had high selectivity by more than 58.63%.After solid superacid SO₄^2-/TiO₂-Al2O3 catalyst is reused 6 times,a-pinene completely converted,the yield of borneol decreases by 2.99%,i.e.The catalyst shows good reusability.（3）Synthesis of borneol from α-pilene catalyzed by SO₄^2-/TiO₂-La³⁺ rare-earth solid superacid.The SO₄^2-/TiO₂-La³⁺ solid superacids were prepared by impregnation method.The structure,acidity strength,acid property and morphology of catalysts were characterized by TEM,XRD,XPS,NH3-TPD,Py-IR and TG.The results showed that the catalyst SO₄^2-/TiO₂ modified with Lanthanum ion increased Bronsted acid sites obviously.The SO₄^2-/TiO₂-La³⁺ catalyst was superacid,and observed particles size lies within 50 nm.The optimum synthesis conditions were obtained as follows:calcinations temperature at 500 0C,0.998mol/L La³⁺ content,a dosage of catalyst 6%,reaction temperature at 80 ℃.reaction time 7 h,n（a-pinene）:n（oxalic acid）=1:0.4.Under these conditions,solid superacid SO₄^2-/TiO₂-La³⁺ catalyst showed the best catalytic performance.The α-pinene completely converted,and borneol exhibited high selectivity by more than 62.60%.The recycled reaction was also performed over this catalyst,revealing a good stability.