Study On Epoxidation Of Cornus Wilsoniana Oil And Reaction Kinetics In Different Catalytic Systems

Epoxidized plant oil is a kind of important plastic additive which is nontoxic, heat resisting and degradable. With the rapid development of plastic industry and the growing demand for environmental-friendly plasticizers, research on the epoxidation of plant oils becomes a hot topic all over the world. Cornus wilsoniana is a species of energy tree greatly developed by our country. Cornus wilsoniana oil extracted from it is a kind of important renewable rescources, which is rich in double bond structure and is ideal for use as the raw material of epoxy plasticizer.The epoxidation process of Cornus wilsoniana oil catalyzed by a conventional method of formic acid without solvent is studied. Optimized condition is obtained by single factor experiments of reaction temperature 60℃, reaction time 3 h, H2O2/ double bond 1.2(mole ratio), formic acid/double bond 0.6. On this condition the epoxy value and iodine value of the product is 5.31% and 12.2 g/100 g respectively.A peroxo phosphotungstic catalyst is pepared with phosphoric acid, tungstic acid and cetyl pyridinium chloride and characterized by FT-IR and TG. It is used in Cornus wilsoniana oil epoxidation without carboxylic acid and effects of different reaction conditions on epoxidation are investigated. Under the conditions of reaction temperature 60℃, reaction time 4 h, H2O2/double bond 1.4(mole ratio), ethyl acetate 10 m L,catalyst 0.1 g,the epoxy value of the product is up to 5.26% and the iodine value is 12.3 g/100 g. Also, the reusability of the catalyst is studied. Results show the recovery rate is 67% and after five times repeated, the epoxy value of the product is still above 4%.A weak acid, boric acid is used instead of phosphoric acid to prepare a peroxo borotungstate catalyst and used in epoxidation of Cornus wilsoniana oil without carboxylic acid. The effect of catalyst preparation conditions on catalytic performance is studied. The catalyst shows greatest activity when tungsten acid: boric acid: methyltrioctylammonium chloride is 3:1:1(mole ratio). Under the conditions of reaction temperature 60℃, reaction time 5 h, H2O2/double bond 1.4(mole ratio), ethyl acetate 10 m L,catalyst 0.1 g,the epoxy value of the product is 4.44% and the iodine value is 31.7 g/100 g. The reactant and product are analyzed by FT-IR and nuclear magnetic. Results show that double bond of the oil has already been converted into epoxy bond.The reaction kinetics of the three catalytic systems is finally studied. Results show that the epoxidation reaction of Cornus wilsoniana oil is an endothermic reaction. Reaction activation energy of the three catalytic systems in order is formic acid(49.21±0.66 k J/mol) < peroxo phosphotungstic catalyst(54.64±0.71 k J/mol) < peroxo borotungstate catalyst(56.95±1.26 k J/mol). The properties of the products with the highest epoxy value obtained from three different catalytic systems are compared. It turns out the product from the traditional formic acid catalytic system has the highest epoxy value but shows poor thermal stability. However, the product from peroxo borotungstate catalytic system has a poor epoxy value but shows good thermal stability. It probably results from the acidity of the catalyst.