Catalytic Oxidation Of Terpenes To Carvone

Carvone is one of the main component of plant essential oils, which is widely used in food industry and chemical industry, in particular, is for candy, toothpaste, and beverages. What's more, it is also commonly used as an effective solvent in the industry. Early, carvone was obtained by natural extracts, but this method obtained very small amount of carvone with high price, and was easily influenced by the natural environment. So, natural carvone can't satisfy the market demand so far. Now, carvone industrial production has become a major research focus. Traditional industrial production methods include epoxidation method, nitrosylation methods etc. have problems of heavy pollution and high cost. That is why a high efficient, economical and environmental production methods is imperative.According to the research at home and abroad, the cheap limonene was chosen as materials to synthesis carvone.This paper is expected to synthesize suitable catalyst and develop an inexpensive, environment friendly and high-quality method, meanwhile, provide a reliable basis for the industrial production.In this paper, three kinds of catalytic systems have been chosen among the whole catalytic systems, the VPO catalysts, the immobilized salen catalysts and the modified PAL catalysts. Catalysts modified by different kinds of metal were prepared by impregnation method and deposition-precipitation method. All catalysts were investigated by the oxidation of limonene to carvone, in the end, optimal catalysts and experimental conditions were obtained. The morphology and physicochemical properties of catalysts were characterized by XRD, TEM, SEM, BET, FT-IR and TG-DSC. The main contents and results are summarized as following.(1) The optimal catalyst in VPO system is B-VPO (P/V=1, B/P=0.1), and the appropriate expermental condition is:0.05 g catalyst,5 mL acetonitrile as solvent,2 mL TBHP as oxidizer, reaction temperature at 82? and reaction time for 10 h. Under this condition, the conversion of limonene reaches 88.9% and the selectivity of carvone is 24.4%.(2) The optimal catalyst in immobilized salen system is B-salen-NH2-MCM-41 synthesised by impregnating 12 h under N2 atmosphere at room temperature, and the appropriate expermental condition is:0.03 g catalyst,5 mL acetonitrile as solvent,2 mL TBHP as oxidizer, reaction temperature at 82? and reaction time for 10 h. Under this condition, the conversion of limonene reaches 96.1% and the selectivity of carvone is 28.2%.(3) The optimal catalyst in PAL system is B-PAL (5%,300), and the appropriate expermental condition is:0.03 g catalyst,5 mL acetonitrile as solvent,2 mL TBHP as oxidizer, reaction temperature at 82? and reaction time for 24 h. Under this condition, the conversion of limonene reaches 88.7% and the selectivity of carvone is 41%.