Study On Catalysts For Epoxidation Of Cyclohexene To 1,2-Epoxycyclohexane

Olefin epoxidation reaction is an important way for the synthesis of epoxy compound.The structurs of epoxides contain more active epoxy groups,epoxides can generate a series of chemical compound by selective ring-opening.Epoxides are widely used in the chemical production process of petrochemical,medicine,pharmaceutical and perfume.With the improvement of people's awareness of environmental protection and the increasing popularization of green chemistry concept,molecular oxygen as a green oxidant has become the research focus of olefin epoxidation in recent years.In this paper,the catalytic performances of different catalysts for cyclohexene epoxidation with oxygen were investigated.Concretely,the following contents were researched in this paper:?1?Co₃O₄/SiO₂ catalyst was synthesized by deposition precipitation method and characterized by XRD and TEM.The catalyst was used in the epoxidation of cyclohexene.The catalytic system uses DMF as solvent and oxygen as oxygen source.Effect of cobalt loading,reaction time,reaction temperature and oxygen pressure on the catalytic results were investigated by signal factor test.The conversion of cyclohexene and the selectivity reached66.5%and 71.03%under the experimental conditions of 0.20 g 3%Co₃O₄/SiO₂,cyclohexene20 ml,50^oC and 4 Mpa.Besides,the effects of different synthetic method?ion exchange method,volume impregnation method?and doped bimetal on catalytic performance of catalysts were investigated.Results show that the performance of catalyst prepared by deposition precipitation method was better than others.?2?LaCoO₃ perovskite-type oxide catalysts were synthesized by co-precipitation method.The influence of various factors in preparation process on the perovskite-type oxide structrures and performance were studied,such as pH,calcination temperature,calcination time,precipitation temperature and AB doping with other metal ions.Results show that there is a great influence in the performance of cyclohexene molecular oxygen epoxidation under different prepared catalysts.LaCoO₃ perovskite-type oxide catalyst was found to be efficient catalyst under the preparation condition of pH=8,precipitated temperatures room temperature,calcination temperature 700^oC,calcination time 4 h.The conversion of cyclohexene and the selectivity reached 64.91%and 68.57%.?3?LaCoO₃ perovskite-type oxide catalysts were synthesized by sol-gel method.The influence of various factors in preparation process on the perovskite-type oxide structrures and performance were studied,such as pH,calcination temperature,calcination time,temperature of forming sol-gel,quantity of citric acid.The catalyst was used in the epoxidation of cyclohexene.LaCoO₃ perovskite-type oxide catalyst was found to be efficient catalyst under the preparation condition of pH=2,citric acid/(La³⁺+Co²⁺)=1.2:1?amount of substance ratio?,temperature of forming sol-gel 80^oC,calcination temperature 600^oC,calcination time 4 h.The conversion of cyclohexene and the selectivity reached 62.89%and63.00%.