Optimization Of The Synthesis Of Epsilon-caprolactone By Catalytic Oxidation Of Cyclohexanone

In recent years,the epsilon-caprolactone(epsilon-caprolactone,?-CL)as an important intermediate in organic chemical reactions,mainly used to manufacture many products with good chemical properties.self polymerization of polycaprolactone or copolymerization or blending with starch esters,etc.,these products have good chemical and biological properties,such as biocompatibility,biodegradability,excellent memory.in addition,they are non-toxic and have good permeability,these good properties have important applications in medicine,environmental protection,materials and life,so the synthesis research of monomer ?-caprolactone has become more and more important.In this paper,W/Sn/Mg composite metal oxides was used as the catalyst,which was prepared previously by the research group,the problems in the synthesis process of ?-caprolactone were studied.the main contents of research are as follows:(1)optimizing the synthesis of ?-caprolactone.combined the single factor experiment and the orthogonal experiment,researched the effects of different factors on the water content and the yield of the product peracetic acid in the first step of the reaction to improve the yield and reduce the water content;optimizing the synthesis of ?-caprolactone by oxidation of cyclohexanone to improve the yield of ?-caprolactone;(2)the reasons of the catalyst deactivation were studied and analyzed to find out the regeneration scheme of the catalyst;the single factor experiments were carried out to determine the regeneration conditions of deactivated catalysts.The result indicated:(1)when the dosage of the W/Sn/Mg composite oxide catalyst was 1.5g,the ratio of reactants n(hydrogen peroxide): n(acetic acid)was 0.5:1,the dosage of the dehydrating butyl acetate was 100 g,the reaction time was 10 h,the yield of peracetic acid in the first step can reach 33.83%,and the water content can be reduced to about 3%.(2)when the reaction temperature was 70? and the ratio of the cyclohexanone and the hydrogen peroxide was 1:1,at this time,the yield of the ?-caprolactone can reach 29.85%.(3)Through the characterization and analysis of deactivated catalyst the reasons why the catalyst was deactivated are as follows: the adsorption of organic matter on the surface of the catalyst,which reduces the pore size of the catalyst;the loss of the active component tungsten,and the covered of the active centers.(4)the effective regeneration process of the deactivated catalyst was that: firstly,washing the catalyst with ethanol under the condition of ultrasound,filtration and drying,then impregnated the deactivated catalyst with the solution of ammonium tungstate under the condition of ultrasound,to promote the process of the impregnation,lastly,filtration,drying and calcinate.(5)the optimum conditions of the regeneration of deactivated catalyst is that: the quality ratio of the deactivated catalyst and the detergent alcohol was 1:3.5,the ultrasonic washing time was 30 min,under the condition of ultrasound,the concentration of the ammonium tungstate solution was 0.60g/mol,impregnation time was 2.5h,calcination temperature was 400?,calcination time is 3h;then crushing the catalyst after they were calcined,and lastly impregnating,filtrating,drying and calcination for one more time according to the conditions before.And in that condition,the yield of epsilon-caprolactone can be restored to 25.94%.