Study Of Synthesis And Evaluation Of The Ceramic Loaded Mg/Sn/W Composite Oxide Catalyst

?-Caprolactone,which is a chemical intermediate and polyester monomer with excellent properties,is mainly used to blend with other organic compounds for modification.Polycaprolactone has excellent biocompatibility,medicinal properties and good degradability,and has broad prospects in the field of medical treatment and environmental protection.The process for synthesizing?-Caprolactone using indirect oxidation method with H₂O₂ has run into the bottleneck.The intermediate peroxide is easy to decompose and the reaction cannot product continuously,which results in poor stability and low yield of product.In order to solve these problems,the continuous production of indirect oxidation process should be realized.However,at present,most of catalysts used in the indirect oxidation process are powder,which causes great resistance to the reaction fluid,at the same time,makes it difficult to realize continuous production.Cordierite honeycomb was used as the carrier this paper and monolithic Mg/Sn/W compound oxide catalyst was prepared through the slurry washcoating process.The preparation process and the synthesis process of the?-caprolactone were optimized.In addition,the catalytic mechanism of catalyst and the cause of inactivation were investigated by means of various characterizations,and the regeneration process of catalyst was determined.The results showed that:?1?The optimal parameters for catalyst slurry is:tungsten oxide content of the catalyst powder is 30%,pH of the slurry is 9,the mass fraction is 25%,and add 1%PVA and alumina sol as additives.When the catalyst load is 1.6 g,after being roasted for 3 h under 500?,monolithic Mg/Sn/W compound oxide catalyst has high mechanical strength.The activity layer is compact and uniform and the yield of?-Caprolactone reaches 54.3%.:?2?In the first step of the synthesis of?-caprolactone,when the adding amount of water-carrying is 80 g,weight ratio of n?hydrogen peroxide?:n?acetic acid?is 0.6,reaction temperature is 54?and reaction time is 6 h,the yield of peroxyacetic acid reaches 26.13%and the water content decreases to 3.1%.?3?In the second step of the synthesis of?-caprolactone,when the weight ratio of n?hydrogen peroxide?:n?cyclohexanone?is 0.6,reaction temperature is 67?and reaction time is 4 h,the conversion rate of cyclohexanone is 64.82%,the selectivity is86.69%,and the yield reaches 56.2%.?4?Through the characterization of the deactivated catalyst,it is found that organics are adsorbed on catalyst surface,the active sites were buried,and some of the active components were changed and lost are the main reasons for the inactivation of the catalysts.The regeneration process of deactivated catalyst is determined to be ultrasonic washing,roasting and active components supplying.?5?The optimal parameters for catalyst regeneration process is:catalysts are washed in ethanol solution under 50?for 20 min in ultrasonic environment,then calcined under 400?for 2 h.The catalysts are washcoated in slurry for two times and calcined under 500?for 2 h.Under the optimal conditions,the conversion rate of cyclohexanone is 62.34%,the selectivity of?-Caprolactone is 85.24%,and the yield reaches 52.7%.