Study On Kinetics Of Synthesis Of ?-caprolactone By Catalytic Oxidation By Composite Oxide

?-Caprolactone??-CL?is a widely used organic synthetic monomer and intermediate.Due to its excellent biocompatibility,degradability and osmotic property,it has been widely used in the fields of medicine,environmental protection and fine chemical industry in recent years,with a broad market prospect.The two-step indirect oxidation of hydrogen peroxide is a hot spot in the synthesis of?-caprolactone.Our research group proposed to use composite oxide to catalyze hydrogen peroxide to oxidize acetic acid to peroxyacetic acid,and then oxidize cyclohexanone to?-caprolactone,good results were achieved.In this paper,the process and kinetics of the two-step reaction for the synthesis of caprolactone were mainly studied,and the optimum process conditions and kinetics parameters were obtained.The following contents were accomplished:?1?In this paper,the intrinsic kinetics of the synthesis of peroxyacetic acid catalyzed by MgxSnyWzO catalyst was studied.The results showed that the oxidation of acetic acid to peracetic acid catalyzed by MgxSnyWzO catalyst is the first order reaction for both hydrogen peroxide and acetic acid.The pre-exponential factor of the kinetic rate equation is 1.01714×10⁷(6.78090×10⁶·g^-1)and the activation energy is6.76141×10⁴ J·mol^-1.The reaction order of the kinetic rate equation for the side reaction of hydrogen peroxide decomposition suitable for the reaction system is1.59345,the pre-exponential factor is 1.63193×10⁸(1.08795×10⁸·g^-1),and the activation energy is 7.50441×10⁴ J·mol^-1.?2?The process conditions and kinetics of synthesis of peracetic acid were studied by using the catalyst packing prepared on the basis of MgxSnyWzO catalyst in this paper.The results showed that the yield of peracetic acid could reach 21.14%under the following conditions:reaction temperature was 60°C,n₀?water?:n?butyl acetate?=2.5:1,n?acetic acid?:n?hydrogen peroxide?=2:1,the filling quantity of catalyst packing was 12g,the circulating reaction solution flow rate was 2.0L·min^-1,w?2-methylpyridine?=0.2%,and reaction time was 6h.The pre-exponential factor of the kinetic rate equation for the oxidation of acetic acid to peracetic acid by hydrogen peroxide catalyzed by catalyst packing is 9.05647×10⁶,and the activation energy is6.81423×10⁴ J·mol^-1.The reaction kinetic rate equation applicable to the side reaction of hydrogen peroxide decomposition of the reaction system has a reaction order of1.59193 for hydrogen peroxide,a pre-exponential factor of 1.70166×10⁸,and a reaction activation energy of 7.60111×10⁴ J·mol^-1.?3?The process conditions and kinetics of the oxidation of cyclohexanone to?-caprolactone by peroxyacetic acid with catalyst packing were also investigated in this paper.The results showed that the yield of?-caprolactone could reached 78.98%when reaction temperature was 65°C,n?peracetic acid?:n?cyclohexanone?=1:1.5,the filling quantity of catalyst packing was 12g,and reaction time was 2h.The reaction of the oxidation of cyclohexanone to?-caprolactone by peracetic acid with catalyst packing is a second-order reversible process.The pre-exponential factor of the positive reaction rate equation is 8.079626×10⁴,and the activation energy is4.33437×10⁴ J·mol^-1.The pre-exponential factor of the inverse reaction rate equation is 8.52612×10⁷,and the activation energy is 7.13752×10⁴ J·mol^-1.