Study On The Synthesis Technology Of δ- Valerolactone By Cyclopentanone Using Aqueous Hydrogen Peroxide

δ-valerolactone is an important fine chemical intermediate and is widely used. In recent years, polyvalerolactone, the ring-opening polymerization product of δ-valerolactone, has wide applications in the field of medical materials and environmental protection in recent years, which causes the market demand of δ-valerolactone has been increasing year by year accordingly. Therefore, the development of a cleaning synthesis route which has the mild reaction conditions and is easy for industrialized production is very important. There are many ways to synthesize δ-valerolactone, of which the Baeyer-Villiger oxidation of cyclopentanone attracts more interest. With the cyclopentanone as the raw material, the synthesis technology and kinetics for the synthesis of the δ-valerolactone was studied, which has important engineering application prospect and academic significance.A variety of catalysts, such as Lewis acids, metal oxides, were firstly screened in the synthesis of δ-valerolactone with aqueous hydrogen peroxide as an oxidant. The results showed that Sn O2 and WO3 had higher catalytic activity than the other catalysts for the reaction. Then using Sn Cl4·5H2O and Na2WO4·2H2O as precursors, a series of Sn-W composite metal oxides were prepared by chemical precipitation and characterized by XRD, FTIR, BET and SEM techniques. The results showed that among all the metal oxides with different metal ratio and calcination temperature, the Sn O2/WO3 catalyst after being calcined at 600℃ with the Sn/W molar ratio of 2:1 presented an excellent performance, so the composite metal oxide Sn/W-2-600 was chosen as the catalyst in later experiments. The preparation of the catalyst was simple, and could be recovered through simple filtraction and drying, the results showed it could be reused three times.A new synthesis technology of cyclopentanone to δ-valerolactone was explored, which used the aqueous hydrogen peroxide containing 30% H2O2 as oxidant, propionic acid as solvent and the composite metal oxide Sn/W-2-600 as catalyst. Besides, the cyclohexane was used as water carrying agent and the whole device was under negative pressure conditions. The product was purified by vacuum distillation and then characterized and analysed by FTIR and 1HNMR. Through the single-factor and orthogonal designs, the synthesis technology of cyclopentanone to δ-valerolactone was optimized. The results was as follows: n(cyclopentanone)=0.025 mol, the amount of catalyst was 40%, n(H2O2):n(cyclopentanone)=1.5, n(propionic acid): n(cyclopentanone)=13.5,the reaction time was 4.5 h, the reaction vacuum degree was 0.07 MPa. And the yield of δ-valerolactone could reach 72.26%. Then upon inquiry, the catalyst can be reused three times with a little change in catalytic activity.Kinetics for the synthesis of the δ-valerolactone was studied. The results showed that the reaction was approximately belong to the first-order reaction, namely the reaction rate was related to the concentration of cyclopentanone. By fitting on the related data, the dynamic equation for this reaction was deduced as: rA=-dcA/dt=98052.66exp(-5089.21/T)cA。.