Study On The Integrated Process Of H₂O₂ Production From Hydrogen And Oxygen And Epoxidation Of Allyl Chloride

Epichlorohydrin(ECH) is an important chemical material and intermediate. Inpresent, the production techniques of ECH have some distinct disadvantages, such assevere pollution, high cost and high-energy consumption. The process of epoxidationof low olefins with H2O2 catalyzed by TS-1 has the advantages of high selectivity andno pollution. Because of the relatively high cost of H2O2 and the transportation andstorage of hydrogen peroxide, this process has not been commercialized up to date. Inorder to overcome the economic obstacle, the integration of the production ofhydrogen peroxide and the epoxidation of olefins is the research orientation of olefinepoxidation. Based on this, the integrated process of production of hydrogen peroxideand epoxidation of allyl chloride has been studied in this thesis.The effects of different solvent, temperature and concentration of hydrogenperoxide on epoxidation of allyl chloride with H2O2 using TS-1 were investigated.Under the room temperature and low concentration of hydrogen peroxide, relativelyhigh yield of ECH was still obtained. Methanol is the optimal solvent for theepoxidation of allyl chloride.Based on above experimental results, the dual-functional catalysts were preparedby taking Pd and Au as the active components for producing hydrogen peroxide fromhydrogen and oxygen and TS-1 as the active component for epoxidation of allylchloride. The effects of preparation methods of catalysts, Pd precursors, reductioncondition, metal loading and Pt supporter on the catalytic performance wereinvestigated. The results indicated that the catalysts made by DP method, usingpalladium chloride as Pd precursor and reduced by 5%H2/95%N2 under 150℃ hasexcellent catalytic performance. The metal loading of 1 wt% for Pd and 2 wt% for Auis optimum. The addition of Pt to Pd/TS-1 catalyst could remarkably improve thecatalytic performance. The optimal loading of Pt is 0.01 wt%~0.02 wt%. The resultsof XPS, TPD-TPR, and TEM indicated that the dispersion and Binding Energy (BE)of palladium supported on TS-1 had been improved by introducing small amount ofPt, and the catalytic performance has been dramatically improved. In view of theabove experimental results, the 0.01%Pt-1%Pd/TS-1 is the optimal catalyst for theprocess integration in our work. The integrated process of producing hydrogenperoxide from hydrogen and oxygen and producing ECH by epoxidation of allylchloride has been studied over the 0.01%Pt-1%Pd/TS-1. The effects of differentsolvent, reaction time, catalyst concentration and initial concentration of allyl chloridewere investigated and the optimal experimental condition were the methanol solutioncontaining 30 percent of water as solvent, 4h, 15g/L and the initial molar ratio of allylchloride to methanol at 0.15:1. Under these conditions, the yield and selectivity ofECH were 0.6% and 0.7%, respectively.Finally, the effects of preparation method and addition of Pt supporter onepoxidation reaction of allyl chloride with H2O2 over Pd/TS-1 catalyst wereinvestigated. The experimental results indicated that the noble metal has a dramaticimprovement to the decomposition of hydrogen peroxide. The addition of Ptsupporter could improve the epoxidation of allyl chloride. The results of XRD andFTIR of dual-function catalyst indicated that the crystal phase structure of TS-1 hadbeen damaged to some extend and the crystallinity of TS-1 decreased, and Ti leachingoccurred in the course of catalyst preparation. These parameters are the main causesto decrease the epoxidation activity of TS-1 catalysts.