Synthesis, Characterization And Catalytic Activity Of Polyoxometalates On MCM-48 Molecular Sieve

In this paper,the Keggin unit polyoxometalate phosphotungstic acid(H₃PW₁₂O₄₀), silicotungstic acid(H₄SiW₁₂O₄₀),H₃PW₁₂O₄₀/MCM-48,H₄SiW₁₂O₄₀/MCM-48 were prepared,and they were characterized by IR and XRD.Both of H₃PW₁₂O₄₀and H₃PW₁₂O₄₀/MCM-48 were used as the photocatalysts to degradate the methyl orange solution under irradiated by visible light.It has been shown that the photocatalyst dosage, the initital concentration of methyl orange,intensity and time under irradiated by visible light are the important factors of decolorizing.With methacrylic acid and n-butyl alcohol as material,the synthesis of n-butyl methacrylate catalyzed by H₃PW₁₂O₄₀/MCM-48 was studied.And effects of the rate of material,catalyst dosage and reaction time on yields of the products were investigated too.Experimental results showed that H₃PW₁₂O₄₀/MCM-48 is an excellent catalyst.In addition,H₄SiW₁₂O₄₀/MCM-48 as an environmental friendly catalysts,the catalytic activities of H₄SiW₁₂O₄₀/MCM-48 in synthesizing 2-methyl-2-ethoxycarbonylmethyl-1, 3-dioxolane,2,4-dimethyl-2-ethoxycarbonyl-methyl-1,3-dioxolane, cyclohexanone ethylene ketal,cyclohexanone 1,2-propanediol ketal, butanoneethylene ketal,butanonel,2-propanediolketal,2-phenyl- 1,3-dioxolane, 4-methyl-2-phenyl-1,3-dioxolane,2-propyl-1,3-dioxolane and 4-methyl-2-propyl-1, 3-dioxolane were reported,while butanone 1,2-propanediol ketal was synthesized from butanone and 1,2-propanediol in the presence of H₄SiW₁₂O₄₀/MCM-48. The factors influencing the synthesis were discussed and the optimum conditions were found out.The experimental results showed that H₄SiW₁₂O₄₀/MCM-48 is an excellent catalyst.