Synthesis, Characterization And Catalytic Activity Of Polyoxometalates

In this paper, the Keggin unit polyoxometalate phosphotungstic acid (H₃PW₁₂O₄₀) and Titania supported the phosphotungstic acid, H₃PW₁₂O₄₀/TiO₂ were prepared, and they were characterized by IR and XRD. Both of them were used as the photocatalysts to degradate the methyl orange solution under irradiated by sun. It has been shown that the photocatalyst dosage, the initital concentration of methyl orange, intensity and time under irradiated by sun are the important factors of decolorizing.In addition, the titanium dioxide which prepared by sol-gel method was used as the photocatalyst to degradate the rhodamine solution under irradiated by sun.Besides, two new environmental friendly catalysts, H₃PW₁₂O₄₀ / MCM-48 and H₄SiW₆Mo₆O₄₀/ PAn were prepared. The catalytic activities of H₃PW₁₂O₄₀/ 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, butanone1,2-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 H₄SiW₆Mo₆O₄₀/PAn. The factors influencing the synthesis were discussed and the optimum conditions were found out. Experimental results showed that both H₃PW₁₂O₄₀/MCM-48 and H₄SiW₆Mo₆O₄₀/PAn are excellent catalysts.