Heteropoly Acid (salt) Supported Heteropoly Acid Catalyst Preparation, Characterization And Catalytic Oxidation Of Thiophene Research

More regorous emission standards of sulful of fuel oil were issuing and implementation that bring more challenge to the hydrodesulfurization . Heteropolyacids are attracting more studys for their unique acidity and oxidation performance. Much attention are been paid on the way of oxidation desulfurization that using heteropolyacids as catalysts. In this paper,the activity of heteropolyacids and their cesium salts for oxidation desulfurization using H₂O₂ as oxidant in the mild condition.The composition, structure and acidity of these catalysts were characterized using various techniques.The main results are summarized as follows:Vanadium-substituted herteropolymolybdates and H₃PW₁₂O₄₀/support were prepared. Oxidative desulfurization activity of thiophene using H₃PW₁₂O₄₀,H₃PMo₁₂O₄₀,H₄PVMo₁₁O₄₀,H₅PV₂Mo₁₀O₄₀,H₆PV₃Mo₉O₄₀,H₄SiW₁₂O₄₀ and HPW12O40/supported as catalysts,H₂O₂ as oxidant at mild conditions was evaluated. such as XRD, IR, TPR-TPD or TG were employed to characterize the catalysis. The main results are summarized as follows:Series of Vanadium-substituted herteropolymolybdates(H3+xPVxMo12-xO40,) were prepared. The results of XRD and IR confirmed that the heteropolyacids maintains Keggin structure.Activity of heteropolyacids for oxidation desulfurization of thiophene are fond in order: H₃PW₁₂O₄₀ > H₃PMo₁₂O₄₀ > H₅PV₂Mo₁₀O₄₀ > H₆PV₃Mo₉O₄₀ > H₄PVMo₁₁O₄₀ >> H₄SiW₁₂O₄₀ . At the optimistic condition , the thiophen conversion reached 70% on the optimic condition .Supported heteropolyacids were prepared by an isovolume impregnation method using different supports (SiO₂,TiO₂,Al₂O₃ or active carbon).The results of IR , N₂-adsorption and XRD indicated that the specific surface area increased greatly and their Keggin structure still remain . The solubilization ratio of the Supported heteropolyacids showed that the interaction between heteropolyacids and supports are in order : H₃PW₁₂O₄₀/AC > H₃PW₁₂O₄₀/SiO₂ > H₃PW₁₂O₄₀/TiO₂ > H₃PW₁₂O₄₀/Al₂O₃ . The interaction effect activity to oxidation desulfurization .By neutralization titration method , series of heteropolyacids salts which have different ratio of Cs and P were prepared and used to oxidation desulfurization for the first time. The desulfurization activities decrease with Cs number for Cs_xH_3-xPW₁₂O₄₀ but slightly change for Cs_xH_3-xPMo₁₂O₄₀ . However , the desulfurization activities depend on Cs/H ratio and the maximal activity is observed at x=3.0.