Papers by Keyword: Keggin Structure

Abstract: A new solid proton conductor Na7[CoCrW11O39 (H2O)]·15H2O has been synthesized for the first time. The percentage composition of the product were determined by inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The product was characterized by infrared spectroscopy (IR) and X-ray diffraction (XRD), which indicate it possesses the Keggin structure. The TG-DTA curve shows the sequence of water loss in the compound, the amount of the loss, as well as the thermostability. Conductivity of the compound was investigated by four-electrode method at room temperature and different measuring temperatures, the results reveal that its proton conductivity is 9.42×10−7S·cm-1 at 25°C.

Abstract: A new solid high-proton conductor Na₇[CoW₁₁O₃₉Cd (H₂O)]·12H₂O has been synthesized for the first time. The percentage composition of the product were determined by Inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The product was characterized by infrared spectroscopy (IR) and X-ray diffraction (XRD), which indicate it possesses the Keggin structure. The TG-DTA curve shows the sequence of water loss in the compound, the amount of the loss, as well as the thermostability. Conductivity of the compound was investigated by four-electrode method at room temperature and different measuring temperatures, the results reveal that its proton conductivity is 4.87×10⁻⁴ S·cm^-1 at 27oC and the activation energy for proton conduction is 15.31 kJ/mol.

Abstract: A new heteropoly salt with Keggin structure of the 1:1:11 series had been synthesized, and characterized the structure by the foruier transform infrared spectroscopy (IR), ultraviolet spectra (UV) and X-ray diffraction (XRD).The thermal stability and the number of the crystal water was analyzed by the thermal gravimetric analysis/differential thermal analysis (TG/DTA). It was showed the molecular formula was Na₅[Ce(ZrMo₁₁O₃₉)]•16H₂O( Abbrev.CeZrMo),it possessed Keggin structure and had good thermal stability. The influences on the degradation rate, such as the amount of the CeZrMo, the initial concentration of the AGB dye wastewater, the ultrasonic frequency and power, were investigated. The results showed that the degradation rate could reach 88.01% after 60min irradiation, when the amount of the CeZrMo was 0.8g•L^-1, the concentration of the AGB was 10mg•L^-1, the ultrasonic frequency was 45kHz and the ultrasonic power was 100W.

Abstract: The organic–inorganic hybrid catalyst [(CH2)5NH2]4SiW12O40 was prepared by matrix acid and piperidine. The matrix acid was synthesized by sodium molybdate and sodium silicate, and the piperidine was organic ligand. The proposed composition and structure of the catalyst were evidenced by XPS, FT-IR, XRD, TG-DTA and elemental analysis. The results indicated that the heteropoly anions still reserved their Keggin structure in the compound. Its catalytic performance was evaluated in the oxidation of benzaldehyde to benzoic acid. Various reaction parameters were changed to attain the optimal conditions. The optimal reaction conditions were found to be: n(catalyst): n(benzaldehyde)=3.1×10-3:1; n(H2O2)： n(benzaldehyde)=4.5：1; reaction temperature was 80°C; reaction time was 4h. The yield of benzoic acid achieved above 85%.

Abstract: The heteropoly salt, Na₆[Mn(Mo₁₁ZrO₃₉)] •19H₂O（MnZrMo）with Keggin structure of the 1:1:11series, was synthesized by the aqueous solution method, and characterized and analyzed. The element analysis showed that the molar ratio of Mn, Zr and Mo was accord with 1:1:11;the thermogravimetric analysis/ differential thermal analysis(TG/DTA) indicated that the MnZrMo had good thermal stability and it contained nineteen molecules of crystallization water; the characterization of the fourier transform infrared spectroscopy(FT-IR),X-ray powder diffraction analysis(XRD) and the ultraviolet spectrum(UV) showed that the anionic of the MnZrMo heteropoly salt possessed Keggin structure; the analysis of the scanning electron microscopy(SEM) showed that it had the basic feature of the macromolecular compound and a regular crystal. The MnZrMo heteropoly salt was used as the catalyst to degrade the acidic-green B(AGB) dyeing wastewater enhanced by the ultrasonic, the degradation rate could reach 95.90%.

Abstract: The present work, the HPA Keggin structure was supported on four different MCM phase types (hexagonal, spherical, elliptical, and cubic); their catalytic properties were tested in the alkylation of benzene with propylene in order to produce cumene. In the reaction, parameters like propylene flow, reaction temperature, phase type, as well as WHSV-1, HPA, and Cs content in the best MCM phase support were studied. The results showed that the MCM-48 with (30 wt. % HPA) catalyst had the best behavior in catalytic activity, showing the higher conversion and selectivity toward cumene as the main product.