Highly Active Sulfided NiPMo Hydrodesulfurization Catalyst Prepared from Keggin-type Phosphomolybdic Acid

A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source.The supported catalysts NiPMo/M41,Ni_(2)P-Mo/M41,and Ni_(2)P/M41 were also prepared to investigate the effects of Mo,S,and the Keggin structure on the HDS performance.The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni_(2)P-Mo/M41,demonstrating that the active phases in the Keggin-structured catalysts were significantly superior to the Mo-modified Ni_(2)P phase.The HDS activities of the catalysts followed the order NiPMo-S/M41(96.7%)>NiPMo/M41(89.9%)>Ni_(2)P-Mo/M41(53.5%)>Ni_(2)P/M41(48.9%).For Ni_(2)P/M41,Ni_(2)P-Mo/M41,and NiPMo/M41,cyclohexylbenzene(CHB)was formed in low concentrations(<21.0%),indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41.By contrast,the CHB selectivity of NiPMo-S/M41 increased to 44.6%,much higher than that of NiPMo/M41(17.6%),demonstrating that sulfidation enhanced the hydrogenation ability,which was ascribed to a metal-acid synergistic effect.

SYNTHESIS AND CHARACTERIZATION OF HYBRID PROTON CONDUCTING MEMBRANES OF POLY(VINYL ALCOHOL) AND PHOSPHOMOLYBDIC ACID

Hybrid proton conducting membranes of poly（vinyl alcohol） （PVA） and phosphomolybdic acid （PMA） were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane properties and proton conductivity were investigated. The crosslinking reaction between the hydroxyl group of PVA and the aldehyde group of glutaraldehyde （GA） was characterized by IR spectroscopy. Proton conductivity of the membranes increases with an increase in concentration of the doped PMA and also with an increase in crosslinking density of the membranes. Proton conductivity results indicate that a significant amount of PMA was maintained in the membranes even after several hours of immersion in water. A maximum conductivity of 0.0101 S cm^-1 was obtained for the membrane with 33.3 wt% PMA and crosslinking density of 5.825 mol%. X-ray diffraction studies were carried out to investigate the influence of PMA doping and crosslinking density on the nature of the membranes. These properties make them very good candidates for polymer electrolyte membranes for direct methanol fuel cell application.

A New Nanocatalytic Spectrophotometric Assay for Cationic Surfactant Using Phosphomolybdic Acid-Formic Acid-Nanogold as Indicator Reaction

In the pH 7.4 Na2HPO4-NaH2PO4 buffer solution, the cationic surfactant （CS） interacted with nanogold particles （NG） to form NG aggregations （NGA） that resulted in its color changing from wine red to blue-violet. NG has a strong catalysis on the formic acid-phosphomolybdic acid （PMo） colored reaction, but that of the NGA catalysis is weak. With the increase of CS concentration, the NGA increased and the NG decreased, the catalysis decreased and the absorption value at 700 nm decreased linearly. The concentrations of 6.25-250 nmol/L tetradecyl dimethyl benzyl ammonium chloride （TDBAC）, 0.625-250 nmol/L cetyltrimethyl ammonium bromide （CTMAB） and 12.5 -500 nmol-L 1 dodecyldimethylbenzyl ammonium chloride （DDBAC） had good linear responses to the decreased absorption value （AA70o nm）, with molar absorption coefficients of 2.2 × 106, 2.1 × 106 and 9 ×105 Lomol 1.cm 1 respectively. This method was simple, highly sensitive and low-cost.

Preparation and Visible-light Photochromism of Phosphomolybdic Acid/Polyvinylpyrrolidone Hybrid Film

The visible-light photochromic hybrid film was constructed by entrapping phosphomolybdic acid（PMoA） into polyvinylpyrrolidone（PVPd） networks. The microstructure, photochromic properties and mechanism were inves- tigated with transmission electron microscopy（TEM）, atomic force microscopy（AFM）, Fourier transform infrared （FTIR） spectroscopy, ultraviolet-visible（UV-Vis） spectra and X-ray photoelectron spectroscopy（XPS）. The results in- dicate that the Keggin geometry of PMoA and the basic structure of PVPd are not destroyed during the composite process. Irradiated with visible light, the transparent PMoA/PVPd film changes color from colorless to blue and ex- hibits reversible photochromism in the presence of oxygen. According to the XPS analysis, the charge-transfer bridge of N-H-O has been built between PMoA and PVPd matrix via non-covalent bonding, and the appearance of Mo5＋ species indicates that the photo-reduction process is in accordance with the proton transfer mechanism.

Visible-light Photochromism of Phosphomolybdic Acid/ZnO Composite

A novel photochromic hybrid ZnO was synthesized by doping with phosphomolybdic acid（PMoA）. It could respond to visible light and fade in color when treated with hydrogen peroxide（H2O2）. The microstlucture and photochromic properties were investigated via X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, ultraviolet-visible spectroscopy（UV-Vis） and X-ray photoelectron spectroscopy（XPS）. The XRD patterns show that the prepared ZnO is pure and has a hexagonal wurtzite structure. The FTIR results demonstrate the existence of a strong interaction between PMoA and ZnO. Due to PMoA doping, the rough surface morphology of ZnO became smooth, as verified by the SEM images. The TEM images illustrate that pure ZnO exhibits a polycrystalline structure with irregular morphology PMoA was wrapped on the surface of ZnO. After visible-light irradiation, the composite changed from slight yellow to blue and returned to the original color in the presence of H2O2. The composite had good photosensitivity and photochromic reversibility. The photochromic process was in accord with photoinduced electrons transfer mechanism.

Synthesis,Characterization and Catalytic Properties of Mesoporous HPMo/SiO_2 Composite

A novel mesoporous HPMo/SiO2 composite was synthesized by the sol-gel method with triblock copolymer EO20PO70EO20 as template.The properties of the product were characterized by X-ray diffraction,transmission electron microscopy,N2 adsorption-desorption isotherms,Fourier transform infrared spectrometer and inductively-coupled plasma analysis.The experimental results show that the product has a very ordered hexagonal mesostructure,and the HPMo is immobilized into the framework of silica.The final mesoporous composite shows excellent stability in polar solvents.Results of catalytic tests indicate that the composite is an effective catalyst for oxidation of dibenzothiophen,and there are few activity losses even after the third cycle of uses.The high catalytic activity and good insolubility make it a promising catalyst in oxidative desulfurization process.