Phosphotungstic acid

About: Phosphotungstic acid is a research topic. Over the lifetime, 1925 publications have been published within this topic receiving 38059 citations. The topic is also known as: Phosphowolframic acid.

Preparation, characterization and catalytic performance of the silica pillared clay incorporated with phosphotungstic acid using different surfactants as template

Abstract: The mesoporous silica pillared clay (SPC) incorporated with Keggin-type H3PW12O40 (HPW) heteropoly acid was prepared by introducing HPW into clay interlayer template in an acidic suspension using sol–gel method. The materials are readily separable mesoporous materials with high specific surface areas. The results indicate that the surfactants play a decisive role in the introduction of HPW molecule and the pore formation. Moreover, the surface area and pore size of the materials can be controlled by the molecular length and functional groups of the surfactants. The formation mechanism of the materials was also proposed. The synthesized materials exhibited good catalytic performance in oxidative desulfurization of dibenzothiophene-containing model oil. Under the best conditions, the sulfur removal can reach up to near 100%. The excellent catalytic performance for oxidative desulfurization opens up new opportunities for applications of the synthesized materials in catalysis.

Highly efficient epoxidation of cyclohexene with aqueous H2O2 over powdered anion-resin supported solid catalysts

Abstract: Resin supported solid acid catalysts have extended the application of conventional solid acid catalysts in the field of selective oxidations. The present work describes selectively catalytic epoxidation of cyclohexene with aqueous 30% H 2 O 2 over powdered anion-resin supported peroxo phosphotungstic acid heterogeneous catalysts prepared through a simple anion-exchange from powdered chloride-form anion resin without any special pre-exchanged treatment. Among these powdered solid catalysts, anion-exchanged resin D201 supported peroxo phosphotungstic acid exhibits the best activity for the titled reaction to obtain 92.4 mol% conversion and 98.1% selectivity of epoxide, for which D201-PWAR(4) behaves as a truly heterogeneous catalyst. Some factors such as various peroxo phosphotungstic acid concentrations, the oxidants, the solvents, the molar ratios of H 2 O 2 /cyclohexene, the catalyst amount, the reaction temperature and time play important roles in controlling the epoxidation.

Photochromic behavior of nanocomposite hybrid films of finely dispersed phosphotungstic acid particles into polyacrylamide

Abstract: A series of nanocomposite hybrid films consisting of phosphotungstic acid (PW12) and polyacrylamide (PAM) were prepared. TEM images showed that PW12 particles with average diameter of tens of nanometer were finely dispersed in the film. FT-IR results suggested that the Keggin geometry of PW12 was still preserved inside the matrix and a charge-transfer bridge was built between PW12 and PAM through hydrogen bonds. Under UV irradiation, PW12 was reduced photochemically to yield various mixed-valency colored species (“heteropoly blues” or “heteropoly browns”). The extent of photoreduction was concerned with the concentration of PW12 and irradiation time. The presence and diffusion of oxygen played an important role in reversibility of photochromism.