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.

Semimicro method for determination of serum uric acid using EDTA-hydrazine.

Abstract: A semimicro method is described for the determination of uric acid by manual and automated procedures. Serum uric acid reduces phosphotungstic acid in an alkaline medium of EDTA sodium tungstate and hydrazine sulfate, the latter being used as a color intensifier. The use of sodium tungstate eliminates the development of interfering turbidity encountered with other alkalizing reagents. This method requires only 0.2 ml. of serum. The presence of ascorbic acid, sodium salicylate, cysteine, and/or glucose does not interfere. A linear relationship is obtained upon comparing this method with the sodium carbonate and the differential ultraviolet spectrophotometric methods.

A dicationic ionic liquid-modified phosphotungstate hybrid catalyst for the heterogeneous oxidation of alcohols with H 2 O 2

Abstract: An ionic hybrid catalyst 1,1′-(butane-1,4-diyl)-bis(3-methylimidazolium) phosphotungstate (abbreviated [Dmim]1.5PW) has been prepared by anion-exchange of the divalent ionic liquid (IL) 1,1′-(butane-1,4-diyl)-bis(3-methylimidazolium) di(bromide) with the Keggin phosphotungstic acid H3PW12O40, and characterized by IR, 1H NMR, 13C NMR, ESI-MS, TG, SEM, XRD, BET surface area measurements, elemental analysis, and melting point. The hybrid material was evaluated as a catalyst for the oxidation of alcohols with aqueous hydrogen peroxide under various conditions. The catalytic performance of [Dmim]1.5PW was also compared with related catalysts bearing other cations or anions. The new hybrid [Dmim]1.5PW proved to be an efficient liquid-solid heterogeneous catalyst for H2O2-based oxidation of alcohols, with the advantages of high conversion and selectivity, easy recovery, and quite good reusability.

Nanocomposite Membranes Based on Sulfonated Poly(etheretherketone) Structured with Modified Silica for Direct Ethanol Fuel Cell

Abstract: Polymer blend of sulfonated poly(oxy-1,4phenyleneoxy-1,4phenylenecarbonyl-1,4phenylene) (SPEEK) and poly(ether sulfone) (PES) was compounded with commercial and synthesized silica. PES phase had important role to improve the stability and to reduce permeability of sulfonated matrix to alcohol solution, but it also reduced the proton conductivity of membrane. The addition of synthesized silica, which had heteropolyacid phosphotungstic acid (HPW) occluded inside the silica matrix (SiO2 · HPW) was evaluated to improve the conductivity.

Environmentally Benign Bifunctional Solid Acid and Base Catalysts

Abstract: Solid bifunctional acid–base catalysts were prepared in two ways on an amorphous silica support: (1) by grafting mercaptopropyl units (followed by oxidation to propylsulfonic acid) and aminopropyl groups to the silica surface (NH2–SiO2–SO3H), and (2) by grafting only aminopropyl groups and then partially neutralizing with phosphotungstic acid, relying on the H2PW12O40– ion for surface acidity (NH2–SiO2–NH3+[H2PW12O40–], denoted as NH2–SiO2–PTA). Surface acidity and basicity were characterized by adsorption calorimetry, using SO2 as a probe for surface basicity and NH3 for surface acidity. Catalytic activities were compared in a two-stage cascade: an acid-catalyzed deacetalization followed directly by a base-catalyzed Henry reaction. Overall, the NH2–SiO2–SO3H catalysts showed higher concentrations and strengths of both acid and base sites, and higher activities than NH2–SiO2–PTA. Both catalysts showed evidence of cooperative acid–base catalysis. Importantly, the bifunctional catalysts exhibited catalytic ...