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.

Beckmann rearrangement over phosphotungstic acid/SiMCM-41 cyclohexanone oxime to ε-caprolactam

Abstract: Vapor-phase Beckmann rearrangement of cyclohexanone oxime to e-caprolactam is reported for the first time on phosphotungstic acid (PWA)-supported SiMCM-41 catalyst. The catalyst was prepared in the laboratory following standard procedures and was characterised by XRD and FT-IR. By N2 adsorption, BET surface area, pore size and pore diameter were measured. The conversion of cyclohexanone oxime over the catalyst was studied in the temperature region of 250–400 °C using mainly acetonitrile as a solvent at different contact times. Increase in the reaction temperature to 325 °C enhances oxime conversion and the selectivity of e-caprolactam. An impressive catalytic performance of cyclohexanone oxime conversion >99% and e-caprolactam selectivity of 75% was observed on 30 wt.% PWA/SiMCM-41 at 325 °C using a feed containing10 wt.% oxime in acetonitrile at WHSV=3.24 h−1. The catalytic efficiency for this rearrangement reaction was studied, varying the PWA content from 10 to 50 wt.% on SiMCM-41 and also using benzene and ethanol as alternate solvents in place of acetonitrile. The rearrangement reaction and e-caprolactam selectivity with respect to catalyst physical characteristics, PWA content and type of solvent are discussed.

Superacid-doped polybenzimidazole-decorated carbon nanotubes: a novel high-performance proton exchange nanocomposite membrane

Abstract: Here we demonstrate design and electrochemical characterization of novel proton exchange membranes based on Nafion and superacid-doped polymer coated carbon nanotubes (CNTs). Polybenzimidazole-decorated CNT (PBI-CNT), a high-performance proton exchange nanostructure, was doped using phosphotungstic acid (PWA) as a super proton conductor. The engineered nanohybrid structure was shown to retain water molecules and provide high proton conduction at low humidity and elevated temperatures. The developed complex nanomaterial was then incorporated into the Nafion matrix to fabricate nanocomposite membranes. The acid–base interactions between imidazole groups of PBI and sulfonate groups of Nafion facilitate proton conductivity, especially at elevated temperatures. The improved characteristics of the membranes at the nanoscale result in enhanced fuel cell power generation capacity (386 mW cm−2) at elevated temperatures and low humidity (40% R.H.), which was found to be considerably higher than the commercial Nafion®117 membrane (73 mW cm−2).