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.

Phosphotungstic Acid Immobilized on Amine-Grafted Graphene Oxide as Acid/Base Bifunctional Catalyst for One-Pot Tandem Reaction

Abstract: In this study, phosphotungstic acid immobilized on amine-grafted graphene oxide (GOAP) was prepared successfully by silylanization and electrostatic interaction. The obtained GOAP was characterized by Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), zeta potential measurements, and X-ray photoelectron spectroscopy (XPS). Systematic studies demonstrated that GOAP had excellent catalytic activities and robustness in the one-pot tandem deacetalization–nitroaldol reaction. The key role of the acid/base ratio in the catalytic performance of this bifunctional catalyst was also revealed by preliminary kinetic studies. This bifunctional catalyst might find promising applications in green chemistry, as it can not only reduce costs and waste by saving separation/purification steps and solvents/reagents, but also increase the yield by avoiding the separation of intermediate products.

POSS-Derived Mesostructured Amphiphilic Polyoxometalate-based Ionic Hybrids as Highly Efficient Epoxidation Catalysts

Abstract: Novel amphiphilic mesostructured polyoxometalate-based ionic hybrids have been successfully synthesized through designing new POSS-derived mesoporous poly(ionic liquids) (POSS-BMx) to interact with Keggin-type phosphotungstic acid (PW). The obtained ionic hybrids POSS-BMx-PW have good thermal stability, adjustable pore structure and surface wettability. Catalytic tests for H2O2-based epoxidation of cyclooctene, along with comparisons to various counterparts, well demonstrate that POSS-BMx-PW (x = 8, 11) exhibit high activity and selectivity, coupled with convenient recovery and steady reuse. The unique mesoporous structure and the amphiphilic catalyst surface are revealed to be responsible for the catalyst’s excellent performances in epoxidation reaction with H2O2.

t-Butylation of phenol over mesoporous aluminophosphate and heteropolyacid supported aluminophosphate molecular sieves

Abstract: Mesoporous aluminophosphate (AlPO) has been synthesized hydrothermally using cetyltrimethylammonium bromide (CTAB) as structure-directing agent in the presence of tetramethylammonium hydroxide (TMAOH) at room temperature. Phosphotungstic acid, H 3 PW 12 O 40 (PW) was supported on the synthesized mesoporous AlPO at various loadings viz., 10, 20 and 40 wt.% to yield PW/AlPOs and characterized by XRD, TGA and FT-IR. XRD patterns confirm that HPA retains the Keggin structure on the AlPO surface and forms finely dispersed heteropoly acid (HPA) species. HPA crystal phase was not developed even at HPA loading as high as 40 wt.%. Catalytic activities of both parent AlPO and HPA loaded AlPOs were studied by carrying out t -butylation of phenol with tert -butanol in vapour phase in the temperature range 190–250 °C. The products obtained were o - tert -butyl phenol ( o-t -BP), p - tert -butyl phenol ( p - t -BP) and tert -butylphenyl ether ( t -BPE) with high selectivity towards p - t -BP. The effects of feed ratio and WHSV towards conversion of phenol were studied and finally the time on stream studies were also carried out to compare the activities of the catalysts. PW/AlPO catalysts were found to yield higher conversion than parent AlPO due to the increase in Bronsted acid sites. Hence, PW/AlPO compositions are promising catalysts exclusively for acid type conversion of large organic molecules.