Catalytic Activity and Selectivity of Unsupported Dodecatungstophosphoric Acid, and Its Cesium and Potassium Salts Supported on Silica

Ibrahim, Shaimaa M.

doi:10.4236/mrc.2013.23016

Cited by 7 publications

(4 citation statements)

References 39 publications

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“…Substitution of one proton of tungstophosphoric acid (HPW) by cesium or potassium cation exerted no measurable effect on the catalytic activity. 11 15 Moreover, Okuhara et al also reported the insoluble heteropoly compounds as highly active catalysts for liquidphase reactions because of the high activity of Cs 2.5 salt. This is due to the large number of surface acid sites and its acid−base bifunctional nature, in which a cesium ion possibly increases the basicity of the heteropolyanion.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, solid acid catalysts can also reduce the production cost because they could be easily recycled and used several times without loss of catalytic activity. Substitution of one proton of tungstophosphoric acid (HPW) by cesium or potassium cation exerted no measurable effect on the catalytic activity . Filek et al studied the preparation and characterization and tested the catalytic properties of GaPW 12 O 40 and InPW 12 O 40 for the etherification of ethanol .…”

Section: Introductionmentioning

confidence: 99%

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Development of Ga Salt of Molybdophosphoric Acid for Biomass Conversion to Levulinic Acid

et al. 2016

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Efficient catalytic methods for biomass conversion present a challenge for the sustainable production of fuels and chemicals. Ga salt of molydophosphoric acid (GaHPMo) is prepared using a sonochemical irradiation method. Simultaneous formation of GaHPMo and entrapment of polyoxometallate in gallium micro-/nanoparticles (Ga@HPMo) is achieved. The amount of entrapped hetropoly acid in Ga particles is estimated to be ∼3 wt %, as determined from thermogravimetric analysis (TGA) and ultraviolet−visible (UV−vis) analysis. The preparation of GaHPMo is accomplished by subjecting an ethanolic solution of polyoxometallate [molybdophosphoric acid (HPMo)] and molten Ga metal to sonication at 50 °C for 12 min. Physicochemical properties of GaHPMo are studied using X-ray diffraction, TGA, temperature-programmed desorption, differential scanning calorimetry, Fourier transform infrared spectroscopy, UV−vis spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and energy-dispersive X-ray spectroscopy analysis. GaHPMo was successfully used as a catalyst for the conversion of various carbohydrates (glucose, starch, and cellulose) and rice straw into levulinic acid via a hydrothermal process. Reaction conditions for obtaining an optimum yield of levulinic acid from glucose are deduced (time, 10 h; temperature, 423 K; and mole ratio of the catalyst/reactant, 1:5). The reaction products are analyzed qualitatively using nuclear magnetic resonance ( 13 C and 1 H) spectroscopy and quantified using high-performance liquid chromatography analysis. The maximum yield of levulinic acid obtained from glucose is 56 wt %. Apart from the major product, levulinic acid, other minor byproducts, such as formic and lactic acids, are also observed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of Ga Salt of Molybdophosphoric Acid for Biomass Conversion to Levulinic Acid

et al. 2016

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“…The increase in surface area and the proton conductivity of metal-substituted TPA are responsible for achieving high fuel cell performance. 21,22 Although there exist many studies on the use of metal-substituted TPA for catalysis, very few report their use for fuel cell applications. Cs-TPA was used as the conducting filler for PEM fuel cell applications.…”

Section: Introductionmentioning

confidence: 99%

Aluminum-substituted phosphotungstic acid/sulfonated poly ether ether ketone nanocomposite membrane with reduced leaching and improved proton conductivity

Banerjee

Kar

2016

High Performance Polymers

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Aluminum-substituted tungstophosphoric acid (AlTPA)/sulfonated poly ether ether ketone (SPEEK) (sulfonation degree approximately 77%) nanocomposite membranes have been prepared for fuel cell application. AlTPA nanoparticles are synthesized by the reaction of TPA and aluminum nitrate in aqueous medium. X-ray diffraction, energy dispersive X-ray, Fourier transform infrared and Raman spectroscopies, and field-emission scanning electron microscopy (FESEM) are used to characterize the AlTPA particles and SPEEK. Study reveals that 2.31 numbers of protons of TPA have been replaced by Al3+ in AlTPA with retention of Keggin’s structure. Nanocomposite membranes with varying AlTPA and TPA content are prepared and evaluated by measuring water uptake, ion exchange capacity, equilibrium water content, water desorption rate, proton conductivity, leaching tendency, and thermal properties. SPEEK/AlTPA nanocomposite membrane exhibits proton conductivity as high as 1.09 mS cm−1 at 10 wt% filler loading. Leaching of filler is reduced by approximately 92% in SPEEK/AlTPA nanocomposite membrane compared to SPEEK/TPA membrane. SPEEK/AlTPA membrane shows approximately 15% higher equilibrium water content and approximately 57% reduction in water desorption rate as compared to SPEEK/TPA membrane. Membranes are thermally stable up to 215°C, which is well above the operating temperature of fuel cells. Composite films are also examined by FESEM to gain further insights into the microstructure.

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“…Therefore, metal-modified HPA supported on the suitable solid is an efficient method to improve the catalytic performance. Recently, benzylation and oxidation reactions over metal-modified HPAs supported on some solids have been studied, − but the benzoylation reaction is still rarely reported.…”

Section: Introductionmentioning

confidence: 99%

Iron(III)-Modified Tungstophosphoric Acid Supported on Titania Catalyst: Synthesis, Characterization, and Friedel–Craft Acylation of m-Xylene

Fang

Liu

et al. 2015

Ind. Eng. Chem. Res.

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The Friedel−Craft acylation of m-xylene with benzoyl chloride over iron-modified tungstophosphoric acid supported on titania was investigated. It was found that FeTPA/TiO 2 catalyst displayed excellent catalytic performance for this reaction. Furthermore, a series of catalysts were prepared and characterized by FT-IR, XRD, BET, NH 3 -TPD, and Py-IR. The results indicated that both the Lewis acidity and the textural properties presented significant influences on their catalytic performance. Moreover, the influence of catalyst calcination temperature to the above reaction was also studied. The reaction parameters, including reaction temperature, catalyst dose, and molar ratio of m-xylene to benzoyl chloride, were optimized, and a 95.1% yield of 2,4-dimethylbenzophenone was obtained under optimal conditions. Finally, the kinetics of the benzoylation of mxylene over 30% FeTPA/TiO 2 was established.

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Catalytic Activity and Selectivity of Unsupported Dodecatungstophosphoric Acid, and Its Cesium and Potassium Salts Supported on Silica

Cited by 7 publications

References 39 publications

Development of Ga Salt of Molybdophosphoric Acid for Biomass Conversion to Levulinic Acid

Development of Ga Salt of Molybdophosphoric Acid for Biomass Conversion to Levulinic Acid

Aluminum-substituted phosphotungstic acid/sulfonated poly ether ether ketone nanocomposite membrane with reduced leaching and improved proton conductivity

Iron(III)-Modified Tungstophosphoric Acid Supported on Titania Catalyst: Synthesis, Characterization, and Friedel–Craft Acylation of m-Xylene

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