@article { ISI:000227845200016, title = {Zirconia-supported phosphotungstic acid as catalyst for alkylation of phenol with benzyl alcohol}, journal = {Journal of Molecular Catalysis A - Chemical}, volume = {230}, number = {1-2}, year = {2005}, month = {APR}, pages = {113-119}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The liquid-phase alkylation of phenol with benzyl alcohol was carried out using zirconia-supported phosphotungstic acid (PTA) as catalyst. The catalysts with different PTA loadings (5-20 wt.\% calcined at 750 degrees C) and calcination temperature (15 wt.\% calcined from 650 to 850 degrees C) were prepared and characterized by (31)p MAS NMR and FT-IR pyridine adsorption spectroscopy. The catalyst with optimum PTA loading (15\%) and calcination temperature (750 degrees C) was prepared in different solvents. 31p MAS NMR spectra of the catalysts showed two types of phosphorous species, one is the Keggin unit and the other is the decomposition product of PTA and the relative amount of each depends on PTA loading, calcination temperature and the solvent used for the catalyst preparation. The catalysts with 15\% PTA on zirconia calcined at 750 degrees C showed the highest Bronsted acidity. At 130 degrees C and phenol/benzyl alcohol molar ratio of 2 (time, I h), the most active catalyst, 15\% PTA calcined at 750 degrees C gave 98\% benzyl alcohol conversion with 83\% benzyl phenol selectivity. (c) 2004 Elsevier B.V. All rights reserved.

}, keywords = {Benzylation, phenol, Phosphotungstic acid, Zirconia}, issn = {1381-1169}, doi = {10.1016/j.molcata.2004.12.028}, author = {Devassy, Biju M. and Shanbhag, G. V. and Lefebvre, F. and Bohringer, Walter and Fletcher, Jack C. Q. and Halligudi, Shivaraj B.} } @article { ISI:000238502400002, title = {Effect of calcination temperature on the catalytic activity of zirconia-supported heteropoly acids}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {253}, number = {1-2}, year = {2006}, month = {JUL}, pages = {8-15}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Zirconia-supported silicotungstic acid (15\% STA) catalyst with different calcination temperatures (600-850 degrees C) was prepared by suspending zirconium oxyhydroxide in methanol solution of STA followed by drying and calcination. These catalysts were characterized by XRD, FTIR pyridine adsorption and DRUV-vis spectroscopy. The catalysts showed both Bronsted as well as Lewis acidity and 15\% STA on zirconia calcined at 750 degrees C (15 SZ-750) had the highest Bronsted acidity. Characterization of 15 SZ-750 catalyst by Raman spectroscopy showed the presence of zirconia-anchored mono-oxotungstate as the major tungsten species present in this catalyst. These catalysts were used in benzoylation of veratrole with benzoic anhydride and 15 SZ-750 catalyst showed the highest activity. For catalyst with support calcined at different temperatures before HPA impregnation, catalytic activity decreases as the support calcination temperature increases due to the decrease in Bronsted acidity. Comparison of the catalytic activity of 15 SZ-750 with that of zirconia-supported phosphotungstic acid (15\%, calcined at 750 degrees C, 15 PZ-750) in benzoylation of veratrole with benzoic anhydride, acylation of anisole with acetic anhydride and in alkylation of diphenylether with 1-dodecene showed that 15 SZ-750 catalyst has higher activity and deactivation resistance due to its higher Bronsted acidity. The deactivated catalyst could be regenerated by calcination without appreciable loss in activity. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Acylation, Alkylation, Anisole, diphenylether, Phosphotungstic acid, Silicotungstic acid, veratrole, Zirconia}, issn = {1381-1169}, doi = {10.1016/j.molcata.2006.02.068}, author = {Devassy, Biju M. and Halligudi, Shivaraj B.} } @article { ISI:000242960400008, title = {Phosphotungstic acid as an efficient solid catalyst for intramolecular rearrangement of benzyl phenyl ether to 2-benzyl phenol}, journal = {Catalysis Communications}, volume = {8}, number = {2}, year = {2007}, month = {FEB}, pages = {139-144}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

An heteropoly acid (phosphotungstic acid, PTA) was found to be a promising solid acid catalyst as an alternative to the conventional stoichiometric reagents for the rearrangement of benzyl phenyl ether giving 2-benzyl phenol as a major product and 4-benzyl phenol and dibenzylated phenols as side products. Catalyst was recovered from the reaction mixture and reused again without loss of activity. Based on the observed product distribution for various substrates a plausible catalytic reaction pathway has also been proposed. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {benzyl phenyl ether, Intramolecular rearrangement, Phosphotungstic acid}, issn = {1566-7367}, doi = {10.1016/j.catcom.2006.05.046}, author = {Bhure, Mahesh H. and Rode, Chandrashekhar V. and Chikate, Rajeev C. and Patwardhan, Neeraj and Patil, Shraddha} } @article { ISI:000344439400007, title = {Regioselective acylation of 2-methoxy naphthalene catalyzed by supported 12-phosphotungstic acid}, journal = {Applied Catalysis A-General}, volume = {486}, year = {2014}, month = {SEP}, pages = {55-61}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

12-Phosphotungstic acid supported on silica gel, zirconium sulfate, and a combination of silica gel and zirconium sulfate (50\% w/w) were employed as solid acid catalysts for regioselective acylation of 2-methoxynaphtalene with acetic anhydride. 1-(6-Methoxynaphthalen-2-yl)ethanone (2,6-AMN), a commercially important intermediate for production of Naproxen, was obtained with excellent selectivity (\>98\%) at 67-68\% conversion using 12-phosphotungstic acid supported on silica gel 20\% (w/w) in refluxing tetrachloroethane. The unreacted starting material can be easily separated from the product by a simple crystallization from nonane. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Acylation, Naproxen, Phosphotungstic acid, Silica gel, Supported, Zirconium sulfate}, issn = {0926-860X}, doi = {10.1016/j.apcata.2014.08.026}, author = {Kumaraguru, Thenkrishnan and Devi, Ayala Vedamayee and Siddaiah, Vidavalur and Rajdeo, Kishor and Fadnavis, Nitin W.} } @article {44505, title = {Synthesis of diesel additives from fructose over PWA/SBA-15 catalyst}, journal = {Fuel }, volume = {217}, year = {2018}, month = {JAN}, pages = {38-44}, type = {Journal Article}, abstract = {A series of composites of phosphotungstic acid (PWA) H3PW12O40 with SBA-15 were prepared by varying PWA amount from 5\% to 30\% by one-step sol-gel hydrothermal as well as by impregnation methods. Successful incorporation of PWA into the SBA-15 framework by sol-gel method was confirmed by 31P NMR in which a shifting of the peak due to tetrahedral {\textquoteleft}P{\textquoteright} atom of PWA from -14.32 and -14.49 ppm was observed. The composites exhibited both Br{\o}nsted and Lewis acidity, large and well distributed three dimensional interconnected pores with high surface areas exhibiting excellent activity for one pot synthesis of 5-(hydroxymethyl) furfural (5-HMF) and 5-(ethoxymethyl) furfural (EMF) from fructose. The minimum loading of 5\% of PWA in SBA-15, gave 78\% fructose conversion with the highest yield of 70\% towards 5-HMF. Increase in PWA loading up to 20\% resulted in the enhanced fructose conversion of 95\% accompanied by further etherification of 5-HMF to 67 and 12\% yield towards EMF and ethyl levulinate (EL), respectively. Increasing the \% of PWA in SBA-15 matrix resulted in increase in the acidity of the composites giving the yield trend as 5-HMF < EMF < EL. Catalyst prepared by sol-gel method showed excellent recyclability up to 3 reuses}, keywords = {5-(Ethoxymethyl) furfural, 5-(Hydroxymethyl) furfural, Phosphotungstic acid, SBA-15}, issn = {162361}, doi = {10.1016/j.fuel.2017.12.027}, author = {Patil, Chetana R.}, editor = {Rode, Chandrashekhar V.} } @article {48029, title = {Immobilization of HPW on UiO-66-NH2 MOF as efficient catalyst for synthesis of furfuryl ether and alkyl levulinate as biofuel}, journal = {Molecular Catalysis}, volume = {531}, year = {2022}, month = {OCT}, pages = {112689}, type = {Article}, abstract = {

Phosphotungustic Acid (HPW) is an inorganic super acid, that is highly soluble in polar solvents limiting its applicability as acid catalysis. To overcome these limitations immobilization of HPW was carried out at room temperature by protonation of-NH2 group of UiO-66-NH2 MOF to UiO-66-NH2-HPW. ATR-FTIR spectroscopy and XPS results confirmed the protonation and chemical interaction between HPW and UiO-66-NH2. STEM-EDS mapping showed homogeneous distribution of HPW on UiO-66-NH2. BET and NH3-TPD confirmed the reduction in specific surface area, total pore volume, and increase in total acidity for UiO-66-NH2-HPW. Further, powder XRD, SEM, and HR-TEM prevailed that there is no change in phase and morphology after post-synthetic modification of UiO-66-NH2. The prepared catalyst is found to be effective for etherification and alcoholysis of furfuryl alcohol (FALc) to Furfuryl ether (FE) and Alkyl levulinate (AL). UiO-66-NH2-HPW has shown 97 mol \% FALc conversions in ethanolic media and 31 mol\% Ethyl furfuryl ether (EFE) yield and 29 mol\% Ethyl lev-ulinate (EL) yield. UiO-66-NH2-HPW is also found to be efficient for the multistep conversion of Furfural (FFR) to FALc, FE, and AL.

}, keywords = {Alcoholysis, etherification, Immobilization, Phosphotungstic acid, UiO-66-NH2-HPW}, issn = {2468-8231}, doi = {10.1016/j.mcat.2022.112689}, author = {Mulik, Nagesh and Bokade, Vijay} }