@article { ISI:000230297800006, title = {tert-Butylation of p-cresol over WOx/ZrO2 solid acid catalysts}, journal = {Journal of Molecular Catalysis A - Chemical}, volume = {235}, number = {1-2}, year = {2005}, month = {JUL}, pages = {44-51}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The tert-butylation of p-cresol with tert-butanol was carried out over WO3/ZrO2 catalysts under flow conditions, The catalysts were prepared by wet impregnation method using zirconium oxyhydroxide and ammonium metatungstate. Catalysts with different WO3 loading (5-30 wt.\%) were prepared and calcined at 800 degrees C and catalyst with 15\% WO,, was calcined from 600 to 900 C. The catalysts were characterized by surface area, XRD, FTIR and TEM. The catalyst 15\% WO3/ZrO2 calcined at 800 degrees C found to be the most active in the reaction. The effect of temperature, space velocity and molar ratio of the reactants on the conversion of p-cresol and products selectivities were studied. Under the optimized reaction conditions of 130 degrees C, tert-butanol/p-cresol molar ratio of 3 and flow rate of 10 ml h(-1). p-cresol conversion was 69.8\% with selectivity to 2-tert-butyl-p-cresol 92.4\%, 2,6-di-tert-butyl-p-cresol 6.3\% and p-cresol tert-butyl ether 1.3\%. The catalytic activity is compared with sulfated zirconia, USY, H beta zeolites and montmorillonite K-10 under the optimized reaction conditions The activity of sulfated zirconia is lower than that of 15\% WO3/ZrO2 catalyst calcined at 800 C and other catalysts showed very low activity, (c) 2005 Elsevier B.V.. All rights reserved.

}, keywords = {p-Cresol, tert-butylation, tungsten oxide, Zirconia}, issn = {1381-1169}, doi = {10.1016/j.molcata.2005.03.019}, author = {Sarish, S. and Devassy, Biju M. and Halligudi, Shivaraj B.} } @conference { ISI:000291657600173, title = {Tungstophosphoric acid and zirconia supported on mesoporous silica catalyst in veratrole acetylation}, booktitle = {From ZEOLITES to Porous Mof Materials: The 40th Anniversary of International ZEOLITE Conference, Proceedings of The 15th International ZEOLITE Conference}, series = {Studies in Surface Science and Catalysis}, volume = {170}, year = {2007}, note = {15th International Zeolite Conference, Beijing, PEOPLES R CHINA, AUG 12-17, 2007}, month = {AUG}, pages = {1325-1330}, publisher = {Elsevier Science BV}, organization = {Elsevier Science BV}, address = {Sara Burgerhartstraat 25, Po Box 211, 1000 AE Amsterdam, Netherlands}, abstract = {

Tungstophosphoric acid (TPA) over zirconia dispersed uniformly in mesoporous silica (MS) channels of MCM-41 and MCM-48 was synthesised and tested for its catalytic activity in veratrole acetylation. Catalysts with different TPA loadings (5 to 50 wt.\%) on 22.4 wt.\% ZrO(2)/MCM-41 and 15 wt.\% TPA on different zirconia loadings (10-70 wt.\%)/MCM-41 were prepared and calcined at 1123 K. Catalysts were characterised by known techniques. Mesoporous silica supports play an important role in stabilising catalytically active TPA along with tetragonal phase of zirconia. Among the catalysts, 15 wt.\% TPA/22.4 wt.\% ZrO(2)/MCM-41 calcined at 1123 K was found to have the highest acidity and be at least four times more active than neat 15 wt.\% TPA/ZrO(2) in veratrole acetylation to acetoveratrone by acetic anhydride.

}, isbn = {978-0-444-53068-4}, issn = {0167-2991}, author = {Halligudi, Shivaraj B.}, editor = {Xu, R. and Gao, Z. and Chen, J. and Yan, W.} } @article { ISI:000245961800012, title = {Tungstophosphoric acid supported on titania: a solid acid catalyst in benzylation of phenol with benzylalcohol}, journal = {Catalysis Communictions}, volume = {8}, number = {5}, year = {2007}, month = {MAY}, pages = {800-806}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

{Benzylation of phenol with benzylalcohol was carried out in liquid phase over tungstophosphoric acid (TPA) supported on titania. The catalysts were prepared with different TPA (10-25\%) loading by wet impregnation method, were calcined at 700 degrees C and characterized by XRD, surface area, FTIR and acidity of the catalysts was measured by temperature programmed desorption of NH(3)-TPD, FTIR pyridine adsorption. The catalysts have been represented by a general formula as xPTiO(2)-Y (where x = wt\%

}, keywords = {benzyl ether, benzyl phenol, benzylalcohol, Heteropolyacid, phenyl benzyl ether, titania, tungstophosphoric acid}, issn = {1566-7367}, doi = {10.1016/j.catcom.2006.08.027}, author = {Kumbar, Suresh M. and Halligudi, Shivaraj B.} } @article { ISI:000244183400015, title = {Tungstophosphoric acid supported over zirconia in mesoporous channels of MCM-41 as catalyst in veratrole acetylation}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {262}, number = {1-2}, year = {2007}, month = {FEB}, pages = {98-108}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Tungstophosphoric acid (TPA) over zirconia dispersed uniformly in mesoporous silica (MS) channels of MCM-41 and MCM-48 were synthesized and tested for their catalytic activity in veratrole acetylation. Catalysts with different TPA loadings (5-50 wt.\%) on 22.4 wt.\%ZrO2/MCM-41 and 15 wt.\%TPA on different zirconia loadings (10-70 wt.\%)/MCM-41 were prepared and calcined at 1123 K. The physico-chemical characterization of the supported catalysts was done by powder X-ray diffraction (XRD), surface area measurement (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed-infrared (FT-IR) spectroscopy, UV-vis diffuse reflectance spectra, Temperature programmed desorption (TPD) of ammonia, FT-IR pyridine adsorption and (31) P cross polarization-magic angle spinning (CP-MAS) NMR spectroscopy. The mesoporous silica supports play an important role in stabilizing catalytically active TPA along with tetragonal phase of zirconia. Among the catalysts, 15 wt.\%TPA/22.4 wt.\%ZrO2/MCM-41 calcined at 1123 K was found to have highest acidity and at least four times more active than neat 15 wt.\%TPA/ZrO2 in veratrole acetylation to acetoveratrone by acetic anhydride. Reaction conditions were evaluated with 15 wt.\%TPA/22.4 wt:\%ZrO2/MCM-41 calcined at 1123 K to get higher conversion of acetic anhydride to acetoveratrone. The reaction was found to be heterogeneously catalyzed and no contribution from homogeneous (leached) TPA into the medium under the reaction conditions. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {acetoveratrone, acetylation, MCM-41, TPA/ZrO2, veratrole}, issn = {1381-1169}, doi = {10.1016/j.molcata.2006.08.027}, author = {Sawant, Dhanashri P. and Vinu, A. and Lefebvre, F. and Halligudi, Shivaraj B.} } @article { ISI:000257016800018, title = {Titania supported silicotungstic acid: an efficient solid acid catalyst for veratrole acylation}, journal = {Catalysis Communications}, volume = {9}, number = {10}, year = {2008}, month = {JUN}, pages = {2026-2029}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Titania supported silicotungstic acid (STA) with different STA loading (10-25 wt\%) and calcination temperature (650-750 degrees C) were prepared by wet impregnation method. The catalysts have been represented by a general formula xSTiO(2)y (where x denotes wt\%, S denotes STA and y denotes calcination temperature in degrees C). These catalysts were characterized by techniques such as X-ray diffraction, surface analysis, FTIR-pyridine and TPD-NH(3) and were used as heterogeneous solid acid catalysts in the liquid phase acylation of veratrole with acetic anhydride (Ac(2)O). It was found that 20STiO(2)700 gave the highest activity in acylation reaction due to its highest acidity. (C) 2008 Elsevier B.V. All rights reserved.

}, keywords = {acetic anhydride, Acylation, Silicotungstic acid, titania, veratrole}, issn = {1566-7367}, doi = {10.1016/j.catcom.2008.03.043}, author = {Waghmare, Nilesh G. and Kasinathan, Palraj and Amrute, Amol P. and Lucas, Nishita and Halligudi, Shivaraj B.} }