@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.} } @article { ISI:000240365800049, title = {Heteropoly acid supported on titania as solid acid catalyst in alkylation of p-cresol with tert-butanol}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {256}, number = {1-2}, year = {2006}, month = {AUG}, pages = {324-334}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Butylation of p-cresol with tert-butanol was investigated on titania modified with 12-tungstophosphoric acid (TPA/TiO2) catalyst under vapor phase conditions. Catalysts with different TPA loadings (10-25 wt.\%) and calcination temperatures (650-750 degrees C) were prepared by suspending titanium hydroxide in methanol solution of TPA followed by drying and calcination. These catalysts were characterized by surface area, XRD, P-31 MAS NMR, XPS, NH3-TPD, and FTIR pyridine adsorption. XRD results indicated that the presence of TPA retarded the crystallization of titania and stabilized TiO2 in anatase phase. P-31 MAS NMR indicated the presence of TPA in various forms (dispersed, highly fragmented and Keggin intact). These catalysts showed both Bronsted and Lewis acidity, and 20\% TPA on TiO2 calcined at 700 degrees C (from here after words 20\% TT 700) had the highest Bronsted as well as total acidity. Further, the catalytic activities were examined in tert-butylation of p-cresol with tent-butanol. The catalytic activity depended on TPA coverage, and the highest activity corresponded to the monolayer of TPA on titania. The most active catalyst 20\% TT-700 gave 82\% conversion of p-cresol and 89.5\% selectivity towards 2-tert-butyl cresol (TBC), 2,6-di-tert-butyl cresol (DTBC) 7.5\% and cresol-tert-butyl ether (CTBE) 3\% under optimized conditions. The activity was always higher than that of WO3/ZrO2, sulfated zirconia (SZ), USY, H-beta zeolites and montmorillonite K-10 (K-10mont) under similar conditions. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {2, 2-tert-butyl-p-cresol, 6-di-tert-butyl-p-cresol, Alkylation, heteropoly acid, p-Cresol, tert-butanol, titania}, issn = {1381-1169}, doi = {10.1016/j.molcata.2006.05.024}, author = {Kumbar, Suresh M. and Shanbhag, G. V. and Lefebvre, F. and Halligudi, Shivaraj B.} } @article { ISI:000266263000034, title = {Liquid phase oxidation of p-cresol over cobalt saponite}, journal = {Topics in Catalysis}, volume = {52}, number = {6-7}, year = {2009}, month = {JUN}, pages = {784-788}, publisher = {SPRINGER/PLENUM PUBLISHERS}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Liquid phase oxidation of p-cresol was carried out over a Co-saponite catalyst in a temperature and pressure range of 333-393 K and 20-827 kPa, respectively in n-propanol. Co-saponites with varying cobalt content (5-30\%) were prepared and screened among which 13\% Co-saponite gave the highest conversion of 92\% of p-cresol with 92\% selectivity to p-hydroxybenzaldehyde without formation of any non-oxidation products.

}, keywords = {Co-saponite, Liquid phase oxidation, p-Cresol, p-Hydroxybenzaldehyde, XPS}, issn = {1022-5528}, doi = {10.1007/s11244-009-9199-z}, author = {Kshirsagar, Vikas S. and Garade, Ajit C. and Patil, Kashinath R. and Shirai, Masayuki and Rode, Chandrashekhar V.} } @article { ISI:000279333000002, title = {Structure-activity studies of dodecatungstophosphoric acid impregnated bentonite clay catalyst in hydroxyalkylation of p-cresol}, journal = {Catalysis Communications}, volume = {11}, number = {11}, year = {2010}, month = {JUN}, pages = {942-945}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Bentonite clay impregnated with dodecatungstophosphoric acid (20\% DTP/BNT) showed an excellent activity, selectivity and stability [95\% product yield with 94\% selectivity to 2, 2{\textquoteright}-methylenebis (4-methylphenol), DAM] for the hydroxyalkylation of p-cresol with formaldehyde at 353 K and for a mole ratio of 5. Ammonia-TPD results showed that an increase in total concentration of acid sites from 4.9 of parent bentonite to 11.6 micromoles per surface area NH(3) (mu molS(-1) NH(3)) of 20\% DTP/BNT was due to a strong interaction of protons of bulk DTP with surface hydroxyl groups of BNT as evidenced by (31)P NMR studies. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {(31)P CPMAS NMR, Bentonite, Hydroxyalkylation, p-Cresol, surface modification}, issn = {1566-7367}, doi = {10.1016/j.catcom.2010.04.008}, author = {Garade, Ajit C. and Kshirsagar, V. S. and Jha, Ajay and Rode, C. V.} } @article { ISI:000328665300008, title = {Effect of SnO2/Al2O3 ratio of Si-based MFI on its acidity and hydrophobicity: application in selective hydroxyalkylation of p-cresol}, journal = {Catalysis Communications}, volume = {44}, number = {SI}, year = {2014}, month = {JAN}, pages = {29-34}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Silica based MR type molecular sieves with various SnO2/Al2O3 ratios were synthesized from gels having molar compositions SiO2:xSnO(2):yAl(2)O(3):0.23(TPA)(2)O:35H(2)O where 0 \<= x \<= 0.02 and 0 \<= y \<= 0.01. Recyclable, Al-free Sn-MFI catalyst showed 31\% conversion of formaldehyde with 100\% selectivity to 2,2{\textquoteright}-methylenebis(4-methylphenol) in hydroxyalkylation of p-cresol with formaldehyde on account of moderate acidity and higher hydrophobicity. (C) 2013 Elsevier B.A. All rights reserved.

}, keywords = {Al-27 MAS NMR, Hydroxyalkylation, Molecular sieves, p-Cresol, Stannosilicate}, issn = {1566-7367}, doi = {10.1016/j.catcom.2013.08.002}, author = {Garade, Ajit C. and Malwadkar, A. V. and Niphadkar, P. S. and Jha, Ratnesh Kumar and Joshi, P. N. and Rode, C. V.} }