@article { ISI:000228633100020,
	title = {Silicotungstate-modified zirconia as an efficient catalyst for phenol tert-butylation},
	journal = {Journal of Molecular Catalysis A-Chemical},
	volume = {233},
	number = {1-2},
	year = {2005},
	month = {MAY},
	pages = {141-146},
	publisher = {ELSEVIER SCIENCE BV},
	type = {Article},
	address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS},
	abstract = {<p>The alkylation of phenol with tert-butanol was investigated using zirconia modified with silicotungstic acid (STA) as catalysts. The catalysts with different STA loading (5-25 wt.\% calcined at 750 degrees C) and calcination temperature (15 wt.\% calcined from 350 to 850 degrees C) were prepared and characterized by X-ray diffraction and NH3-TPD measurements. The XRD results indicate that STA stabilizes the tetragonal phase of zirconia. The catalyst with 15\% STA on ZrO2 calcined at 750 degrees C shows the highest acidity and hence highest activity. Under the reaction conditions of 140 degrees C, tert-butanol/phenol molar ratio of 2 and LHSV of 4 h(-1), phenol conversion was 95.4\% with selectivity to 2-tert-butyl phenol 4.3\%, 4-tert-butyl phenol 59.2\% and 2,4-di-tert-butyl phenol 35.8\%. The reaction was studied as a function of time for 50 It without appreciable change in phenol conversion and product selectivity. The deactivated catalyst could be regenerated by calcination with out appreciable lose in catalytic activity and product selectivity. (c) 2005 Elsevier B.V. All rights reserved.</p>},
	keywords = {phenol, Silicotungstic acid, tert-butylation, Zirconia},
	issn = {1381-1169},
	doi = {10.1016/j.molcata.2005.02.021},
	author = {Devassy, Biju M. and Shanbhag, G. V. and Mirajkar, Subhash P. and Bohringer, Walter and Fletcher, Jack C. Q. and Halligudi, Shivaraj B.}
}
@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 = {<p>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.</p>},
	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.}
}
