@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: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 = {<p>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.</p>},
	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.}
}
