02005nas a2200253   4500008004100000022001400041245009000055210006900145260007300214300001200287490000800299520111400307653001101421653002401432653002001456653001301476100002201489700002101511700002601532700002201558700002601580700002801606856011701634       2005                        eng d  a1381-116900aSilicotungstate-modified zirconia as an efficient catalyst for phenol tert-butylation0 aSilicotungstatemodified zirconia as an efficient catalyst for ph  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY  a141-1460 v2333 a<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>10aphenol10aSilicotungstic acid10atert-butylation10aZirconia1 aDevassy, Biju, M.1 aShanbhag, G., V.1 aMirajkar, Subhash, P.1 aBohringer, Walter1 aFletcher, Jack, C. Q.1 aHalligudi, Shivaraj, B.  uhttps://library.ncl.res.in/content/silicotungstate-modified-zirconia-efficient-catalyst-phenol-tert-butylation-002208nas a2200241   4500008004100000022001400041245009900055210006900154260007300223300001200296490000800308520132100316653003001637653002301667653002501690653001301715100002201728700001701750700002201767700002601789700002801815856012301843       2005                        eng d  a1381-116900aSynthesis of linear alkyl benzenes over zirconia-supported 12-molybdophosphoric acid catalysts0 aSynthesis of linear alkyl benzenes over zirconiasupported 12moly  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL  a162-1670 v2363 a<p>The liquid-phase alkylation of benzene with 1-octene and 1-dodecene was investigated using zirconia-supported 12-molybdophosphoric acid (MPA) as catalyst. The catalysts with different MPA loading (5-25 wt.% calcined at 700 degrees C) and calcination temperature (15 wt.% calcined from 500 to 750 degrees C) were prepared by suspending zirconium oxyhydroxide in methanol solution of MPA followed by drying and calcination. These catalysts were characterized by X-ray diffraction, and P-31 MAS NMR spectroscopy measurements. The XRD results indicated that MPA stabilizes the tetragonal phase of zirconia. 3 1 P MAS NMR spectra show that the nature of phosphorous species depend on MPA loading and calcination temperature, and it show the existence of three types of phosphorous species, one is the Keggin unit and the other is the decomposition product of MPA and third one an unidentified species. FTIR pyridine adsorption on 15% MPA catalyst calcined at 700 degrees C showed the presence both Bronsted and Lewis acidity. Under the reaction conditions of 83 C, benzene/1-olefin molar ratio of 10 (time, 1 h), the most active catalyst, 15% MPA calcined at 700 C gave more than 90% olefin conversion with selectivity to 2-phenyl octane, 55% and 2-phenyl dodecane, 45%. (c) 2005 Elsevier B.V. All rights reserved.</p>10a12-molybdophosphoric acid10abenzene alkylation10alinear alkyl benzene10aZirconia1 aDevassy, Biju, M.1 aLefebvre, F.1 aBohringer, Walter1 aFletcher, Jack, C. Q.1 aHalligudi, Shivaraj, B.  uhttps://library.ncl.res.in/content/synthesis-linear-alkyl-benzenes-over-zirconia-supported-12-molybdophosphoric-acid-0