02440nas a2200253 4500008004100000022001400041245010300055210006900158260007300227300000900300490000800309520155700317653001401874653001501888653001201903653001801915653002501933653002401958653001401982653001301996100002202009700002802031856012702059 2006 eng d a1381-116900aEffect of calcination temperature on the catalytic activity of zirconia-supported heteropoly acids0 aEffect of calcination temperature on the catalytic activity of z aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL a8-150 v2533 a

Zirconia-supported silicotungstic acid (15% STA) catalyst with different calcination temperatures (600-850 degrees C) was prepared by suspending zirconium oxyhydroxide in methanol solution of STA followed by drying and calcination. These catalysts were characterized by XRD, FTIR pyridine adsorption and DRUV-vis spectroscopy. The catalysts showed both Bronsted as well as Lewis acidity and 15% STA on zirconia calcined at 750 degrees C (15 SZ-750) had the highest Bronsted acidity. Characterization of 15 SZ-750 catalyst by Raman spectroscopy showed the presence of zirconia-anchored mono-oxotungstate as the major tungsten species present in this catalyst. These catalysts were used in benzoylation of veratrole with benzoic anhydride and 15 SZ-750 catalyst showed the highest activity. For catalyst with support calcined at different temperatures before HPA impregnation, catalytic activity decreases as the support calcination temperature increases due to the decrease in Bronsted acidity. Comparison of the catalytic activity of 15 SZ-750 with that of zirconia-supported phosphotungstic acid (15%, calcined at 750 degrees C, 15 PZ-750) in benzoylation of veratrole with benzoic anhydride, acylation of anisole with acetic anhydride and in alkylation of diphenylether with 1-dodecene showed that 15 SZ-750 catalyst has higher activity and deactivation resistance due to its higher Bronsted acidity. The deactivated catalyst could be regenerated by calcination without appreciable loss in activity. (c) 2006 Elsevier B.V. All rights reserved.

10aAcylation10aAlkylation10aAnisole10adiphenylether10aPhosphotungstic acid10aSilicotungstic acid10averatrole10aZirconia1 aDevassy, Biju, M.1 aHalligudi, Shivaraj, B. uhttps://library.ncl.res.in/content/effect-calcination-temperature-catalytic-activity-zirconia-supported-heteropoly-acids-001722nas a2200229 4500008004100000022001400041245014100055210006900196260007300265300001200338490000800350520085900358653001601217653001101233653001301244653001401257653002101271100002601292700002101318700002801339856012501367 2007 eng d a1387-181100aEffect of pretreatment conditions on the catalytic activity of nano-sized TPA/ZrO2 dispersed in SBA-15 channels in acetylation reactions0 aEffect of pretreatment conditions on the catalytic activity of n aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY a223-2330 v1023 a

Acetylation of an aromatic compounds such as veratrole (1,2-dimethoxybenzene), anisole, thioanisole, isobutyl benzene and 2-methoxynaphthalene with acetic anhydride has been investigated over a nano-sized 12-tungstophosphoric acid (TPA)/22.4 wt.%ZrO2/SBA- 15 catalysts in the liquid phase conditions. Catalysts with different (%) TPA and zirconia loadings calcined at different temperatures were prepared by wet-impregnation and characterized by XRD, N-2 adsorption-desorption, FT-Rarnan, X-ray photoelectron spectroscopy (XPS). The acidic behavior of the catalyst was studied by TPD of ammonia and FT-IR pyridine adsorption. Among the catalysts, 15 wt.%TPA/22.4 wt.%ZrO2/SBA- 15 calcined at 1123 K had the highest acidity and was the most active catalyst in veratrole acetylation with acetic anhydride. (C) 2007 Elsevier Inc. All rights reserved.

10aacetylation10aSBA-1510aTPA/ZrO210averatrole10awet-impregnation1 aSawant, Dhanashri, P.1 aHartmann, Martin1 aHalligudi, Shivaraj, B. uhttps://library.ncl.res.in/content/effect-pretreatment-conditions-catalytic-activity-nano-sized-tpazro2-dispersed-sba-1502438nas a2200241 4500008004100000022001400041245012100055210006900176260007300245300001100318490000800329520157000337653001901907653001601926653001101942653001301953653001401966100002601980700001302006700001702019700002802036856013202064 2007 eng d a1381-116900aTungstophosphoric acid supported over zirconia in mesoporous channels of MCM-41 as catalyst in veratrole acetylation0 aTungstophosphoric acid supported over zirconia in mesoporous cha aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB a98-1080 v2623 a

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.

10aacetoveratrone10aacetylation10aMCM-4110aTPA/ZrO210averatrole1 aSawant, Dhanashri, P.1 aVinu, A.1 aLefebvre, F.1 aHalligudi, Shivaraj, B. uhttps://library.ncl.res.in/content/tungstophosphoric-acid-supported-over-zirconia-mesoporous-channels-mcm-41-catalyst-veratrole01641nas a2200253 4500008004100000022001400041245010000055210006900155260007300224300001400297490000600311520074000317653002101057653001401078653002401092653001201116653001401128100002501142700002301167700002101190700001901211700002801230856012901258 2008 eng d a1566-736700aTitania supported silicotungstic acid: an efficient solid acid catalyst for veratrole acylation0 aTitania supported silicotungstic acid an efficient solid acid ca aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUN a2026-20290 v93 a

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.

10aacetic anhydride10aAcylation10aSilicotungstic acid10atitania10averatrole1 aWaghmare, Nilesh, G.1 aKasinathan, Palraj1 aAmrute, Amol, P.1 aLucas, Nishita1 aHalligudi, Shivaraj, B. uhttps://library.ncl.res.in/content/titania-supported-silicotungstic-acid-efficient-solid-acid-catalyst-veratrole-acylation-0