02150nas a2200337 4500008004100000022001400041245009600055210006900151260007700220300001400297490000600311520104700317653001101364653002801375653001501403653002001418653001301438100001901451700001501470700001801485700001801503700002101521700001601542700002001558700002301578700002801601700001601629700001401645700002401659856012901683 2012 eng d a1867-388000aOne-pot sol-gel preparation for efficient cobalt-molybdenum-titania hydrotreating catalysts0 aOnepot solgel preparation for efficient cobaltmolybdenumtitania  aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcDEC a2112-21200 v43 a

Titania-based hydrodesulfurization catalysts were prepared by using a one-pot solgel method with the titanium peroxo complex as titanium precursor and molybdenum and cobalt precursors dissolved in the aqueous hydrogen peroxide solution used during synthesis. Catalysts with MoO3 loadings varying from 5 to 40 wt?% and a Co/Mo atomic ratio of 0.5 were prepared. Solids with molybdenum loadings below 20 wt?% MoO3 demonstrated poor hydrodesulfurization activity for the model compound thiophene. This was attributed to the presence of a large amount of embedded cobalt and molybdenum species in the titania matrix. A significant increase in the catalytic activity was observed for solids containing 20 and 25 wt?% of MoO3 on which active species appeared to be accessible on the titania surface. Furthermore, the highest conversion obtained on these solgel solids was superior to the highest conversion obtained on reference catalysts prepared through the impregnation of ammonium heptamolybdate and cobalt nitrate on commercial titania.

10acobalt10aheterogeneous catalysis10aMolybdenum10asol-gel process10atitanium1 aNguyen, D., L.1 aGillot, S.1 aSouza, D., O.1 aBlanchard, P.1 aLamonier, Carole1 aBerrier, E.1 aKotbagi, T., V.1 aDongare, Mohan, K.1 aUmbarkar, Shubhangi, B.1 aCristol, S.1 aPayen, E.1 aLancelot, Christine uhttps://library.ncl.res.in/content/one-pot-sol-gel-preparation-efficient-cobalt-molybdenum-titania-hydrotreating-catalysts-001686nas a2200325 4500008004100000022001400041245008800055210006900143260007700212300001400289490000600303520057400309653002800883653001600911653001400927653002200941653002400963100002000987700002201007700002401029700002101053700003101074700001501105700002001120700003101140700002801171700002301199700002201222856011601244 2012 eng d a1864-563100aTransesterification of diethyl oxalate with phenol over sol-gel MoO3/TiO2 catalysts0 aTransesterification of diethyl oxalate with phenol over solgel M aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUL a1467-14730 v53 a

The transesterification of diethyl oxalate (DEO) with phenol to form diphenyl oxalate (DPO) has been carried out in the liquid phase over very efficient MoO3/TiO2 solid-acid solgel catalysts. A selectivity of 100?% with a remarkable maximum yield of 88?% were obtained, which opens the route to downstream phosgene-free processes for the synthesis of polycarbonates. Interpretation of the results of various acidity measurements (NH3 and pyridine desorption, methanol oxidation as a probe reaction) allowed us to identify the catalytic sites as Lewis acid sites.

10aheterogeneous catalysis10aLewis acids10aOxidation10asol-gel processes10atransesterification1 aKotbagi, Trupti1 aNguyen, Duy, Luan1 aLancelot, Christine1 aLamonier, Carole1 aThavornprasert, Kaew-Arpha1 aWenli, Zhu1 aCapron, Mickael1 aJalowiecki-Duhamel, Louise1 aUmbarkar, Shubhangi, B.1 aDongare, Mohan, K.1 aDumeignil, Franck uhttps://library.ncl.res.in/content/transesterification-diethyl-oxalate-phenol-over-sol-gel-moo3tio2-catalysts-002485nas a2200241 4500008004100000022001400041245014800055210006900203260007700272300001400349490000600363520154400369653002901913653002801942653001501970653001201985653002201997100002402019700002402043700002802067700002302095856012502118 2013 eng d a1867-388000aIsolation, characterization, and identification of catalytically active species in the MoO3/SiO2 catalyst during solid acid catalyzed reactions0 aIsolation characterization and identification of catalytically a aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUN a1531-15370 v53 a

We report the isolation, characterization, and identification of the catalytically active species formed during various acid-catalyzed reactions if silica-supported MoO3 was used as a catalyst. We have reported previously the synthesis and extensive characterization of the silica-supported MoO3 catalyst prepared by the sol-gel process with ammonium heptamolybdate and ethyl silicate-40 as molybdenum and silica precursors, respectively. The TEM images showed uniformly distributed MoO3 nanoparticles on the high-surface area mesoporous silica support and high acidity (0.9mmolg-1) by using temperature-programmed desorption of ammonia (NH3-TPD) analysis. This catalyst has already shown high activity for various acid-catalyzed reactions. To understand the nature of catalytically active species formed during the reaction, the liquid-phase esterification of acetic acid and ethanol was studied as a probe reaction with very high acid conversion (83%) in 8h. During esterification, the reaction mixture turned blue, which indicated a change in the nature of the catalyst under reaction conditions. These catalytically active species formed in the reaction mixture were isolated and extensively characterized by using FTIR, Raman, powder XRD, BET surface area, NH3-TPD, energy dispersive X-ray, and TEM analysis. The characterization results revealed the insitu formation of silicomolybdic acid on the silica surface in the presence of water, which acts as catalytically active species responsible for the acid-catalyzed reactions.

10aesterification reactions10aheterogeneous catalysis10aMolybdenum10asilicon10asol-gel processes1 aKotbagi, Trupti, V.1 aBiradar, Ankush, V.1 aUmbarkar, Shubhangi, B.1 aDongare, Mohan, K. uhttps://library.ncl.res.in/content/isolation-characterization-and-identification-catalytically-active-species-moo3sio2-002686nas a2200229 4500008004100000022001400041245011300055210006900168260007300237300001200310490000800322520181200330653002302142653002802165653001902193653002202212653002302234100001802257700002302275700002802298856013002326 2016 eng d a0926-337300aSol-gel synthesised WO3 nanoparticles supported on mesoporous silica for liquid phase nitration of aromatics0 aSolgel synthesised WO3 nanoparticles supported on mesoporous sil aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR a142-1520 v1823 a

A series of WO3/SiO2 catalysts have been prepared by sol-gel method using ammonium metatungstate and ethyl silicate-40 (ES-40) as WO3 and SiO2 precursors respectively. The sol-gel method has led to the formation of WO3 nano-particles of 2-5 nm well dispersed on mesoporous silica along with some WO3' agglomerates. Formation of monoclinic WO3 was seen on the catalysts above 5 wt% WO3 loading by XRD analysis. Silica has shown very high surface area of 606 m(2)/g which decreased gradually upto 368 m(2)/g with 20 wt% WO3 loading. 20 wt% WO3/SiO2 catalyst has shown maximum acidity (0.56 mmol NH3/g) with presence of both Lewis and Bronsted acidity. UV-vis DRS analysis showed formation of polytungstate species along with WO3 on silica surface. The prepared catalysts were used for liquid phase nitration of aromatics using 70% nitric acid as nitrating agent without using any sulfuric acid. Very high conversion (99%) was obtained for p-cresol nitration with very high selectivity (99%) for 2-nitro p-cresol. The water formed during the reaction was removed azeotropically using ethylene dichloride as solvent. In case of o-xylene 74% conversion was obtained with 54% selectivity for 4-nitro o-xylene. The effect of different WO3 precursors on nitration efficiency was studied using sodium tungstate and tungstic acid as precursors. However,ammonium metatungstate showed the highest acidity. Sodium tungstate showed formation of dimer of sodium tungstate which did not show any acidity and hence no activity for nitration. The mechanism for nitration using WO3/SiO2 has been proposed based on polarisation of water on tungsten centre generating Bronsted acidity which can further generate nitronium ion giving subsequently nitration of the aromatic ring. (C) 2015 Elsevier B.V. All rights reserved.

10aAromatic nitration10aheterogeneous catalysis10aRegioselective10aSol-gel synthesis10aWater polarization1 aKulal, A., B.1 aDongare, Mohan, K.1 aUmbarkar, Shubhangi, B. uhttps://library.ncl.res.in/content/sol-gel-synthesised-wo3-nanoparticles-supported-mesoporous-silica-liquid-phase-nitration-002487nas a2200253 4500008004100000022001400041245008100055210006900136260000800205300001200213490000800225520170000233653002301933653001301956653002801969653001601997653002202013100001802035700001902053700001902072700002002091700002102111856010102132 2019 eng d a0926-860X00aHydrophobic WO3/SiO2 catalyst for the nitration of aromatics in liquid phase0 aHydrophobic WO3SiO2 catalyst for the nitration of aromatics in l cMAR a105-1130 v5743 a

WO3/SiO2 solid acid catalyst synthesized using sol gel method has shown promising activity (up to 65% conversion) for aromatic nitration in liquid phase using commercial nitric acid (70%) as nitrating agent without using any sulfuric acid. The water formed during the reaction as well as water from dilute nitric acid (70%) was removed azeotropically, however due to the hydrophilic nature of the catalyst, some water gets strongly adsorbed on catalyst surface forming a barrier layer between catalyst and organics. This prevents effective adsorption of substrate on catalyst surface for its subsequent reaction. To improve the activity further, the hydrophilic/hydrophobic nature of the catalyst was altered by post modification by grafting with commercial short chain organosilane (Dynasylan 9896). The modified 20% WO3/SiO2 catalyst when used for o-xylene nitration in liquid phase, showed significant increase in the conversion from 65% to 80% under identical reaction conditions. Catalyst characterization revealed decrease in the surface area of 20% WO3/SiO2 from 356 m(2)/g to 302 m(2)/g after grafting with Dynasylan 9896. The fine dispersion of WO3 particles (2-5 run) on silica support was not affected due to modification. NMR and FTIR study revealed the decrease in surface hydroxyl groups imparting hydrophobicity to the catalyst. Interestingly the total acidic sites of the catalyst remained almost unaltered (0.54 mmol NH3/g) even after modification. Even though, the acidity and other characteristics of the catalyst did not change appreciably, there was a considerable increase in the o-xylene conversion which can be ascribed to the hydrophobic nature of the catalyst.

10aAromatic nitration10agrafting10aheterogeneous catalysis10aHydrophobic10aSol-gel synthesis1 aKulal, A., B.1 aKasabe, M., M.1 aJadhav, P., V.1 aDongare, M., K.1 aUmbarkar, S., B. uhttps://library.ncl.res.in/content/hydrophobic-wo3sio2-catalyst-nitration-aromatics-liquid-phase