02169nas a2200229   4500008004100000022001400041245008000055210006900135260007300204300001200277490000800289520135800297653002001655653002101675653001401696653002201710653002401732100002401756700002801780700002301808856010801831       2005                        eng d  a0926-860X00aTransesterification of diethyl oxalate with phenol using MoO3/SiO2 catalyst0 aTransesterification of diethyl oxalate with phenol using MoO3SiO  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY  a190-1950 v2853 a<p>Transesterification of diethyl oxalate (DEO) with phenol to form diphenyl oxalate (DPO) has been carried out in liquid phase using MoO3/ SiO2 solid acid catalyst with high conversion and 100% selectivity. A series Of MoO3/SiO2 catalysts with different Mo loadings (1-20 wt%) were prepared using sol-gel technique and characterized using X-ray diffraction analysis (XRD), BET specific surface area, temperature-programmed desorption (TPD) of ammonia, and FTIR spectroscopic analysis of adsorbed pyridine. XRD analysis revealed the amorphous nature of the catalyst up to 10 wt% MoO3 loading and the formation of crystalline α-MoO3 phase on amorphous silica support with higher MoO3 loading. BET surface area showed high surface area for catalysts prepared by sol-gel technique with lower MoO3 content; the surface area decreases with increasing MoO3 loading. Ammonia TPD shows much higher acid strength compared to the catalysts prepared by impregnation technique. Among the series of catalysts prepared, MoO3/SiO2 containing 1 wt% MoO3 was found to be the most active catalyst for transesterification reaction, with a maximum DEO conversion of 80.9 and 100% selectivity for DPO. The effects of reaction temperature and catalyst concentration on conversion and product selectivity have been investigated. © 2005 Elsevier B.V. All rights reserved.</p>10adiethyl oxalate10adiphenyl oxalate10aMoO3/SiO210asol-gel technique10atransesterification1 aBiradar, Ankush, V.1 aUmbarkar, Shubhangi, B.1 aDongare, Mohan, K.  uhttps://library.ncl.res.in/content/transesterification-diethyl-oxalate-phenol-using-moo3sio2-catalyst-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<p>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.</p>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-002340nas a2200157   4500008004100000245013300041210006900174260000800243300001400251490000700265520171600272100002001988700002802008700002302036856012302059       2016                        eng d00aTemplate-free sol-gel synthesis of high surface area mesoporous silica based catalysts for esterification of di-carboxylic acids0 aTemplatefree solgel synthesis of high surface area mesoporous si  cOCT  a1247-12530 v193 aHigh surface area mesoporous silica based catalysts have been prepared by a simple hydrolysis/sol-gel process without using any organic template and hydrothermal treatment. A controlled hydrolysis of ethyl silicate-40, an industrial bulk chemical, as a silica precursor, resulted in the formation of very high surface area (719 m(2)/g) mesoporous (pore size 67 angstrom and pore volume 1.19 cc/g) silica. The formation of mesoporous silica has been correlated with the polymeric nature of the ethyl silicate-40 silica precursor which on hydrolysis and further condensation forms long chain silica species which hinders the formation of a close condensed structure thus creating larger pores resulting in the formation of high surface mesoporous silica. Ethyl silicate-40 was used further for preparing a solid acid catalyst by supporting molybdenum oxide nanoparticles on mesoporous silica by a simple hydrolysis sol gel synthesis procedure. The catalysts showed very high acidity as determined by NH3-TPD with the presence of Lewis as well as Brensted acidity. These catalysts showed very high catalytic activity for esterification: a typical acid catalyzed organic transformation of various mono- and di-carboxylic acids with a range of alcohols. The in situ formed silicomolybdic acid heteropoly-anion species during the catalytic reactions were found to be catalytically active species for these reactions. Ethyl silicate-40, an industrial bulk silica precursor, has shown a good potential for its use as a silica precursor for the preparation of mesoporous silica based heterogeneous catalysts on a larger scale at a lower cost. (C) 2016 Published by Elsevier Masson SAS on behalf of Academie des sciences.1 aMore, Pavan, M.1 aUmbarkar, Shubhangi, B.1 aDongare, Mohan, K.  uhttps://library.ncl.res.in/content/template-free-sol-gel-synthesis-high-surface-area-mesoporous-silica-based-catalysts