02480nas a2200217 4500008004100000022001400041245020600055210006900261260009500330300001000425490000800435520158100443653001102024653002202035653001402057653001502071653001302086100001602099700001802115856012902133 2006 eng d a0021-951700aHeterogenized vanadyl cations over modified silica surfaces: a comprehensive understanding toward the structural property and catalytic activity difference over mesoporous and amorphous silica supports0 aHeterogenized vanadyl cations over modified silica surfaces a co a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcNOV a52-640 v2443 a

Using a postsynthesis grafting method, 3-aminopropyltriethoxysilane (3-APTS) was functionalized over silica gel and mesoporous silica materials like SBA-15 and MCM-41. Vanadyl cations were then immobilized over the functionalized amino groups of the silica samples and used as a catalyst in the liquid-phase oxidation reaction of cyclohexane. Elemental analysis, PXRD, TEM, N-2 adsorption-desorption isotherms, FTIR, C-13 and Si-29 MAS NMR, UV-vis, and EPR techniques were used to characterize the developed materials. Characterization results suggest that the percentage of 3-APTS grafting depends on the number of isolated and genlinal silanol sites of the support material, the solvents used during the grafting reactions, and the sample pretreatment conditions. We found that using toluene as the dispersing medium and Si-MCM-41 as a support provides the maximum amount of amine functionalization, and thereby the highest percentage of vanadium immobilization. Catalytic activity and metal leaching studies show that vanadium-immobilized mesoporous solids are more active and stable than the silica gel-functionalized vanadium catalyst and a framework-substituted V-MCM-41 catalyst. The enhanced activity and stability of the immobilized vanadium catalysts compared with the V-MCM-41 and silica gel samples are attributed to the active metal site isolations, as well as to the spatial restrictions imparted from the concave silica surfaces of the mesoporous solids rather than the convex silica surfaces of the silica gel sample. (c) 2006 Published by Elsevier Inc.

10a3-APTS10amesoporous solids10aOxidation10aSilica gel10aVanadium1 aShylesh, S.1 aSingh, A., R. uhttps://library.ncl.res.in/content/heterogenized-vanadyl-cations-over-modified-silica-surfaces-comprehensive-understanding-002058nas a2200241 4500008004100000022001400041245009300055210006900148260009900217300001200316490000800328520118700336653002701523653002201550653001301572653001501585653001601600100001901616700001901635700001901654700001901673856012401692 2013 eng d a0016-236100aInfluence of contact medium and surfactants on carbon dioxide clathrate hydrate kinetics0 aInfluence of contact medium and surfactants on carbon dioxide cl aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAR a664-6710 v1053 a

Carbon dioxide (CO2) hydrate formation kinetic was investigated in a fixed bed crystallizer at constant pressure (3.55 MPa) and temperature (274 K). Porous media of three different silica gels were used, with a mesh size of 60-120, 100-200 and 230-400 having different surface area. The observed trends indicate that silica gel with larger surface area leads to higher gas consumption as well as reduces the induction time. The effect of pore diameter and particle size distribution has already been reported in a previous study [1]. In this study the effect of additives on hydrate formation kinetics were also investigated. The additives studied were nonionic surfactant Tween-80 (T-80), cationic dodecyltrimethylammonium chloride (DTACl) and anionic Sodium Dodecyl Sulphate (SDS). Out of the three surfactants used in this study, SDS was found to be most effective in enhancing the rate of hydrate formation as well as reducing the induction time. The current result shows significant improvement in water to hydrate conversion in silica gel media compared to quiescent water or surfactant-water system under similar conditions. (C) 2012 Elsevier Ltd. All rights reserved.

10aCarbon dioxide capture10aClathrate hydrate10akinetics10aSilica gel10aSurfactants1 aKumar, Asheesh1 aSakpal, Tushar1 aLinga, Praveen1 aKumar, Rajnish uhttps://library.ncl.res.in/content/influence-contact-medium-and-surfactants-carbon-dioxide-clathrate-hydrate-kinetics-001635nas a2200265 4500008004100000022001400041245010100055210006900156260007300225300001000298490000800308520069500316653001401011653001301025653002501038653001501063653001401078653002201092100002901114700002701143700002401170700001901194700002401213856013201237 2014 eng d a0926-860X00aRegioselective acylation of 2-methoxy naphthalene catalyzed by supported 12-phosphotungstic acid0 aRegioselective acylation of 2methoxy naphthalene catalyzed by su aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcSEP a55-610 v4863 a

12-Phosphotungstic acid supported on silica gel, zirconium sulfate, and a combination of silica gel and zirconium sulfate (50% w/w) were employed as solid acid catalysts for regioselective acylation of 2-methoxynaphtalene with acetic anhydride. 1-(6-Methoxynaphthalen-2-yl)ethanone (2,6-AMN), a commercially important intermediate for production of Naproxen, was obtained with excellent selectivity (>98%) at 67-68% conversion using 12-phosphotungstic acid supported on silica gel 20% (w/w) in refluxing tetrachloroethane. The unreacted starting material can be easily separated from the product by a simple crystallization from nonane. (C) 2014 Elsevier B.V. All rights reserved.

10aAcylation10aNaproxen10aPhosphotungstic acid10aSilica gel10aSupported10aZirconium sulfate1 aKumaraguru, Thenkrishnan1 aDevi, Ayala, Vedamayee1 aSiddaiah, Vidavalur1 aRajdeo, Kishor1 aFadnavis, Nitin, W. uhttps://library.ncl.res.in/content/regioselective-acylation-2-methoxy-naphthalene-catalyzed-supported-12-phosphotungstic-acid-002177nas a2200301 4500008004100000022001400041245012500055210006900180260000900249300001100258490000800269520115900277653004601436653002701482653002401509653002201533653002001555653001601575653001301591653001301604653001501617100001601632700001901648700002601667700002901693700002201722856013101744 2021 eng d a0195-073800aHydrate-based carbon capture process: assessment of various packed bed systems for boosted kinetics of hydrate formation0 aHydratebased carbon capture process assessment of various packed cMAR  a0330050 v1433 a

The case for developing novel technologies for carbon dioxide (CO2) capture is fast gaining traction owing to increasing levels of anthropogenic CO2 being emitted into the atmosphere. Here, we have studied the hydrate-based carbon dioxide capture and separation process from a fundamental viewpoint by exploring the use of various packed bed media to enhance the kinetics of hydrate formation using pure CO2 as the hydrate former. We established the fixed bed reactor (FBR) configuration as a superior option over the commonly used stirred tank reactor (STR) setups typically used for hydrate formation studies by showing enhanced hydrate formation kinetics using the former. For the various packing material studied, we have observed silica gel with 100 nm pore size to return the best kinetic performance, corresponding to a water to hydrate conversion of 28 mol% for 3 h of hydrate growth. The fundamental results obtained in the present study set up a solid foundation for follow-up works with a more applied perspective and should be of interest to researchers working in the carbon dioxide capture and storage and gas hydrate fields alike.

10aair emissions from fossil fuel combustion10aCarbon dioxide capture10acombustion of waste10aFixed bed reactor10afuel combustion10aGas hydrate10ahydrates10akinetics10aSilica gel1 aArora, Amit1 aKumar, Asheesh1 aBhattacharjee, Gaurav1 aBalomajumder, Chandrajit1 aKumar, Pushpendra uhttps://library.ncl.res.in/content/hydrate-based-carbon-capture-process-assessment-various-packed-bed-systems-boosted-kinetics