01505nas a2200265 4500008004100000022001400041245013700055210006900192260007300261300001400334490000600348520052600354653001600880653002300896653002100919653001500940653003500955653000800990100002200998700001901020700001901039700002401058700002901082856012801111 2008 eng d a1566-736700aPhosphotungstic acid on silica with modified acid sites as a solid catalyst for selective cleavage of tert-butyldimethylsilyl ethers0 aPhosphotungstic acid on silica with modified acid sites as a sol aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY a1863-18680 v93 a

The strength and nature of acid sites of bulk phosphotungstic acid could be modified after dispersing it on silica support which was characterized by XRD, ammonia TPD and (31)P MAS NMR techniques. This solid acid catalyst was found to be highly selective for the cleavage of tert-butyldimethylsilyl ethers at room temperature. The catalyst was easily recovered by filtration and could be reused for several times without loss of any activity giving a TON of 9.5 x 10(5). (C) 2008 Elsevier B.V. All rights reserved.

10aAmmonia TPD10aCatalytic cleavage10areaction pathway10asolid acid10atert-butyldimethylsilyl ethers10aXRD1 aBhure, Mahesh, H.1 aKumar, Indresh1 aNatu, Arun, D.1 aChikate, Rajeev, C.1 aRode, Chandrashekhar, V. uhttps://library.ncl.res.in/content/phosphotungstic-acid-silica-modified-acid-sites-solid-catalyst-selective-cleavage-tert-002433nas a2200277 4500008004100000022001400041245009000055210006900145260000800214490000600222520155000228653002201778653002301800653002301823653003201846653002101878653001701899653001501916100002101931700001701952700001701969700001701986700002102003700001702024856011402041 2017 eng d a2190-553300aCarbonylation of glycerol with urea to glycerol carbonate over supported Zn catalysts0 aCarbonylation of glycerol with urea to glycerol carbonate over s cAPR0 v73 a

Glycerol carbonylation with urea is a very feasible option to produce glycerol carbonate with a net result of CO2 fixation through urea synthesis. The prerequisite of an efficient catalyst for this reaction is to possess both acid and basic sites together. Several acidic supports were screened for ZnO catalyst in this work and Zn/MCM-41 was found to exhibit the best activity and almost complete selectivity to glycerol carbonate (GC). Although, non-catalytic glycerol carbonylation resulted in GC formation but glycerol conversion achieved was twice with Zn/MCM-41 as a catalyst. Further to that increase in Zn loading from 2 to 5% resulted in increase in glycerol conversion from 63 to 82%. The prepared catalysts were characterized by XRD, NH3 and CO2-TPD and effects of reaction parameters such as catalyst loading, glycerol to urea mole ratio and temperature on glycerol conversion and GC selectivity in batch mode of operation were also studied. Time on stream activity of 5% Zn/MCM-41 catalyst for continuous carbonylation of glycerol was also studied for ~100 h with an average conversion of ~55% and complete selectivity to GC. This indicated five times lower productivity of GC per h due to lower residence time than that in a batch operation as compared to that of a continuous operation. Activation energy estimated from the Arrhenius plot was found to be 39.82 kJ mol−1 suggesting that the reaction is kinetically controlled. A reaction pathway mediated by acid and basic sites of the Zn/MCM-41 catalyst is also proposed.

10aAcid–base ratio10aContinuous process10aGlycerol carbonate10aGlycerol-urea carbonylation10areaction pathway10aSupported Zn10aZn loading1 aKondawar, S., E.1 aMane, R., B.1 aVasishta, A.1 aMore, S., B.1 aDhengale, S., D.1 aRode, C., V. uhttps://library.ncl.res.in/content/carbonylation-glycerol-urea-glycerol-carbonate-over-supported-zn-catalysts02147nas a2200217 4500008004100000022001400041245016000055210006900215260000800284300001600292490000800308520134400316653001701660653002301677653001101700653002101711653002901732100002201761700002201783856012401805 2020 eng d a2468-823100aUnderstanding the influence of alumina supported ruthenium catalysts synthesis and reaction parameters on the hydrodeoxygenation of lignin derived monomers0 aUnderstanding the influence of alumina supported ruthenium catal cJAN aUNSP 1105250 v4803 a

Up-gradation of lignin derived monomers to value-added and fuel grade products is important to make overall bio-refinery process economical. Although, few studies are devoted on this work yet, systematic study on commercially viable (low loading of metal, recyclable catalyst, mild conditions, high selectivities etc.) is scarce and typically done under harsh conditions. Herein, we report, the methodical effect of support (SiO2, Al2O3 (acidic, basic and neutral), SiO2-Al2O3) on the hydrodeoxygenation (HDO) of lignin derived various monomers, guaiacol, veretrol, eugenol, phenol using very low loading (0.5 wt%) Ru catalyst. Very high yield (82%) of cyclohexanol from guaiacol could be achieved in presence of cyclohexane as a solvent and Ru/Al2O3-Acidic catalyst at 225 degrees C and under 1 MPa H-2 pressure. The detailed study on the effect of solvent, stability and adsorption of reactant & products etc. is done and it was observed that products are more prone to adsorb and undergo further reactions. The complete characterization of fresh and spent catalysts revealed that lower catalyst reduction temperature and presence of Ru in partially higher oxidation state proved by XPS, helps in enhancing the cyclohexanol formation. Subsequently, role of Ru particle size and support on the activity was also investigated.

10aCyclohexanol10aHydrodeoxygenation10alignin10areaction pathway10asupported metal catalyst1 aSingh, Dheerendra1 aDhepe, Paresh, L. uhttps://library.ncl.res.in/content/understanding-influence-alumina-supported-ruthenium-catalysts-synthesis-and-reaction