01720nas a2200265   4500008004100000022001400041245010200055210006900157260008600226300001200312490000800324520073800332653004201070653003001112653002101142653001501163653002401178653002801202653002701230653002001257100001501277700001601292700001701308856012901325       2005                        eng d  a0942-935200aTi-oxo radicals and product selectivity in olefin oxidations over titanosilicate molecular sieves0 aTioxo radicals and product selectivity in olefin oxidations over  aLEKTORAT MINT, POSTFACH 80 13 60, D-81613 MUNICH, GERMANYbOLDENBOURG VERLAGcJUL  a905-9200 v2193 a<p>The O-O bond of Ti-oxo species (Ti-peroxo, Ti-hydroperoxo or Ti-superoxo) generated on titanosilicate molecular sieves contacted with H2O2 cleaves either heterolytically or homolytically. While the former type of O-O cleavage (generating non-radical reactive oxygen intermediates) leads to selective epoxide products, the latter (generating reactive oxygen radical intermediates, O-2(-center dot) and HOOcenter dot) results in non-sclective, allylic oxidation products in cyclohexene oxidation. These radicals were detected using EPR spin trapping techniques 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used as the spin trap. Radical quenchers like hydroquinone suppressed their concentration and enhanced epoxide selectivity.</p>10acyclic voltammetry of titanosilicates10aEPR-spin trap experiments10aMolecular sieves10aoxidations10aproduct selectivity10areactive oxygen species10atitaniunz-oxo radicals10aTitanosilicates1 aShetti, VN1 aSrinivas, D1 aRatnasamy, P  uhttps://library.ncl.res.in/content/ti-oxo-radicals-and-product-selectivity-olefin-oxidations-over-titanosilicate-molecular-002449nas a2200229   4500008004100000022001400041245009600055210006900151260011700220300000900337490000800346520152700354653001301881653004301894653002501937653002401962653002001986653004102006100002002047700002102067856013102088       2009                        eng d  a0920-586100aSelective oxidations over zeolite- and mesoporous silica-based catalysts: selected examples0 aSelective oxidations over zeolite and mesoporous silicabased cat  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbCatalysis Soc India; Petrotech Soc; Indo US Sci & Technol ForumcMAR  a3-110 v1413 a<p>Selective oxidation of hydrocarbons/terpenes in the liquid phase are reported over three categories of zeolite- and mesoporous silica-based catalysts: (1) transition metal complexes (metal phthalocyanines, copper acetate dimers and Co/Mn acetate trimer) encapsulated in zeolite-Y, (2) transition metal complexes (Mn-Salen), grafted on SBA-15, and (3) transition metal ions in framework positions of zeolites and mesoporous molecular sieves like Ti-silicates. Upon heterogenization, the metal complexes exhibited enhanced catalytic acitivity/selectivity. The causes for the enhanced catalytic activity/product selectivity have been explored. Dimer formation (copper acetate) or geometric distortion in the zeolite cavities (metal phthalocyanines) and consequent changes in energy levels and redox potentials are shown to modify the catalytic activity (in the selective oxidation of hydrocarbons) of the encapsulated metal complexes. In the case of Mn-Salen grafted on SBA-15, increasing the acidity of the siliceous surface (by -SO(3)H groups, for example) leads to a more facile reduction of the Mn ions and, thereby, enhanced catalytic activity in the selective epoxidation of limonene. When Ti ions are introduced in framework positions, reactive metal-oxo species are formed on contact with H(2)O(2) or O(2), Which influence the mode of O-O cleavage (heterolytic/homolytic) and product selectivity. The structure-function relationships in these catalysts are reported. (c) 2008 Elsevier B.V. All rights reserved.</p>10aMn-Salen10aOxidation of hydrocarbons and limonene10aReactive oxo species10aSelective oxidation10aTitanosilicates10aZeolite-encapsulated metal complexes1 aRatnasamy, Paul1 aSrinivas, Darbha  uhttps://library.ncl.res.in/content/selective-oxidations-over-zeolite-and-mesoporous-silica-based-catalysts-selected-examples-002000nas a2200241   4500008004100000022001400041245014400055210006900199260007300268300001000341490000800351520108600359653003401445653002501479653002101504653002401525653001401549653001401563653002001577100001601597700002101613856012401634       2012                        eng d  a0920-586100aSelective oxidation of cyclic olefins over framework Ti-substituted, three-dimensional, mesoporous Ti-SBA-12 and Ti-SBA-16 molecular sieves0 aSelective oxidation of cyclic olefins over framework Tisubstitut  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC  a59-680 v1983 a<p>Framework Ti-substituted, three-dimensional, mesoporous titanosilicates, Ti-SBA-12 and Ti-SBA-16, were prepared by direct hydrothermal synthesis method. These catalysts showed catalytic activity higher than the hitherto known titanosilicates for the oxidation of cyclic olefins (cyclohexene and cyclooctene) with tert.-butyl hydroperoxide. An epoxide selectivity of 100% and olefin conversion greater than 92% were obtained. Cubic Ti-SBA-16 with interconnected cage-like mesopore structure was more active than hexagonal Ti-SBA-12. X-ray diffraction and diffuse reflectance UV-vis, Fourier transform infrared, Raman and electron paramagnetic resonance spectroscopies provided evidence for the substitution of Ti4+ (for Si4+) in the framework locations. The catalytic activity correlated with the concentration of framework-substituted, tetrahedral Ti4+ ions. Easy accessibility of the active sites and the three-dimensional mesoporous structure are the possible causes for the superior activity of these titanosilicate catalysts. (C) 2012 Elsevier B. V. All rights reserved.</p>10aEpoxidation of cyclic olefins10amesoporous materials10aMolecular sieves10aSelective oxidation10aTi-SBA-1210aTi-SBA-1610aTitanosilicates1 aKumar, Anuj1 aSrinivas, Darbha  uhttps://library.ncl.res.in/content/selective-oxidation-cyclic-olefins-over-framework-ti-substituted-three-dimensional-001769nas a2200253   4500008004100000022001400041245010500055210006900160260007300229300001000302490000800312520087000320653001401190653003301204653002501237653002501262653001401287653001401301653002001315100002301335700001601358700002101374856012001395       2013                        eng d  a1381-116900aThree-dimensional, mesoporous titanosilicates as catalysts for producing biodiesel and biolubricants0 aThreedimensional mesoporous titanosilicates as catalysts for pro  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcOCT  a65-730 v3773 a<p>The application of three-dimensional, mesoporous titanosilicates, Ti-SBA-12 and Ti-SBA-16, as reusable solid acid catalysts for producing biodiesel and biolubricants is reported for the first time. Biodiesel was prepared by esterification of oleic acid with monohydric methanol and biolubricants by esterification with polyhydric alcohols (glycerol, trimethylolpropane, neopentyl glycol and pentaerythritol). High catalytic activity of these catalysts is attributed to the presence of dispersed Lewis acidic Ti sites and mesoporosity in the structure. Biodiesel yields as high as 90 mol% were obtained at 443 K. Surface hydrophobicity of the catalyst has also a predominant role, especially, in reactions involving polyhydric alcohols. In those reactions, Ti-SBA-16 showed higher catalytic activity than Ti-SBA-12. (c) 2013 Elsevier B.V. All rights reserved.</p>10aBiodiesel10aEsterification of fatty acid10aLubricant basestocks10amesoporous materials10aTi-SBA-1210aTi-SBA-1610aTitanosilicates1 aKotwal, Mehejabeen1 aKumar, Anuj1 aDarbha, Srinivas  uhttps://library.ncl.res.in/content/three-dimensional-mesoporous-titanosilicates-catalysts-producing-biodiesel-and-001588nas a2200229   4500008004100000022001400041245016600055210006900221260000800290300001100298490000800309520073100317653002201048653003001070653003801100653002101138653002001159100001701179700001801196700001801214856012601232       2021                        eng d  a2468-823100aRole of metal-support interaction for atmospheric pressure CO2 hydrogenation over Pd/(Ti)-SBA-15 catalyst: effect of titanium composition on products selectivity0 aRole of metalsupport interaction for atmospheric pressure CO2 hy  cJUL  a1117320 v5113 aThe potential role of metal-support interaction for tuning the product selectivity during atmospheric pressure CO2 hydrogenation has been demonstrated on Pd/(Ti)-SBA-15 catalyst. Highly dispersed Pd NPs on SBA-15 (Pd/ SBA-15) was synthesized and further modified with titanium of varying composition. Comparison of catalytic activity of Pd/Ti-SBA-15 with its counterparts (Pd/SBA-15 and Pd/TiO2) illustrated the significance of strong PdTi interface in this catalyst and its role in tuning the product selectivity of CO2 hydrogenation. The generation of an ample amount of oxygen vacancies in the Pd/Ti-SBA-15 catalyst with maximum metallic Pd sites in close vicinity of Ti is proposed to boost the CO2 hydrogenation activity.10aCO2 hydrogenation10aMetal-support interaction10aModified deposition precipitation10aoxygen vacancies10aTitanosilicates1 aSoni, Yogita1 aGupta, Sharad1 aVinod, C., P.  uhttps://library.ncl.res.in/content/role-metal-support-interaction-atmospheric-pressure-co2-hydrogenation-over-pdti-sba-15