http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/692 Wed, 22 May 2013 04:50:54 GMT 2013-05-22T04:50:54Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2322 Vanadia supported on ceria: Characterization and activity in liquid-phase oxidation of ethylbenzene Radhika, T; Sugunan, S Vanadia/ceria catalysts (2–10 wt% of V2O5) were prepared by wet impregnation of ammonium metavanadate in oxalic acid solution. Structural characterization was done with energy dispersive X-ray analysis (EDX), powder X-ray diffraction (XRD), BET surface area measurements, FT-IR spectroscopy and nuclear magnetic spectral analysis (51V MASNMR). XRD and 51V MASNMR results show highly dispersed vanadia species at lower loadings and the formation of CeVO4 phase at higher V2O5 loading. The catalytic activity of catalysts was conducted in liquid phase oxidation of ethylbenzene with H2O2 as oxidant. The oxidation activity is increased with loading up to 8 wt% V2O5 and then decreased with further increase in V2O5 content to 10 wt%. Different vanadia species evidenced by various techniques were found to be selective towards ethylbenzene oxidation. The CeVO4 formation associated with increased concentration of vanadia on ceria results the production of acetophenone along with 2-hydroxyacetophenone. Thu, 01 Feb 2007 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2322 2007-02-01T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2321 Influence of surface and acid properties of vanadia supported on ceria promoted with rice husk silica on cyclohexanol decomposition Radhika, T; Sugunan, S Cyclohexanol decomposition activity of supported vanadia catalysts is ascribed to the high surface area, total acidity and interaction between supported vanadia and the amorphous support. Among the supported catalysts, the effect of vanadia over various wt% V2O5 (2–10) loading indicates that the catalyst comprising of 6 wt% V2O5 exhibits higher acidity and decomposition activity. Structural characterization of the catalysts has been done by techniques like energy dispersive X-ray analysis, X-ray diffraction and BET surface area. Acidity of the catalysts has been measured by temperature programmed desorption using ammonia as a probe molecule and the results have been correlated with the activity of catalysts. Tue, 01 Aug 2006 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2321 2006-08-01T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2320 Sulfated titania mediated regioselective nitration of phenol in solid state Sunajadevi, K R; Sugunan, S Titania, sulfated titania and chromium loaded sulfated titania were prepared by sol–gel method and characterized using different technique. Phenol is nitrated regioselectively by nitric acid using chromium loaded sulfated titania catalysts. A remarkable ortho selectivity is observed in solid state nitration to yield exclusively ortho-nitrophenol. Compared to the conventional process, phenol nitration over solid acid catalyst is a clean and environment friendly process. Catalytic activity well correlates with the Brönsted acid sites of these catalysts. Thu, 01 Sep 2005 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2320 2005-09-01T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2319 Synthesis of dimethyl acetal of ketones: design of solid acid catalysts for one-pot acetalization reaction Bejoy, Thomas; Prathapan, Sreedharan; Sugunan, Sankaran The synthesis of dimethyl acetals of carbonyl compounds such as cyclohexanone, acetophenone, and benzophenone has successfully been carried out by the reaction between ketones and methanol using different solid acid catalysts. The strong influence of the textural properties of the catalysts such as acid amount and adsorption properties (surface area and pore volume) determine the catalytic activity. The molecular size of the reactants and products determine the acetalization ability of a particular ketone. The hydrophobicity of the various rare earth exchanged Mg–Y zeolites, K-10 montmorillonite clay, and cerium exchanged montmorillonite (which shows maximum activity) is more determinant than the number of active sites present on the catalyst. The optimum number of acidic sites as well as dehydrating ability of Ce3+-montmorillonite and K-10 montmorillonite clays and various rare earth exchanged Mg–Y zeolites seem to work well in shifting the equilibrium to the product side. Sun, 01 May 2005 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2319 2005-05-01T00:00:00Z