http://nopr.niscair.res.in/handle/123456789/5053 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/5198 Title: Liquid phase non-solvent selective oxidation of styrene using aqueous hydrogen peroxide with supported 12-tungstophosphoric acid <br/> <br/>Authors: Sharma, Pankaj; Patel, Anjali <br/> <br/>Abstract: Non-solvent oxidative cleavage of styrene has been carried out over supported 12-tungstophosphoric acid with H₂O₂. The present catalysts show very high conversion and selectivity towards benzaldehyde, an important product used as intermediate in many synthetic preparations. Further, the catalytic activity of calcinated catalysts has also been evaluated under optimized conditions. The present study shows the best catalysts to be PWA₃/Z and PWA₃/A with PWA₃/A thermally more stable than PWA₃/Z.<b style=""><i></i></b> <br/> <br/>Page(s): 964-968 http://nopr.niscair.res.in/handle/123456789/5197 Title: Kinetics and mechanism of palladium(II) catalysed oxidation of dimethyl sulfoxide by alkaline periodate <br/> <br/>Authors: Koli, B I; Nandibewoor, S T <br/> <br/>Abstract: The kinetics of oxidation of dimethyl sulfoxide by periodate, has been carried out in the presence of palladium(II) catalyst in alkaline medium at 298 K. The stoichiometry is [DMSO]: [IO₄^-] = 1:1. The reaction exhibits first order dependence with respect to [IO₄^-], an apparent less than unit order in [DMSO], [OH^-] and [palladium(II)] under the experimental conditions. A probable mechanism is proposed. The reaction constants involved in the different steps of the mechanism have been calculated. The activation parameters with respect to slow step of the mechanism have been computed and discussed. <br/> <br/>Page(s): 958-963 http://nopr.niscair.res.in/handle/123456789/5196 Title: Synthesis of TiO₂-SiO₂ powder and thin film photocatalysts by sol-gel method <br/> <br/>Authors: Aziz, Radhiyah Abd; Sopyan, Iis <br/> <br/>Abstract: Binary metal oxide TiO₂-SiO₂ powder and thin film photocatalysts have been synthesized via sol-gel method using tetraethoxysilane and a titanium chelate compound as the silicon and titanium precursors respectively. The physico-chemical properties of the TiO₂-SiO₂ powder and thin film<b style=""> </b>are characterized using TG-DTA, FTIR, XRD, FESEM, and UV-vis data. XRD analysis shows that the TiO₂-SiO₂ powder and thin film obtained are in fully anatase structure after calcination at 500°C, which is also confirmed by TG-DTA analysis. The FESEM picture shows that the TiO₂-SiO₂ particles in both powder and film are nano-sized spheres. The addition of low composition SiO₂ to the TiO₂ matrix suppresses the crystal growth of TiO₂ and enhances the photocatalytic performance. The photocatalytic properties have been evaluated by studies on the degradation of gaseous acetaldehyde. <br/> <br/>Page(s): 951-957 http://nopr.niscair.res.in/handle/123456789/5195 Title: Co-supported hexagonal mesoporous silicas for catalytic oxidation of 4-<i style="">t</i>-butyltoluene <br/> <br/>Authors: Yu, Weihua; Zhou, Chunhui; Fan, Yongxian; Lou, Caiying; Tong, Dongshen; Fang, Mei <br/> <br/>Abstract: Co-supported hexagonal mesoporous silicas (Co 2, 4 and 8 wt. %) have been prepared by incipient wetness impregnation, using cobalt acetate tetrahydrate as metal precursors and ethylene glycol as impregnation solvent. The materials have been characterized by XRD, N₂ adsorption-desorption isotherms and diffuse reflectance UV-vis spectroscopy. The divalent cobalt with a tetrahedral oxygen exists mainly in the calcined sample with loading Co ≤ 4 wt. %. The Co₃O₄particles have been detected in calcined 8 wt. % Co-HMS. The catalytic properties have been tested for oxidation of 4-<i style="">t</i>-butyltoluene with dioxygen in liquid phase under mild conditions. Co-HMS catalyst (8 wt. %) affords higher yield (17.6%) of 4-<i>t</i>-butylbenzaldehyde at 24.7% conversion in a reaction time of 5 h. The oxides of cobalt, especially Co₃O₄particles, are responsible for the partial oxidation of 4-<i style="">t</i>-butyltoluene. The divalent cobalt ions in tetrahedral environment in the Co-HMS catalysts are unstable during the oxidation reaction.<i style=""></i> <br/> <br/>Page(s): 946-950