NOPR Collection:

Active sites for conversion of light paraffins into aromatics over ZSM-5 and SAPO-5 zeolites modified by zinc

2019-03-20T09:12:45Z

Title: Active sites for conversion of light paraffins into aromatics over ZSM-5 and SAPO-5 zeolites modified by zinc Authors: Kustov, L M; Kazansky, V B; Hegde, S G; Kamble, K R; Ratnasamy, P Abstract: The conversion of n-hexane into aromatics has been studied over ZSM-5 and SAPO-5 zeolites doped with zinc. Lewis acid-base centres consisting of zinc and oxide ions are shown to be the active centres for this reaction. A direct relationship is observed between the IR intensity of the Zn-H bond and the yield of aromatic hydrocarbons. Page(s): 101-103

Magnetic properties of nickel molybdena hydrodesulfurisation catalysts

2019-03-20T09:11:06Z

Title: Magnetic properties of nickel molybdena hydrodesulfurisation catalysts Authors: Alias, M O; Srinivasan, V Abstract: The gram susceptibilities and magnetic moments of oxidic nickel molybdena hydrodesulfurisation catalysts have been measured. The results show that nickel located in octahedral sites is only responsible for promoting desulfurisation of thiophene. Susceptibility measurements made with catalysts in reduced state show that highly active catalysts are relatively more susceptible to changes in paramagnetic nature occurring during reduction by hydrogen. Decrease in magnetic moment values is observed for sulfide catalysts. Page(s): 104-107

Topological investigation of mollecular interactions in ternary mixtures of non-electrolytes: excess Gibbs free energy of mixing

2019-03-20T09:10:09Z

Title: Topological investigation of mollecular interactions in ternary mixtures of non-electrolytes: excess Gibbs free energy of mixing Authors: Singh, Prem P; Maken, S; Bhatia, M Abstract: An approach is presented for evaluating excess Gibbs free energy of mixing for a ternary (i + j + k) mixture when the corresponding G^E data for the constituent binary mixtures are available. While the approach describes very well the reported G^E data for water + ethylene glycol+ ethanol and acetone + ethanol + water mixtures, it succeeds only moderately well for ethanol + trichloromethane + 1,4-dioxane mixtures. The results have been further utilized to understand the nature of molecular interactions in these ternary mixtures. Page(s): 108-112

Prediction of viscosity of multicomponent liquid mixtures

2019-03-20T09:08:49Z

Title: Prediction of viscosity of multicomponent liquid mixtures Authors: Pandey, J D; Agrawal, (Mrs) N; (Miss) Shikha; Misra, (Mrs) K Abstract: Viscosities of three quaternary, viz. n-hexadecane + n-tetradecane + n-hexane + 2-bromobutane (I), n-hexadecane + carbon tetrachloride + benzene + n-hexane (II) and n-hexadecane + n-tetradecane + 4-methylcyclohexanone + n-hexane (III) and eleven ternary liquid mixtures (IA-D, IIA-D and IIIA-C) have been evaluated theoretically, using various empirical relations (Frenkel, Kendall-Munroe, Bingham and Additive relations) applicable to binary mixtures. The theoretical values of viscosity of these mixtures are compared with the experimental viscosities given in literature. The results of calculation show that the viscous behaviour of these liquid mixtures having constituent components with likelihood of better interactions with each other, can be best explained by Frenkel relation as it takes into account all the possible major interactions. Still better results by Frenkel relation are obtained when some small molecules like CCl₄ is one of the components of the mixture (II) which can take up interstitial positions resulting in enhanced interaction. The presence of planar molecules, like benzene with its 3t-electron cloud above and below the ring, certainly inhibits the interaction between the components to some extent and results in somewhat ideal behaviour of mixtures. This is evident for some systems where Kendall-Munroe and Additive relations give better results than those given by Frenkel relation. The presence of substituent and polar groups on one of the components affects the extent of interaction more than when they are present in a cyclic molecule than on a straight chain hydrocarbon. Thus, the presence of bromine in system (I) and the ternary mixtures still allows interaction to a greater extent since in the possible compact structure 2-bromobutane can fit with bromine protruding out. However, the presence of polar and substituent groups in cyclic molecule (4-methylcyclohexanone) does not allow interaction and also inhibits the interaction of other components resulting in ideal mixing and thus better. Page(s): 113-123