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228 results on '"Marin, G. B."'

2. Reciprocal Relations Between Kinetic Curves

Author

Yablonsky, G. S., Gorban, A. N., Constales, D., Galvita, V., and Marin, G. B.

Subjects
Condensed Matter - Statistical Mechanics, Physics - Chemical Physics
Abstract

We study coupled irreversible processes. For linear or linearized kinetics with microreversibility, $\dot{x}=Kx$, the kinetic operator $K$ is symmetric in the entropic inner product. This form of Onsager's reciprocal relations implies that the shift in time, $\exp (Kt)$, is also a symmetric operator. This generates the reciprocity relations between the kinetic curves. For example, for the Master equation, if we start the process from the $i$th pure state and measure the probability $p_j(t)$ of the $j$th state ($j\neq i$), and, similarly, measure $p_i(t)$ for the process, which starts at the $j$th pure state, then the ratio of these two probabilities $p_j(t)/p_i(t)$ is constant in time and coincides with the ratio of the equilibrium probabilities. We study similar and more general reciprocal relations between the kinetic curves. The experimental evidence provided as an example is from the reversible water gas shift reaction over iron oxide catalyst. The experimental data are obtained using Temporal Analysis of Products (TAP) pulse-response studies. These offer excellent confirmation within the experimental error., Comment: 6 pages, 1 figure, the final version

Published
2010
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20. Influence of nitrogen on diamond growth in oxyacetylene combustion chemical vapor deposition.

Author

Okkerse, M., de Croon, M. H. J. M., Kleijn, C. R., Marin, G. B., and van den Akker, H. E. A.

Subjects
NITROGEN, DIAMONDS, CHEMICAL vapor deposition
Abstract

Addition of di-nitrogen to the feed gas has been shown to greatly influence growth rates and morphology of the deposited layer in various diamond chemical vapor deposition (CVD) techniques. In this article, several hypotheses for these phenomena, as presented in literature, are tested for the case of diamond combustion CVD with the aid of an atmospheric pressure oxyacetylene flame. For this purpose, one-dimensional and two-dimensional simulations are performed of the hydrodynamics, the combustion and deposition chemistry, and the nitrogen chemistry. Based on the simulation results, several proposed hypotheses can be ruled out as possible explanations for the observed phenomena. It is concluded, that the most likely hypotheses are: (i) the presence of nitrogen atoms in the diamond lattice, enhancing diamond growth by acting on the electron structure of surface dimer bonds, and (ii) selective adsorption of nitrogen-containing species on the surface, selectively increasing growth in the (100) direction. It is found that possible gas phase candidates for affecting diamond growth are NH, NH[sub 2], NH[sub 3], CN, HCN, H[sub 2]CN, and NCO. [ABSTRACT FROM AUTHOR]

Published
2002
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28. A microkinetic vision of High-Throughput catalyst formulation and optimization: development of an appropriate software tool

Author

Thybaut, J. W., Morra, G., Farrusseng, D., Mirodatos, C., Marin, G. B., Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), 21-22 juillet 2008, and IRCELYON, ProductionsScientifiques

Subjects
[CHIM.CATA] Chemical Sciences/Catalysis, [SDE.ES] Environmental Sciences/Environmental and Society, [CHIM.CATA]Chemical Sciences/Catalysis, [SDE.ES]Environmental Sciences/Environmental and Society
Abstract

international; International audience

Published
2008

31. New supported vanadia catalysts for oxidation reactions prepared by sputter deposition

Author

UCL - AGRO/CABI - Département de chimie appliquée et des bio-industries, Poelman, H., Paul, Julie, Sels, B. F., Olea, M., Eufinger, K., Moens, B., Sack, I., Balcaen, V., Bertinchamps, Fabrice, Gaigneaux, Eric M., Jacobs, Pierre A., Marin, G. B., Poelman, D., De Gryse, R., UCL - AGRO/CABI - Département de chimie appliquée et des bio-industries, Poelman, H., Paul, Julie, Sels, B. F., Olea, M., Eufinger, K., Moens, B., Sack, I., Balcaen, V., Bertinchamps, Fabrice, Gaigneaux, Eric M., Jacobs, Pierre A., Marin, G. B., Poelman, D., and De Gryse, R.

Abstract

Model vanadia catalysts were synthesised using magnetron sputtering of the active species for precisely controlled and clean catalyst design. Two series of supported vanadia catalysts were produced on inert beads with silica surface: vanadia/silica through single vanadia coating and vanadia/titania/silica by subsequent deposition of titania and vanadia. Loadings were varied by changing deposition time. All catalysts were characterised for structure and reducibility. Catalytic performance was tested by steady-state and transient experiments with propane oxidative dehydrogenation. Both supports yielded similar vanadia structures and equal dispersion. The vanadia loading strongly influenced structure and chemical behaviour. Shorter depositions gave surface vanadia monomers and polymers, whereas for longer depositions, crystalline species developed on either support. In propane oxidative dehydrogenation, very high turnover frequencies were obtained, especially for thinner depositions. An intermediate titania layer strongly influenced the vanadia activity. Maximum activity was obtained for a few vanadia layers supported on titania. (c) 2006 Elsevier Inc. All rights reserved.

Published
2007

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