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Dynamics of internal diffusion during the hydrogenation of 1,5,9-cyclododecatriene on Pd/Al2O3

Julcour-Lebigue, Carine and Le Lann, Jean-Marc and Wilhelm, Anne-Marie and Delmas, Henri Dynamics of internal diffusion during the hydrogenation of 1,5,9-cyclododecatriene on Pd/Al2O3. (1999) Catalysis Today, vol. 48 . pp. 147-159. ISSN 0920-5861

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Official URL: http://dx.doi.org/10.1016/S0920-5861(98)00369-1

Abstract

Dynamic and pseudo-steady state diffusion–reaction models were simulated for the three-phase consecutive hydrogenation of 1,5,9-cyclododecatriene on a shell Pd/Al2O3 catalyst in order to examine the time evolution of concentration profiles inside the catalyst pellet: a model accounting only for the dynamics of the active layer and a model taking also into account the inert part of the catalyst were compared. In the conditions of the semibatch experiments (T=433 K, pH2=1.2 MPa), all the models lead to the same bulk concentration–time curves, but the hydrocarbon concentration profiles in the pores are dependent on the model. The influence of the diffusion in the inert part of the catalyst on the bulk concentrations becomes nonnegligible only when the external liquid volume (out of the catalyst) is reduced. The transient evolution of the concentration profiles in the pores show that hydrogen concentration reaches its steady state within a few seconds, while the evolution of the organic concentration profiles is slower. Furthermore, the reaction rate has been found to be only affected by the hydrogen diffusion. The diffusion of organics can control the reaction rate only for low values of organic concentration and higher pressure in hydrogen.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Thermochimica Acta website : http://dx.doi.org/10.1016/S0920-5861(98)00369-1
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Laboratory name:
Laboratoire de Génie Chimique - LGC (Toulouse, France) - Réaction, mélange & séparation (RMS)
Laboratoire de Génie Chimique - LGC (Toulouse, France) - Procédés Systèmes Industriels (PSI)
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Deposited By: Carine JULCOUR
Deposited On:11 Sep 2012 12:48

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