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Modeling reaction and diffusion in a spherical catalyst pellet using multicomponent flux models / Jin Yang Lim in Industrial & engineering chemistry research, Vol. 51 N° 49 (Décembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 49 (Décembre 2012) . - pp. 15901–15911 Titre : Modeling reaction and diffusion in a spherical catalyst pellet using multicomponent flux models Type de document : texte imprimé Auteurs : Jin Yang Lim, Auteur ; John S. Dennis, Auteur Année de publication : 2013 Article en page(s) : pp. 15901–15911 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalyst  Multicomponent Résumé : This work presents the derivation and evaluation of a nonisothermal, steady-state model for a spherical pellet of catalyst, where the intraparticle diffusion is modeled by the Cylindrical Pore Interpolation Model (CPIM), a multicomponent flux model based on the Stefan-Maxwell equations, modified by a momentum balance. Since many reactions involve more than two chemical species and most industrial catalysts operate under diffusion-limited regimes, understanding intraparticle, multicomponent diffusion is crucial for the accurate modeling of reaction and diffusion within a catalyst pellet. The model was applied to the methanation reaction, where its industrial importance and high exothermicity makes it an ideal candidate as a concrete example. The profiles within the catalyst of composition, pressure, temperature, and rate of reaction were generated for various conditions. Several key dimensionless groups were identified in order to study the system over a large range of conditions and identify the important parameters. The predictions from the CPIM and the Dusty Gas Model (DGM) were compared. It was found that under most circumstances, only minor differences were observed between the predictions of the CPIM and the DGM. However, appreciable discrepancies were found when catalyst pellets, which had low thermal conductivities and contained pores of size such that values of both Knudsen and binary diffusivity were comparable, were reacted at low pressure. In summary, the work shows that the CPIM is well-suited to modeling multicomponent diffusion and reaction in pseudohomogenous catalyst pellets because (i) the assumptions used in the derivation are reasonable and explicit, (ii) an interpolation procedure allows diffusion to be modeled for the range from Knudsen diffusion through to continuum flow, and (iii) the equations can be presented in a compact form suitable for numerical solution. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie302528u [article] Modeling reaction and diffusion in a spherical catalyst pellet using multicomponent flux models [texte imprimé] / Jin Yang Lim, Auteur ; John S. Dennis, Auteur . - 2013 . - pp. 15901–15911. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 49 (Décembre 2012) . - pp. 15901–15911 Mots-clés : Catalyst  Multicomponent Résumé : This work presents the derivation and evaluation of a nonisothermal, steady-state model for a spherical pellet of catalyst, where the intraparticle diffusion is modeled by the Cylindrical Pore Interpolation Model (CPIM), a multicomponent flux model based on the Stefan-Maxwell equations, modified by a momentum balance. Since many reactions involve more than two chemical species and most industrial catalysts operate under diffusion-limited regimes, understanding intraparticle, multicomponent diffusion is crucial for the accurate modeling of reaction and diffusion within a catalyst pellet. The model was applied to the methanation reaction, where its industrial importance and high exothermicity makes it an ideal candidate as a concrete example. The profiles within the catalyst of composition, pressure, temperature, and rate of reaction were generated for various conditions. Several key dimensionless groups were identified in order to study the system over a large range of conditions and identify the important parameters. The predictions from the CPIM and the Dusty Gas Model (DGM) were compared. It was found that under most circumstances, only minor differences were observed between the predictions of the CPIM and the DGM. However, appreciable discrepancies were found when catalyst pellets, which had low thermal conductivities and contained pores of size such that values of both Knudsen and binary diffusivity were comparable, were reacted at low pressure. In summary, the work shows that the CPIM is well-suited to modeling multicomponent diffusion and reaction in pseudohomogenous catalyst pellets because (i) the assumptions used in the derivation are reasonable and explicit, (ii) an interpolation procedure allows diffusion to be modeled for the range from Knudsen diffusion through to continuum flow, and (iii) the equations can be presented in a compact form suitable for numerical solution. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie302528u