Effect of micropores diffusion on kinetics of CH4 decomposition over a wood-derived carbon catalyst

Dufour A., Cembrzynski T., Ouartassi B., Broust François, Fierro V., Zoulalian A.. 2009. Effect of micropores diffusion on kinetics of CH4 decomposition over a wood-derived carbon catalyst. Applied Catalysis. A, General, 360 : 120-125.

Quartile : Q1, Sujet : ENVIRONMENTAL SCIENCES / Quartile : Q2, Sujet : CHEMISTRY, PHYSICAL

Résumé : In order to optimise hydrogen production from biomass gasification, catalytic conversion of methane contained in a surrogate biomass syngas (CH4 14%; CO 19%; CO2 14%; H2 16%; H2O 30%; N2 7%) is investigated over a fixed bed of porous wood char as a function of temperature (800-1000 8C) and space time (1.6-6.2 min g L_1). Determination of Thiele modulus evidences a change of kinetic regime from chemically- to diffusion-controlled when the temperature increases; this finding is particularly relevant when porous chars having an average pore width of 1 nm are used as catalysts. Mass diffusion transfers are accounted for by a model introducing an internal effectiveness factor. Knudsen diffusion in micropores is shown to limit the conversion rate of methane per unit mass of catalyst, and explains why such a rate is not proportional to the BET surface area, especially when the latter is higher than typically 300 m2/g. It is concluded that diffusion limitations in micropores should be taken into account, otherwise underestimated activation energy and intrinsic kinetic constant are obtained in some experimental conditions.

Mots-clés Agrovoc : hydrogène, biomasse, charbon de bois, gazéification

Classification Agris : K50 - Technologie des produits forestiers
P06 - Sources d'énergie renouvelable

Champ stratégique Cirad : Axe 2 (2005-2013) - Biomasse énergie et sociétés du sud

Auteurs et affiliations

• Dufour A., Gaz de France (FRA)
• Cembrzynski T., ENSTIB (FRA)
• Ouartassi B., ENSAIA (FRA)
• Broust François, CIRAD-PERSYST-UPR Biomasse-énergie (FRA) ORCID: 0000-0003-3132-6495
• Fierro V., Université de Nancy I (FRA)
• Zoulalian A., ENSAIA (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/548997/)

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