ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Kinetics of Partial Methane Oxidation Process over the Fe-ZSM-5 Catalysts

B. Michalkiewicz

Institute of Chemical and Environment Engineering, Szczecin University of Technology, PL-70 322 Szczecin

E-mail: beata.michalkiewicz@ps.pl

Abstract: Kinetics of a partial methane oxidation over the Fe-ZSM-5 catalysts was investigated. A set of rate equations describing the reaction system was suggested and verified by comparison with experimental data. It was found that all the reactions considered were of the zero order with respect to oxygen and of the first order with respect to the oxidized species (methane, methanol, or formaldehyde). Values of the reaction rate constant for the temperature range 350—550^oC as well as the reaction apparent activation energy values were determined. The studies on the process of partial methane oxidation conducted over the Fe-ZSM-5 catalysts confirmed the assumption that methanol and carbon dioxide are the primary products of the reaction. As a result of the methanol oxidation, formaldehyde is generated, the oxidation of which leads to receiving slight quantities of CO₂. The decline of the iron content results in the decrease of the rate of every reaction. In order to impede the oxidation of methanol to formaldehyde, the H catalysts should be employed. This form is responsible for the production of methanol; yet it also leads to the direct methane to carbon dioxide oxidation. Bearing such dependences in mind, it could be concluded that the introduction of the Fe-ZSM-5 catalyst demonstrating certain content might result in a favoured reaction of synthesis of methanol, with the process of its further oxidation being hampered. Unfortunately, this makes the elimination of the reaction of oxidation to CO₂ virtually impossible. It is also evident that the activation energy of methane to methanol or carbon dioxide oxidation is markedly higher than the activation energy of the unwelcome reactions, which are methanol and formaldehyde oxidations.

Full paper in Portable Document Format: 596aa403.pdf

Chemical Papers 59 (6a) 403–408 (2005)