Kinetic study of the oxidation of n-butane on vanadium oxide supported on Al/Mg mixed oxide
- Univ. de Valencia, Burjassot (Spain). Dept. de Ingenieria Quimica
- UPV-CSIC, Valencia (Spain). Inst. de Technologia Quimica
The reaction kinetics of the oxidative dehydrogenation (ODH) of n-butane over vanadia supported on a heat-treated Mg/Al hydrotalcite (37.3 wt % of V{sub 2}O{sub 5}) was investigated by both linear and nonlinear regression techniques. A reaction network including the formation of butenes (1-, 2-cis-, and 2-trans-butene), butadiene, and carbon oxides by parallel and consecutive reactions, at low and high n-butane conversions, has been proposed. Langmuir-Hinshelwood (LH) models can be used as suitable models which allows reproduction of the global kinetic behavior, although differences between oxydehydrogenation and deep oxidation reactions have been observed. Thus, the formation of oxydehydrogenation products can be described by a LH equation considering a dissociative adsorption of oxygen while the formation of carbon oxides is described by a LH equation with a nondissociative adsorption of oxygen. Two different mechanisms operate on the catalyst: (i) a redox mechanism responsible of the formation of olefins and diolefins and associated to vanadium species, which is initiated by a hydrogen abstraction; (ii) a radical mechanism responsible of the formation of carbon oxides from n-butane and butenes and associated to vanadium-free sites of the support. On the other hand, the selectivity to oxydehydrogenation products increases with the reaction temperature. This catalytic performance can be explained taking into account the low reducibility of V{sup 5+}-sites and the higher apparent activation energies of the oxydehydrogenation reactions with respect to deep oxidation reactions.
- OSTI ID:
- 529745
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 36, Issue 7; Other Information: PBD: Jul 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
Influence of the acid-base character of supported vanadium catalysts on their catalytic properties for the oxidative dehydrogenation of n-butane
Effect of cesium modification of silica-supported vanadium oxide catalysts in butane oxidation