Chemical Engineering Journal 94 (2003) 11–18 Kinetic investigations on the oxidehydrogenation of propane over vanadium supported on -Al 2 O 3 Aldo Bottino a , Gustavo Capannelli a,∗ , Antonio Comite a , Silvia Storace a , Renzo Di Felice b a Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, Via Dodecaneso 31, 16146 Genova, Italy b Dipartimento di Ingegneria Chimica e di Processo “G. Bonino”, Università degli Studi di Genova, Via Opera Pia 15, 16145 Genova, Italy Received 22 May 2002; accepted 29 November 2002 Abstract This work deals with the experimental determination of the reaction kinetic of the oxidative dehydrogenation (ODH) of propane and the evaluation of possible competitive reactions. The reaction network, composed of consecutive and simultaneous reactions, with kinetics expressed through simple power law equations, involves 18 unknown variables (12 order of reaction and 6 kinetic constants). They were determined through non-linear regression analysis. The overall reaction scheme was broken up for convenience and the three sub-schemes were separately investigated. Experimental measurements were carried out in a isothermal differential quartz reactor by varying the ratio between carbon compound (propane, propylene or CO) and oxygen. The chosen operating conditions proved the system was working in kinetic controlling conditions in the temperature range of 653–753 K. A simple rate equation that assumed the reactant adsorption, reaction on the catalyst surface and re-oxidation of the active site through molecular oxygen was used. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Catalytic reactor; Propane oxidehydrogenation; Kinetic; Redox mechanism 1. Introduction Some important processes such as ammoxidation of propylene to acrylonitrile, epoxidation of propylene or ethylene and the oxidation of propylene to acrolein produce highly desirable chemical intermediates from light olefins [1]. Nowadays, light olefins are obtained by processes such as steam cracking and fluid catalytic cracking of light oil fractions [2] or catalytic dehydrogenation. These processes are endothermic and operate under very severe conditions (high temperature and low contact time) with a subsequent high energy consumption. Their process yields are strongly influenced by the operating conditions (feed, hydrocarbon– water ratio, temperature and contact time). Numerous by-products are also obtained (with subsequent high sepa- ration costs) and the catalyst must be frequently regenerated owing to coke deposition. The demand of each olefin [3] is growing at different rates (e.g. the demand of propylene is foreseen to overtake that of ethylene). Therefore, there is a need to develop new specific processes, with lower costs and a reduced environmental impact. ∗ Corresponding author. Tel.: +39-010-353-6197; fax: +39-010-353-6199. E-mail address: capannel@chimica.unige.it (G. Capannelli). Although the oxidative dehydrogenation (ODH) of paraf- fins for the production of light olefins (ethylene, propylene or butenes) continues to be of interest at laboratory research level, industrial applications are still hindered by unsatis- factory yields (due to the formation of carbon oxides) and technical conditions (flammability of the reaction mixture and reactor choice) [4]. The catalysts generally employed [5] are based on vana- dium and the majority of studies concern their prepara- tion, evaluation of performance in terms of the selectivity– conversion trend and correlation among catalytic activity, vanadium co-ordination and surrounding environment [6,7]. There are several papers that deal with the determination of the kinetic parameters of reactions involved in the ODH pro- cess and several mechanism pathways have been proposed [8–18]. However, little research has been done on the cat- alytic system V/-Al 2 O 3 from a kinetic point view. We studied a vanadium catalyst supported on alumina (-Al 2 O 3 ). This catalyst presents lower yields than those of other catalysts studied in the past, but it has the great advan- tage that it limits the formation of oxygenated secondary products (e.g. acrolein and acrylic acid), which are also dif- ficult to separate [19]. This work investigates the kinetic of the oxidative dehydrogenation of propane, taking into ac- count the reaction network reported in Fig. 1. The reaction 1385-8947/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S1385-8947(03)00003-2