Basile et al also observed a considerable temperature

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Unformatted text preview: tion reaction for reaction mixtures diluted by 57 vol% N2 [94]. Basile et al. also observed a considerable temperature rise in the reactor upon increasing the GHSV, even at a dilution of the feed by 87 vol% He [9]. 1. Introduction 36 1.5.1.2. Total oxidation followed by reforming Prettre et al. were in 1946 among the first to study the CPOM over Ni catalysts [10, 107]. They observed an exothermic reaction in the entry of the catalyst bed, which was followed by an endothermic reaction. The composition of the gas mixture at the outlet corresponded to thermodynamic predictions considering side products. On the basis of these results they proposed a two step reaction scheme. The exothermic reaction at the entry of the catalyst’s bed was attributed to the complete deep oxidation of 25% of the CH4 by 100% of the O2 yielding CO2 and H2O. The subsequent following endothermic reaction was believed to be the reforming of the remaining CH4 by CO2 and H2O formed previously. Heitnes et al., Dissanayake et al. and Basile et al. observed the same general temperature profile [9, 97, 107]. Looji et al. compared CPOM to the reforming of the same reaction mixture where all the O 2 was consumed in the total combustion step prior to the reforming over the Ni catalyst at rather long contact times [109]. They observed no differences between the two reactions and also proposed the reaction mechanism total combustion followed by the combined steam and CO2 reforming (mixed reforming). Though the observations made by the authors are strong evidence for the possibility of such a reaction scheme, the only mechanistic studies here are the comparison of the CPOM with the mixed reforming. However the experiments were performed at long contact time. It might be that the contact time was long enough for both reactions to achieve the same result. Studies concerning the CPOM and the mixed reforming at different contact times or other mechanistic studies were not performed. 37 1. Introduction 1.5.1.3. Pyrolysis mechanism Au et al. performed CPO...
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This document was uploaded on 10/07/2013.

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