Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PL-5intrinsic kinetics of CH 4 steam reforming and total oxidation under differential conditions; (3)the need for independent kinetic expressions for the direct and the reverse WGS reaction,when far from equilibrium.Moreover, a thermodynamically consistent C 1 microkinetic model for the conversion ofCH 4 to syngas on Rh-based catalysts was also developed. It was verified that the model isable to predict correctly the behavior of several reacting mixtures, including CH 4 /H 2 O (SR)and CH 4 /CO 2 (DR) reforming, CH 4 /O 2 (CPO), H 2 /O 2 and CO/O 2 , CO/H 2 O (WGS). Using themicrokinetic model, a detailed analysis of the reaction mechanisms of CH 4 CPO, by theidentification of the Rate Determining Step and the main elementary paths that occur underdifferent operating conditions. In addition, the possibility of modeling in detail the surfacechemistry allowed to propose also a possible explanation of the main molecular pathwaysinvolved in the process. Adopting a systematic reduction methodology, a hierarchy of modelsfor CPO was proposed and overall molecular rate expressions were derived. In doing so, themolecular models are not based on an assumed mechanism and the effective parameters arenot determined by regression of experimental data, but are directly related to the rateconstants of the elementary reactions of the full microkinetic model.Finally, results concerning reactor-engineering related aspects will be presented. Theanalysis has been carried out both experimentally and theoretically, by means of a dedicatedadiabatic experimental study and of a comprehensive mathematical model of the CPOreformer,incorporating the previously derived kinetics. Among others, this study allowed toclarify the mechanism of reactor light-off and blow-out and to pinpoint the governingphenomena at steady-state.15