The kinetics of methane steam reforming over a Ni/α-Al2O catalyst

Experiments have been carried out to study the kinetics of the methane steam reforming, accompanied by the reverse water gas shift reaction over a commercial Ni/alpha -Al2O3 catalyst in an integral reactor under conditions of no diffusion limitation. The experiments demonstrated that both CO and CO2 are formed as primary products, and the rate of methane disappearance is proportional to the partial pressure of methane at low product concentrations. The effect of total pressure on initial reaction rates indicated that the rate controlling steps of steam reforming are surface reactions between adsorbed species. Six possible reaction mechanisms were considered in detail, and intrinsic rate equations were derived by using the Langmuir-Hinshelwood-Hougen-Watson (LH-HW) approach and Freundlich's adsorption concept. Applying the method of parameter estimation and model discrimination, a satisfactory model of intrinsic kinetics for methane steam reforming over the catalyst used was determined. Good agreement was obtained between the experimental data and results predicted from the kinetic model. (C) 2001 Elsevier Science B.V. All rights reserved.