Interplay of Kinetics and Thermodynamics in Catalytic Steam Methane Reforming over Ni/MgO-SiO2

Abstract

The steam methane reforming (SMR) reaction was studied on a Ni/MgO-SiO2 catalyst at 923 K (650 °C) and 0.40 MPa in a tubular packed-bed reactor. The partial pressures of CH4 and H2O were varied between 20 and 140 kPa and 80 and 320 kPa, respectively. Measurements were carried out without mass and heat transport limitations, as verified by the Weisz–Prater and Mears criteria. Experimentally, the CH4 conversion increased with the inlet partial pressure of H2O and decreased with the inlet partial pressure of CH4. However, at low CH4 inlet partial pressures, i.e., at 40 and 60 kPa, the conversion passed through a maximum. Rate expressions were derived based on a simple two-step sequence. A statistical analysis led to a globally significant, weighted regression and resulted in a good agreement between the model and the experimental data, as indicated by a low F value of model adequacy of 2.84. The rate and equilibrium coefficient parameters were statistically significant as indicated by narrow confidence inter...