Effectiveness factor correlations from simulations of washcoat nickel catalyst layers for small-scale steam methane reforming applications

In this paper, the effectiveness factors of Ni/MgAl2O4 washcoat catalyst layers under steam methane reforming (SMR) conditions relevant to small-scale hydrogen production systems (1-3 bar pressure, 600-800 °C temperature, and 2-4 steam-to-carbon ratio) are numerically investigated. The effects of the washcoat properties, including the layer thickness (20-80 μm), the mean pore diameter (10-40 nm), and the volume-specific catalyst surface area (1.1-3.3 × 107 m2/m3), are also considered. The simulation is conducted by fully considering the intrinsic reaction kinetics (Xu and Froment model) and multicomponent mass diffusion (Maxwell-Stefan equation). The numerically obtained effectiveness factors are presented as a function of the methane conversion ratio and effective Thiele moduli, and simple correlation equations are proposed for easy evaluation of the effectiveness factors.