This study involved the development of a mathematical model of a multi-tubular packed-bed reactor to produce hydrogen via catalytic steam reforming of biogas. The model was validated by comparing its results with experimental data from published literature, and good agreement was observed. COMSOL Multiphysics was used to build and simulate the 3D computational fluid dynamics model, considering mass and momentum transfer processes. Given that species transport and chemical reaction occur at dimensions of different orders of magnitude, a multiscale approach was taken in model development, enabling the characterization of gas composition at both micro- and macro scales, as well as pressure drop profiles along the reactor length. Sensitivity studies were carried out to evaluate the effects of various biogas compositions, with a particular focus on the carbon dioxide mole fraction, as well as gas velocities.