Radial Generation of Pore Network Structures in Spherical Porous Particles: Application to Benzene Hydrogenation in Catalytic Pellets

The accurate generation of pore networks is essential for simulating diffusion and reaction processes within catalytic pellets. Traditional methods, which rely on Cartesian coordinates, are not well aligned with the inherent symmetry and geometry of spherical particles. This study introduces an innovative approach for constructing pore networks within spherical domains by utilizing a spherical coordinate system. A stochastic network generation algorithm was employed to preserve realistic porosity and pore connectivity. The generated networks were then used to simulate diffusion and catalytic reactions, with a particular focus on the hydrogenation of benzene as a case study. The model was validated for a wide range of porosities (0.35–0.7) and average network connectivity (4–8). The effect of node density on pore size and porosity was investigated, showing that increasing the number of nodes from 3000 to 10,000 leads to a denser and more interconnected network, requiring a reduction in mean pore radius to maintain the target porosity. Furthermore, the impact of particle size on the effectiveness factor (η) was examined and compared to the results of the classical continuum model, where a deviation of less than 5% was observed between the two approaches. The concentration profile showed greater variation along the radial direction, leading to a significant reduction in η at lower porosities. It was observed that for smaller particles (radii ≤ 1 mm), η remains close to unity. In contrast, in particles with radii larger than 4 mm, the radial concentration gradients intensified, leading to a noticeable decrease in η. These findings highlight the strong interplay between geometry, diffusion limitations, and reaction kinetics, providing a valuable framework for optimizing catalyst design.