Impacts on the Reactor Performance of Intra-Particle Multicomponent Mass Diffusion Limitations: Knudsen Diffusion

A heterogeneous model has been derived for a fixed-packed bed reactor producing methanol. The intra-particle mass diffusion fluxes are described according to the Maxwell-Stefan and dusty gas closure laws and a bi-dispersed random pore model is adopted to elucidate the effects of the pellet pore size distribution on the impact of the reactor performance. The simulation results reveal that the overall reactor performance is sensitive to the the bimodal description of the pore size within the catalyst pellet due to the Knudsen diffusion mechanism. Although the dusty gas model has been frequently adopted in chemical reactor modeling, the model has certain shortcomings that have been subjected to criticism in the literature.