Computational Design of Pore Structure in Heavy Paraffin Dehydrogenation Catalyst Pellets

A multiscale model is developed to describe the coupled flow, diffusion, heat-transfer, and reaction processes at catalyst pellet and fixed bed reactor levels for heavy paraffin dehydrogenation. With this model, the pore structures of monodisperse, bidisperse, and egg-shell catalyst pellets are optimized to improve the yield of mono-olefin under two assumptions about intrinsic activity. The optimal pore structure is determined by compromising between the void space for diffusion and the catalyst volume or surface area for reactions. The optimized monodisperse and bidisperse catalysts show an improvement of 50.7–83.6% in the yield relative to the benchmark catalyst. In addition, using the egg-shell structure for the optimized monodisperse and bidisperse catalysts would not further significantly improve the yield, as their diffusion limitation is very weak. There results should serve to guide the design of catalyst pellets for heavy paraffin dehydrogenation and even for other reaction systems.