Kinetic Perspective on Methanol to Propylene Process via HZSM-5 Catalyst: Balancing between Reaction and Diffusion

The methanol-to-propylene (MTP) reaction was analyzed in its intrinsic kinetics, diffusion, and reaction–diffusion aspects for maximized propylene yield. An intrinsic MTP kinetic model was introduced to account for the combined path of hydrocarbon pool and dual-cycle mechanisms of the MTP reaction over HZSM-5 catalyst. The MTP reaction was performed under several olefin cofeeding cases to study the effects of olefin recycling on the MTP mechanism and propylene production. Analyses on olefin cofeeding have shown to improve propylene yield by 10–20% as the added olefins enhance olefin methylation and cracking rates for higher propylene production. Development of a reaction–diffusion model also showed the recommended temperature use of 480 °C for optimum reaction and diffusion rates within the HZSM-5 catalyzed MTP process. These findings provide important insights for future works on the optimum design of the HZSM-5 catalyzed MTP process with an olefin recycling feature.