High-Fidelity CFD Analysis of Methanol-to-Olefins Fluidized-Bed Reactor: Large Eddy Simulation versus RANS Turbulence Models

The methanol-to-olefins (MTO) process is an important catalytic route for producing light olefins, particularly ethylene and propylene. Fluidized-bed reactors provide effective gas–solid contact, but predicting their transient multiphase hydrodynamics and its interaction with reaction kinetics remains challenging. In this study, a computational fluid dynamics (CFD) framework was developed to compare large eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) turbulence models for a pilot-scale MTO fluidized-bed reactor. The models were assessed based on pressure distribution, velocity fields, gas-phase volume fraction, temperature distribution, and reaction performance, including methanol conversion and ethylene and propylene selectivities. The simulations employed a gas–solid multiphase formulation with SAPO-34 catalyst particles. The results showed that LES captured the heterogeneous gas-solid flow structures and transient mixing behavior, while the RANS predictions exhibited larger deviations in the investigated hydrodynamic fields. The LES simulation predicted a methanol conversion of 96%, with ethylene and propylene selectivities of 46% and 36%, respectively, corresponding to a total olefin selectivity of 82%. These results illustrate the potential of LES for analyzing coupled hydrodynamics and reaction behavior in fluidized-bed MTO systems. Further validation against independently documented experimental data and evaluation across a broader range of operating conditions are needed to establish the predictive accuracy and generality of the framework.