Modeling and Simulation of Isobutylene Polymerization in gas-liquid-solid Circulating fluidized bed Reactor

Methyl tert‑butyl ether (MTBE) was widely utilized as a standard additive in high-octane gasoline due to its ability to improve combustion efficiency and provide effective knock resistance. However, its extensive use resulted in significant environmental concerns, prompting its prohibition in numerous countries. As an alternative, di-isobutylene (DIB), derived from the selective oligomerization of isobutylene, can be hydrogenated to produce high-quality, clean gasoline. This indirect alkylation process yields a blend rich in isooctane, characterized by a high-octane number and low vapor pressure while freeing sulfur, benzene, and aromatic compounds. This study provides an in-depth modeling and simulation analysis of a novel gas–liquid–solid circulating mini-fluidized bed reactor designed for isobutylene polymerization. A detailed hydrodynamic and kinetic model was created using COMSOL Multiphysics version 6.3 to investigate how operating parameters affect isobutylene conversion and di-isobutylene yield. The simulation outcomes were thoroughly validated by comparing them to experimental data from a mini circulating fluidized bed reactor with a 10 mm inner diameter, 260 mm riser, and 160 mm downers. The results indicate that the circulating mini-fluidized bed can achieve high isobutylene conversion and high di-isobutylene yield. This improved performance is linked to the synergistic effects of solid particles and gas bubbles, which enhance the specific surface area of the reactor and promote advantageous hydrodynamic alterations. These findings validate the efficacy of the simulation framework and underscore the reactor’s potential for optimizing industrial polymerization processes.