Simulating Gas-Solid Phase Isomerization of C8 Aromatics Affected by Catalyst Shapes in Fixed Bed Reactors with Particle-Resolved CFD Approach

Paraxylene (PX) is essential for producing polyethylene terephthalate fibers. We conduct particle-resolved CFD simulations, coupled with our reaction kinetics, on a fixed bed reactor randomly filled with catalyst shapes including sphere, cylinder, trilobe and quadrilobe to enlarge PX productivity in the catalytic isomerization of C8 aromatics. Our findings reveal the effects of catalyst shapes on velocity, concentration, temperature fields, and pressure drop. Although all catalyst shapes present particle utilization above 70 %, trilobes and quadrilobes show superior PX yield and ethylbenzene conversion due to their larger surface area and reduced mass transfer distance. Yet, among these catalysts, trilobes have twice the pressure drop of the others for complex geometric surface. Therefore, quadrilobes are more practical as their higher bed voidage, smaller pressure drop, better reactivity for desired reactions, and lower adiabatic temperature rise. This work provides guidance for catalyst design and process optimization to enhance PX productivity in aromatic isomerization.