ANALYSIS AND OPTIMIZATION OF TRANSPORT AND REACTION PROCESSES IN THE CYLINDRICAL FLOW-THROUGH CATALYTIC MEMBRANE REACTORS

Abstract

Cylindrical flow-through catalytic membrane reactors, employing porous membranes impregnated with catalysts, offer enhanced selectivity and yield in chemical reactions. This work is focused on mathematical modeling and numerical analysis of a cylindrical flow-through catalytic membrane reactor. The reactor's geometry, which incorporates a porous membrane, is specially tailored for the cylindrical configuration, addressing a research gap in realistic geometries. The proposed mathematical model includes a series of irreversible reactions with power-law kinetics occurring under non-isothermal conditions. A system of non-linear diffusion-convection-reaction equations is formulated for a cylindrical catalytic membrane reactor under both steady and unsteady-state. The study investigates the occurrence of dead zones within the membrane reactor as a result of rapid reactant depletion, a phenomenon that has not been extensively studied in prior literature for cylindrical membrane reactors. Problems with fractional reaction exponents require efficient numerical solvers since conventional iterative solvers encounter difficulties due to the fact that the power-law reaction term with fractional reaction exponent is not differentiable at the vanishing concentration. A novel time-marching scheme specifically designed for the cylindrical catalytic flow-through membrane reactor is developed and applied for simulations to get valuable insights into dead-core phenomena. The effects of dimensionless process parameters such as Thiele modulus, mass Peclet number, heat Peclet number, etc. and a model parameter (i.e., geometry parameter) on the concentration and temperature profiles, as well as dead-zone formation, are extensively investigated under steady-state. The simulation results demonstrate that these parameters affect the occurrence of dead zones and their size. The impact of convective flow on the reactor performance indicators under steady-state is also presented. Moreover, the investigation extends to unsteady-state conditions, exploring the dynamic behavior of concentration and temperature profiles as well as productivity under both isothermal and non-isothermal scenarios. In the case of a single reaction, the analysis of productivity reveals substantial percent increments, offering insights into the identification of optimal conditions. Finally, a comprehensive exploration into the optimal conditions for productivity in a sequential reaction is conducted.