Catalyst pellets with Gaussian activity distribution under forced periodic operation for reactions with Langmuir-Hinshelwood kinetics

Abstract

This research investigates how combining forced periodic operation with spatially distributed catalyst activity can enhance heterogeneous catalytic processes. It focuses on analyzing reaction-diffusion phenomena within porous catalyst pellets. These pellets exhibit a Gaussian distribution of active sites, and the study investigates how externally forced periodic variations in bulk reactant concentration and temperature affect the reaction process. The paper establishes a mathematical model for a non-isothermal reaction based on Langmuir-Hinshelwood kinetics. This model is then transformed into its dimensionless form for numerical analysis. Numerical simulations are employed to investigate the impact of various parameters on the concentration and temperature profiles within the pellet, as well as on the pellet productivity. These parameters include the position and width of the Gaussian distribution of active sites, the Thiele modulus, the mass and heat Biot numbers, the Arrhenius number for reaction, the energy generation function, the ratio of characteristic times for diffusion and heat conductivity, and frequencies and amplitudes of periodic variations. The simulations reveal complex relationships between the spatial and temporal profiles of concentration and temperature within the pellets. Using porous granules with a non-uniform catalyst activity profile alongside forced periodic operations for reaction-diffusion processes enables higher productivity compared to granules with a uniform activity profile and subject to the steady-state operation. This study demonstrates the potential for optimizing catalytic processes in porous pellets with non-uniform activity profiles under forced periodic operation, offering valuable insights into enhancing process efficiency.