Application of a CFD code (FLUENT) to formulate models of catalytic gas phase reactions in porous catalyst pellets

A method is described by which a computational fluid dynamic (CFD) code known as FLUENT, may be adapted to model the reactions that take place inside catalyst structures. To test the CFD code, simulations of gas flow in a circular tube are performed and compared with anal. solns. Then the coupled processes of diffusion and chem. reaction, combined with heat and mass transfer effects are modeled in a catalyst pellet. To illustrate the technique, the catalytic combustion of propane is simulated in spherical and cylindrical shaped pellets, at gas temps. from 500-700 K and at atm. pressure. To help validate the approach adopted, the results of the CFD simulations are compared with solns. obtained from a one-dimensional model using MATLAB. It is shown that the CFD simulations provide comparable results with MATLAB, and that the CFD code can provide valuable addnl. information about temp. and concn. gradients in and around the catalyst pellet-this is not available in a simple one-dimensional approach. It is discussed how the technique could be extended to model reactions in a packed bed which would be a valuable design tool.