Mathematical Modeling of the Catalyst Deactivation Process inside a Grain Using Mathcad

Resumo

The problem of the mathematical modeling of the catalyst deactivation process inside a spherical grain with a parallel first-order deactivation mechanism has been solved in the work [9] by the finite difference method. This paper presents a simpler method for the solution of this problem. It is shown that the set of nonlinear partial differential equations for planar, cylindrical, and spherical grains can be reduced to a boundary problem for two ordinary differential equations with respect to the spatial variable, where time is a parameter. The obtained equations are solved by the shooting method using Mathcad functions. For illustration, the profiles of relative catalyst activity and dimensionless reagent concentration are calculated for a spherical grain at a Thiele parameter of 5 and different time moments, together with the dependence of the degree of internal grain surface utilization on dimensionless time. Some asymptotic dependences are proposed for these parameters over a long time period.