Optimal Catalyst Distribution and Dilution in Nonisothermal Packed Bed Reactors

The problem of the optimal distribution of two different catalysts in a nonisothermal packed bed reactor is analyzed. State variable constraints, such as maximum allowable temperature, may be incorporated through a penalty function approach into the steepest ascent solution of this problem. Loading a wall-cooled reactor with two chemically different catalysts is compared to dilution of a single catalyst with inerts for temperature moderation. A criterion is presented for estimating whether catalyst dilution may be necessary in order to keep reactor temperature below some maximum allowable value. Conditions for optimal loading with a two-dimensional reactor model are presented and applied to catalyst dilution in a butane oxidation reactor. Suboptimal catalyst loadings are compared with the optimal loading.