Complex heterogeneous catalytic reactions. Some aspects of simulation

Abstract

Heterogeneous catalytic reactions take place by stage mechanisms. The existence of reactants and products (at reactor input and output) and intermediates (not included in final equations of reactions) enables to derive a series of linear algebraic equations observed in stationary conditions in each point of reactor and in each point of catalyst grain. This “theory of stationary complex reactions” was developed first in the works of J. Horiuti and M.I. Temkin. Accounting some relationships of this theory enables to derive the first integrals for the set of the differential equations describing the zero-gradient reactors, flow reactors, and fluidized-bed reactors. Their consideration in the internal diffusion processes results in the relationships of diffusion stoichiometry and similar relationships for the grain surface concentrations and temperature. All the said relationships should be taken into account for calculation of the relevant reactors. Accounting the given relationships provides the correct solution of the relevant problem and reduces the order of the set of the differential equations to be solved. Some calculation features and restrictions in solution of inverse kinetic problems arise also if the mechanism of reactions involves reversible and equilibrium routes. This study systematizes the aforesaid issues and indicates to applicability and importance of the features of complex heterogeneous catalytic reactions for simulation of catalytic processes.