Integral Characteristic of Complex Catalytic Reaction Accompanied by Deactivation

New theoretical relationships for a complex catalytic reaction accompanied by deactivation are obtained, using as an example the two-step catalytic mechanism (Temkin-Boudart mechanism) with irreversible reactions and irreversible deactivation. In the domain of small concentrations, A(lim)( )= N-S k(1)C(A)/k(d), where A(lim), is the limit of the integral consumption of the gas substance, N-S is the number of active sites per unit of catalyst surface; k(1) and k(d), are kinetic coefficients which relate to two reactions which compete for the free active site Z. C-A is the gas concentration. One reaction belongs to the catalytic cycle. The other reaction with kinetic coefficient k(d) is irreversible deactivation. The catalyst lifetime, tau(cat) = 1/C'(z) 1/k(d), where C'(Z) is the dimensionless steady-state concentration of free active sites. The main conclusion was formulated as follows: the catalyst lifetime can be enhanced by decreasing the steady-state (quasi-steady-state) concentration of free active sites. In some domains of parameters, it can also be achieved by increasing the steady-state (quasi-steady-state) reaction rate of the fresh catalyst. We can express this conclusion as follows: under some conditions, an elevated fresh catalyst activity protects the catalyst from deactivation. These theoretical results are illustrated with the use of computer simulations.

Automated summary

New theoretical relationships for a complex catalytic reaction accompanied by deactivation are obtained in this study. It is found that the catalyst lifetime can be enhanced by decreasing the steady-state concentration of free active sites or by increasing the steady-state reaction rate of the fresh catalyst. These theoretical results are validated through computer simulations.