Micro- and macro-kinetics: their relationship in heterogeneous catalysis

Attempts to model macroscopic steady-state rates of catalytic reactions on the basis of microscopic kinetic parameters for elementary steps, determined independently from transient kinetic data on model, single-crystal metal catalysts, will be reviewed. The methods used in getting microkinetic parameters will be discussed. Recent studies which determine microkinetics for more complex model catalysts consisting of vapor-deposited metal islands on single-crystal oxides will also be outlined. Finally, the degree of rate control of a step will also be mathematically defined. This new concept is useful in kinetic modeling, and in putting terms such as rate-controlling step and rate-limiting step into a more rigorous framework.