Finding the rate-determining step in a mechanism - Comparing DeDonder relations with the "degree of rate control"

In a recent paper (J.A. Dumesic, J. Catal. 185, 496 (1999)), Dumesic argued that "DeDonder relations offer a rigorous approach for assessing whether a reaction scheme contains a rate deter-mining step," Here, we argue that, while analysis with DeDonder relations is a very powerful approach that has many advantages, it has a limitation with respect to finding the rate determining step, and another method, previously proposed by this author (C.T. Campbell, Topics Catal. 1, 353 (1994)) involving the "degree of rate control," is preferable in that particular respect. An approach for extending this latter method to transient kinetic conditions is also suggested. (C) 2001 Elsevier Science.