Compensation effect heterogeneous catalysis

G. Parravano and M. Boudart The Compensation Effect in Heterogeneous Catalysis E. Cremer... 

Normally in heterogeneous catalysis compensation effect behaviour is obtained either for the same reaction upon using differently prepared catalysts of the same type, or with the same catalyst upon using a homologous set of reactants. In the case of electrochemical promotion (Figs. 4.38 and 4.39) one has the same catalyst and the same reaction but various potentials, i.e. various amounts of promoter on the catalyst surface. 

W. M. H. Sachtler and R. A. van Santen Mossbauer Spectroscopy Applications to Heterogeneous Catalysis James A. Dumesic and Henrik Tops0e Compensation Effect in Heterogeneous Catalysis... 

Case 3 will be of special interest in this paper. It is encountered in all the examples listed above for Equations (1) and (2). Especially in heterogeneous catalysis it shows what has been called the compensation effect (C.E.). This term indicates that an increase in the enthalpy of activation AH frequently has not the expected result of a considerable decrease in the rate constant, because there occurs a simultaneous increase in the entropy of activation AS or of the frequency factor A, which compensates partly or entirely for the change in the exponent (AH /Er, or AE/ET). 

---