Three methods to evaluate apparent activation energies for reduction from temperature-programmed reduction (TPR) measurements are discussed. Application of the well known method of Gentry results in values of the experimental activation energy, Ee, which are dependent on the heating rate in the region 8-15 K min-1. Two new approaches are described: the reference method and the curve-fitting method. Application of a curve-fitting method, by integration of an appropriate nucleation equation, results in an activation energy for the growth of nuclei, Ea, of 60 ± 3 kJ mol-1 for both bulk and supported V2O5. In the reference method, the onset of a single TPR peak of a sample under investigation is compared to the onset of the TPR peak of a reference sample with a known value of Ee. Activation energies obtained by the reference method are in good agreement for almost all heating rates applied (8-20 K min-1). Agreement with the activation energy obtained by Gentry's method exists only in a limited region of heating rates.
|Number of pages||13|
|Journal||Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases|
|Publication status||Published - 1 Dec 1989|