Kinetics of desorption of hydrogen from copper chromite catalyst

Abstract

Isothermal desorption of hydrogen from copper chromite has been studied from 50 to 300° C. An empirical expression, β exp [-α q]= t, is found to fit the desorption data satisfactorily, while the application of the Elovich and the first order desorption rate expressions lead to the detection of three kinetic stages in the desorption process. The rate parameters obtained using these latter two models have a complex trend in their behaviour with temperature. The Elovich rate parameters are found to undergo undulatory changes with temperature like those of the adsorption isobar and their transition regions are very close to those of the adsorption isobar. Also, there seems to be a close relationship between the surface coverage at transition points and the adsorption isobars. The presence of the three kinetic stages in the desorption process may be accounted for by considering the three distinctly different types of adsorption sites on the reduced copper chromite.