The detailed kinetics of the desorption of hydrogen from polycrystalline copper catalysts

The kinetics of desorption of hydrogen from the copper component of an alumina-supported polycrystalline copper catalyst has been studied in detail by temperature-programmed desorption (TPD). Line-shape analysis of the hydrogen TPD spectra shows: (i) that the desorption is second order, (ii) that the desorption activation energy is in the range 64–68 kJ mol−1 in the coverage range 7–44% of a monolayer, and (iii) that the desorption pre-exponential term has a value ∼10−5 cm2 s−1 atom−1 consistent with the desorption being second order, involving mobile adsorbates and a mobile desorption transition state.