The Temperature-Programmed Desorption of H2 from Cu/ZrO2

Abstract

The desorption kinetics of hydrogen from a polycrystalline Cu/ZrO2 catalyst was investigated under atmospheric pressure using temperature-programmed desorption (TPD) experiments in a microreactor set-up. Different heating rates were applied under equal conditions with a carefully reduced catalyst. The hydrogen TPD peaks were symmetric and centered slightly above 300 K indicating associative desorption of H2 from metallic Cu. Using heating rate variation, the kinetic parameters $$A_{des}$$ and $$E_{des}$$ were determined to be 1.24 × 109 s−1 and 68 kJ mol−1, respectively. As the modeling with constant values of $$A_{des}$$ and $$E_{des}$$ yielded signals which were too narrow, dependence of $$E_{des}$$ on coverage was introduced applying $$E_{des} - K (\Theta _H)^n$$ . By application of the “full-analysis” method an optimal fit to the experimental data was found. Setting n = 1 resulted in the best fit and a value of 61 kJ mol−1 − (6.25 kJ mol−1 × $$\Theta _H$$ ) for $$E_{des}$$ was determined.