Hydrogen Isotopes Absorption Kinetics of Palladium/Kieselguhr

The pressure-time curves of hydrogen reacting with Pd/K were investigated at 223-393 K by using the method of the reaction rate analysis at constant temperature and volume. Dynamics analysis suggests that the adsorption reaction at the whole temperature range can be divided into two stages, the low temperature range(223-313 K) and the high temperature range(313-393 K). At the low temperature range, the rate constants increase with the temperature for protium and deuterium. The activity energy is 19.5 kJ/mol, 19.2 kJ/mol, respectively. However, the rate constants decline with the temperature increasing at the high temperature range, and the activity energy is -18.6 kJ/mol,-12.1 kJ/mol,respectively. The changing of activation energy shows remarkable kinetics isotope effects and the isotope effects depend on temperature.