Three Methods for Application of Data from a Volumetric Method to the Kissinger Equation to Obtain Activation Energy

Abstract

Thermal analysis methods have been used in many reports to determine the activation energy for hydride decomposition (dehydrogenation). In our preceding work, we showed that the dehydrogenation rate of Mg-5Ni samples obeyed the first-order law, and the Kissinger equation could thus be used to determine the activation energy. In the present work, we obtained the activation energy for dehydrogenation by applying data from a volumetric method to the Kissinger equation. The quantity of hydrogen released from hydrogenated Mg-5Ni samples and the temperature of the reactor were measured as a function of time at different heating rates (Φ) in a Sieverts-type volumetric apparatus. The values of dHd/dt, the dehydrogenation rate, were calculated as time elapsed and the temperature (Tm) with the highest dHd/dt was obtained. The values of dHd/dT, the rate of increase in released hydrogen quantity (Hd) to temperature (T) increase, were calculated according to time, and the temperature (Tm) with the highest dHd/dT was also obtained. In addition, the values of dT/dt, the rate of increase in temperature to time (t) increase, were calculated according to time, and the temperature (Tm) with the highest dHd/dt was obtained. Φ and Tm were then applied to the Kissinger equation to determine the activation energy for dehydrogenation of Mg-5Ni samples.

Keywords

• hydrogen storage
• volumetric method
• Sieverts-type volumetric apparatus
• Kissinger equation
• activation energy