Analysis of the Impact of CO₂ on the Cyclic Stability of the Hydralloy C5 Alloy

The submitted paper addresses the impact of exposing an activated metal hydride alloy of the Hydralloy C5 type to carbon dioxide (CO₂). This contaminant is commonly present as one of the components during hydrogen production, either through steam reforming or from synthesis gas generated by conventional gasification of organic materials and waste, or by using plasma-based technologies.The study investigates the effect of a 4% volumetric concentration of CO₂ on the cyclic stability of hydrogen absorption into the metal hydride alloy structure. The objective is to quantify changes in the absorption behavior of the material and to identify potential degradation mechanisms associated with the presence of carbon dioxide in the gas phase.Testing confirmed a high degree of alloy degradation, caused by the poisoning effect of CO₂ on the selected alloy type. A deterioration of cyclic stability and a reduction in the alloy’s hydrogen absorption capacity were also observed – from 1.827 wt.% to 1.14 wt.%– as well as a significant extension of the absorption time due to slower hydrogen absorption kinetics into the intermetallic structure of the metal.