Characterization of getter compounds for use in hydrogen purification

Hydrogen is a promising energy carrier for zero-emission mobility and power generation, because it is characterized by high energy density and produces only water as a by-product when reacted with oxygen in fuel cells. However, hydrogen also poses some challenges for its production, distribution, and utilization. One of these challenges is the need for high-purity standards, as hydrogen can be contaminated by various impurities during its production from fossil fuels or renewable sources, affecting performance and durability of fuel cells. Another challenge is the need for efficient storage systems, as hydrogen presents low volumetric density and high explosiveness in gas phase, and requires high pressures and low temperatures to be liquefied. These conditions increase the energy consumption and the safety risks of hydrogen storage. Hydrogen getters are intermetallic compounds which can absorb hydrogen at very low equilibrium pressures. They are able to getter even small amounts of hydrogen in contaminated feed streams, however, they also form very stable hydrides requiring high temperature and low pressures to decompose. This thesis focuses on the characterization of ST707 and ZAO1 getter compounds, manufactured and supplied by SAES Getters. Since their use in hydrogen storage is a research topic under active development, the main objective of this work is to characterize their microstructure and assess their cycling performance in pure hydrogen. Literature data and experimental results presented here will hopefully be useful for future research on purification of contaminated bio-hydrogen streams, produced by University of Zaragoza from pyrogasification of biomass sources as part of UNITA GFI project.