Metal
hydrides are promising hydrogen storage materials. As a result of
their high volume adsorption density and excellent adsorption selectivity,
they have also been proposed for use in hydrogen purification; that
is, as hydrogen adsorbents for the direct separation of hydrogen from
complex mixed gases. In this review, the properties of metal hydride
adsorbents are reviewed, including their thermodynamic properties
and susceptibility to poisoning by impurity gases. The differences
and similarities between common pressure swing adsorption (PSA) techniques
and PSA using metal hydride adsorbents are analyzed on the basis of
which the principles for cycle procedure design are given. The potential
utility of metal hydrides for hydrogen purification has been demonstrated
by some lab- and pilot-scale tests, which are also introduced here.
On the basis of this review and analysis, elevated-temperature PSA
techniques using metal hydrides appear to be a feasible direction
for the development of hydrogen purification processes.