On efficiency of metal hydride extraction of hydrogen from a mixture with methane

Abstract

Abstract Extraction of hydrogen from dilute mixtures with natural gas differs from traditional separation processes, since hydrogen is the minor component with low partial pressure. Metal hydrides absorb hydrogen selectively and can be used for purification. Exergy analysis shows that the metal hydride separation of binary mixture of a gas with hydrogen has a maximum at hydrogen content of 5-15%, and the main factors affecting efficiency are the need to spend heat to compensate the reaction enthalpy and pressure losses of methane during filtration through the metal hydride bed. We have experimentally demonstrated successful separation of the hydrogen (10%) – methane (90%) mixture at inlet pressure of 9.5 bar by the LaNi4.8Mn0.3Fe0.1 intermetallic compound in one step with roundtrip (absorption/ desorption) hydrogen recovery of 74% and absorption hydrogen recovery of 76%, which is close to the value of 77% calculated based on the thermodynamic analysis.