LAUSR

Abstract AB5-type intermetallic compounds are suitable materials for hydrogen separation due to their ability selectively absorb hydrogen from different gas streams, including biologically produced ones. Recent studies show that metal hydride-based purification systems can effectively extract hydrogen from biogas with high CO2 concentration. Alloys LaNi5-xMx (M = Fe, Al, Mn, Sn) are prepared and activated during several cycles of H2 sorption/desorption and their PCT properties are measured in Sievert's type apparatus. Two compositions LaNi4.4Fe0.3Al0.3 and LaNi4.6Mn0.2Al0.2 are chosen for further investigations because they meet the requirements for biohydrogen separation system. After PCT measurements of 50-g samples, metal hydride powders are investigated by means of Quantochrome Nova 1200 and scanning electron microscopy to determine porosity, average particle size, specific surface area and permeability of metal hydride bed. Powder bed permeabilities are defined as 9.08 × 10−13 m2 for LaNi4.4Fe0.3Al0.3 and 6.86 × 10−13 m2 for LaNi4.6Mn0.2Al0.2 by Kozeny-Carman equation. AB5 type LaNi4.4Fe0.3Al0.3 and LaNi4.6Mn0.2Al0.2 alloys show good characteristics: low equilibrium pressures 0.025–0.03 MPa and acceptable reversible hydrogen capacity 1.1 %wt. for stationary hydrogen separation system.