Poisoning-tolerant metal hydride materials and their application for hydrogen separation from CO2/CO containing gas mixtures

• Published in: International journal of hydrogen energy 2013-08, Vol.38 (23), p.9800-9810
• Main Authors: Modibane, K.D., Williams, M., Lototskyy, M., Davids, M.W., Klochko, Ye, Pollet, B.G.
• Format: Article
• Language: English
• Subjects: AB5; Alternative fuels. Production and utilization; Applied sciences; Carbon dioxide; Carbon monoxide; Deterioration; Energy; Exact sciences and technology; Fuels; Gas mixtures; Hydrogen; Hydrogen separation; Hydrogen storage; Materials selection; Metal hydride; Metal hydrides; Separation; Surface modification
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.05.102

Metal hydride materials offer attractive solutions in addressing problems associated with hydrogen separation and purification from waste flue gases. However, a challenging problem is the deterioration of hydrogen charging performances resulting from the surface chemical action of electrophilic gases. In this work, the feasibility study of poisoning tolerance of surface modified AB5-type hydride forming materials and their application for hydrogen separation from process gases containing carbon dioxide and monoxide was carried out. Target composition of La(Ni,Co,Mn,Al)5 substrate was chosen to provide maximum reversible hydrogen capacity at the process conditions. The selected substrate alloy has been shown to be effectively surface-modified by fluorination followed by electroless deposition of palladium. The surface-modified material exhibited good coating quality, high cycle stability and minimal deterioration of kinetics of selective hydrogen absorption at room temperature, from gas mixtures containing 10% CO2 and up to 100 ppm CO. The experimental prototype of a hydrogen separation unit, based on the surface-modified metal hydride material, was tested and exhibited stable hydrogen separation and purification performances when exposed to feedstocks containing concentrations of CO2 and CO of up to 30% and 100 ppm, respectively. •Metal hydrides for H2 separation at PH2≥2.5bar/T≤80°C; H2 output at P ∼ 1 bar/T∼200 °C.•La(Ni,Co,Al,Mn)5 is suitable for the operation at the specified conditions.•Surface modification of the alloy adds tolerance to its poisoning by CO2 and CO.•Prototype H2 separation system (25%H2, ≤30%CO2, 100 ppm CO) successfully demonstrated.•Efficiency of N2 and CO2 removal about 90%.