Hydrogen storage alloys for high-pressure suprapure hydrogen compressor

In this work, AB(5) type rare earth-based and AB(2) type TiCr2-based hydrogen storage alloys were studied for the purpose of high-pressure hydrogen compression. A pair of hydrogen storage alloys, Ml(0.55)Mm(0.2)Ca(0.25)M(5) (MI: La-rich mischmetal; Mm: Ce-rich mischmetal) and (Ti0.97Zr0.03)(1.1)Cr1.6Mn0.4, with favorable hydrogen storage properties was developed as the alloys for a double-stage high-pressure metal hydride hydrogen compressor (MHHC). With the developed alloy pair, we designed and built a MHHC prototype with hydrogen capacity of 100 L, which could produce high-pressure ultrapure hydrogen with pressure of 45 MPa and purity of 99.9999% from industrial grade hydrogen (98% purity) at pressure of around 2 MPa. During the compression procedure, only hot water is used as the heating source. The compression characteristics were studied and the thermal efficiency was calculated. (c) 2005 Elsevier B.V. All rights reserved.