Abstract
Zr-Ni based amorphous alloy membranes are potentially alternative materials to Pd alloys which are having been utilized for hydrogen separation. We investigate on various characteristics of Zr-Ni based amorphous membranes, assuming the utilizations for hydrogen separation in the steam-reforming process of hydrocarbons. Gas permeation measurements are carried out with introducing the simulated steam-reforming gas mixture of methanol, as well as with a pure H2 gas, at 573K and 0.2-0.7MPa in pressure difference (introduced gas pressure: 0.3-0.8MPa, permeated gas pressure: 0.1MPa). Some of Zr-Ni based amorphous membranes, e.g. Zr50Ti15Ni10Al10Cu15 membrane show excellent hydrogen permeability. As a result of the gas separation measurement from the gas mixture, comprised of approximately 23vol% CO2, 2.3vol% CO, 8vol% steam and H2 in balance, we confirm that Zr36Ni64 amorphous membrane keeps its good hydrogen permeability and has excellent hydrogen selectivity, and demonstrate that separation of H2 gas by the membrane. We have investigated the relationships between alloy compositions and the permeability and the structural durability of those alloys', the latter of which is estimated by isothermal aging test conducted at 523K in the air. As a result, we find that both of the characteristics are strongly dependent on alloy compositions, especially on Zr-content. We find that several membranes including Zr36Ni64 show excellent structural durability at 523K over 17,000h. As for a Zr36Ni64 membrane, the structural durability at 573K in 0.5MPa H2 atmosphere is also investigated. It shows good durability even after more than 5,500h hydrogenation aging.
