Sputtering of very thin palladium-alloy hydrogen separation membranes

Microstructural characterization of self-supported 1.6μm Pd/Ag membranes

“…A simple regression based on an estimation of the hydrogen partial pressure difference from the concentration of hydrogen measured with the GC is however not sufficient to determine the n-value in the general flux equation (J = P/t(p n 1 − p n 2 ), in particular, in the presence of fluctuations in the data and with possible occurrences of concentration gradients close to the surface. However, using such hydrogen partial pressure estimation, and the highest permeance (6.10 × 10 −6 mol/(m 2 s Pa)) obtained from similar membranes [3], the maximum transport capacity of M300 is about 0.4 mol/(m 2 s), which is 10 times larger than the initial value. This, together with the deactivation of M300 and M350 during time on stream, indicates that the surface processes involving the components of the WGS mixture restrict the permeation.…”

“…They can also be applied in self-supported membrane configurations. A hydrogen permeance of 6 × 10 −6 mol/(m 2 s Pa) at 300 • C in pure hydrogen was observed from 1.3 m self-supported Pd/Ag membranes [3]. Similarly, a permeance of 2 × 10 −5 mol/(m 2 s Pa) was achieved from a membrane heat treated in air for 2-3 days prior to the permeation test [3].…”

“…A hydrogen permeance of 6 × 10 −6 mol/(m 2 s Pa) at 300 • C in pure hydrogen was observed from 1.3 m self-supported Pd/Ag membranes [3]. Similarly, a permeance of 2 × 10 −5 mol/(m 2 s Pa) was achieved from a membrane heat treated in air for 2-3 days prior to the permeation test [3]. To the best of our knowledge, the latter value is the highest ever reported for a dense 100% selective metallic membrane.…”

“…Palladium has a catalytic surface, high hydrogen permeability, infinite hydrogen selectivity, good temperature stability and corrosion resistance [1] in most atmospheres. As a result, it has wide applications in both commercial and exploratory processing ranging from hydrogen purification to catalytic hydrogenation/dehydrogenation, energy storage, sensors, fuel cell technology and hydrogen separation from gases containing CO 2 in the pre-combustion decarbonisation process [2,3].…”

“…Self-supported Pd-based membranes, in the form of tubes or foils, are mainly fabricated by fine metallurgical processes [5] and they are often relatively thick (20-70 m) [3]. It is necessary to prepare much thinner membranes to gain higher hydrogen permeation.…”