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Development of thin binary and ternary Pd-based alloy membranes for use in hydrogen production

Peters, T.A., Kaleta, T., Stange, M., Bredesen, R.
Journal of membrane science 2011 v.383 no.1-2 pp. 124-134
X-ray diffraction, activation energy, alloys, artificial membranes, copper, hydrogen, hydrogen production, manufacturing, molybdenum, permeability, temperature
The manufacturing, characterisation, and H₂ permeation properties of thin membranes of a variety of binary Pd–Cu (∼5–53at.% Cu), Pd–TM (∼5at.% TM=Au, Ru, Mo, Ta, Nb, Y), and ternary Pd–Cu–TM alloys (base alloy∼Pd₇₀Cu₃₀ where Cu is replaced by various amounts of TM) prepared by magnetron sputtering are reported. From the XRD characterisation it can be concluded that all the membranes prepared by magnetron sputtering exhibit a strong preferential orientation along the 〈111〉 direction. Among the components investigated, Pd–Au and Pd–Y prove to result in binary Pd-alloys with the highest H₂ permeability. While Pd₉₅Au₅ shows a similar H₂ permeability compared to pure Pd, Pd₉₅Y₅ gives a H₂ permeability around 15% larger than pure Pd. Binary Pd-alloy with the addition of 5at.% Cu, Ru, and Nb gives rise to similar H₂ permeabilities in the range of 80% of pure Pd. The addition of 5at.% Mo and Ta does not result in binary Pd-alloy materials with a large H₂ permeability. Among the ternary Pd–Cu–TM alloys explored the addition of ∼1at.% TM always result in an increase in permeability. For the investigated alloys a trend is found showing that the permeability increases and its activation energy decreases with increasing fcc lattice constant of the alloy in the temperature range 300–400°C. The addition of Ta or Y, resulting in the Pd₇₃Cu₂₆Ta₁ and Pd₇₃Cu₂₆Y₁ alloys, gives rise to an increase in H₂ permeability of roughly 10 and 45%, respectively. For the Pd₆₅Cu₂₁Ag₁₄ alloy, a H₂ permeability gain of almost 65% is obtained compared to the binary Pd–Cu counterpart at the same Pd content.