Palladium–gold membranes in mixed gas streams with hydrogen sulfide: Effect of alloy content and fabrication technique

Pd-Alloy membranes for hydrogen separation

“…Coulter [44] and Gade [56] evaluated Pd 94 Au 6 and Pd 88 Au 12 alloys, both in pure H 2 and in synthetic WGS streams containing up to 50 ppm H 2 S. The pure H 2 permeabilities of both alloys, measured at 400 C, were, as expected, greater than that of pure Pd. In the WGS mixture, the H 2 permeability of Pd 94 Au 6 was $30% lower (slight differences in samples made by different methods are likely within experimental repeatability) than in pure H 2 [44,56].…”

“…Roa reported similar indifference to non-H 2 WGS components for a Pd 89 Au 11 membrane [20]. Addition of 20 ppm H 2 S to the WGS mixture reduced the permeability of Gade's Pd 88 Au 12 by 40% [56]. Palladium sulfides, detected by XRD on the surface of Gade's Pd 94 Au 6 after testing in a H 2 S/WGS mixture, likely contributed to that membrane's flux loss [56].…”

“…Addition of 20 ppm H 2 S to the WGS mixture reduced the permeability further, to $50% of its WGS value. Increasing Au content improves response to WGS components: the permeability of a Pd 88 Au 12 membrane in the WGS mixture was the same as it was as in pure H 2 [56]. Roa reported similar indifference to non-H 2 WGS components for a Pd 89 Au 11 membrane [20].…”

“…In the WGS mixture, the H 2 permeability of Pd 94 Au 6 was $30% lower (slight differences in samples made by different methods are likely within experimental repeatability) than in pure H 2 [44,56]. Addition of 20 ppm H 2 S to the WGS mixture reduced the permeability further, to $50% of its WGS value.…”

“…Addition of 20 ppm H 2 S to the WGS mixture reduced the permeability of Gade's Pd 88 Au 12 by 40% [56]. Palladium sulfides, detected by XRD on the surface of Gade's Pd 94 Au 6 after testing in a H 2 S/WGS mixture, likely contributed to that membrane's flux loss [56]. As noted earlier, Chen did not observe sulfide formation upon exposure of Pd 95.5 Au 4.5 H 2 S in a H 2 background [19].…”