Palladium-silver alloy membrane system

The palladium-silver alloy membrane system was successfully commercialized in the early 1960s [12], but the reduction of palladium content by the addition of silver would still not be a cost-effective alternative for large-scale processes [42] unless micron-scale films could be prepared, a goal currently being addressed by many researchers. In recent years, the Pd-Cu system has been the most heavily investigated alloy for hydrogen membrane applications due to the high permeability of select alloys [67, 90, 91], enhanced mechanical properties [92] and reported chemical resistance. The elevated permeability identifled for select Pd-Cu alloys is attributed to an increase in both the solubility and diffusivity of the B2 crystalline phase [86-88] as compared to the face-centered-cubic (fee) phase that exhibits permeability values proportional to the Pd-content [89, 91, 93]. 

Siloxane compounds, in vitreous silica manufacture, 22 414 Siloxane materials, 20 240 Siloxane oligomers, in silicone polymerization, 22 555-556 Siloxanols, silylation and, 22 703 Silsesquioxane hybrids, 13 549 Silsesquioxanes, 15 188, 22 589-590 SilvaGas process, 3 696, 697 Silver (Ag), 22 636-667. See also Silver compounds. See Ag entries Argentothiosulfate complexes Batch desilverizing Lead-silver alloys Palladium-silver alloy membranes analytical methods for, 22 650-651 applications of, 22 636-637, 657-662 as bactericide, 22 656, 657, 660 barium alloys with, 3 344 in bimetallic monetary system, 22 647-648 in cast dental gold alloys, 8 307t coke formation on, 5 266 colloidal precipitation color, 7 343t colloidal suspensions, 7 275 color, 7 334, 335... 

Tong, H.D., Berenschot, J.WIE., de Boer, M.J. et al. (2003) Microfabrication of palladium-silver alloy membranes for hydrogen separation. Journal of Microelectromechanical Systems, 12,622-629. 

Other potential temperature variations or cycling may also occur as a result of feed or control disturbances. Thus it is important to ensure that the temperature of the system is in control so that no damage is done to the membrane, catalyst or other system components. It is well known, for example, that [Ktlladium can become embriuled under hydrogen-rich conditions particularly at a temperature near 300 or so. Some remedy in the case of palladium is to introduce certain metal such as silver as the alloying element. 

---