Palladium-silver alloy membrane

Selective gas permeation has been known for generations, and the early use of palladium silver-alloy membranes achieved sporadic industrial use. Gas separation on a massive scale was used to separate U from U using porous (Knudsen flow) membranes. An upgrade of the membranes at Oak Ridge cost 1.5 billion. Polymeric membranes became economically viable about 1980, introducing the modern era of gas-separation membranes. H2 recovery was the first major application, followed quickly by acid gas separation (CO2/CH4) and the production of N2 from air. 

Uemiya, S., T. Matsuda, and E. Kikuchi, Hydrogen permeable palladium-silver alloy membrane supported on porous ceramics, /. Membr. Sci., 56, 315,1991b. 

Palladium-silver alloy membranes, 15 813-814 Pall rings, 1 28 8 770... 

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Jayaraman V., Lin Y.S. Synthesis and hydrogen permeation properties of ultrathin palladium-silver alloy membranes. J.Membr.Sci 1995 104 251-262. 

One of the earliest applications of membrane to shift equilibrium was developed by Wood(5) (1960). He showed that by imposing a nonequilibrium condition on a hydrogen-porous palladium silver alloy membrane, an otherwise stable cyclohexane vapor is rapidly dehydrogenated to cyclohexene. 

E. Kikuchi and S. Uemiya, Preparation of supported thin palladium-silver alloy membranes and their characteristics for hydrogen separation. Gas Sep. Purif. 5 261 (1991). 

Z.Y. Li, H. Maeda, K. Kusakabe, S. Morooka, H. Anzai and S. Akiyama, Preparation of palladium-silver alloy membranes for hydrogen separation by the spray pyrolysis method. J. Membr. Sci., 78 (1993) 247. 

Palladium and palladium-silver alloy membranes on porous alumina tubes were prepared by means of simultaneous and sequential electroless plating techniques [234], The membrane reactor was used for the direct formation of hydrogen peroxide by catalytic reaction of H2 and 02 at 293 K. The concentration of H202 increased with increases in the transmembrane partial pressure gradient of H2. A high concentration of H202 was obtained with a membrane that consisted of a palladium layer on the outer surface, porous alumina in the middle, and a palladium-silver alloy layer on the inside. 

Selective gas permeation has been known for generations, and the early use of palladium silver-alloy membranes achieved sporadic industrial use. Gas separation on a massive scale was used to separate U235 u 38 porous (Knudsen flow) membranes. An upgrade... 

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]. 

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. 

Gielens F C, Tong H D, van Rijn C J M, Vorstman MAG and Kementjes J T F (2002), High-flux palladium-silver alloy membranes fabricated by microsystem technology . Desalination, 147,417 23. 

McLeod L S, Degertekin F L and Fedorov A G (2009), Determination of the rate-limiting mechanism for permeation of hydrogen through microfabricated palladium-silver alloy membranes , J Membrane Sci, 341,225-232. 

Tong H D, Gielens F C, Gardeniers J G E, Jansen H V, Berenschot J W, de Boer M J, de Boer J H, van Rijn C J M and Elwenspoek M C (2005a), Microsieve supporting palladium-silver alloy membrane and application to hydrogen separation , 7 Microelectromech S, 14(1), 113-124. 

The membrane module has a plate-type structure 40 mmW x 460 mmL x 8 mmT in size. Figure 12.2 illustrates the configuration of the membrane module, and Fig. 12.3 shows a view of the membrane modules. The membrane modules consist of palladium-rare earth alloy thin film with thickness of less than 20 pm and a porous structural support. The hydrogen permeability of the membrane is several times higher than that of the widely used conventional palladium-silver alloy membrane (Sakamoto, 1992). 

Okazaki, J., Ikeda, T., Tanaka, D. A. P., Sato, K., Suzuki, T. M., Mizukami, F. (2011). An investigation of thermal stability of thin palladium—silver alloy membranes for high temperature hydrogen separation. Journal of Membrane Science, 366(1), 212—219. 

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