Composite metallic membranes

Metal-matrix composites Metal membranes Metal-metal bonds Metal naphthenates Metal oleates... 

R.E. Buxbaum, Composite Metal Membrane for Hydrogen Extraction, US Patent 4,215,729 (June, 1993). 

D.J. Edlund and D.T. Friesen, Hydrogen-permeable Composite Metal Membrane and Uses Thereof, US Patent 5,217,506 (June, 1993). 

D.J. Edlund and J. McCarthy, The Relationship Between Intermetallic Diffusion and Flux Decline in Composite-metal Membranes Implications for Achieving Long Membrane Lifetime, 7. Membr. Sci. 107, 147 (1995). 

Composite metal membranes are most often the structure of choice when a reactive group 3-5 metal or alloy is the principle constituent of the membrane. The relative chemical reactivity of these metals dictates that an inert coating must be applied to at least the feed surface of the membrane. Palladium, or better yet a palladium alloy, customarily serves as the coating layer. If it can be guaranteed that the permeate side of the membrane will never be exposed to reactive gases (e.g., water, carbon oxides, and hydrocarbons), then a two-layer composite membrane is a satisfactory choice. However, normal operating procedures and the potential for process upsets typically favors the selection of a three-layer composite structure. 

The first commercial metal membranes for hydrogen separation and purification were made of palladium alloyed with 23-25 wt % silver. These membrane were of the unsupported type and tubular in shape. Nevertheless, the wall thickness was substantial by current standards—typically at least 100- an thick. Advances in drawing thin-walled metal tubes has allowed for palladium-silver tubular membranes to be made with much thinner walls, about 20- an thick. Composite membranes are also usually at least 25-/an thick. REB Research and Consulting (Oak Park, MI) provides tubular composite metal membranes consisting of a palladium coating over a tantalum base metal, although other group 4 or 5 base metals may be used. 

Edlund, D.J. and McCarthy, J.M. The relationship between intermetallic diffusion and flux decline in composite-metal membranes Implications for achieving long membrane hfetime. Journal of Membrane Science, 1995, 107, 147-153. 

D.J. Edlund and W.A. Pledger, A study of long-term stability of composite metal membranes. Paper presented at the 3rd International Conference on Inorganic Membranes, July 10-14,1994, Worcester, MA, USA. 

Peachey, Nathaniel M, Dye, Robert C, Snow, Ronny C, BirdseU, Stephan A. Composite Metal Membrane. US Patent 5,738,708,14 April 1998. 

Buxbaum RE. Composite metal membrane for hydrogen extraction. US Patent 5215729, 1999. 

Peachey NM, Dye RC, Show RC, Birdsell SA (1998) Composite metal membrane. US Patent 5738708... 

Edlund DJ, Friesen DT (1993) Hydrogen-permeable composite metal membrane and uses thereof. US Patent 5,217,5006... 

Schematic diagram of a steam reformer of biofuel. A composite metallic membrane is used to extract hydrogen and feed a HJO2 PEM fuel cell. 

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