Palladium alloy membranes permeation

Hydrogen permeation flux data (pmoles/cm -min) of activated and non-activated palladium alloy membranes... 

Corrosive reaction streams. In some application environments, the reactive or corrosive nature of one or more of the reaction components in a membrane reactor can pose a great technical challenge to the selection as well as the design of the membrane element Feed streams often contain some Impurities that may significantly affect the performance of the membrane. Therefore, attention should also be paid to the response of the selected membrane material to certain impurities in the reactant or product streams. Care should be taken to pretreat the feed streams to remove the key contaminants as far as the membrane is concerned in these cases. For example, palladium alloy membranes can not withstand sulfur- or carbon-containing compounds at a temperature higher than, say, 500 C [Kamcyama et al., 1981]. Even at lOO C, the rate of hydrogen absorption (and, therefore, permeation) in a pure palladium disk is... 

Hydrogen is able to permeate selectively through palladium or palladium alloy membranes. This has led to the demonstration of membrane reformers in the labora-... 

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. 

Palladium-based dense metallic membranes have been known to be completely selective for hydrogen permeation and are used in commercially available small-scale hydrogen purification units (e.g., Johnson Matthey, 2007 REB Research, 2007 Power + Energy, 2007 ATI Wah Chang, 2007). These hydrogen purification units typically use palladium-alloy... 

Hara, S., N. Hatakeyama, N. Itoh, H.-M. Kimura, and A. Inoue, Hydrogen permeation through palladium-coated amorphous Zr-M-Ni (M=Ti, Hf) alloy membranes, Desalination, 144,115-120, 2002. 

F.L. Chen, Y. Kinari, F. Sakamoto, Y. Nakayama and Y. Sakamoto, Hydrogen Permeation through Palladium-Based Alloy Membranes in Mixtures of 10% Methane and Ethylene in the Hydrogen , Int. J. Hydrogen Energy, 21 [7] 555-61 (1996). 

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

The feasibility of the palladium membrane system with an oxidation reaction on the permeation side and 1-butene dehydrogenation reaction on the reaction side in a membrane reactor has been successfully demonstrated. The palladium and its alloy membrane not only can withstand high temperature but also are selectively permeable to hydrogen... 

Dense palladium-based membranes. Shown in Table 10.1 are modeling studies of packed-bed dense membrane shell-and-tube reactors. All utilized Pd or Pd-alloy membranes except one [Itoh et al., 19931 which used yttria-stabilized zirconia membranes. As mentioned earlier, the permeation term used in Ihe governing equations for the tube and shell sides of the membrane is expressed by Equation (10-51b) with n equal to 0.5 [c.g., Itoh, 1987] or 0.76 [e.g., Uemiya et al., 1991]. 

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. 

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... 

F. Sakamoto, Effect of carbon monoxide on hydrogen permeation in some palladium-based alloy membranes, Int. J. Hydrogen Energy 1996, 21(11/12), 1017-1024. 

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