Supported Palladium Membrane

Lee et al. [95] fabricated a palladium membrane on a 400 mm thick silicon wafer. The process applied was very similar to the method applied by Franz et al. [93], Silicon nitride and silicon oxide were deposited on the wafer and then the silicon was removed from the reverse side by DRIE. A100 pm thick palladium layer forming the membrane was deposited on the support by an evaporation method. 

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Lin, Y.M. and M.H. Rei, Separation of hydrogen from the gas mixture out of a catalytic reformer by using supported palladium membrane, Sep. Purif. Technol., 25,87-95,2001a. 

Lin, Y.-M., Rei, M.-Fl. 2000. Proeess development for generating high purity hydrogen by using supported palladium membrane reaetor as steam reformer. Int J Flydrogen Energy 25 211-219. 

Lin YM, Rei MH (2001) Study on the hydrogen production from methanol steam reforming in supported palladium membrane reactor. Catal Today 67 77—84... 

A two-step membrane manufacturing process has been reported where a defect free Pd-alloy membrane is first prepared by sputtering deposition onto the perfect surface of a silicon wafer, for example. In a second step the membrane is removed from the wafer and transferred to a porous stainless steel support (see Figure 11.1). This allows the preparation of very thin ( 1-2 pm) defect-free membranes supported on macroporous substrates (pore size equals 2 pm). By this technique, the ratio of the membrane thickness over the pore size of the support may become less than 1, which is two orders of magnitude smaller than obtained by more conventional membrane preparation techniques. Tubular-supported palladium membranes prepared by the two-step method show a H2/N2 permselectivity equal to 2600 at 26 bars and hydrogen flux of 2477 mL(STP) min cm . Since the method enables the combination of macro-porous stainless steel supports and thin membrane layers, the support resistance is negligible. ... 

Basile, A., Pinacci, P., lulianelli, A. et al. (2011) Ethanol steam reforming reaction in a porous stainless steel supported palladium membrane reactor. International Journal of Hydrogen Energy, 36,2029-2037. 

Kikuchi [111] described a natural gas MR, which had been developed and operated by Tokyo Gas and Mitsubishi Heavy Industries to supply PEM fuel cells with hydrogen. It was composed of a central burner surrounded by a catalyst bed filled with commercial nickel catalyst. Into the catalyst bed 24 supported palladium membrane tubes were inserted. The membranes had been prepared by electroless plating and were 20 pm thick. Steam was used as sweep gas for the permeate. The reactor carried 14.5 kg catalyst. It was operated at 6.2 bar pressure, S/C ratio of 2.4, and 550°C reaction temperature. The conversion of the natural gas was close to 100%, wdiile the equilibrium conversion was only 30% under the operating conditions. The retentate composition was 6 vol.% hydrogen, 1 vol.% carbon monoxide, 91 vol.% carbon dioxide, and 2 vol.% methane. 

SSP = self-supported palladium membrane Sbet - BET specific surface area -reaction pressure SV = space velocity WHSV = weight-hourly-space-velocity GHSV =... 

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