Design of Thin Film Membranes for Intermediate-Temperature Hydrogen Separation


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Pişkin F., Öztürk T.

3 rd International Hydrogen Technologies Congress, Antalya, Turkey, 15 - 18 March 2018, vol.1, no.1, pp.100

  • Publication Type: Conference Paper / Summary Text
  • Volume: 1
  • City: Antalya
  • Country: Turkey
  • Page Numbers: pp.100

Abstract

[Abstract:0243] Design of Thin Film Membranes for Intermediate-Temperature Hydrogen Separation Fatih Pişkin1 , Tayfur Öztürk2 1 ENDAM, Center for Energy Materials and Storage Devices, Dept. of Metallurgical and Materials Engineering, Middle East Technical University, Ankara, Turkey Dept. of Metallurgical and Materials Engineering, Muğla Sıtkı Koçman University, Muğla, Turkey 2 ENDAM, Center for Energy Materials and Storage Devices, Dept. of Metallurgical and Materials Engineering, Middle East Technical University, Ankara Separation membranes allow purification of hydrogen from gas mixtures that could be generated by various production methods such as steam reformation of hydrocarbons, coal gasification or biomass-based fermentation process. Here, each production method sets conditions for separation membranes in terms of operating conditions. Thus, the separation membranes are required to meet different process temperatures varying from ~600 °C to as low temperature as possible. The temperature intervals for hydrogen separation processes might be expressed into three categories such as; low temperature, RT-200 °C, intermediate-temperature, 300-450 °C, and high temperature, ≥450 °C. The current study concentrates on intermediate-temperature separation membranes, i.e. temperature 300-450 °C which are applicable to steam reformation of natural gas including the water gas shift reaction. Metallic membranes used for this purpose are quite attractive due to their high permeability together with a selectivity that is exceptional among other alternatives. The study adopts a membrane design methodology based on combinatorial material science. This approach makes use of magnetron sputtering whereby a library of thin film membranes are produced in a single experiment each membrane with a different composition. The library is then screened by four-probe resistivity measurements so as to identify compositions that react with hydrogen. A map of reactive index is prepared in the compositional field from which candidates were identified for hydrogen separation. The membranes were then fabricated in the form of foils and tested for hydrogen permeability. Using the above methodology, three ternary alloy system were evaluated, namely Nb-Pd-Ti, Pd-Ag-Ti, and Pd-Ag-Ni. Keywords: Hydrogen separation membranes, combinatorial approach, Pd-based membranes, Nb-based membranes, resistivity measurements.