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An investigation into thin film palladium alloy composite membranes with a powdered tungsten intermediate layer for the separation of hydrogen

Simpson, George Innes (2012)
M.Res. thesis, University of Birmingham.

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Abstract

The development of a composite (Pd-alloy thin film / Porous stainless steel substrate)hydrogen separation membrane was investigated, that is able to operate at high temperatures (600°C), for use in a hydrocarbon reformation reactor for the production of pure hydrogen. An intermediated layer of tungsten powder was deposited onto the surface of macroporous 316L stainless steel (PSS) substrates. This layer served to create an interdiffusion barrier against iron diffusion and also to reduce the surface pore size of the PSS. The dual performance of this intermediate layer within a composite membrane was tested, in terms of surface pore size reduction and ability to prevent interdiffusion. The extent of the powder filling and surface pore reduction was calculated along with the effect on hydrogen transport through the modified substrate. The results showed that both one and three layers of tungsten powder were successful. Production of a defect-free membrane layer was also investigated, coating the tungsten modified PSS substrate with various thicknesses of stainless steel (SS) (as a low-cost proxy for a Pd-alloy thin film). The results showed that a more continuous defect-free membrane layer was achieved when the surface of the substrate was most uniform. The performance of both dense and powdered tungsten intermediate barriers on their ability to prevent iron diffusing into sputtered Pd/PdCu membrane layers, was also investigated. SEM-EDX analysis showed that dense tungsten was very successful at preventing iron diffusion while the powdered particles were also clearly preventing interdiffusion within the pores. It was concluded that a combination of both dense and powdered tungsten would need to be used to fully prevent iron diffusion.

Type of Work:M.Res. thesis.
Supervisor(s):Book, David and Fletcher, Sean
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Metallurgy and Materials
Subjects:TN Mining engineering. Metallurgy
TS Manufactures
Institution:University of Birmingham
ID Code:3625
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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