Dense ceramic membranes hydrogen permeable membrane

Figure 9.10a shows a concept for scale-up of cermet (ceramic-metal) type membranes. Ceramic closed-one-ended tubes coated with thin, dense hydrogen permeable materials are envisioned for the cermet-type membranes (Fig. 9.10a) As with the all-metal systems, the closed-one-ended tube arrangement allows free chemical and thermal expansion and minimizes the seal area. CoorsTek has had previous...

It was not equally obvious that dense ceramic hydrogen-permeable membranes would be of similar interest. There are clearly needs for hydrogen purification membranes, but polymers and microporous materials as well as metals such as palladium and its alloys appeared to fill these needs. In addition, possible candidates for dense ceramic hydrogen-permeable materials were not as appealing as the oxygen-permeable ones in terms of performance and stability. 

This chapter aims to keep these challenges in mind as we review the defect chemistry, transport theory and aspects of characterization of hydrogen permeation in dense ceramics. We will first look at some applications and simple schemes of operation of hydrogen-permeable membranes and then, briefly, at the literature and status of hydrogen-permeable dense ceramics. 

Dense inorganic membranes for hydrogen separation may consist either of a metal or an alloy, a ceramic (oxide), or a mixture of both, a so-called cermet. One may also envisage a mixture of two ceramics ( cercer ). In the following, we discuss literature on hydrogen permeability in some of these classes of dense membranes. 

As discussed elsewhere in this text, there are two types of dense, hydrogen-permeable metal membranes to consider from the perspective of module scale-up and design thin metal foils and permselective metal layers formed on a porous support. Another class of hydrogen-permeable inorganic membranes - dense proton-conducting ceramic membranes - are still under development and are addressed in Chapter 2. 

Kniep, J., Lin, Y. S. (2011). Oxygen- and hydrogen-permeable dense ceramic membranes. In V. V. Kharton (Ed.), Solid state electrochemistry I, fundamentals, materials and their applications (pp. 467—500). Springer (Chapter 10). 

The search for a high permeability at low cost have led to the development of membranes composed of an ultrathin Pd-Ag layer (<10 pm) on a ceramic or stainless steel porous supports [16-18]. They combine the infinite selectivity to hydrogen of the dense Pd-Ag film with a mechanical strength of the porous support, which resistance to hydrogen transfer is negligible. These membranes are very promising, since they exhibit remarkably high fluxes [0.5-2.5 mol/(m s). 

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