Nowadays, more than 90% of hydrogen production comes from fossil fuels, as estimated by the US Department of Energy (DOE). Therefore, the systems of purification of hydrogen from by-products such as CH₄, H₂O, CO and CO₂ represent a crucial step of the entire manufacturing process.

One of more efficient and economically more advantageous separation systems is based on membranes, which allows separating hydrogen with a purity degree. Currently, the most efficient membranes in terms of purity and selectivity are those based on precious metals and their alloys (especially alloys based on Pd). However, their cost is high and it has been estimated that, to meet cost targets such as that of the US DOE (1000 $ per m²), elements such as palladium must be eliminated or reduced to thicknesses below 5 μm.

Critical aspects such as embrittlement and sulfur poisoning also limit their application. To overcome these problems, recent research has focused on both the development of new materials (porous or dense ceramic membranes) and the reduction of the platinum group metals content in those already exploited.
For this purpose, by exploiting the expertise developed by the group over the years on proton conducting ceramics and on coating depositions by magnetron sputtering, in ICMATE we are studying dense ceramic membranes (composite ceramic membranes, cer-cer, formed by two ceramic phases, one proton-conducting and other electron conducting) operating at around 500-700°C and bilayer membranes with porous ceramic substrates and a metallic film deposited by magnetron sputtering operating at about 400°C.

Development of composite “cer-cer” membranes (a ceramic proton conductor and a ceramic electronic conductor)

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One of the highest hydrogen fluxes ever measured in dense bulk ceramic membranes:
0.27 mL∙min_-1∙cm_-2 at 755 ºC feeding 50% H₂.

Development of membranes based on thin films of palladium alloys deposited onto porous ceramic substrates by magnetron sputtering