Engineering: The burning issue

Burning fossil-fuels in pure oxygen not only improves efficiency, it also produces a cleaner stream of carbon dioxide which can be separated more easily, and potentially used as a chemical feedstock.

Pure oxygen is normally produced by liquefying air, but this cryogenic process is relatively expensive. Ceramic membranes that allow only oxygen to pass through could provide a much cheaper option.

At the University of Newcastle in the UK, Ian Metcalfe's team has been experimenting with new production methods for hollow fibres of the material LSCF, La_0.6Sr₀.₄Co₀.₂Fe₀.₈O_3-, where  represents the oxygen vacancy within the lattice.

At temperatures greater than 700 C, and with oxygen at a greater concentration on one side of the membrane, oxygen molecules dissociates into charged ions. The oxygen vacancies within the lattice can diffuse, allowing oxygen ions to seep through to the other side of the membrane, with electrons flowing in the opposite direction.

Associated URL: www.rsc.org/chemistryworld/News/2007/August/07080701.asp

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