High temperature gas separation membranes

Gas separation membranes are electrochemical devices that allows the separation of specific components contained in gas streams at high temperatures (500-800°C). These systems can be classified on the bases of the materials used as :

Oxygen separation membranes;

Hydrogen separation membranes.

These devices are ceramics or ceramic-metallic bilayers constituted of a supporting element and an active layer. Separation membranes are produced at ISTEC starting from commercial or synthesized powders by tape casting or /and screen printing. Substrates and active layers for this application were developed with different compositions:

La0.6Sr0.4Fe0.8Co0.2O3 (LSCF);

La0.8Sr0.2MnO3 / Ce0.8Gd0.2O2,(LSM-GDC);

NiO/ Ba(Ce,Y,Zr)O3, Ba(YCe)O3.

Products with diameter up to 5 cm were obtained after a careful suspension and thermal treatment optimizations needed to reach a suitable microstructure for the required application (in Figure) .

The as-produced bilayers are generally sintered via co-firing. For this purpose a great attention is given to the sintering behavior of each layer that, even subjected to the same heat treatment, must satisfy two different requirements: a suitable porosity of the supporting element and an high density of the active layer.