La0.6Sr0.4Co0.2Fe0.8O3−δ microtubular membranes for hydrogen production from water splitting

Reactor modules consisting of four gas-tight microtubular membranes made of the mixed oxygen ion and electron conducting perovskite, La0.6Sr0.4Co0.2Fe0.8O3−δ have been tested for oxygen permeation and hydrogen production by membrane-based steam reforming, i.e., simultaneous syngas production coupled with water splitting. The membranes were subjected to two known axial temperature profiles in the temperature of 900 °C. The microtubes showed good stability under reaction conditions, operating over a total operation period of ca 400 h of oxygen permeation followed by ca 400 h of steam reforming. An induction period of approximately 30 h was observed before steam reforming commenced. Both the methane and water side outlet gas compositions were measured which allowed for accurate material balance; this indicated that the hydrogen production occurred due to oxygen flux across the membrane and not just surface reaction. Post operation analysis of the microtubes revealed the presence of a strontium enriched dense layer on the water exposed membrane surface and of crystallites enriched with cobalt and sulfur on the methane feed side surface.