Carbon monoxide fuel oxidation within SOFC

Sol-gel technique has also been applied to modify the anode/electrolyte interface for SOFC running on hydrocarbon fuel [16]. ANiA SZ cermet anode was modified by coating with SDC sol within the pores of the anode. The surface modification of Ni/YSZ anode resulted in an increase of structural stability and enlargement of the TPB area, which can serve as a catalytic reaction site for oxidation of carbon or carbon monoxide. Consequently, the SDC coating on the pores of anode leads to higher stability of the cell in long-term operation due to the reduction of carbon deposition and nickel sintering. 

The SOFC module is set (sized) to operate at 0.69 volts per cell. The spent fuel and air effluents of the SOFC are combusted within the module to supply heat for oxidant preheating. Unlike the natural gas case, the fuel does not require a pre-reformer with only 0.3% methane along with 36% hydrogen and 43% carbon monoxide. The carbon monoxide will be either water gas shifted to hydrogen or utilized directly within the fuel cell. A gas recirculation loop for the... 

In direct-flame SOFCs, part of the fuel gas is combusted in an ordinary burner with an open flame. When the combustible fuel-oxygen mixture is fuel-rich, then a partial fuel reforming wiU occur in the flame yielding hydrogen and carbon monoxide CO. The SOFC anode is set up in the immediate vicinity of the flame, within a few millimeters. There these reforming products are oxidized elec-trochemically. The surrounding air has immediate access to the cathode surface, located on the opposite side of the cell. The fuel cell itself is heated to its working temperature by the flame. 

In the case where the fuel type is hydrocarbon for a solid oxide fuel cell (SOFC) unit, it can be catalyticaUy converted into hydrogen and carbon monoxide within the cell stack, known as internal reformation. Carbon monoxide and hydrogen thus produced are then electronically oxidised to carbon dioxide and water at the anode with the production of heat and electric current. Internal reforming can be of two types, as shown in Fig. 9.6 ... 

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