(258d) Reverse Water Gas Shift Reaction over Cu-Fe/Al2O3 Catalyst in Solid Oxide Electrolysis Cells

Reverse water gas shift (RWGS) reaction is a practical method to convert CO₂ to CO utilizing hydrogen supplied from clean energy sources. Solid oxide electrolysis cells (SOECs) are new energy conversion devices with high efficiency and environmental compatibility. They can split steam (H₂O) into hydrogen and oxygen by using electricity generated from clean energy sources (such as solar energy and wind energy). Thus, applying the SOECs in the RWGS reaction could be a feasible way for efficient conversion of CO₂ using renewable energy sources. RWGS reaction was carried out over Fe-Cu/Al₂O₃ catalyst by a fixed-bed quartz tube reactor using externally supplied hydrogen at temperature of 700 ^oC, while fixing total flow rates of H₂ and CO₂ at 100 ml/min (CO₂:H₂ is 1:1). The catalyst showed good catalytic activity with CO­₂ conversion of 42% which is close to the equilibrium conversion. TEM and XRD analysis results confirmed that the sintering of active sites was prevented during the reaction. Cu-Fe/Al₂O₃ catalyst was then utilized as a functional reforming layer for the cathode of a conventional SOEC single cell. The single cell consisted of Ni-yttria stabilized zirconia (YSZ) cathode support/YSZ/Ce_0.8Sm_0.2O_1.9 (SDC) bi-layer electrolyte/La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ anode. Using this SOEC single cell with the catalysts layer, the RWGS reaction was investigated under the applied electric load condition. Our results indicated that by electrolysing H₂O over the cathode of SOEC cell, a reduced amount of external hydrogen is needed to obtain a similar CO₂ conversion as the fixed-bed quartz tube test.