Development of Electrochemical Methanation Reactor with Co-Electrolysis of Humidified CO2

Solid oxide fuel cells (SOFCs) have received a great deal of attention recently, due to in part to their high energy conversion efficiency and environmental compatibility. Recently, an electrochemical cell with the same components as SOFCs has also been used as a solid oxide electrolysis cell (SOEC) for Power-to-Gas process. The use of alternative high performance electrolytes and electrodes materials means that the input power for electrolysis can be reduced. Co-electrolysis of CO₂ and H₂O with SOEC is considered to be one of the effective technologies to convert CO₂ and H₂O into CO and H₂ gases [1]. Typical operation temperature of SOEC above 600ºC prevents further methanation reaction of CO and H₂, while CO and H₂ gases (syngas) are useful raw material for CH₄ at lower reaction temperatures around 400ºC. Very recently, various researchers reported the excellent electrochemical performances and durability of heat-cycles for SOEC designs. Most of the cells are supported by a porous fuel-electrode tube. Therefore the tubular fuel-electrode support works as a current collector and gas diffusion layer as well as support medium of SOEC. Thus, the aim of this study is to realize the electrochemical reactor development with a reliable electrolyte layer on the excellent gas permeation, conductivity and mechanical strength for direct methanation process using co-electrolysis of CO₂ and H₂O at lower cell operation temperatures. In this presentation, we will report SOEC reactor fabrication technologies and the methanation properties.

This research is partially supported by CREST program of the Japan Science and Technology Agency (JST).

Ref 1. Energy and Environmental Science, 7 (2014) 4018-4022