Preparation of Ni/YSZ Catalysts for Application of Solid Oxide Electrolysis Cell Methanation

Abstract

Co-electrolysis of CO2 and steam using solid oxide electrolysis cells (SOECs) is a major focus of the CO2 conversion. Furthermore, SOECs have the potential to drive high value-added products with reduced carbon footprint. For example, the syngas (mixture of CO and H2) can be produced by SOEC-driven co-electrolysis of CO2 and steam, and utilized in the Fischer-Tropsch (FT) process for the synthesis of artificial hydrocarbon. The artificial hydrocarbons would be environmentally friendly fuels when CO2 is obtained from carbon capture and storage (CCS) technology. The Ni-based cermet, such as Ni with yttria-stabilized zirconia (Ni/YSZ), is a typical material of SOEC device, and Ni has been found to be an active catalyst for CH4 production (methanation). Therefore, use of the Ni/YSZ has potential to directly convert CO2 and H2O to CH4. In the catalytic process, the activity, selectivity and durability of the Ni/YSZ catalyst are significantly influenced by the structural property of Ni and YSZ, which is varied by the Ni loading and calcination conditions in addition to the studied reaction conditions. The preparation of Ni/YZS catalyst with high performance in co-electrolysis and methanation is still challenging.Herein, the preparation of the Ni/YSZ catalysts with enhanced activity in SOEC methanation was studied. The Ni/YSZ catalysts were prepared by wet impregnation, one of the catalyst preparation methods, and characterized by several conventional methods. Effects of Ni loading and calcination conditions on the performance of Ni/YSZ catalysts were examined by CO2 methanation. A Ni/YZS catalyst gave a high CO2 conversion of 86% and a high methane selectivity at around 300 ºC under ambient pressure. With Ni/YSZ prepared using the optimized method, we are planning to prepare tubular cells and evaluate their activity in SOEC methanation.