Synergistic construction of nano nickel and lanthanum tungstate matrix for CO2-tolerant PCEC: Achieving stable CO2 methanation

CO2 hydrogenation using protonic ceramic electrolysis cells (PCECs) to produce fuel gases such as CH4 and CO has been considered as a promising technology for effective CO2 utilization. However, the long-term stability of conventional PCECs based on Y and Yb doped BaZrO3-BaCeO3 (BCZYYb) proton conductors is severely limited by their susceptibility to carbonate formation under high concentration CO2. In this work, a new type PCEC based on CO2-tolerant La5.6WO11.4−δ(LWO) material is firstly constructed. A three-layer porous-dense-porous LWO ceramic scaffold is fabricated via a pressing, dip-coating and co-sintering process, followed by Ni and La0.6Sr0.4CoO3−δ (LSC) catalyst impregnation to ensure the chemical compatibility among materials and form an efficient PCEC-based CO2 hydrogenation reactor. Benefits from the synergistic catalysis of nano nickel and LWO, the reactor gets a CH4 selectivity of over 50 % at 600 °C under 20 % CO2 concentration, and it operates stably for over 320 h at 600–650 °C under high CO2 concentrations of 50–80 %, showing no degradation in CO2 conversion rate or CH4 selectivity. Post-mortem analysis demonstrates that the CO2 absorption characteristics of LWO and the morphological uniformity of nano nickel lead to stable CO2 methanation. This study provides a viable strategy for designing highly stable PCEC-based CO2 hydrogenation reactors.