Direct electrocatalytic CO2 reduction in a pressurized tubular protonic membrane reactor
Imanol Quina, Laura Almar, David Catalán‐Martínez, Amir Masoud Dayaghi, Agustı́n Martı́nez, Truls Norby, Sonia Escolástico, José M. Serra
Abstract
Power-to-methane technology enables storage of renewable electricity in chemical energy, which can be transported and converted using existing infrastructure. The moderate energy efficiency of this process is associated with high reactor exothermicity and complex thermal integration. Proton-ceramic electrochemical cells (PCECs) enable thermal combination of methanation and electrochemically driven H2 steps via endothermic reactions, boosting energy efficiency and heat management. Here, we report single-step methane production from CO2 in a tubular PCEC at 450°C and less than 30 bar. The H2 reactant is supplied by electrochemical pumping of protons from H2 in the external chamber. The electrochemical cell consists of an ∼25-μm-thick electrolyte (BaZr0.8Ce0.1Y0.1O3-δ) supported on a BaZr0.8Ce0.1Y0.1O3-δ/Ni composite acting as a methanation catalyst. The reaction was studied as a function of total pressure, H2/CO2 ratio, and current density, reaching CH4 yields greater than 99% above 20 bar. High pressure and a CO2-rich atmosphere ameliorated the electrochemical behavior because of higher electrolyte hydration and boosted electrode kinetics.