Proton conduction-assisted direct CO2 methanation using Ni/CaO/Y-doped BaZrO3 proton conductor

Abstract

This study investigates the conversion of captured CO2 to CH4 with Ni and CaO supported on 10 mol% Y-doped BaZrO3 (BZY10) proton-conducting oxides. The on-site treatment of CO2 to cut back CO2 emission has been demonstrated, further transforming it into an energy carrier. This report describes direct CO2 methanation using Ni materials in O2– and H2O-containing gases at the carbonation step. Ni and CaO supported on BZY10 were used to capture CO2 in simulated flue gas containing O2 or H2O and convert it into CH4 at the same temperature (380–450 °C). High reducibility of Ni and high methanation reactivity were observed. Through the FTIR spectra observation, it was found out that transformation of bicarbonate to formate was facile due to proton-conducting property of the BZY10 support, i.e., hydrogen spillover, compared to BaZrO3-supported materials., It is hypothesized that the hydroxyl ions at the interface of CaO and BZY10 intervene in the carbonation and methanation steps. Also, carbonation accelerates the kinetic and diffusion-controlled regions with a high affinity for CO2. In the methanation step, the adsorbed CO2 enables the hydrogen species to produce CH4.