The production of consumables through In-Situ Recourse Utilization (ISRU) is an essential concept for NASA-Mars exploratory missions. The production of methane as a potential propellant can be achieved through the Sabatier reaction, whereby CO2 is hydrogenated to produce water and methane. Due to the limited available energy in extraterrestrial settings, catalysts must exhibit exceptional CO2 conversion and methane yield at mild operating conditions and the lowest energy input. In Ni-supported catalyst, metal-oxide interfaces result in highly active and stable sites for CO2 activation, where facile hydrogenation of surface-bound carbonate and formate species occurs. Moreover, studies suggest that the concentration of oxygen vacancies in reducible metal-oxide supports can be tailored by incorporating rare-earth metals, whereby oxygen vacancies are formed by compensation of charge imbalances in the host metal-oxide. In this work, we studied the effect of rare-earth metals (La, Gd, Pr) in inverse Ni/CeO2 catalyst for the reduction of CO2 to methane at low temperatures (&lt;573 K). Kinetic studies of metal-doped inverse Ni/CeO2 show low loadings (&lt;1wt%) of rare-earth metals is sufficient to significantly increase CO2 conversion and methane formation rates at mild reaction conditions (548 K and atmospheric pressure). Catalyst characterization (H2-TPR, CO2-TPD, XPS, XRD, FTIR, and Raman spectroscopy) coupled with kinetic studies assists in elucidating structural, electronic, and interface effects between rare-earth metals and CeO2, which contribute towards low-temperature CO2 methanation.

Tuning oxygen vacancies in Ni/CeO2 using rare-earth metal dopants for CO2 methanation

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.