In the context of CO2 valorization, the possibility of shifting the selectivity of Ni catalysts from CO2 methanation to reverse water gas shift reaction could be economically attractive provided that the catalyst presents sufficient activity and stability. Remarkably, the addition of sulfur (0.2–0.8% w/w) to nickel on a Ni/TiO2 catalyst induces a complete shift in the catalyst selectivity for CO2 hydrogenation at 340 °C from 99.7% CH4 to 99.7% CO. At an optimal Ni/S atomic ratio of 4.5, the productivity of the catalyst reaches 40.5 molCO2 molNi−1 h−1 with a good stability. Density functional theory (DFT) calculations performed on various Ni surfaces reveal that the key descriptor of selectivity is the binding energy of the CO intermediate, which is related to the local electron density of surface Ni sites.
Bibliographical noteKAUST Repository Item: Exported on 2022-10-19
Acknowledgements: This work was financially supported by “Région Occitanie” through a Readynov contract “Valorisation du CO2 par méthanation catalytique” (2005314). Thanks to Marion Technologies for the scale-up of catalysts synthesized. TD and CHH are supported by the National Science Foundation through the Division of Materials Research under grant no. DMR-1956403 and the Camille and Henry Dreyfus Foundation. Computations were performed in the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the National Science Foundation [ACI-1548562] and the PICS Coeus High Performance Computer, which is supported by the National Science Foundation . The authors acknowledge Dr. Spiros Zafeiratos (ICPEES-UMR 7515 CNRS-ECPM-Strasbourg University, France) for access to XPS.
ASJC Scopus subject areas