Thermocatalytic conversion of CO2 into liquid fuels and chemicals is a promising approach to mitigate global warming. Although, the CO2 conversion and long-chain hydrocarbon selectivity are highly dependent on the choice of metal-oxide promoter, but role of the promoter remains unclear. Herein, the role of MgO as a promoter for an Fe-based catalyst was investigated. Bimetallic Na-FeMgOx catalyst exhibited a high C5+ yield of 25.1% with a CO2 conversion of 49.1% at the early stage of the reaction. The presence of MgO facilitates the reduction of Fe oxides and formation of oxygen vacancies by transferring electrons to Fe-based phases. In addition, at the early stage of reaction, the decoration of the Mg oxide surface with nanosized χ-Fe5C2 enhances the C5+ yield. However, the progressive transformation of MgO to MgCO3 during CO2 conversion deactivates the Na-FeMgOx catalyst. A detailed deactivation mechanism is also discussed.
This study received funding from the Korea Institute of Energy Technology Evaluation and Planning (KETEP) under the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20224C10300010 ); and National Research Council of Science & Technology (NST) grant from the Korean government (MSIT) (No. CAP21012\u2013100 ). Additional supports from the National Research Foundation (NRF) of Korea, funded by the Ministry of Science, ICT & Future Planning (No. 2020H1D3A1A02079883 and 2021R1I1A1A01043314 ) were appreciated. Some experiments were performed at 8 C synchrotron beamline of the Pohang Accelerator Laboratory (PAL, Republic of Korea) under contract no. 2023\u20131st-8 C-032.
