Stabilized Fe<sub>7</sub>C<sub>3</sub> catalyst with K-Mg dual promotion for robust CO<sub>2</sub> hydrogenation to high-value olefins.

Qian, Fei; Wang, Maolin; Wei, Zidu; Cai, Yi; Sun, Zeping; Liang, Ruikang; Liu, Guangbo; Qing, Ming et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Iron carbide catalysts, particularly the Fe<sub>7</sub>C<sub>3</sub> phase, hold significant potential for efficient CO<sub>2</sub> hydrogenation to olefins, yet stabilizing this phase under reactive conditions remains a major challenge. Herein, we report a robust and efficient synthesis of nearly phase-pure Fe<sub>7</sub>C<sub>3</sub> catalysts derived from Prussian blue analogues, whose stability is significantly enhanced by strategically incorporating K and Mg promoters. Comprehensive characterization reveals that K accelerates the carbonization process and markedly enhances olefin selectivity, whereas Mg effectively suppresses water-induced oxidation, preserving the structural integrity of the Fe<sub>7</sub>C<sub>3</sub> phase. Under optimized reaction conditions (340 °C, 2 MPa, H<sub>2</sub>/CO<sub>2</sub> = 3), the Fe<sub>7</sub>C<sub>3</sub>-KMg catalyst achieves a high CO<sub>2</sub> conversion of 41.5% and an olefin selectivity of 67.1%, maintaining exceptional catalytic stability for over 1000 hours. These findings offer valuable new insights into the rational design of robust iron carbide catalysts for sustainable and efficient CO<sub>2</sub> conversion into high-value chemicals.