Stabilized Fe7C3 catalyst with K–Mg dual promotion for robust CO2 hydrogenation to high-value olefins

Abstract Iron carbide catalysts, particularly the Fe 7 C 3 phase, hold significant potential for efficient CO 2 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 7 C 3 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 7 C 3 phase. Under optimized reaction conditions (340 °C, 2 MPa, H 2 /CO 2 = 3), the Fe 7 C 3 -KMg catalyst achieves a high CO 2 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 2 conversion into high-value chemicals.