Structural Regulation of Modified Fe₃O₄ Microspheres for Enhanced Synthesis of Linear α-Olefins by CO₂ Hydrogenation

The hydrogenation of CO₂ to produce α-olefins and other high-value chemicals plays a crucial role in energy transformation and sustainable low-carbon development. However, the CO₂ hydrogenation pathway for α-olefin synthesis still encounters various challenges, such as limited CO₂ conversion and low α-olefin selectivity. To tackle these issues, this study initially assessed the catalytic properties of iron-based catalysts with varying morphologies and particle sizes. The findings indicated that the spherical Fe₃O₄ catalysts with large specific surface area demonstrated high CO₂ conversion (20.8%) and α-olefin selectivity (14.4%) To improve CO₂ adsorption and facilitate carbon chain growth, K and Sr were introduced to modify the spherical Fe₃O₄ catalysts. The synergistic electronic and structural effects of K and Sr contributed to enhanced α-olefin formation. Experimental data revealed that, under reaction conditions of 340 °C, 2.5 MPa, and a space velocity of 5000 h^-1, the optimized 5K10Sr/Fe₃O₄ microsphere catalyst achieved a CO₂ conversion of 45.4%, C_2⁺ selectivity of 68%, chain growth factor of 0.67, and LAO (linear α-olefins in C_4⁺ products) selectivity of 53.6%.