Co-Based Catalysts Derived from Layered-Double-Hydroxide Nanosheets for the Photothermal Production of Light Olefins.

Abstract

Solar-driven Fischer-Tropsch synthesis represents an alternative and potentially low-cost route for the direct production of light olefins from syngas (CO and H₂ ). Herein, a series of novel Co-based photothermal catalysts with different chemical compositions are successfully fabricated by H₂ reduction of ZnCoAl-layered double-hydroxide nanosheets at 300-700 °C. Under UV-vis irradiation, the photothermal catalyst prepared at 450 °C demonstrates remarkable CO hydrogenation performance, affording an olefin (C_2-4⁼ ) selectivity of 36.0% and an olefin/paraffin ratio of 6.1 at a CO conversion of 15.4%. Characterization studies using X-ray absorption fine structure and high-resolution transmission electron microscopy reveal that the active catalyst comprises Co and Co₃ O₄ nanoparticles on a ZnO-Al₂ O₃ mixed metal oxide support. Density functional theory calculations further demonstrate that the oxide-decorated metallic Co nanoparticle heterostructure weakens the further hydrogenation ability of the corresponding Co, leading to the high selectivity to light olefins. This study demonstrates a novel solar-driven catalyst platform for the production of light olefins via CO hydrogenation.