Metal-organosilicate complexation-driven assembly toward a promising Co@SiO₂-Al₂O₃ catalyst for syngas to sustainable aviation fuel

A metal-organosilicate complexation-driven assembly method–grafting Al-complexed organosilicate onto Co₃O₄ nanoparticles (NPs)–was developed to synthesize an acidic SiO₂-Al₂O₃ encapsulated Co nanocatalysts (Co@SA-x; x, mass ratio of Al₂O₃ to SiO₂). This approach allows for precise manipulation of spatial confinement and enhances extensive interfacial contact between active metal sites and acid sites. Consequently, a cooperative relay catalytic process was developed between the spatially confined active Co NPs and acidic functionalities, enabling the highly efficient direct conversion of syngas into SAF. The standout Co@SA-0.1 catalyst achieved a 72.5% CO conversion and a high SAF selectivity of 68.8% with a notable iso-paraffin fraction of 20.3 % in SAF, and was stable for at least 120 h. Notably, CH₄ formation was effectively suppressed at a low level of 6.6%. The uniform embedment of Co NPs within SiO₂-Al₂O₃ composite not only mitigated their aggregation but also enhanced the adsorption and retention of −CH_x intermediates on Co sites, thereby improving the selectivity toward long-chain hydrocarbons. Moreover, the SiO₂-Al₂O₃ support contributed appropriate acidity, which promoted the cracking and isomerization of long-chain hydrocarbons, thereby enhancing the yield of SAF components and their isomers.