Uniform silica-infused ZIF-67 derived Fischer−Tropsch cobalt catalyst integrated with ZSM-5 for sustainable aviation fuel synthesis

The direct production of sustainable aviation fuel (SAF) through Fischer−Tropsch synthesis (FTS) has garnered significant interest within the energy and petrochemical sectors. However, attaining high SAF selectivity remains a critical hurdle, as the inherent maximum selectivity for the C₈−C₁₆ hydrocarbon fraction in traditional FTS process hovers around 41%. Here, we report a promising bifunctional catalyst system for FTS to SAF, featuring cobalt nanoparticles (Co NPs) embedded within amorphous silica (Co@xSi) integrated with ZSM-5 zeolite. The optimal catalyst system was identified by combining Co@3Si derived from an APTES-infused ZIF-67 (with a 3:1 mass ratio of APTES to ZIF-67) with two mass fractions of a ZSM-5 (Co@3Si&2Z5). This formulation achieved a 75.2% selectivity to C₈−C₁₆ hydrocarbons with an iso-paraffins proportion of 24.3%, while effectively minimizing CH₄ formation to 6.3%. It also sustained a high CO conversion of 85.1% and was stable for at least 168 h. The Co@3Si, leveraging its abundant active cobalt sites and distinctive confined structure, not only improved CO adsorption and activation but also extended the residence time of −CH_x intermediates on the surface of Co NPs, thereby efficiently facilitating the formation of long-chain hydrocarbons. The ZSM-5 zeolite facilitated the selective catalytic cracking and isomerization of long-chain hydrocarbons, effectively converting them into SAF-range paraffins. The collaborative synergy between the two core components forms an efficient catalytic process akin to an assembly line, enabling the highly selective direct transformation of syngas into SAF.