Fischer–Tropsch Synthesis: ZIF-8@ZIF-67-Derived Cobalt Nanoparticle-Embedded Nanocage Catalysts

Abstract

The preparation of highly active and stable catalysts for syngas conversion is a major challenge for Fischer–Tropsch synthesis (FTS). Herein, we report a strategy to prepare a highly dispersed Co-embedded porous carbon nanocage (CoPCN) structure derived from a core–shell metal–organic framework (MOF) ZIF-8@ZIF-67 precursor. High Co loading (over wt 30%) is achieved while maintaining an optimal dispersion and particle size of the active Co phase when a ZIF-8@ZIF-67 is pyrolyzed at 920 °C. Besides, the porous channels and hollow structures of the CoPCN strengthen the diffusion of reactants and the hydrocarbon product, enhancing the C5+ selectivity and CO conversion. The CoPCN shows high stability in FTS with a CO conversion of 18.3%, 80.2% selectivity for long-chain hydrocarbons (C5+), and 8.9% selectivity for short-chain hydrocarbons (C2–C4) after 100 h time on stream. Compared with other MOF-derived FTS catalysts, CoPCN-920 can achieve higher C5+ selectivity at a lower reaction temperature. The present work uncovers the relationship between the porous structure and catalytic performance, providing an efficient method to prepare promising materials for enhanced FTS stability, activity, and selectivity.