Precise tuning of N configurations on Fe/CN catalysts achieves high selectivity for linear α-olefins in Fischer-Tropsch synthesis

Although Fe-based Fischer-Tropsch synthesis catalysts exhibit advantages in linear α-olefins (LAOs) synthesis, how to promote C C coupling and inhibit the secondary hydrogenation of olefins remains a challenge. Herein, we report an N-doped carbon supported Fe-based catalyst fabricated via a self-templated combustion activation strategy and impregnation method, which enables the highly selective conversion of syngas to LAOs. Systematic characterizations revealed that sodium citrate-assisted activation optimized the pore structure of the supports, facilitated the transformation of N configurations and enhanced the relative content of pyrrolic N. Pyrrolic N regulated the surface electron density of the active sites, which enhanced the adsorption and activation of CO and facilitated the C C coupling reactions, leading to an increase in C 5 + selectivity from 25.64% to 40.71%. Meanwhile, the electronic effect of pyrrolic N effectively weakened the interaction between olefins and active sites, thereby suppressing the secondary hydrogenation of olefins. The Fe/CN(Act.)-550 catalyst exhibited LAOs selectivity increasing from 29.89% over Fe/CN550 catalyst to 70.15%. The catalyst outperforms most previously reported results and maintains stability during 120 h long-term operation without significant sintering or coking. This work provides new insights for the design of catalysts for the highly efficient conversion of syngas to LAOs.