Quick microwave assembling nitrogen-regulated graphene supported iron nanoparticles for Fischer-Tropsch synthesis

Facile preparation of highly efficient iron-based catalysts is vital to improve the performance of Fischer-Tropsch synthesis (FTS), a sustainable process for converting non-petroleum carbon resources to valuable hydrocarbons. In this work, a convenient preparation for nitrogen-regulated graphene supported iron nanoparticles, with the assistant of microwave treatment, was developed. Thereinto, the nitrogen-containing groups in graphene support were introduced by NH₃·H₂O treatment. By comparison with ordinary calcination, microwave treatment could significantly shorten the heating time to few seconds, and promote the reduction of iron species. The existence of a small number of nitrogen-containing groups could effectively anchor iron species, and improve the dispersion of iron species. Meanwhile, the duration length of NH₃·H₂O treatment time could regulate the content of N configuration (pyridinic-N and pyrrolic-N). The size of supported iron species from 120 nm to 10 nm could be well controlled via increasing microwave time from 0 to 14 s. For N-regulated graphene supported iron catalysts, evenly dispersed small particles of iron species, improved surface reduction behavior and reasonable N configuration all promoted FTS. Under relevant industrial conditions (320 °C, 2.0 MPa, 5 g h mol⁻¹), the optimized 15%Fe/AG(12 h)-W(10) catalyst achieved CO conversion as high as 97.2% and C₅₊ selectivity of 40.0% while maintaining a mild CO₂ selectivity (28.2%). The superior preparation and catalytic performance disclosed that the catalyst could be one of ideal candidates for industrial iron-based FTS catalysts in future.