Synergistic effect over Fe-N and graphitic N sites in Fe-N-C porous materials for adsorption desulfurization

The porous carbon materials co-coordinated with Fe and N (Fe-N-C) were successfully synthesized through one-step pyrolysis with the zeolitic imidazolate framework (ZIF-8) as the precursor. Through systematic optimization of iron ion concentration during synthesis, the Fe-N-C-20 specimen exhibited optimal adsorption performance toward dibenzothiophene (DBT), demonstrating a maximum sulfur adsorption capacity of 22.14 mg S/g with a corresponding removal efficiency of 92 %. This superior performance can be primarily ascribed to the formation of Fe-S bonds anchored on Fe-N active sites, N-S interactions mediated by graphitic nitrogen species and appropriate pore size that allows access to thiophenic compounds. Furthermore, the experimental adsorption isotherms for DBT exhibited strong correlation with the Density Functional Theory (DFT) calculation. Additionally, the material's adsorption process followed pseudo-second-order kinetics and Langmuir isotherms of Fe-N-C, and the pseudo-second-order model shows the smallest RMSE (0.66), extremely low SSE (3.03) and AIC (-1.86), which further proves its excellent fitting ability. And the best balance between parameter efficiency and fitting performance. The high stability and recyclability of ZIF-derived Fe-N-C porous adsorbents contribute to sustainable industrial practices.