Insight into effects of SO42- species on hydrodesulfurization of dibenzothiophene over an Fe-based bulk catalyst

The electron-rich Fe-based bulk catalysts are developed to promote the hydrodesulfurization (HDS) performance of dibenzothiophene (DBT). In this study, the Fe-Ti bulk catalyst was modified by the SO42- species to investigate the dispersibility, acidity, electron effect, and isolation effect impacting on HDS performance for DBT. Besides, as sulfidation degree (SD) improves, more the coordinately unsaturated sites (CUSs) will be available for the DBT molecules to be adsorbed and desulfurized that is conducive to the improvement of HDS performance for DBT over Fe-based bulk catalysts. Eventually, compared with Fe-Ti bulk catalyst, the HDS rate of DBT has a remarkable increase from 7.8% to 29.9%, 41.5% to 65.0%, and 70.2% to 90.5% under the reaction temperature with 300, 320, and 340 °C upon the introduction of the SO42- species for 0.3-SO42-/Fe-Ti catalyst, respectively. On the one hand, the Ti species can improve the conversion of electrons to Fe species that form electron-rich Fe-based catalysts, resulting in the improvement of the Fe-based bulk catalysts activity. On the other hand, the addition of SO42- species not only promote the SD by forming the Fe(III)-S and Fe1‐xS species but also strengthen the electron effect between Ti and Fe species, which is conducive to the improvement of HDS performance for DBT. In addition, the SO42- species also worked as an “isolate agent”, and can promote increasing the SD for this series of Fe-based bulk catalysts to improve the HDS rate of DBT. Thus, exploring the impact of SO42- species on the HDS performance of Fe-based catalysts is a promising direction for the design and development of environmentally friendly and economical low-cost HDS catalysts in the field of fossil fuel processing.