Zr-Regulated Electron Cloud Density of Active Sites Via an Optimized Loading Environment in a NiMoS/nZr-A600 Catalyst...

Developing high-performance directional hydrodesulfurization (HDS) catalysts is crucial for effectively upcycling highly unsaturated 4,6-dimethyldibenzothiophene (4,6-DMDBT, C14H12S) precursor molecules in coal tar-derived diesel into methyl-cyclohexyl-toluene (MCHT), a liquid naphthenic aromatic hydrocarbon-derived jet fuel with a high H/C ratio (C14H20). Herein, electron-rich NiMoS active phases with high stacking and short sheet characteristics were effectively established by regulating the microregion electron environments on the support surface by doping nanosized ZrO2 species into disordered Al2O3 and calcinating at 600 °C (nZr-A600, n = 0.5, 1, 2, and 4 wt %). Compared with the NiMoS/0.5Zr-A600 catalyst, the 4,6-DMDBT conversion rate on the best NiMoS/2Zr-A600 catalyst greatly increased by 133%, and the total reaction rate significantly enhanced by 265%. Notably, the MCHT selectivity was sharply improved from 58.52 to 92.17%, and its proportion was approximately 15.6 and 1.3 times higher than that of catalysts with ordered mesoporous carriers for NiMoS/Al2O3 and NiMoS/TiO2(SiO2)-Al2O3, respectively. This excellent performance was due to the moderate downward shift of the d-band center of the active phase, which reconciled the average reaction energies of the direct desulfurization (DDS) and hydrodesulfurization pathways, decreasing the overall reaction barriers. Meanwhile, the synergistic effect of the electrostatic attraction and charge compensation of the Mo-edge active site enabled products generated via the DDS pathway at the corner active site to further hydrogenate into MCHT.