Cetyltrimethylammonium Bromide-Assisted Adsorption Synthesis of Highly Dispersed NiMoS/C_SAP-CTAB Catalyst for Efficient Hydrodesulfurization

Carbon is well-known to support highly active Type II NiMoS catalysts for hydrodesulfurization. However, compared to the industrially applied Al₂O₃, the synthesis of highly dispersed active sites on carbon, unrestricted to weak carbon-metal interactions, is yet to be explored. Herein, we reported a cetyltrimethylammonium bromide (CTAB) assisted adsorption method for synthesis of highly dispersed NiMoS/C_SAP-CTAB catalyst for efficacy HDS of sluggish dibenzothiophene (DBT) and 4,6-dimethyl-dibenzothiophene (4,6-DMDBT). Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy energy dispersive X-Ray Spectroscopy (SEM-EDX), inductively coupled plasma-optical emission spectrometer (ICP-OES), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) characterizations demonstrate the crucial role of electrostatic attractions between cationic CTAB and anionic molybdates for dispersion of molybdate ions and resisting metal loss during the acid washing sodium removal process. Importantly, upon sulfidation activation, the well-structured micropores and highly dispersed Type II active NiMoS sites were confirmed. More importantly, the optimized NiMo/C_SAP-CTAB catalyst demonstrated a turnover frequency of 3.61 h⁻¹ for converting challenging 4,6-DMDBT, 29% and 473% improvement compared to catalysts based on Al₂O₃ and general carbon, thus highly promising for practical applications.