Improved Dispersion and Ultradeep Activity of HDS Catalyst by New Synthesis Approach

The syntheses of highly dispersed NiMoS catalysts for ultradeep hydrodesulfurization (HDS) of refractory organosulfur compounds is carried out by adopting different metal deposition strategies on mesoporous silica: (i) single-pot approach (SP), (ii) modified-single-pot approach (MSP); and (iii) addition of chelating agent (CA) with MSP (MSP-CA). The characteristics of catalysts were evaluated by means of N₂-physisorption, chemisorption by thermal desorption and reduction (TPD and TPR), scanning electron microscopy (SEM), High resolution transmission electron microscope (HRTEM), and spectroscopy techniques; X-ray diffraction (XRD), fluorescence (XRF), photoelectron (XPS), Fourier transform infrared (FTIR) and with pyridine adsorption (FTIR-pyridine). Simultaneous desulfurization activity of dibenzothiophene (DBT) and dimethyl-dibenzothiophene (4,6-DMDBT) was carried out in a batch autoclave reactor at 350 °C and 5 MPa. MSP approach showed notable improvement in the Ni loading, textural properties and dispersion of active metals compared to the SP method. Consequently, MSP catalyst outperformed for the HDS rate of refractory organosulfur compounds (DBT and 4,6-DMDBT) by both the direct desulfurization and hydrogenation routes. The addition of CA further improved the performance of MSP, especially for the HDS of 4,6-DMDBT.