Dibenzothiophene Hydrodesulfurization Performance Over Hierarchically Porous NiMoS(Si,Zr)/Al2O3 Catalysts

The effects of the synthesis method, dopant nature, and porosity on the dibenzothiophene hydrodesulfurization performance of hierarchically porous NiMoS(Si,Zr)/Al2O3 catalysts were studied. Si and Zr incorporation was carried out using grafting (G) and sol-gel (SG) methods. The catalysts were characterized using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), N-2 physisorption, Hg intrusion porosimetry (MIP), X-ray diffraction, hydrogen temperature-programmed reduction (H-2-TPR), pyridine-adsorbed Fourier transform infrared spectroscopy (Py-FTIR), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy and then correlated with the kinetic parameters. The experimental results showed that Si- and Zr-modified catalysts promoted different degrees of activity and selectivity. The NMS/A-Zr(G) catalyst displayed the highest HDS activity, followed by NMS/A-Zr(SG), NMS/A, NMS/A-Si(G), and NMS/A-Si(SG) in descending order. The presence of Si and Zr in the catalysts and their incorporation methods were identified as the main reasons for this trend. More active catalysts exhibited an increased total acidity. Furthermore, Lewis sites were positively related to k(DDS) (CUS sites), while Bronsted sites were related to k(HYD) (BRIM sites). These modifications were found to enhance various characteristics of the catalysts, such as larger edge sites, Mo and NiMo coordination, and large pores.