A Novel Self-Assembled Hierarchical-Structured Catalyst for the Diffusion of Macromolecules

Abstract

A novel self-assembled catalyst, FA-Z30, possessing a mesoporous/macroporous structure is prepared and applied to FCC diesel hydrodesulfurization (HDS). The catalyst has 54 % of the total pore volume lying within 30–60 nm pores, greater than 26 % of the continuous phase. This indicates interconnected pores. N2 adsorption data show a bimodal structure with pores ranging between 30–60 nm and <10 nm. Textural properties of the catalyst show that the pore volume is 0.78 cm g–1 having a specific surface area of 181 m2 g–1 with a most probable pore diameter of 20 nm. The catalyst possesses a low active metal concentration of ~154.9 g L–1 per unit volume and a low bulk density of ~0.50 g cm–3. X-Ray diffraction, high resolution transmission electron microscopy, and X-ray photoelectron spectroscopy show improved active metal dispersion with an average MoS2 layered slab number of 3–7, having lengths ranging from 5 to 10 nm. Molybdenum sulfide sulfidity at 75 % is higher than the commercial catalyst, FCB, at 62 %. The activity and stability of HDS and hydrodenitrification (HDN) are improved, as is aromatics saturation (HDAr) reflected by limited coke formation. Average conversion rates of HDS, HDN, and HDAr are 95, 97, and 67 % at 100 h on stream for FA-Z30, respectively, and their respective rates of 6.1, 6.3, and 4.3 % per unit volume of active metal is twice that of the commercial catalyst. The low bulk density of FA-Z30 improves the utilization rate and relative activity of the active metals. FA-Z30 is a promising catalyst for FCC diesel hydrogenation.