Insights into the Active Sites of Al₂O₃-Supported NiMo Catalysts in the Hydrodenitrification Reaction

Abstract

Hydrodenitrification is an important reaction in the petrochemical industry. However, the study of active sites at the atomic scale is still not clear. Herein, sulfurized NiMo/Al 2 O 3 catalysts were prepared and the relationship between the structure and catalytic performance was investigated in detail through many advanced technologies, such as atomic-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF−STEM), energy-dispersive spectroscopy elemental mapping, and X-ray photoelectron spectroscopy (XPS). A commercial catalyst C1 showed the highest denitrification percent, and the developed catalyst C2 could also present a catalytic performance comparable to C1 with a lower material cost. HAADF−STEM analysis results showed the catalyst with small MoS 2 stack length, and many MoS 2 stack layers tended to have high activity due to more active sites being exposed. The S/Mo ratio on the catalyst surface was detected by XPS, and the highest value at 1.92 was obtained for the C1 catalyst, leading to obtaining high activity in the reaction. This work provides fundamental investigation of highly efficient Ni-modified MoS 2 catalysts for industrial application at the atomic scale.

Structural Design of Single‐Atom Catalysts for Enhancing Petrochemical Catalytic Reaction Process

“…The results show that porphyrins are prone to hydrogenation at lower temperatures, while hydrodenitrification of porphyrins and their intermediates requires higher temperatures. Guo et al [135] NiMoP/Al 2 O 3 catalysts were prepared by continuous impregnation of 𝛾-Al 2 O 3 by NiMoP aqueous solution containing different organic additives, and the microstructure of the catalyst was further studied by atomic resolution HAADF-STEM. The HAADF-STEM image and its corresponding FFT image show that in addition to the crystal structure of the catalyst surface, multiple isolated dispersion highlights are observed, which means that some single atoms belonging to the catalyst surface Ni atoms may be formed on the catalyst, due to the detection of high Ni atom dispersion in the energy spectrum (EDS) element mapping results, which increases the dispersion of MoS 2 and the rate of HDN by enhancing hydrogenation capacity, which is different from commercial NiMo/ Al 2 O 3 catalyst, the new NiMoP/Al 2 O 3 catalyst also has considerable catalytic performance, with the nitrogen removal rate reaching 95%, and the material cost is low, indicating great industrial application potential.…”