Objective The aim is to study the effects of different metal loading modes on the metal chemical state of hydrogenation catalyst and the distribution of hydrogenation reaction products.

Method Three active metal loading methods (saturated impregnation, stepwise impregnation, and unsaturated impregnation) were used to prepare corresponding hydrogenation catalysts with molybdenum and nickel as active metal components. The influence of metal loading mode on the chemical state of active metals in hydrogenation catalysts was characterized using transmission electron microscope, Raman spectroscopy, X-ray photoelectron spectroscopy and other analysis methods, and the reaction performance of hydrogenation catalysts was evaluated by using a small hydrogenation micro-reactor.

Result The change of metal loading mode affected the morphology and structure of MoS₂ slabs on the sulfided catalyst. Among them, the catalyst obtained through stepwise impregnation exhibited a lower average lamellar length-to-stacking layer ratio and a higher content of octahedral molybdenum species. Stepwise impregnation can enhance the synergistic process between nickel and molybdenum atoms during the sulfurization process. The NiMoS phase has the highest proportion on the prepared catalyst, reaching 55.81%. Compared to the reaction feedstock, the use of this catalyst resulted in increases of 27.9, 3.9, 2.0 percentage points in the mass fraction of total monocyclic aromatic hydrocarbons, total saturated hydrocarbons, and total cycloalkanes, respectively, all surpassing those achieved with other catalysts.

Conclusion Stepwise impregnation of active metals is beneficial for enhancing the aromatic saturation performance of catalysts.