Abstract: Boron was added in the preparation process of alumina carrier for modification. The hydrofining catalyst for low viscosity PAO based on the modified carrier was prepared by equal volume impregnation. The modified carrier and catalysts were characterized by BET, XRD, H₂-TPR, and Hy-IR techniques. The characterization results showed that the boron modified hydrofining catalyst carrier reduced the interaction between the active metal components and the carrier. The acidity of the catalyst was greatly enhanced and B acid was produced at the same time. At atemperature of 240 ℃, a hydregen pressure of 4.5MPa,a space velocity of 0.2h^-1 and a volume ratio of hydrogen to oil of 300:1, the aromatics saturation performance of modified hydrofining catalyst applied to PAO4 hydrogenation was investigated and compared with that of unmodified catalyst, the results showed that both of the catalysts could effectively improve the color of the product, but the aromatic saturation performance of the modified catalyst was much better than that of the unmodified catalyst. The stability evaluation results of the modified hydrofining catalyst showed that the catalyst had good activity and stability, which can meet the requirements of industrial application.

Key words: poly-α-olefin synthetic oil, aromatic saturation, hydrofining, modification