HDN and HDS of model compounds and light gas oil derived from Athabasca bitumen using supported metal phosphide catalysts

The HDN and HDS activity of supported Co 0.4Ni 2P and Ni 0.3MoP is reported. Increased support acidity (Al 2O 3 < fluorinated Al 2O 3 < MCM-41) led to increased cracked products from carbazole and 4,6-dimethyldibenzothiophene. With light gas oil, Ni 0.3MoP/Al 2O 3 had higher activity than a conventional Ni-Mo-S catalyst, whereas the low activity of Co 0.4Ni 2P/Al 2O 3 is related to a high S uptake during reaction. ▪ Co 0.4Ni 2P and Ni 0.3MoP catalysts, supported on Al 2O 3, fluorinated Al 2O 3 (Al 2O 3-F) and Mobil Catalytic Material (MCM-41), have been prepared from metal phosphate precursors by temperature-programmed reduction (TPR) to 1200 K. The catalysts have been characterized and their activity determined for the hydrodenitrogenation (HDN) of carbazole, the hydrodesulphurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and the HDN and HDS of a light gas oil (LGO) derived from Athabasca bitumen. The formation of metal phosphides after TPR was confirmed by both X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The acidity of the catalysts, as measured by n-propylamine uptake, was determined by the support acidity and increased in the order Al 2O 3 < Al 2O 3-F < MCM-41. Activity measurements using model compounds showed that increased support acidity led to increased cracked products. The Co 0.4Ni 2P/Al 2O 3 catalyst promoted the direct desulphurization of 4,6-DMDBT at 583 K and 3.0 MPa H 2 compared to Ni 2P/Al 2O 3, and the Ni 0.3MoP/Al 2O 3 catalyst had the highest selectivity (83%) for bicyclohexyl (BCHX) among the catalysts tested for the HDN of carbazole at the same conditions. The Ni 0.3MoP/Al 2O 3 also had the highest activity for both the HDN and HDS of LGO, compared to Co 0.4Ni 2P/Al 2O 3 and a conventional NiMoS/Al 2O 3 catalyst that also contained P. The low activity of the Co 0.4Ni 2P/Al 2O 3 catalyst was attributed to low metal dispersion, a high S uptake and the possible formation of less active phosphosulphide species such as NiPS 3, on this catalyst.