Hydrotreating of coker light gas oil on SBA-15 supported nickel phosphide catalysts

SBA-15-supported nickel phosphides with a Ni/P atomic ratio of 2 and 0.5 were prepared by temperature programmed reduction method (TPR). The phase purity and structural/surface properties were studied by X-ray diffraction and N2 sorption measurements respectively. X-ray diffraction (XRD) analysis of the passivated catalysts confirmed the presence of Ni12P5 and Ni2P phases in catalysts prepared from oxidic precursors. Supports and catalysts were thoroughly characterized using other techniques such as SEM, EDAX, and TEM. Results from low angle XRD measurements confirmed the presence of hexagonally ordered mesoporous structure in SBA-15 material. Hydrotreating experiments were conducted under industrial conditions using coker light gas oil (CLGO) as feed which contains 2439 ppm nitrogen 23,420 ppm sulfur respectively. The activity results show that SBA-15 supported NixPy catalysts show higher catalytic activities compared to reference NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts under similar reaction conditions. This higher catalytic activity of NixPy/SBA-15 is due to the structure and surface chemical properties of this phase which is resistant to sulfur poisoning. It was also found that the Ni/P ratio had a profound effect on the active structure and hydroprocessing behavior of the NixPy/SBA-15 catalysts. The HDS and HDN conversions was found in the following order NixPy/SBA-15 (0.5) > NixPy/SBA-15 (2.0) > NiMo/SBA-15 > NiMo/γ-Al2O3. The NixPy/SBA-15 (0.5) catalyst showed higher HDS and HDN activities compared with NixPy/SBA-15 (2.0) catalyst which has lower P content. The higher amount of P content in NixPy/SBA-15 (0.5) catalyst modifies the nature of the nickel in that catalyst and increased the amount of octahedral nickel species and causes higher hydrotreating activity.