Effect of phosphorus addition on the hydrotreating activity of NiMo/Al2O3 carbide catalyst

摘要

A series of phosphorus promoted gamma-Al2O3 supported NiMo carbide catalysts with 0-4.5 wt.% P,13 wt.% Mo and 2.5 wt.% Ni were synthesized and characterized by elemental analysis,pulsed CO chemisorption,BET surface area measurement,X-ray diffraction,near-edge X-ray absorption fine structure,DRIFT spectroscopy of CO adsorption and H2 temperature programmed reduction.X-ray diffraction patterns and CO uptake showed the P addition to NiMo/gamma-Al2O3 carbide,increased the dispersion of beta-Mo2C particles.DRIFT spectra of adsorbed CO revealed that P addition to NiMo/gamma-Al2O3 carbide catalyst not only increases the dispersion of Ni-Mo carbide phase,but also changes the nature of surface active sites.The hydrodenitrogenation(HDN)and hydrodesulfurization(HDS)activities of these P promoted NiMo/gamma-Al2O3 carbide catalysts were performed in trickle bed reactor using light gas oil(LGO)derived from Athabasca bitumen and model feed containing quinoline and dibenzothiophene at industrial conditions.The P added NiMo/gamma-Al2O3 carbide catalysts showed enhanced HDN activity compared to the NiMo/gamma-Al2O3 catalysts with both the feed stocks.The P had almost no influence on the HDS activity of NiMo/gamma-Al2O3 carbide with LGO and dibenzothiophene.P addition to NiMo/gamma-Al2O3 carbide accelerated C-N bond breaking and thus increased the HDN activity.