SRGO hydrotreating over Ni-phosphide catalysts on granulated Al2O3

Ni-phosphides present a promising alternative to the conventional hydrotreatment NiMo sulfides. The hydro treatment catalysts are supported on Al2O3 granules, and the similarly Al2O3 supported Ni-phosphide catalysts provide an interesting case for comparison. In this work the Ni-phosphide catalysts supported on Al2O3 granules were prepared using two procedures: 1) temperature-programmed reduction of phosphite-type precursor in hydrogen flow (TPR_I catalyst), 2) treatment of Ni nanoparticles with triphenylphosphine solution at elevated temperature (LP catalyst). The catalysts were characterized by ICP-AES chemical analysis, N-2 physisorption, XRD, TEM, XPS, Al-27 MAS NMR. The Ni2P particles were found in LP samples, while TPR method gives the mixture of Ni12P5 and Ni2P particles and amorphous AlPO4 on the alumina surface. The behavior of granulated Ni phosphide and conventional sulfided NiMo/Al2O3 catalysts was compared in hydroprocessing of straight-run gas oil (SRGO) at 340 degrees C, 4 MPa, V(H-2)/V(feed) - 400 Nm(3)/m(3), LHSV - 1,5 h(-1). Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activity of nickel phosphide catalysts were shown to be lower in comparison with NiMo/Al2O3. Hydrotreating of S-containing model compounds (DBT, 4-MDBT, 4,6-DMDBT) was carried out over TPR_I catalyst, and a negative effect of dimethyl disulfide (DMDS) and acridin additions on the HDS activity was observed.

Automated summary

Ni-phosphides are a promising alternative to conventional NiMo sulfides for hydrotreatment, but their activity is lower compared to NiMo/Al2O3 catalysts and can be negatively affected under certain conditions.