Bifunctional Nature of a SiO2-Supported Ni2P Catalyst for Hydrotreating: EXAFS and FTIR Studies

Journal Article · Sun Jan 01 00:00:00 EST 2006 · J. Catal.

DOI:https://doi.org/10.1016/j.jcat.2005.12.029· OSTI ID:914196

Lee, K; Oyama, S

A Ni{sub 2}P catalyst supported on a high-surface area SiO{sub 2} (350 m{sup 2} g{sub -1}) was prepared by temperature-programmed reduction, and its structural and surface properties were studied. X-ray diffraction and extended X-ray absorption fine structure measurements were used to obtain structural parameters for the supported Ni{sub 2}P phase, and Fourier transform infrared (FTIR) analysis with the probe molecules CO and pyridine was carried out to characterize the surface properties. The catalytic activity was measured at 573 K and 3.1 MPa in a three-phase fixed-bed reactor for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) using a model liquid feed. At standard conditions using 500 ppm S as 4,6-dimethyldibenzothiophene (4,6-DMDBT), 3000 ppm S as dimethyldisulfide, 200 ppm N as quinoline, and 1% tetralin in a tridecane solvent, the Ni{sub 2}P/SiO{sub 2} gave an HDS conversion of 85%, an HDN conversion of 100%, and a tetralin conversion of 37%, which were much higher than those of a commercial Ni-Mo-S/Al{sub 2}O{sub 3} catalyst, which gave an HDS conversion of 41%, an HDN conversion of 98%, and a tetralin conversion of 20% based on equal numbers of sites (240 {micro}mol) loaded in the reactor. The sites were counted by CO chemisorption for the phosphide and by low-temperature O{sub 2} chemisorption for the sulfide. The Ni{sub 2}P/SiO{sub 2} catalyst favored the hydrogenation (HYD) pathway for 4,6-DMDBT HDS to generate methylcyclohexyltoluene and dimethylbicyclohexane with a relative HYD selectivity of 95%. It also favored hydrogenation for tetralin to give decalin with a relative HYD selectivity of 89%. The Ni{sub 2}P/SiO{sub 2} catalyst also showed better resistance to N-compounds than the Ni-Mo-S/Al{sub 2}O{sub 3} catalyst. The FTIR spectra of adsorbed CO showed that the Ni site in the Ni{sub 2}P phase gave rise to considerable {pi}-back bonding, which was related to the high activity of the Ni{sub 2}P/SiO{sub 2} catalyst in the hydrogenation of aromatics. The FTIR spectra of adsorbed pyridine showed that the Ni{sub 2}P phase had a P{single_bond}OH group associated with Br{o}nsted acidity that was active for the protonation of N compounds. These results thus suggest that the supported Ni{sub 2}P catalyst has bifunctional properties that are beneficial for catalytic activity in hydroprocessing.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: DE-AC02-98CH10886
• OSTI ID: 914196
• Report Number(s): BNL-78764-2007-JA; JCTLA5; TRN: US200804%%327
• Journal Information: J. Catal., Vol. 239, Issue 2; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
NICKEL PHOSPHIDES
CATALYTIC EFFECTS
CATALYST SUPPORTS
SILICON OXIDES
CHEMICAL PREPARATION
MORPHOLOGY
SURFACE PROPERTIES
CARBON MONOXIDE
PYRIDINE
CHEMISORPTION
HYDROGENATION
DESULFURIZATION
DENITRIFICATION
POLYCYCLIC SULFUR HETEROCYCLES
DISULFIDES
QUINOLINES
CATALYSIS
national synchrotron light source