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Title: The Active Site of Nickel Phosphide Catalysts for the Hydrodesulfurization of 4,6-DMDBT

Abstract

Ni2P catalysts supported on SiO2 and MCM-41 were prepared by temperature-programmed reduction (TPR), and the effect of the dispersion on catalyst structure and hydroprocessing performance was studied. The surface areas of the samples varied from low (Ni2P/SiO2-L, 88 m2 g?1) to high (Ni2P/SiO2-H, 240 m2 g?1), to very high (Ni2P/MCM-41, 487 m2 g?1), with corresponding Ni2P average crystallite sizes decreasing from 10.1 to 6.5 and 3.8 nm. X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) studies were used to obtain structural parameters for the supported Ni2P phase. The catalytic activity in hydrodesulfurization (HDS) was measured at 613 K and 3.1 MPa in a three-phase fixed bed reactor using a model liquid feed containing 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) and quinoline in a tridecane solvent. At standard conditions using 500 ppm S as 4, 6-DMDBT, 6000 ppm S as dimethyldisulfide (DMDS), and 500 ppm N as quinoline, the catalytic activity followed the sequence Ni2P/MCM-41 > Ni2P/SiO2-H > Ni2P/SiO2-L, based on equal sites (230 ?mol) loaded in the reactor. In particular, Ni2P/MCM-41 gave an HDS conversion of 90%, which was much higher than that of a commercial Ni-Mo-S/Al2O3 catalyst which gave an HDS conversion of 68%, based on equal number ofmore » sites (230 ?mol) loaded in the reactor. The sites were counted by CO chemisorption for the phosphide and by low-temperature O2 chemisorption for the sulfide. EXAFS analysis of the samples confirmed the presence of two types of sites, tetrahedral Ni(1) sites and square pyramidal Ni(2) sites, with the latter growing in number in the same order as the reactivity Ni2P/MCM-41 > Ni2P/SiO2-H > Ni2P/SiO2-L, as the crystallite size decreased. From the selectivity to the direct desulfurization (DDS) product (dimethylbiphenyl) and the hydrogenation (HYD) products (methylcyclohexyltoluenes and dimethylbicyclohexyls) it is concluded that the Ni(1) sites are responsible for DDS while the Ni(2) are highly active sites for the HYD route.« less

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
959705
Report Number(s):
BNL-82691-2009-JA
Journal ID: ISSN 0021-9517; JCTLA5; TRN: US201016%%849
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 258; Journal ID: ISSN 0021-9517
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; CATALYSTS; CHEMISORPTION; DESULFURIZATION; FINE STRUCTURE; HYDROGENATION; NICKEL PHOSPHIDES; PERFORMANCE; PHOSPHIDES; QUINOLINES; SURFACE AREA; X-RAY DIFFRACTION; national synchrotron light source

Citation Formats

Oyama, S, and Lee, Y. The Active Site of Nickel Phosphide Catalysts for the Hydrodesulfurization of 4,6-DMDBT. United States: N. p., 2008. Web. doi:10.1016/j.jcat.2008.06.023.
Oyama, S, & Lee, Y. The Active Site of Nickel Phosphide Catalysts for the Hydrodesulfurization of 4,6-DMDBT. United States. https://doi.org/10.1016/j.jcat.2008.06.023
Oyama, S, and Lee, Y. 2008. "The Active Site of Nickel Phosphide Catalysts for the Hydrodesulfurization of 4,6-DMDBT". United States. https://doi.org/10.1016/j.jcat.2008.06.023.
@article{osti_959705,
title = {The Active Site of Nickel Phosphide Catalysts for the Hydrodesulfurization of 4,6-DMDBT},
author = {Oyama, S and Lee, Y},
abstractNote = {Ni2P catalysts supported on SiO2 and MCM-41 were prepared by temperature-programmed reduction (TPR), and the effect of the dispersion on catalyst structure and hydroprocessing performance was studied. The surface areas of the samples varied from low (Ni2P/SiO2-L, 88 m2 g?1) to high (Ni2P/SiO2-H, 240 m2 g?1), to very high (Ni2P/MCM-41, 487 m2 g?1), with corresponding Ni2P average crystallite sizes decreasing from 10.1 to 6.5 and 3.8 nm. X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) studies were used to obtain structural parameters for the supported Ni2P phase. The catalytic activity in hydrodesulfurization (HDS) was measured at 613 K and 3.1 MPa in a three-phase fixed bed reactor using a model liquid feed containing 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) and quinoline in a tridecane solvent. At standard conditions using 500 ppm S as 4, 6-DMDBT, 6000 ppm S as dimethyldisulfide (DMDS), and 500 ppm N as quinoline, the catalytic activity followed the sequence Ni2P/MCM-41 > Ni2P/SiO2-H > Ni2P/SiO2-L, based on equal sites (230 ?mol) loaded in the reactor. In particular, Ni2P/MCM-41 gave an HDS conversion of 90%, which was much higher than that of a commercial Ni-Mo-S/Al2O3 catalyst which gave an HDS conversion of 68%, based on equal number of sites (230 ?mol) loaded in the reactor. The sites were counted by CO chemisorption for the phosphide and by low-temperature O2 chemisorption for the sulfide. EXAFS analysis of the samples confirmed the presence of two types of sites, tetrahedral Ni(1) sites and square pyramidal Ni(2) sites, with the latter growing in number in the same order as the reactivity Ni2P/MCM-41 > Ni2P/SiO2-H > Ni2P/SiO2-L, as the crystallite size decreased. From the selectivity to the direct desulfurization (DDS) product (dimethylbiphenyl) and the hydrogenation (HYD) products (methylcyclohexyltoluenes and dimethylbicyclohexyls) it is concluded that the Ni(1) sites are responsible for DDS while the Ni(2) are highly active sites for the HYD route.},
doi = {10.1016/j.jcat.2008.06.023},
url = {https://www.osti.gov/biblio/959705}, journal = {Journal of Catalysis},
issn = {0021-9517},
number = ,
volume = 258,
place = {United States},
year = {2008},
month = {1}
}