X-ray absorption spectroscopy and x-ray photoelectron spectroscopy studies of cobalt catalysts. 3. Sulfidation properties in H sub 2 S/H sub 2

Journal Article · Thu Aug 22 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100170a044· OSTI ID:7017463

Castner, D G; Watson, P R ^[1]

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1. Chevron Research Co., Richmond, CA (United States)

In petroleum-refining applications, Co-containing catalysts are used for hydrodesulfurization. X-ray absorption spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize the sulfidation properties of bulk Co{sub 3}O{sub 4} and Co{sub 3}O{sub 4} supported on large (Co/SiO{sub 2}-62) and small (Co/SiO{sub 2}-923) pore size silica. The sulfidation process in H{sub 2}S/H{sub 2} proceeded as Co{sub 3}O{sub 4} {yields} CoO {yields} Co {yields} Co{sub 9}S{sub 8}, with direct conversion of the Co oxides into Co{sub 9}S{sub 8} also being observed. For all three samples, the surface of the Co{sub 3}O{sub 4} particles readily sulfided at 200 C. This surface sulfide layer appeared to inhibit further sulfidation of the larger Co{sub 3}O{sub 4} particles by restricting the diffusion of the sulfiding species. These diffusion limitations were overcome by increasing the reaction temperature. The ease of sulfidation increased in the order Co{sub 3}O{sub 4} < Co/SiO{sub 2}-62 < Co/SiO{sub 2}-923, which correlated with decreasing Co{sub 3}O{sub 4} particle size. The ease of sulfidation ranking for these catalysts were opposite to their ease of reduction, because direct sulfidation of the Co oxides on the supported catalysts eliminated the high-temperature CoO {yields} Co hydrogen reduction step. Upon sulfidation of the Co{sub 3}O{sub 4}-supported particles to Co{sub 9}S{sub 8}, the particles size decreased {approximately}20%. For the sulfided Co/SiO{sub 2}-62 sample, the XPS measured Co{sub 9}S{sub 8} particle size was 145 {angstrom}. For the sulfided Co/SiO{sub 2}-923 sample, the XPS measured Co{sub 9}S{sub 8} particle size was 40 {angstrom}.

• OSTI ID: 7017463
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:17; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
01 COAL, LIGNITE, AND PEAT
COBALT OXIDES
SULFIDATION
CATALYST SUPPORTS
CATALYSTS
EXPERIMENTAL DATA
HYDROGEN
HYDROGEN SULFIDES
PARTICLE SIZE
PHOTOELECTRON SPECTROSCOPY
REDUCTION
SILICON OXIDES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
X-RAY SPECTRA
CHALCOGENIDES
CHEMICAL REACTIONS
COBALT COMPOUNDS
DATA
ELECTRON SPECTROSCOPY
ELEMENTS
HYDROGEN COMPOUNDS
INFORMATION
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SILICON COMPOUNDS
SIZE
SPECTRA
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical &amp; Physicochemical Properties
010402 - Coal
Lignite
&amp; Peat- Purification &amp; Upgrading