X-ray absorption spectroscopy, x-ray photoelectron spectroscopy, and analytical electron microscopy studies of cobalt catalysts. 2. Hydrogen reduction properties

Journal Article · Thu Jan 25 00:00:00 EST 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100365a057· OSTI ID:6623380

Castner, D G; Watson, P R; Chan, I Y ^[1]

---

1. Chevron Research Co., Richmond, CA (USA)

XAS, XPS, AEM, and temperature-programmed reduction were used to characterize the hydrogen reduction of bulk Co{sub 3}O{sub 4} and Co{sub 3}O{sub 4} supported on small (Co/SiO{sub 2}-62) and large (Co/SiO{sub 2}-923) pore size silica. The reduction process proceeded as Co{sub 3}O{sub 4} {yields} CoO {yields} Co, with the CoO intermediate species spectroscopically identified on all three samples. The first step of the reduction, Co{sub 3}O{sub 4} {yields} CoO, occurred near 300{degree}C for all three catalysts. The second step of the reduction, CoO {yields} Co, showed significant differences among the samples, with the ease of reduction decreasing in the order Co{sub 3}O{sub 4} > Co/SiO{sub 2}-62 > Co/SiO{sub 2}-923. The ease of reduction appeared to be correlated to the ease of removing the H{sub 2}O produced during the CoO {yields} Co step. The small pores (ca. 30 {angstrom}) of the Co/SiO{sub 2}-923 sample made H{sub 2}O removal and reduction for that sample the most difficult. Upon reduction of the Co{sub 3}O{sub 4} supported particles to metallic Co the particle size decreased by 30-50% due to removal of oxygen from the Co{sub 3}O{sub 4} particles. For the reduced Co/SiO{sub 2}-62 sample, the Co particles were 90 {angstrom} in size and grouped together in 0.1-1-{mu}m aggregates. The crystallographic orientation of the individual particles in each aggregate became radomized upon reduction and reoxidation. For the reduced Co/SiO{sub 2}-923 sample the Co particles were 35 {angstrom} in size.

• OSTI ID: 6623380
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 94:2; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CATALYST SUPPORTS
ABSORPTION SPECTROSCOPY
ELECTRON SPECTROSCOPY
PHOTOELECTRON SPECTROSCOPY
COBALT OXIDES
DATA ANALYSIS
EXPERIMENTAL DATA
HYDROGEN
MEASURING INSTRUMENTS
MEASURING METHODS
REDUCTION
SILICA
CHALCOGENIDES
CHEMICAL REACTIONS
COBALT COMPOUNDS
DATA
ELEMENTS
INFORMATION
MINERALS
NONMETALS
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SILICON COMPOUNDS
SILICON OXIDES
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
400201 - Chemical & Physicochemical Properties