Role of surface defects in the chemisorption of NO and SO sub 2 on variable-sized crystalline. alpha. -FeOOH

Journal Article · Thu Nov 30 04:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100361a023· OSTI ID:7197249

Kaneko, Katsumi; Matsumoto, Akihiko ^[1]

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1. Chiba Univ. (Japan)

{alpha}-FeOOH crystals of different crystalline sizes were prepared by aging Fe{sub 2}(SO{sub 4}){sub 3} solution at 303 K for various periods up to 10 days. The synthetic {alpha}-FeOOH crystals were examined by x-ray diffraction, BET surface area measurements, Fe K-edge XANES, and dc and microwave conductivity measurements. The precipitates without aging were amorphous solids. Aging for more than 18 h gave highly crystalline {alpha}-FeOOH, whereas {alpha}-FeOOH obtained by aging for less than 18 h was very defective. The XANES examination showed the presence of tetrahedral Fe(III) sites in the insufficiently aged {alpha}-FeOOH. The chemisorption abilities for NO and SO{sub 2} increase with the crystallite size up to 18 h of aging and become almost constant after 18 h of aging. The dc electrical conductivity of {alpha}-FeOOH decreases upon the first dose of NO or SO{sub 2}; the succeeding dose of the gas increases the conductivity. FT-IR examinations showed the formation of a nitrosyl, nitrito, and nitrato species and a sulfito species for chemisorption of NO and SO{sub 2}. The relationship between the increase in the electrical conductivity upon chemisorption of NO or SO{sub 2} and the formation of the pseudo oxygen vacancy due to the chemisorbed species is discussed from the viewpoint of the surface defect chemistry.

• OSTI ID: 7197249
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:24; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400000* -- Chemistry
400400 -- Electrochemistry
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
DATA
DATA ANALYSIS
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
IRON COMPOUNDS
IRON HYDROXIDES
MEASURING INSTRUMENTS
MEASURING METHODS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SEPARATION PROCESSES
SORPTION
SULFUR COMPOUNDS
SULFUR OXIDES
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS