Crystallite size effect in the selective oxidation of butene to butadiene on iron oxide. 1. Moessbauer, X-ray, and magnetization characterization of the catalysts

Journal Article · Sun Jan 01 04:00:00 EST 1984 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150656a019· OSTI ID:5827374

Hong, F; Yang, B L; Schwartz, L H; Kung, H H

A series of silica-supported and unsupported iron oxide catalysts were characterized by X-ray diffraction, room-temperature Moessbauer spectroscopy, and low-temperature magnetization measurements. The average crystallite sizes were determined by the X-ray line-broadening technique. They ranged from 2.5 to 9.5 nm for the supported samples and from 14.5 to 61 nm for the unsupported samples. X-ray diffraction detected only the presence of ..cap alpha..-Fe/sub 2/O/sub 3/. Fourier line-shape analyses showed that the samples were rather strain free, and the width of the crystallite size distribution increased with increasing average crystallite size. The Moessbauer parameters of both components are consistent with the assignment of ..cap alpha..-Fe/sub 2/O/sub 3/. In particular, no component with zero quadrupole splitting assignable to ..gamma..-Fe/sub 2/O/sub 3/ was observed. Magnetization measurements showed that the small crystallite samples possess magnetic moments higher than that of bulk ..cap alpha..-Fe/sub 2/O/sub 3/ but much lower than that of ..gamma..-Fe/sub 2/O/sub 3/. The data was explained by the absence of Morin transition and incomplete cancellation of spins in very small crystallites of ..cap alpha..-Fe/sub 2/O/sub 3/. 29 references, 6 figures, 3 tables.

• Research Organization: Northwestern Univ., Evanston, IL
• OSTI ID: 5827374
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 88:12; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKENES
BUTADIENE
BUTENES
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTALS
DATA
DIENES
DIFFRACTION
EXPERIMENTAL DATA
GAMMA SPECTROMETERS
HYDROCARBONS
INFORMATION
IRON COMPOUNDS
IRON OXIDES
MAGNETISM
MAGNETIZATION
MEASURING INSTRUMENTS
MOESSBAUER EFFECT
MOESSBAUER SPECTROMETERS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
POLYENES
SCATTERING
SIZE
SPECTROMETERS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION