Coking, aging, and regeneration of zeolites VII. Electron microscopy and EELS studies of external coke deposits on USHY, H-OFF, and H-ZSM-5 zeolites

Journal Article · Tue Nov 01 04:00:00 EST 1988 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(88)90012-7· OSTI ID:6911436

Gallezot, P; Leclercq, C ^[1]; Guisnet, M; Magnoux, P ^[2]

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1. Institut de Recherches sur la Catalyse, Villeurbanne (France)
2. Universite de Poitiers (France)

External coke deposits produced by n-heptane cracking on USHY, H-OFF, and H-ZSM-5 zeolites have been located by a combination of transmission electron microscopic observations and electron energy loss spectroscopic (EELS) measurements performed with a field-emission gun scanning transmission electron microscope equipped with an electron spectrometer. The local structure of coke is determined from the fine structure at the high-energy side of the C{sub K} EELS peak, in comparison with reference compounds such as graphite, coronene, and pentacene. In H-ZSM-5 and H-OFF the coke forms an external envelope around the zeolite crystal and stands as an empty mold after zeolite extraction. Its structure is similar to that of coronene (polyaromatic-pregraphitic). In USHY part of the coke is in the form of 1-nm-large carbon filaments protruding from the zeolite mesopores and micropores. Its structure is more like that of pentacene (linear polyaromatic).

• OSTI ID: 6911436
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 114:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ALKANES
CATALYTIC CRACKING
CHEMICAL REACTIONS
COKE
COMPARATIVE EVALUATIONS
CRACKING
CRYSTAL STRUCTURE
DEACTIVATION
DECOMPOSITION
DEPOSITION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ENERGY-LOSS SPECTROSCOPY
HEPTANE
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MICROSCOPY
MICROSTRUCTURE
MINERALS
ORGANIC COMPOUNDS
POROSITY
PYROLYSIS
SHAPE
SPECTROSCOPY
THERMOCHEMICAL PROCESSES
TRANSMISSION ELECTRON MICROSCOPY
ZEOLITES