Electron microscope investigation of mesopore formation and aluminum migration in USY catalysts

Journal Article · Wed Mar 31 23:00:00 EST 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1093· OSTI ID:6204686

Choi-Feng, C; Hall, J B; Huggins, B J; Beyerlein, R A ^[1]

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1. Amoco Research Center, Naperville, IL (United States)

Combined high resolution electron microscope (HREM) and analytical electron microscope (AEM) investigations have been used to study the formation and evolution of mesopores in hydrothermally dealuminated ultrastable Y (USY) materials. The HREM results give clear evidence for an inhomogeneous formation and distribution of the 5- to 50-nm defect regions attributed to mesopores. Such features are characteristic of extended hydrothermal treatment. In regions with high defect concentration, mesopores coalesce to form channels and cracks, which ultimately define the boundaries of fractured crystallite fragments. At these boundaries, a dark band is often observed which is highly enriched in aluminum, while within the mesopore itself, aluminum appears to be deficient. These dark bands are observed both in a neat USY material subjected to several cycles of steam/acid treatment and in a high-temperature steam-deactivated USY fluid catalytic cracking (FCC) catalyst. Individual grains of both the neat USY and the dealuminated USY catalyst exhibit extreme fracturing into small crystallites of dimensions 20 to 50 nm. The fracturing is attributed to the nonequilibrium nature of the high-temperature steam treatments which characterizes accelerated deactivation procedures in the laboratory. 17 refs., 8 figs., 1 tab.

• OSTI ID: 6204686
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 140:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
CATALYSTS
CATALYTIC CRACKING
CHEMICAL REACTIONS
CRACKING
CRACKS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEACTIVATION
DECOMPOSITION
DIMENSIONS
DISTRIBUTION
ELECTRON MICROSCOPY
FRACTURING
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MICROSCOPY
MICROSTRUCTURE
MIGRATION
MINERALS
POROSITY
PYROLYSIS
RESOLUTION
SILICATE MINERALS
STEAM
THERMOCHEMICAL PROCESSES
ZEOLITES