Coking, aging, and regeneration of zeolites. II. Deactivation of HY zeolite during n-heptane cracking

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · J. Catal.; (United States)

OSTI ID:5231335

Magnoux, P; Cartraud, P; Mignard, S; Guisnet, M

Heavy carbonaceous compounds (coke) are deposited very rapidly during n-heptane cracking on a stabilized HY zeolite at 450/sup 0/C, decreasing its activity, modifying its selectivity and its adsorption properties. Deactivation of the zeolite can be explained mainly by partial or total blocking of access to the active centers, even for low coke content. Indeed, while the decrease of the pore volume accessible to n-hexane (hence to the reactant n-heptane) is about 3 times less than the decrease of the activity, calorimetric study of NH/sub 3/ adsorption shows that the sites which no longer adsorb NH/sub 3/ are the strongest. Moreover, the diffusivity of n-hexane in the pore volume which remains accessible is definitely smaller than in the coke-free zeolite. Finally, the pore volume which has become inaccessible to n-hexane is, even at low coke content, about three times smaller than the volume really occupied by coke (estimated from its density). This deactivation through pore blockage is due to the fact that, even at low coke content, the coke molecules are sufficiently large to prevent access of the reactant to the supercages of the zeolite.

• Research Organization: Universite de Poitiers (France)
• OSTI ID: 5231335
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 106:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ALKANES
CATALYTIC CRACKING
CHEMICAL REACTIONS
COKE
CRACKING
CRYSTAL STRUCTURE
DEACTIVATION
DECOMPOSITION
DEPOSITION
FLOW BLOCKAGE
HEPTANE
HEXANE
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MICROSTRUCTURE
MINERALS
ORGANIC COMPOUNDS
POROSITY
PYROLYSIS
THERMOCHEMICAL PROCESSES
ZEOLITES