Influence of framework aluminium gradients on the catalytic activity of Y zeolites: cracking of gas-oil on Y zeolites dealuminated by different procedures

Journal Article · Sun Nov 01 04:00:00 EST 1987 · J. Catal.; (United States)

OSTI ID:5269674

Arribas, J; Corma, A; Fornes, V; Melo, F

The catalytic cracking of gas-oil has been studied in a series of REHY and HY zeolite catalysts dealuminated by deep bed calcination, steaming, and SiCl/sub 4/ treatment. The samples have been characterized by X-ray diffraction, pyridine adsorption, and X-ray photoelectron spectroscopy (XPS). It has been found that the framework Si/Al ratio determined by XPS (surface Si/Al) and that determined from unit cell dimension measurements (bulk Si/Al) differ, indicating a gradient in the concentration of the framework aluminum normal to the surface of the zeolite crystallites. When the gas-oil cracking activity is plotted versus unit cell dimension, three different volcano curves are obtained, with activity maxima located at about 24.59, 24.35, and 24.33 A for deep bed, steamed, and SiCl/sub 4/-treated zeolites, respectively. These results, together with the behavior of the selectivity curves to gasoline, light cycle oil (LCO), gases, coke, and butene/butane ratio, are discussed on the basis of Si/Al gradients. Comparison of the cracking behavior of a short molecule such as n-heptane with that of gas-oil, in relation to the acidity of the samples measured by pyridine adsorption, supports the idea that gas-oil does not penetrate the zeolite deeply and, therefore, that the activity of the catalyst is controlled by the framework Si/Al ratio close to the external surface, instead of the bulk Si/Al ratio of the zeolite crystallites.

• Research Organization: CSIC, Madrid (Spain)
• OSTI ID: 5269674
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 108:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ADSORPTION
ALKANES
ALKENES
ALUMINIUM
AZINES
BUTANE
BUTENES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC CRACKING
CATALYTIC EFFECTS
CHEMICAL REACTIONS
COHERENT SCATTERING
COKE
CRACKING
DECOMPOSITION
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
GAS OILS
GASOLINE
HEPTANE
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
LIQUID FUELS
MATERIALS
METALS
MINERALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PETROLEUM
PETROLEUM FRACTIONS
PETROLEUM PRODUCTS
PHOTOELECTRON SPECTROSCOPY
PYRIDINE
PYRIDINES
PYROLYSIS
QUANTITY RATIO
SCATTERING
SEMIMETALS
SILICON
SORPTION
SPECTROSCOPY
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
ZEOLITES