Surface properties and catalytic activities of pure and silica-coated aluminas
Nitrogen adsorption isotherms were measured for a mesoporous pseudoboehmite (A), a microporous gibbsite (B), and a nonporous g-alumina and used to calculate BET surface areas and pore size distributions. All the samples showed monodisperse pore size distributions, and the most probable pore radius increased as the calcining temperature was raised from 600/sup 0/ to 800/sup 0/C. Precipitation of silica onto A reduced the most probable pore size but had little effect on the number of pores, whereas the same treatment of B had the opposite effect. Apparently, silica blocks micropores and coats the walls of mesopores. Coating with silica increased the total number of surface hydroxyl groups as determined by ignition but decreased the number of acidic hydroxyl groups as determined by pyridine chemisorption and thus, also decreased the activity for cumene cracking at 500/sup 0/C. For all except the very microporous B samples for which access to active sites is limited, a logarithmically linear correlation was found between the activity for cumene cracking and the product of BET surface area and number of acidic hydroxyl groups.
- Research Organization:
- Ain-Shams Univ.
- OSTI ID:
- 6789054
- Journal Information:
- J. Colloid Interface Sci.; (United States), Journal Name: J. Colloid Interface Sci.; (United States) Vol. 70:3; ISSN JCISA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ADSORPTION ISOTHERMS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AROMATICS
CALCINATION
CHALCOGENIDES
CHEMICAL REACTIONS
CORRELATIONS
CRACKING
CRYSTAL STRUCTURE
CUMENE
DECOMPOSITION
DEPOSITION
ELEMENTS
HYDROCARBONS
ISOTHERM
MICROSTRUCTURE
MINERALS
NITROGEN
NONMETALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PYROLYSIS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SURFACE COATING
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES