Adsorption of carbon monoxide on ZSM-5 zeolites. Infrared spectroscopic study and quantum-chemical calculations
Low temperature adsorption of CO was studied on H-ZSM-5 zeolites modified by dehydroxylation, ionic exchange with Al/sup 3 +/, and impregnation with Al/sub 2/O/sub 3/ and on Na-ZSM-5 and CaH-ZSM-5 zeolites. It was found that interaction of CO with framework OH groups results in the formation of a hydrogen-bonded CO complex whose OH bond frequency is decreased by 310-320 cm/sup -1/ compared with that of free hydroxyls. For the less acidic framework hydroxyls in large cavities of H/sub 70/Na/sub 30/-Y zeolite the observed shift is 275 cm/sup -1/. With ZSM-5 zeolites, at least six types of electron-accepting sites are observed originating from nonframework Al species (band of CO in the interaction complex: 2132, 2222, 2202, 2195, and 2198 cm/sup -1/) and the Al/sub 2/O/sub 3/ microcrystalline phase (CO band at 2153 cm/sup -1/). The CO bond orders calculated by the CNDO/2 method for the CO interaction complexes with models of surface sites increase in the following order: > O-CO < > OH-CO approx. ..-->.. Al-CO approx. = Na-CO < alumina-CO approx. = Ca-CO < ..-->.. Si-CO < Al(cationic)-CO. A correlation between the calculated bond orders of CO and the observed vibrational frequencies of CO-forming interaction complexes is drawn.
- Research Organization:
- N.D. Zelinsky Institute of Organic Chemistry, Moscow, USSR
- OSTI ID:
- 5615777
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 91:20
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON MONOXIDE
ADSORPTION
ABSORPTION SPECTROSCOPY
ALUMINIUM OXIDES
CALCIUM COMPLEXES
EXPERIMENTAL DATA
INFRARED SPECTRA
MATHEMATICAL MODELS
SODIUM COMPLEXES
SURFACE PROPERTIES
VIBRATIONAL STATES
ZEOLITES
ALKALI METAL COMPLEXES
ALKALINE EARTH METAL COMPLEXES
ALUMINIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
COMPLEXES
DATA
ENERGY LEVELS
EXCITED STATES
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MINERALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SORPTION
SPECTRA
SPECTROSCOPY
400201* - Chemical & Physicochemical Properties