Active sites of dealuminated hydrogen mordenite
Calcining of hydrogen mordenite and dealuminated hydrogen mordenite catalysts at 400/sup 0/-700/sup 0/C controlled the acid characteristics of the catalyst and hence, the catalytic activity, which was a maximum after calcining at 500/sup 0/C. At low temperatures, water in the pores apparently lowered the activity for cumene cracking in a pulse microreactor at 250/sup 0/C. Removal of aluminum from hydrogen mordenite initially increased catalytic activity for cumene cracking up to about 50% aluminum removal, above which the activity decreased linearly with the degree of aluminum removal. Quinoline poisoning studies also showed that pores opened up as calcining became severe and that the number of active sites for cumene cracking decreased markedly above 500/sup 0/C. This temperature corresponds to that at which the Broensted acids, the active centers in cumene cracking are removed. IR studies of pyridine adsorption at 1400-1700 cm/sup -1/ showed that the number of Broensted acid sites decreased with increasing pretreatment temperature. Cumene cracking activity decreased at a slower rate than the decrease in number of Broensted acid sites. The data emphasized that only the strong acid sites participate in catalysis.
- OSTI ID:
- 5410700
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ABSORPTION
ALUMINIUM
AROMATICS
AZINES
BROENSTED ACIDS
CALCINATION
CATALYSIS
CATALYSTS
CATALYTIC CRACKING
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CRACKING
CUMENE
DEACTIVATION
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTS
HETEROCYCLIC COMPOUNDS
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN COMPOUNDS
INFRARED RADIATION
INORGANIC ACIDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KINETICS
MATERIALS
METALS
MINERALS
MORDENITE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
POISONING
PYRIDINE
PYRIDINES
PYROLYSIS
RADIATIONS
REACTION KINETICS
REMOVAL
SILICATE MINERALS
THERMOCHEMICAL PROCESSES
ZEOLITES