Influence of oxonium ion and carbenium ion stabilities on the alcohol/H-ZSM-5 interaction
The authors have examined the adsorption of methanol, ethanol, 1-propanol, 1-butanol, 2-propanol, and 2-methyl-2-propanol on H-ZSM-5 using temperature-programmed desorption (TPD) and thermogravimetric analysis (TGA). For each of the alcohols except 1-butanol, there exists a clearly defined desorption state corresponding to one alcohol molecule per Al atom in the zeolite. For 2-methyl-2-propanol and 2-propanol, this molecule at the Al site completely reacts to olefin products and water; however, reaction occurs at 295 K for 2-methyl-2-propanol, while 2-propanol does not react until 360 K. Most of the methanol, ethanol, and 1-propanol adsorbed at the Al sites at this coverage desorbs unreacted. A substantial amount of the 1-butanol adsorbed near the Al sites reacts, but differs from the other alcohols in that it reacts through a dibutyl ether intermediate. These results can be understood in terms of the stabilities of the carbenium ion intermediates which can be formed during reaction. A potential energy scheme, based on gas-phase proton affinity, is developed. This scheme provides a formalism for explaining relative reactivities of alcohols on H-ZSM-5 in TPD. 25 references.
- Research Organization:
- Univ. of Pennsylvania, Philadelphia (USA)
- OSTI ID:
- 5205997
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 98:2; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010408* -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
ADSORPTION
ALCOHOLS
ALKENES
ALUMINIUM
BUTANOLS
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHARGED PARTICLES
CHEMICAL REACTIONS
DESORPTION
ELEMENTS
ETHANOL
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
IONS
MATERIALS
METALS
METHANOL
MINERALS
MOLECULAR IONS
ORGANIC COMPOUNDS
OXONIUM IONS
OXYGEN COMPOUNDS
PROPANOLS
REACTION INTERMEDIATES
REFORMER PROCESSES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
SYNTHESIS
WATER
ZEOLITES