The hydrogenation and oligomerization of propyne over an ion-exchanged copper on silica catalyst
- Macquarie Univ., Sydney (Australia)
The hydrogenation of propyne over an ion-exchanged copper on silica catalyst has been investigated. The system has a high selectivity for the production of propene over propane but is accompanied by the formation of oligomeric material that causes catalyst deactivation. Oligomer deposition can be readily followed by in situ infrared spectroscopic measurements. The amount of oligomer falls with increase in temperature and hydrogen pressure. The mechanism has been investigated through analysis of the oligomer fraction and by the use of deuterium in place of hydrogen. Greater than 70% of the C[sub 6] products are dienes, principally trans-2-methylpenta-1,3-diene, trans-2-trans-4-hexadiene, and 2,3-dimethyl-buta-1,3-diene. Three C[sub 6]H[sub 8] compounds, 2-methylpenta-1-ene-3-yne and the cis and trans isomer of hex-2-ene-4-yne make up the bulk of the remainder. Their amounts decrease steeply with increase in hydrogen pressure. The reaction with deuterium leads to dienes with an average of two deuteriums and ene-ynes averaging almost one deuterium. Unreacted propyne is exchanged to a significant extent very largely at the C[sub 1] position. Product propenes contain zero to three deuterium atoms distributed throughout the vinyl part of the molecule. There is a moderate kinetic isotope effect on going from hydrogen to deuterium which affects propene production a much greater extent than oligomer formation. The significance of these findings in relation to the steps by which hydrogenation and oligomerization occur is discussed. 23 refs., 7 figs., 4 tabs.
- OSTI ID:
- 6798147
- Journal Information:
- Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 148:1; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
100200 -- Synthetic Fuels-- Production-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
ALKYNES
CATALYSIS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COPPER
DEUTERIUM COMPOUNDS
ELEMENTS
HETEROGENEOUS CATALYSIS
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGENATION
ISOTOPE EFFECTS
KINETICS
METALS
MINERALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
POLYMERIZATION
PROPYNE
REACTION KINETICS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SPECTROSCOPY
TRANSITION ELEMENTS