General aspect of catalytic hydrogenation and isomerization reactions on oxide catalyst. Characteristics of the reactions via ionic and nonionic intermediates
Hydrogenation and isomerization reactions taking place on oxide and/or on sulfide catalysts are divided into two types depending on the intermediates being either ionic or nonionic. The reactions via nonionic species such as sigma-alkyl and sigma- or ..pi..-allyl intermediates require specific structure for active sites, while the reactions via ionic intermediates such as alkyl cation or allyl carbanion require no specific structure for active sites and depend entirely on acidity or basicity of the surface. The reactions on such oxides as Co/sub 3/O/sub 4/, Cr/sub 2/O/sub 3/, ZrO/sub 2/, ThO/sub 2/, and La/sub 2/O/sub 3/ are the former case, which are controlled by the structure of active sites. CdO and MgO are a typical case of ionic intermediates and are active for the hydrogenation of conjugated diene via allyl carbanion but not for the hydrogenation of olefin. Allyl as well as allyl carbanion bring about both the 1,2- and 1,4-additions, and the relative contribution of these two types of addition depends on kinetic facility. A larger cis/trans ratio in the 1,4-addition reflects allyl carbanion intermediates because of preferential Z-conformation of allyl carbanions. From a view of ionic and nonionic intermediates in catalysis, a new type of hydrogenation reaction via cationic intermediates is predicted.
- Research Organization:
- Hokkaido Univ., Sapporo, Japan
- OSTI ID:
- 6800837
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 65:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTINIDE COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANTHANUM OXIDES
CADMIUM COMPOUNDS
CADMIUM OXIDES
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COBALT COMPOUNDS
COBALT OXIDES
HYDROCARBONS
HYDROGENATION
ISOMERIZATION
KINETICS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MOLECULAR STRUCTURE
MOLYBDENUM COMPOUNDS
MOLYBDENUM SULFIDES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
SULFIDES
SULFUR COMPOUNDS
THORIUM COMPOUNDS
THORIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS
ZINC OXIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES