Catalysis and surface chemistry. I. Cyclopropane reactions over reduced molybdena--alumina

Journal Article · Sat Jan 01 04:00:00 EST 1977 · J. Colloid Interface Sci.; (United States)

OSTI ID:5241880

Jacono, M L; Hall, W K

The surface chemistry of an 8% Mo on alumina catalyst was varied by a method which determines the extent of reduction, the hydroxyl concentration introduced into the molybdena layer, the number of anion vacancies formed by removal of H/sub 2/O as the catalyst is reduced with H/sub 2/, and the amount of reversibly adsorbed hydrogen, H/sub R/. The latter was found to correlate linearly with the vacancy concentration. The isomerization of cyclopropane was studied using a microcatalytic pulse technique at temperatures between 0 and 109/sup 0/C. At a very low extent of reduction the mass balance was good when He-carrying gas was used and the only products observed were propene and a trace of ethene. As the extent of reduction was increased, however, nearly equal quantities of ethene and n-butenes appeared in increasing amounts together with propene. The isomerization reaction correlated linearly with the sum of the concentrations of vacancies and hydroxyls introduced as Mo-OH during the reduction with H/sub 2/. Olefin metathesis and loss from the mass balance could be correlated with vacancies. When H/sub 2/-carrying gas was used, the olefins were completely hydrogenated under all conditions tested and the reaction of the cyclopropane reacted was increased considerably. At a low extent of reduction, the metathesis rate was about the same as in He. As the extent of reduction was increased, however, both metathesis and formation of carbonaceous residues were repressed by H/sub 2/ until propane was the only product. Hydrogenolysis of either cyclopropane or propane (to form methane) was not appreciable below 390/sup 0/C. Both isomerization and metathesis were poisoned by adsorption of H/sub 2/O; both activities could be restored by evacuation of the catalyst at elevated temperatures. Carbon monoxide also exhibited poisoning effects.

• Research Organization: Univ. of Wisconsin, Milwaukee
• OSTI ID: 5241880
• Journal Information: J. Colloid Interface Sci.; (United States), Journal Name: J. Colloid Interface Sci.; (United States) Vol. 58:1; ISSN JCISA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400 -- Petroleum-- Processing
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBONACEOUS MATERIALS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
COAL
CYCLOALKANES
DESULFURIZATION
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROCARBONS
ISOMERIZATION
METALS
MOLYBDENUM
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PETROLEUM
POISONING
REFRACTORY METALS
TRANSITION ELEMENTS