Rh/SiO/sub 2/: catalyst characterization and study of the hydrogenolysis of methylcyclopropane

Journal Article · Thu May 01 04:00:00 EDT 1986 · J. Catal.; (United States)

OSTI ID:5231269

Karpinski, Z; Chuang, T K; Katsuzawa, H; Butt, J B; Burwell, Jr, R L; Cohen, J B

The adsorption of hydrogen, carbon monoxide, and oxygen and X-ray line profile analysis have been investigated on a series of Rh/SiO/sub 2/ catalysts made by ion exchange with Rh(NH/sub 3/)/sub 5/(H/sub 2/O)/sup 3 +/ and by impregnation with Rh/sub 4/(CO)/sub 12/ and Rh/sub 6/(CO)/sub 16/. The percentage exposed (D) of the series of catalysts as measured by hydrogen chemisorption at 25/sup 0/C varied from 11 to 108%. Ease of reduction of the oxidized catalysts decreased as D increased and reduction in hydrogen was incomplete in hydrogen at 25/sup 0/C except for the catalysts of smallest D. The rates of hydrogenolysis of methylcyclopropane (MCP) at 0/sup 0/C decreased with increasing D by a factor of about 9 over the range of D of the series of catalysts for catalysts pretreated O/sub 2/, 300/sup 0/, 0.5; H/sub 2/, 300/sup 0/, 1; He, 450/sup 0/, l where the last number in triad was the time of exposure in hours. Omission of He, 450, l led to decreased rates and augmented structure sensitivity, but H/sub 2/, 25/sup 0/, l without He,450/sup 0/ l led to inverted structure sensitivity, presumably because of residual oxygen on rhodium. The activation energy for hydrogenolysis was about 37 kJ/mol. The ratio of isobutane to butane in the products was about 20 for D = 11%, declined rapidly with increasing D, and became about 3.5 for D > 50%. Pretreatment conditions (temperature of pretreatment by H/sub 2/, presence or not of terminal He, 450/sup 0/, l) had little effect on the ratio. 47 references.

• Research Organization: Northwestern Univ., Evanston, IL (USA)
• DOE Contract Number: AC02-77ER04254
• OSTI ID: 5231269
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 99:1; ISSN JCTLA
• 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
ACTIVATION ENERGY
ALKANES
ALKENES
BUTANE
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CYCLOALKENES
ELEMENTS
ENERGY
FLUIDS
GASES
HELIUM
HYDROCARBONS
HYDROGEN
METALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PLATINUM METALS
RARE GASES
REDUCTION
REFORMER PROCESSES
REFRACTORY METAL COMPOUNDS
RHODIUM
RHODIUM COMPOUNDS
RHODIUM OXIDES
SYNTHESIS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS