Clustering of metal atoms in organic media. II. Effect of support on nickel catalysts prepared by solvated metal atom dispersion (SMAD)
Highly dispersed Ni/support catalysts were prepared from toluene-solvated nickel atoms (solvated metal atom dispersed or SMAD). Catalysts were prepared on MgO, Al/sub 2/O/sub 3/, SiO/sub 2/, and carbon, and their activities were tested for hydrogenolysis of methylcyclopentane, hydrogenation of toluene, dehydrogenation of isopropyl alcohol, and methanation of carbon monoxide. Conventional catalysts were also studied and compared with the SMAD systems. The effect of the support on SMAD catalyst activities was minimal for hydrogenolysis of methylcyclopentane, hydrogenation of toluene, and dehydration of isopropyl alcohol. However, conventional catalysts showed a significant effect of support when these reactions were studied. This difference between SMAD and conventional catalysts is attributed to the presence of an insulating layer of carbonaceous species between Ni and the support in the SMAD systems. Conversely, catalyst activity for methanation of carbon monoxide was significantly affected by support, especially MgO. This phenomenon reflects a synergistic effect of MgO when Ni is present, where CO can be adsorbed readily on MgO which apparently aids in the initial CO reduction step. The SMAD method in combination with high surface area supports yields highly dispersed catalysts with very small particle sizes. Carbon, a support with a particularly high surface area, allows formation of the smallest particle sizes, and this phenomenon is believed to indicate a direct dependency ofmetal particle size on the surface area of the support. The implications of this finding on the mechanism of particle formation are discussed, as well as the observation of optimum nickel particle size effects for the reactions studied. 5 figures, 4 tables.
- Research Organization:
- Kansas State Univ., Manhattan
- OSTI ID:
- 5741470
- Journal Information:
- J. Org. Chem.; (United States), Vol. 47:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CATALYST SUPPORTS
SYNTHESIS
NICKEL
ALUMINIUM OXIDES
CARBON
CARBON MONOXIDE
CATALYSTS
CYCLOALKANES
DEHYDROGENATION
HYDROGENATION
MAGNESIUM OXIDES
METALS
METHANATION
ORGANIC COMPOUNDS
PARTICLE SIZE
PROPANOLS
REACTION KINETICS
SILICON OXIDES
SOLID CLUSTERS
TOLUENE
ALCOHOLS
ALKALINE EARTH METAL COMPOUNDS
ALKANES
ALUMINIUM COMPOUNDS
AROMATICS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
HYDROCARBONS
HYDROXY COMPOUNDS
KINETICS
MAGNESIUM COMPOUNDS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
SILICON COMPOUNDS
SIZE
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties