Heterogeneous catlaysts: Mechanisms of service clevage of strong carbon-carbon bonds

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:254780

Farcasiu, M; Petrosius, S C ^[1]

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1. Pittsburgh Energy Technology Center, Pittsburgh, PA (United States)

This paper discusses the catalytic cleavage of strong carbon-carbon bonds in compounds which also contain relatively weaker carbon-carbon bonds which can be cleaved thermally by a homolytic, free radical process. The majority of the reactions described here arc performed under condition where the thermal background is very small or nonexistent. We will discuss the reactivity of two model compounds relevant to fossil fuels (oil and coal) in the presence of several heterogenous catalysts: carbon black, graphite and solid acids. Previously, we have reported a very selective carbon black C-C cleavage of bonds between a polycondensed aromatic moiety and an adjacent aliphatic carbon and on carbon black catalyzed dehydroxylation and dehalogenation of polycondensed aromatic phenols and halogenated polycondensed compounds. We attributed the observed catalytic activity and selectivity in hydrocracking reactions to the formation of radical cations on the surface of carbon-based catalysts at temperatures over 320{degrees}C{sup 2} and the dehydroxylation and dehalogenation reactions to a free radical mechanism identical with that of the thermal reaction. We concluded that two types of catalytic active centers are present on carbon black. In this presentation we will elaborate on the nature of carbon black catalytic activity and contrast it to that of graphite.

• OSTI ID: 254780
• Report Number(s): CONF-940813--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
02 PETROLEUM
CARBON BLACK
CATALYTIC EFFECTS
CHEMICAL BONDS
CLEAVAGE
COAL
DEHALOGENATION
GRAPHITE
HETEROGENEOUS CATALYSIS
HYDROCRACKING
PETROLEUM
PROCESSING
RADICALS
SOLVENTS