Hydrogen pressure dependence of the ring-opening reactions of propylcyclobutane over Pt/SiO[sub 2] catalyst at different temperatures

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1258· OSTI ID:5738355

Toeroek, B; Palinko, I; Molnar, A; Bartok, M ^[1]

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1. Jozsef Attila Univ., Szeged (Hungary)

The hydrogen pressure dependence of the ring-opening reactions of propylcyclobutane was studied at three different temperatures over Pt/SiO[sub 2] catalyst. At 373 and 573 K, only hydrogenative ring opening occurs, while appreciable amounts of aromatics, ring enlargement, and cracking products are formed at 673 K. At 373 K, the ring opens selectively in the sterically more hindered direction over both the clean and the working catalyst, yielding heptane as the major product. The selectivity is lost at 573 K and 673 K: 2,3 C-C bond scission, i.e., formation of 3-methylhexane occurs with initial rates comparable to that of 1,2 C-C bond scission. Over the working catalyst, the selectivity is close to statistical, with a slight excess of 3-methylhexane. An increase of hydrogen pressure has different effects on the ring-opening reactions, depending on the reaction temperature. The initial rate of product formation vs hydrogen pressure curves exhibit three extremes at 373 K, but they increase monotonously at 573 and 683 K. Over the working catalyst, the hydrogen pressure dependence curves display three extremes at 373 K, pass through a maximum at 573 K, and increase monotonously at 673 K. Mechanisms over both the initial and working catalysts are discussed on the basis of regioselectivity data and hydrogen pressure dependence curves. 24 refs., 3 figs., 1 tab.

• OSTI ID: 5738355
• Journal Information: Journal of Catalysis; (United States), Vol. 143:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
PLATINUM
CATALYTIC EFFECTS
AROMATICS
CATALYST SUPPORTS
CATALYSTS
CRACKING
CYCLOALKANES
HEPTANE
HETEROGENEOUS CATALYSIS
HYDROGEN
PRESSURE DEPENDENCE
SILICON OXIDES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
ALKANES
CATALYSIS
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTS
HYDROCARBONS
METALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
PYROLYSIS
SILICON COMPOUNDS
TEMPERATURE RANGE
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing