Platinum/zeolite catalyst for reforming n-hexane: Kinetic and mechanistic considerations

Journal Article · Wed May 01 04:00:00 EDT 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90018-Y· OSTI ID:5537928

Lane, G S; Modica, F S; Miller, J T ^[1]

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1. Amoco Oil Co., Naperville, Illinois (USA)

A platinum/L-zeolite-reforming catalyst exhibits activity and selectivity for converting n-hexane into benzene than other Pt catalyst. The reaction pathways indicate that for all catalysts, e.g., Pt/K L or Pt/K Y, benzene is formed as a primary product by one-six-ring closure and methylcyclopentane is formed as a primary product via one-five-ring closure. The ratio for one-six to one-five-ring closure, however, is about two times greater for the Pt/K L than for the Pt/K Y, or other platinum catalysts. The preference for the one-six-ring closure in L zeolite appears to be related to the optimum pore size of the L zeolite. In addition to an increased selectivity for one-six-ring closure, the Pt/K L-zeolite catalyst also displays increased reactivity. For example, the turnover frequency of the Pt/K L-zeolite catalyst is 10 times higher for formation of benzene and 3.3 times higher for formation of methylcyclopentane compared with the Pt/K Y-zeolite catalyst. Although the Pt/K L is more reactive than Pt/K Y, the apparent activation energies, 54 kcal/mol for one-six-ring closure and 39 kcal/mol for one-five-ring closure, are the same for both catalysts. Differences in reactivity are associated with an increase in the preexponential term for the Pt/K L catalyst. The increased aromatics selectivity for Pt/K L is consistent with the confinement model which proposes that n-hexane is adsorbed as a six-ring pseudo-cycle resembling the transition state for one-six-ring closure.

• OSTI ID: 5537928
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 129:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ACTIVATION ENERGY
ALKALI METALS
ALKANES
AROMATICS
BENZENE
CATALYSIS
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CYCLOALKANES
ELEMENTS
ENERGY
ENERGY SOURCES
FOSSIL FUELS
FUELS
HEXANE
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KINETICS
MATERIALS
METALS
MINERALS
ORGANIC COMPOUNDS
PETROLEUM
PLATINUM
PLATINUM METALS
POTASSIUM
PROCESSING
REACTION KINETICS
REFINING
REFORMER PROCESSES
SYNTHESIS
TRANSITION ELEMENTS
ZEOLITES