In situ {sup 13}C MAS NMR study of n-hexane conversion on Pt and Pd supported on basic materials

Journal Article · Thu Feb 01 00:00:00 EST 1996 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1996.0051· OSTI ID:263705

Ivanova, I I; Pasau-Claerbout, A; Seivert, M; Derouane, E G ^[1]

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1. Facultes Universitaires N.D. de la Paix, Namur (Belgium); and others

n-Hexane conversion was studied in situ on Pt and Pd supported on aluminum-stabilized magnesium oxide and Pt on Zeolite KL catalysts (Pt/Mg(Al)O, Pd/Mg(Al)O and Pt/KL) by means of {sup 13}C MAS NMR spectroscopy. n-Hexane 1-{sup 13}C was used as a labelled reactant. Forty NMR lines corresponding to 14 different products were resolved and identified. The NMR line assignments were confirmed by adsorption of model compounds. The NMR results were further quantified and compared with continuous flow microreactor tests. Four parallel reaction pathways were identified under flow conditions: isomerization, cracking, dehydrocyclization, and dehydrogenation. Aromatization occurs via two reaction routes: (1) n-hexane dehydrogenation towards hexadienes and hexatrienes, followed by dehydrogenation of a cyclic intermediate. The former reaction pathway is prevented under NMR batch conditions. High pressures induced in the NMR cells at high reaction temperatures (573, 653 K) shift the reaction equilibrium towards hydrogenation. NMR experiments showed that on Pt catalysts aromatization occurs via a cyclohexane intermediate, whereas on Pd it takes place via methylcyclopentane ring enlargement. 54 refs., 15 figs., 3 tabs.

• OSTI ID: 263705
• Journal Information: Journal of Catalysis, Vol. 158, Issue 2; Other Information: PBD: Feb 1996
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
40 CHEMISTRY
ZEOLITES
CATALYTIC EFFECTS
HEXANE
CHEMICAL REACTIONS
PLATINUM
PALLADIUM
MAGNESIUM OXIDES
NUCLEAR MAGNETIC RESONANCE
CATALYST SUPPORTS
DEHYDROGENATION
ELECTROLYTIC CELLS
ISOMERIZATION
CATALYTIC CRACKING
CYCLIZATION
AROMATIZATION
REACTION INTERMEDIATES
HETEROGENEOUS CATALYSIS