Aromatization of n-hexane by platinum-containing molecular sieves. 2. n-Hexane reactivity

Journal Article · Sat Feb 29 23:00:00 EST 1992 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(92)90235-A· OSTI ID:7169205

Mielczarski, E; Hong, Suk Bong; Davis, M E ^[1]; Davis, R J ^[2]

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1. Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)
2. Univ. of Virginia, Charlottesville (United States)

Pt/KL, Pt/BaKL, Pt/KBaKL, Pt/NaY, Pt/CsNaY, Pt/NaFAU(C), Pt/hex, Pt/SSZ-24, Pt/silica, and Pt/carbon were tested as catalysts for the aromatization of n-hexane at 460-510 C and atmospheric total pressure in order to study the influence of Pt cluster size and support acidity/basicity, microstructure, and chemical composition on activity and selectivity. Analysis of the catalytic and NH{sub 3} temperature-programmed desorption results from Pt/KL, Pt/BaKL, and Pt/KBaKL reveals that the presence of any acidity increases hydrogenolysis at the expense of benzene production. In addition, no increase in aromatization selectivity is observed by the addition of base sites to a Pt/zeolite catalyst, confirming that aromatization of n-hexane over Pt clusters on nonacidic carriers is monofunctional. High selectivity to benzene over most of the zeolite samples demonstrates that support microstructure does not contribute directly to the aromatization selectivity over Pt catalysts. High selectivity to benzene is observed for a Pt/carbon catalyst suggesting that a zeolitic support is not necessary for good performance. In fact, similar reactivity is obtained from microporous (Pt/SSZ-24) and nonmicroporous (Pt/silica) silica supported platinum catalysts with similar H/Pt values. A clear trend of increasing benzene selectivity with decreasing Pt cluster size is found. These observations suggest that the exceptional reactivity of Pt/KL for the aromatization of n-hexane results from the lack of any acidity in the support and the ability of zeolite L to stabilize the formation of extremely small Pt clusters.

• OSTI ID: 7169205
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 134:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ACTIVATED CARBON
ADSORBENTS
ALKANES
AMMONIA
AROMATICS
AROMATIZATION
BENZENE
CARBON
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL PREPARATION
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CONTROL
CRYSTAL STRUCTURE
DEHYDROGENATION
DESORPTION
ELEMENTS
FAUJASITE
HEXANE
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
METALS
MICROSTRUCTURE
MINERALS
MOLECULAR SIEVES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
PERFORMANCE TESTING
PH VALUE
PLATINUM
PLATINUM METALS
SILICATE MINERALS
SILICON COMPOUNDS
SILICON OXIDES
SIZE
SOLID CLUSTERS
SORPTION
SYNTHESIS
TEMPERATURE CONTROL
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TESTING
TRANSITION ELEMENTS
YIELDS
ZEOLITES