Pt-KL zeolite catalysts of different preparation. Part II. Catalytic properties in n-hexane transformations

I. Manninger, Z. Zhan, X. L. Xu, Z. Paál

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Abstract

Pt-KL zeolite samples reduced by H2 and by NaBH4, respectively, and characterized by EM, XRD, H2 titration and IR acidity measurements (cf. Part I [9]) were tested in the catalytic reactions of n-hexane at 603 K and 693 K. Rates per mass unit and turnover numbers as well as selectivities for fragmentation, isomerization, C5-cyclization and aromatization are given. NaBH4 reduction results in a less stable catalyst than H2 reduction, but the former could be stabilized by heating in hydrogen. This treatment gives the highest aromatization-to-hydrogenolysis ratio. Reduction by hydrogen creates additional acidic centres; these can be eliminated by after-treatment with KNO3. These basic catalysts gave the highest aromatization selectivity, whereas acidity increased isomerization without being able to catalyze bifunctional aromatization. Hexenes were almost exclusive primary products; the low amount of cis-2-hexene may indicate its enhanced reactivity in aromatization. Pt particles within the framework are considered as the main but not exclusive carriers of the metallic activity. Both the zeolitic structure and the cooperation of metallic and acidic functions are important in determining the catalytic properties.

Original languageEnglish
Pages (from-to)223-237
Number of pages15
JournalJournal of molecular catalysis
Volume66
Issue number2
DOIs
Publication statusPublished - Jun 1991

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ASJC Scopus subject areas

  • Engineering(all)

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