The effect of adamantane addition on the conversion of n-heptane over H- and Pt/H-zeolites

• Published in: Applied catalysis. A, General General, 2002-04, Vol.229 (1), p.135-146
• Main Authors: Valyon, J., Engelhardt, J., Lónyi, F., Kalló, D., Gömöry, Á.
• Format: Article
• Language: English
• Subjects: Adamantane co-catalyst; Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; H-mordenite; H-Y; n-Heptane isomerization; Pt/H-mordenite; Pt/H-Y; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/S0926-860X(02)00022-4

H- and Pt/H-forms of zeolites Y and mordenite were studied in atmospheric n-heptane ( n-C 7) hydroconversion at 423–443 K. Adamantane (Ad) additive was found to increase the isomerization and suppress the cracking activity of the H-zeolites. It had minor or no influence on the hydroconversion activity of the Pt/H-forms. Species obtained from Ad adsorbed on zeolites were examined by IR spectroscopy. The Ad-saturated samples (Ad/H-zeolites) were boiled with n-C 7 and the liquid phase was analyzed by GC–MS. Results suggested that Ad was activated over the H-zeolites for further reactions via protolysis of its CH bonds. The Ad and the formed adamantyl carbenium ions (Ad +) participated in hydride transfer processes. In these processes, the Ad remained unconverted and acted as co-catalyst increasing n-C 7 isomerization selectivity. Results suggested that under conditions of n-C 7 hydroconversion no or minor amount of Ad + was generated on the Pt/H-zeolite catalysts. Over strong acid mordenite bulky carbocations and Ad compounds were rapidly formed contributing to the decay of the activity in n-C 7 conversion.