ABSTRACT

Ever since its discovery by Bernard1 in the early 1980s, Pt/KL has been used as a monofunctional aromatization catalyst with high activity and selectivity. The microporous channels of the zeolite are proposed to improve activity, benzene selectivity, and stability by decreasing coking as compared to nonmicroporous supports (e.g., Al2O3).2 The current isotopic tracer study for a Pt/KL catalyst agrees with the results of Azzam et al.,3 confirming that at atmospheric pressure, little H/D exchange occurs in the alkane and there is virtually no kinetic isotope effect (KIE) effect displayed for the conversion of hexane in the competitive reaction between H-hexane and D-hexane for aromatization. The narrow windows of the zeolite channels inhibit bimolecular pathways by providing single-file access of hexane to Pt clusters situated in the wider lobes of the channels. At atmospheric pressure,

19.1 Introduction ..................................................................................................344 19.2 Experimental ................................................................................................346