Aromatization of n-hexane over Pt clusters

Effect of Catalyst Preparation on the Aromatization of n-Hexane over Pt Clusters Supported on Hydrotalcite... 

Recently, Pt clusters supported on hydrotaleite-derived magnesia, Mg(Al)0, were shown to catalyze the aromatization of n-hexane as effectively as a Pt/KL catalyst (8). A high surface area basic oxide was chosen to support the metal clusters in order to investigate the influence of carrier structure on aromatization. In that study, significant quantities of cracked products were produced by both the zeolite and non-zeolite catalysts. Since the zeolite catalyst was prepared in a fashion that resulted in residual acidity being present, observation of cracked products is not surprising. However, cracking reactions over Pt/Mg(Al)0 are not as easily explained. 

Dehydrocyclization of n-hexane to form benzene has been a subject of considerable academic and industrial interest since Bernard first reported that platinum clusters supported inside the channels of zeolite L catalyze the reaction with exceptional activity and selectivity (7). The nonacidic nature of the Pt-zeolite L catalyst and correlation of reaction rate with Pt content are consistent with the accepted view that the catalyst is monofunctional, depending solely on Pt metal for catalytic activity (7). However, comparison of aromatization reactivity over nonacidic Pt-zeolites to conventional non-zeolitic catalysts revealed that additional factors contribute to the unusual performance of Pt-zeolites (2). 

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