Comparison between β and L zeolites supported platinum for n-hexane aromatization Original Research Article

The performance of zeolite Kβ supported platinum as a bifunctional catalyst for the reforming of n-hexane has been examined using pulse and continuous flow microreaction methods. A comparison under the same conditions with zeolite KL supported platinum was carried out. It is found that due to the stronger acidity of zeolite β, PtKβ exhibits more skeletal isomerization and cracking than does PtKL zeolite, while the latter shows superior aromatization activity. Ion exchange of β zeolite with alkali cations as Cs+ can reduce the acidity and increase benzene selectivity. Ba2+ exchange also can lead to better dispersion of platinum and so can improve the aromatization activity. In contrast to the high sensitivity to sulphur poisoning of PtKL, PtKβ is relatively stable to sulphur poisoning and regains to some extent its initial activity. All these observations are explained in terms of support acidity, the electron state and the dispersion of platinum.