| Abstract |
Various Pt/NaCs beta catalysts with decreasing Na/Cs ratios and a Pt/KL sample taken as a reference catalyst for aromatization of n-hexane, have been prepared by exchange of NaCs beta and KL zeolites in a Pt tetraammine solution then calcination and reduction. The increase of the Cs content in the NaCs beta zeolitic support results in a decrease of the cyclohexane adsorption and Pt exchange capacities. The Pt/Cs beta and Pt/KL samples show similar behaviors which strongly differ from those of the Na-containing Pt/NaCs beta samples in terms of(i) reducibility of the Pt ions after calcination, (ii) shape of the FTIR spectra of CO adsorbed on the Pt clusters after reduction, and (iii) catalytic activity of these clusters in the conversion of n-hexane. In particular, the selectivity to aromatization is much higher on the Pt/Cs beta and Pt/KL catalysts than on the Na-containing Pt/NaCs beta ones. The reasons for the specific behaviors of the Pt/Cs beta and Pt/KL samples are discussed. (C) 1999 Academic Press. |
