J. Zheng et al., COMPARISON BETWEEN BETA-ZEOLITES AND L-ZEOLITES SUPPORTED PLATINUM FOR N-HEXANE AROMATIZATION, Applied catalysis. A, General, 126(1), 1995, pp. 141-152
The performance of zeolite KP supported platinum as a bifunctional cat
alyst for the reforming of n-hexane has been examined using pulse and
continuous flow microreaction methods. A comparison under the same con
ditions with zeolite KL supported platinum was carried out. It is foun
d that due to the stronger acidity of zeolite beta, Pt/K beta exhibits
more skeletal isomerization and cracking than does Pt/KL zeolite, whi
le the latter shows superior aromatization activity. Ion exchange of b
eta zeolite with alkali cations as Cs+ can reduce the acidity and incr
ease benzene selectivity. Ba2+ exchange also can lead to better disper
sion of platinum and so can improve the aromatization activity. In con
trast to the high sensitivity to sulphur poisoning of Pt/KL, Pt/K beta
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.