Catalysts Pt/BEA–Al2O3 for Isomerization of the Benzene/Heptanes Mixture: I. Optimization of the Support Composition

Abstract

Catalysts Pt/BEA–Al₂O₃ for hydroisomerization of benzene-containing gasoline fractions were studied using model feedstock (20 % benzene and 80 % n-heptane). The catalysts were prepared by varying the content of zeolite from 5 to 70 wt.% at the constant Pt loading equal to 0,3 wt.% inall the samples; an aqueous solution of H₂PtCl₆ was used as the Pt precursor. Acid properties of the samples were studied by TPD. The influence of the zeolite/binder ratio in the support on the activity of the catalysts under study was demonstrated: an increase in the zeolite proportion resulted in an increase in the system acidity and in shifting of the reaction region towards lower temperature. The optimal zeolite/binder ratio was found to be 30 % BEA/70 % Al₂O₃. A change in the acid modulus SiO₂/Al₂O₃ of the zeolite from 25 to 40 was shown not to affect noticeable the catalyst activity. Catalysts supported on 30 % BEA/70 % Al₂O₃ used for hydroisomerization of benzene-containing gasoline fractions can be recommended for improvement of the environmental performance.