Pt/BEA–Al2O3 catalysts for the isomerization of benzene/heptane mixtures. I: Optimizing the support’s composition

Resumo

Pt/BEA–Al₂O₃ catalysts for the hydroisomerization of benzene-containing gasoline fractions are studied using a model feedstock (20% benzene and 80% n-heptane). The catalysts are prepared by varying the zeolite content from 5 to 70 wt % at a constant Pt loading of 0.3 wt % in all samples, with an aqueous H₂PtCl₆ solution being used as the Pt precursor. The acid properties of the samples are studied by means of temperature-programmed desorption (TPD). The effect of the support’s zeolite/binder ratio on the activity of the catalysts is determined: an increase in the zeolite content raises the system’s acidity and shifts the range of the reaction toward lower temperatures. The optimum zeolite/binder ratio is found to be 30% BEA/70% Al₂O₃. Changing the SiO₂/Al₂O₃ ratio of the zeolite from 25 to 40 is shown to have no noticeable effect on catalyst activity. The use of the catalysts supported on 30% BEA/70% Al₂O₃ in the hydroisomerization of benzenecontaining gasoline fractions can be recommended for improving environmental performance.