Effect of Catalyst Preparation on Hydroisomerization of n-Heptane over Pt/Silicalite-1

The isomerization of n-heptane was comparatively investigated over Pt catalysts prepared by deposition (Pt/S-1-DP) and impregnation precipitation (Pt/S-1-IMP) method with a low loading, separately. It was found that Pt/S-1-DP catalyst produced a much higher catalytic conversion compared with the counterpart catalyst prepared by impregnation. Combined with various characterization techniques, the better performance over Pt/S-1-DP was attributed to not only the well improved dispersity and the smaller size of Pt particles but also the faster transfer of reactive species between Pt sites and acid sites. The activity could be improved by increasing the reduction temperature. Moreover, the (de)hydrogenation of Pt over Pt/S-1 catalyst was verified by in situ infrared spectroscopy through H/D isotope exchange experiment.