Simultaneous Hydroconversion of n-Hexane and Benzene over Pt/WO3-ZrO2 in the Presence of Sulfur Impurities

The properties of a commercial Pt/WO3-ZrO2 for the simultaneous hydro-isomerization of n-hexane and benzene have been assessed at varying values of total system pressure, fixed reaction temperature (300 degrees C), and molar ratio H-2/HC = 6. A total pressure of 20 atm was satisfactory for performing both the hydrogenation of benzene and the isomerization of C-6 at convenient reaction rates. Greater pressures increased the cracking and formation of light gases. Also, the total conversion was decreased at higher pressures. Benzene conversion proceeded by metal-catalyzed hydrogenation and subsequent acid-catalyzed ring contraction with no occurrence of ring opening. The results show that the presence of a small amount of benzene (3%, vol/vol) is beneficial for the hydro-isomerization of n-hexane over Pt/WO3-ZrO2. Hydrocracking is largely suppressed, and both the liquid C5+ yield and the selectivity to branched isoparaffins are enhanced. Sulfur impurities in the feed decrease the n-hexane and benzene conversion by poisoning the metallic function, and their concentration should be lowered to less than 10 ppm to avoid producing an important inhibiting effect.