Study On N-hexane Isomerization Over Pt-SO₄^2-/ZrO₂ Solid Acid Catalyst

Sulfated zirconia possessed lots of advantages, such as super acid properties, high thermal stability and high catalytic activity at low reaction temperature. Therefore, SZ catalyst has been widely studied in hydroisomerization reaction of n-alkane. The object of the present work is to investigate the effect of calcination temperature of sulfated samples, the contents and the species of the sulfur, the adsorbed water on the isomerization performances of PSZ and midified PSZ catalysts.The suitable calcination temperature for PSZ is 650℃.however,for the modified PSZA and PSZAY, the suitable temperature ranges from 650℃～700℃. The reduction of PSZA prior to reaction could not influenced the isomerization activity, but shorterned the reaction induction period.Compared with the equivalent impregnation method, the traditional excessive H2SO4 impregnation-fiteration led to PSZ and PSZA catalysts with high isomerization activity. However, for PSZAY, the above two sulfated procedures did not cause the marked difference in the catalytic. The removal of partial sulfur species in different steps led to the catalysts with different isomerization activity. The sulfated procedure of the excessive H2SO4 impregnation-fiteration-water washing notebley reduced the catalytic activity. Likewise, the finished catalyst after water wahsing showed very low catalytic activity. In contrast, the washing with water for calcined sulfated could hardly change the activity. The correlation of sulfur content and the catalytic activity could be made.The quantity of the adsorbed water was one of the important factors to determing the catalytic activity. PSZ and PSZA with excessive hydration or dehydration almost lost their isomerization activity. The moderately hydrated two sample showed good catalytic performances. In contrast to the above two samples, PSZA showed high catalytic activity when it was excessively dehydrated or moderately hydrated.