Influence of benzene on isomerization of n-hexane over Pt/Ga_2O_3/WO_3/ZrO_2 and Pd/Al_2O_3/WO_3/ZrO_2 catalysts

The effect of benzene on the isomerization of n-hexane over Pt/Ga2O3/WO3/ZrO2(PtGWZ) and Pd/Al2O3/ WO3/ZrO2(PdAWZ) catalysts were investigated comparatively.The results indicate that the activities of both PtGWZ and PdAWZ catalysts for n-hexane isomerization decrease with the increase of benzene amounts in the feed.Compared with PdAWZ catalyst,PtGWZ catalyst is less influenced by benzene.The inhibiting effect of benzene on the isomerization activities of PtGWZ is reversible and the activity for n-hexane isomerization can be fully recovered when benzene containing feed is replaced by pure n-hexane.However,the inhibiting effect of benzene on n-hexane isomerization activity of PdAWZ is irreversible.For the benzene containing feed,the deactivating effect can be observed on PdAWZ catalyst,but no deactivating effect on PtGWZ catalyst can be found.This deactivating effect is due to a rapid coke formation from cyclohaxane,which formed from benzene hydrogenation on the catalysts.The reasons for the different inhibiting effects of benzene on the isomerization activities of PtGWZ and PdAWZ catalysts are discussed.