| 摘要 |
<p>Isomerisation of alkylaromatic hydrocarbons is carried out by contacting the feed with H2 and a catalyst in several successive stages, using a different catalyst in each stage. At least one stage is carried out using a catalyst as claimed in the Parent Patent, i.e. comprising an acidic support, 0.02-2 (pref. 0.10-0.70) wt.% of >=1 Pt-group metal and 0.02-2 (pref. 0.05-0.60)wt.% of >=1 metal selected fr-Sn, Pb and Ge. The process is esp. useful for producing p-xylene from C8 feeds contg. ethylbenzene. Improved results can be obtained by using the catalyst of the Parent Patent in only one stage of a multi- stage process. The process is pref. effected in 2 stages, the 1st using a Pt/Al2O3 Pt/Si/Al2O3, Pt/Sn/Zr/Al2O3 or Pt/Sn/Zr/Si/Al2O3 catalyst and the 2nd using a Pt/Sn/Al2O3 or Pt/Sn/Si/Al2O3 catalyst. The Si-contg. catalyst pref. contain 0.-1.2 wt.% Si. In another embodiment, the 1st stage catalyst pref. contains 0.05-0.50% more halogen (based on catalyst wt.) than the 2nd - stage catalyst.</p> |
