| 摘要 |
A p-xylene and o-xylene prepn. is claimed. A substantially 8C alkyl aromatic hydrocarbon mixture is ehated to 250-550deg.C in the presence of an improved catalyst. This comprises a high silica zeolite in acid form containing small amounts of Group VIII metals dispersed on a porous matrix. Xylene in the mixture is isomerised to an equilibrium mixture. Ethyl is dealkylated producing a lighter (top) product (benzene and toluene) and a heavier (bottoms) product rich in p- and o-xylene. The bottoms prod. is then sepd. into individual prods. Pref. the catalyst is a mixt. of amorphous silica and crystalline alumino-silicate on an alumina support, with an SiO2 : Al2O3 ratio of 90-200, and contg. Pt, or Pt combined with e.g. Ni or Pd. It may be in the form of an extrudate, an aq. slurry being extruded, dried then calcined at e.g. 500deg.C for 16 hrs. The catalytic isomerisation is effected in the presence of H2, with an H2 : hydrocarbon mole ratio of 0.5 : 10. The reaction temp. is 350-500deg.C. |
