| 摘要 |
8C Aromatic fractions, esp. those low in p- and/or o-xylene and rich in m-xylene and/or ethyl benzene, are isomerised in presence of hydrogen at 350-500 degrees C under 10-40 atmos. with hydrogen/hydrocarbon molar ratio of 5 : 1 to 15 : 1. The catalyst consists of a mixt. of alumina, pref. eta-alumina with surface area of 250-400 m2/g, and mordenite, contg. elements of Groups IV (inc. rare earths), VII and/or VIII, or their cpds., inc. at least one noble metal, pref. Pt. By varying the mordenite content from 5-50 wt.%, the feed rate can be varied over the range 0.5-5 v/v/h. The mordenite is pref. de-aluminised by treatment with mineral acids to a SiO2/Al2O3 ratio of 12-60 pref. 18-30. In addition to achieving the thermodynamic equilibrium conc. for p-xylene and approx. that for o-xylene, pure ethyl benzene can be selectively isomerised to xylenes. |
