| 摘要 |
Aromatic carboxylic acid anhydrides are prepared by reacting o-xylene or durene with mol. O2 in vapour phase in presence of an oxidation catalyst formed by calcination, at temp. not below 560 degrees C of a mixture of (a) vanadium dioxide or a V-compd. which is convertible to VO2 at calcination temp. (b) a Cr-oxide or Cr-compd. convertible to Cr-oxide at calcination temp. and (c) at least one oxide of one of the promoter constituents Sn + Sb, Ge, Sn + In, Ni.Ta, Ga, or Zr, or at least one compd. of such a promoter constituents which is convertible to the corresponding oxide at the calcination temp.
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