a catalyst for use in the manufacture of pyromellithsaeure and / or pyromellithsaeureanhydrid.

摘要

A supported catalyst on an inert carrier suitable for the preparation of pyromellitic acid or its anhydride by catalytic vapor phase oxidation of a tetra- C1 -C4 alkylbenzene, said catalyst comprising catalytically active material composed of 1 to 20 parts by weight of V2O5, 99 to 80 parts of weight of TiO2 and/or SnO2 and/or ZrO2, and per one hundred parts by weight of V2O5, TiO2 and/or SnO2 and/or ZrO2, 0.02 to 10 parts by weight, calculated as P2O5, of a phosphorus compound, 0.01 to 5 parts by weight, calculated as Nb2O5, of a niobium compound, 0 to 1.2 parts by weight, calculated as oxide, of at least one metal selected from the group consisting of potassium, cesium, rubidium and thallium, and 0 to 10 parts by weight, calculated as Sb2O3, of an antimony compound, and an inert carrier supporting said catalytically active material thereon.