Patent ID: 7169732
Filing Date: 2007-01-30
Classification: B01J,C07C

Abstract:
1. A process for preparing a vanadium, phosphorus, and oxygen catalyst precursor for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a hydrocarbon having at least four carbon atoms, which comprises (a) reacting vanadium pentoxide with from 102 to 110% strength phosphoric acid in the presence of a primary or secondary, noncyclic or cyclic, unbranched or branched, saturated alcohol having from 3 to 6 carbon atoms in a temperature range from 80 to 160° C.; (b) isolating the precipitate formed; (c) setting an organic carbon content of ≦1.1% by weight in the isolated precipitate by heat treatment in a temperature range from 250 to 350°, the heat-treated product, following the addition of 3.0% by weight of graphite as internal standard and using CuKα radiation (λ=1.54·10 (d) shaping the heat-treated product obtained from step (c) into particles having an averaged diameter of at least 2 mm.