Catalyst precursor for the production of maleic anhydride and process for its preparation

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, in which DOLLAR A (a) of vanadium pentoxide in the presence of a primary or secondary, noncyclic or cyclic, unbranched or branched, saturated alcohol having 3 to 6 carbon atoms, with 102 to 110% phosphoric acid in a temperature range of 80 to 160 DEG C is reacted; DOLLAR A (b) the precipitate formed is isolated; DOLLAR A (c) by heating in a temperature range of 250 to 350 DEG C sets an organic carbon content of 1.1 wt .-% in the isolated precipitate, wherein the heat-treated product after the addition of 3.0 wt .-% of graphite, a X-ray powder diffraction pattern obtained which has a peak height ratio of the peak of any pyrophosphate phase present at 28.5 ° to the peak originating from the graphite at 26.6 ° of 0.1 in 2-theta range; and DOLLAR A (d) shaping the obtained from step (c), heat-treated product to particles having an average diameter of at least 2 mm, DOLLAR A of this method, available catalyst precursor, methods for preparing a catalyst from the catalyst precursor, from this method available catalyst and a process for producing maleic anhydride on this catalyst.