Patricio Ruiz

Oxidation of n-pentane to phthalic or maleic anhydride: The role of the VPO catalyst structural disorder

Vanadium phosphate catalysts are obtained from precursors prepared by a two-step synthesis. In the first step, a VOPO4-mixed isobutanol-water intercalate was obtained by precipitation from a solution containing vanadyl isobutoxide, K3PO4 and carefully adjusted water content (precursor A). In the second step, precursor B was formed by reflux of precursor A in (i) an inert (n-octane) or (ii) reductive (isobutanol) medium. By such a procedure, precursors and catalysts (with P/V atomic ratio equal to 1.05) displaying widely different structural defects (XRD, IR) were prepared. Catalysts were tested in the oxidation of n-pentane into maleic (AM) and phthalic (PA) anhydrides. Formation of PA demands a highly ordered structure, while AM could be formed on a highly defective VPO catalyst.