VIIIVIV3O3(PO4)3:  A Novel Vanadium Phosphate for Selective Oxidation of Light Hydrocarbons

A novel vanadium(IV) phosphate VIIIVIV3O3(PO4)3 has been synthesized and crystallized (1073 K, sealed silica tube, a few milligrams of PtCl2 as mineralizer). According to the single-crystal structure analysis [orthorhombic, F2dd (No. 63), Z = 24, a = 7.2596(8) Å, b = 21.786(2) Å, c = 38.904(4) Å (lattice parameters from Guinier photographs), R1 = 0.032, wR2 = 0.067, κ-CCD diffractometer, 83 949 reflections measured, 6836 independent, 5986 with I > 2σ(I), 299 variables], VIIIVIV3O3(PO4)3 belongs to the Lipscombite/Lazulite structure family. At 1073 K VIIIVIV3O3(PO4)3 is in thermodynamic equilibrium with (VO)2P2O7, VO2, and VPO4. Substitution of V3+ in VIIIVIV3O3(PO4)3 by Cr3+ and Fe3+ is possible. Like vanadylpyrophosphate the oxide phosphates MIIIVIV3O3(PO4)3 (MIII:  V, Cr, Fe) show significant catalytic activity in selective oxidation of n-butane and 1-butene to maleic acid anhydride.