Molybdenum-doped V-P-O system. I. Preparation and characterization

Attempts to prepare and to characterize new catalysts belonging to the (V-P-Mo-O) system selective in the mild oxidation of butane or butene to maleic anhydride lead to the conclusion that molybdenum can be substituted up to 7% in VOPO4 phases. Thermal analysis of the hydrated precursor, XRD, ESR spectroscopies, UV-visible and IR spectroscopies of both hydrated and anhydrous solid phases obtained show that the solid solutions isostructural with VOPO4 2H2O and α1-VOPO4, respectively, can be formulated: [(VO)/sub 0.07/2+(VO)/sub 0.93/3-(MoO4)/sub 0.07/2- nH2O] (n = 1 to 2) and [(VO)/sub 0.93/3+(VO/sub 0.07/3-(MoO4)/sub 0.07/2-]