THERMAL, STRUCTURAL AND ACIDIC CHARACTERIZATION OF SOME VANADYL PHOSPHATE MATERIALS MODIFIED WITH TRIVALENT METAL-CATIONS

A set of new materials with general formula [M(H2O)](x)(VO)(1-x)PO4 . 2H(2)O (M3+ = Al, Cr, Ga, Mn), isomorphous with layered tetragonal VOP O4 . 2H(2)O and having potential catalytic properties, have been chara cterized by TG and DTA, X-ray diffraction and surface acid strength. D uring heating the compounds transform in the monohydrated and anhydrou s phases, all maintaining a layered structure, with a proper interlaye r spacing. Catalytic tests performed with 1-butene show that the M3+-v anadyl phosphates greatly improve the conversion of the olefine with r espect to pure vanadyl phosphate.