The chemistry of catalysts based on vanadium-phosphorus oxides. Part IV. Catalytic behavior of catalysts prepared in organic medium in oxidation of C4 fraction

V-P mixed oxides, catalysts for C4 oxidn. to maleic anhydride, were prepd. in an org. medium and tested in butane and butene selective oxidns. These catalysts were compared with those prepd. in aq. medium. Before calcination, the 2 methods of prepn. gave rise to the same phase, but the catalysts prepd. in org. medium were characterized by higher surface area and lower oxidizability in air. The latter characteristic makes it possible to obtain the selective compd. of V(IV) B-phase, (after calcination in air), in the full 0.95-1.15 P-V ratio range without the phases of V(V) obtained in the case of catalysts prepd. in aq. medium. Unlike catalysts prepd. in aq. medium, an excess of P with respect to the ratio 1.0 led to a decrease both in activity and selectivity to maleic anhydride. The higher surface area of catalysts prepd. in org. medium makes it possible to oxidize butane at lower temps. than with catalysts prepd. in aq. medium. [on SciFinder(R)]