Five catalysts, contg. one or more phases of vanadium(IV) [(VO)2P2O7.2H2O, B-phase] and/or phases of vanadium(V) (α-VOPO4, β-VOPO4), were prepd. in the V-P range of 1.0-1.15. These catalyst were tested in 1-butene oxidn. to maleic anhydride (I) following the structural modification during the reaction. (VO)2P2O7.2H2O (α-phase) is active only in butadiene formation, but does not possess centers able to form I. At ∼400°, this phase can be transformed, in flow of reacting mixt., to B-phase and in air to α-VOPO4 (for a P-V ratio 1.02) or to a mixt. of B-phase and α-VOPO4 (for a P-V ratio (1.13). The catalysts with B-phase or the mixt. of B-phase and α-VOPO4 are both selective in I formation, but the former in a wider range of temps. α-VOPO4 is also selective in I formation but at lower temps. and with lower yields than in the case of B-phase. At the temp. at which the B-phase is active the α-VOPO4 is no more selective; at this temp., it is partially reduced to B-phase during reaction. β-VOPO4 is not selective in I formation, but only in Me vinyl ketone formation. This phase is less reducible to B-phase than α-VOPO4; one of the causes of the deactivation of P-V catalysts can be attributed to the formation of β-VOPO4 by transformation of α-VOPO4. [on SciFinder(R)]
The chemistry of catalysts based on vanadium-phosphorus oxides. Part III. Catalytic behavior of different phases in 1-butene oxidation to maleic anhydride
CENTI, Gabriele;
1984-01-01
Abstract
Five catalysts, contg. one or more phases of vanadium(IV) [(VO)2P2O7.2H2O, B-phase] and/or phases of vanadium(V) (α-VOPO4, β-VOPO4), were prepd. in the V-P range of 1.0-1.15. These catalyst were tested in 1-butene oxidn. to maleic anhydride (I) following the structural modification during the reaction. (VO)2P2O7.2H2O (α-phase) is active only in butadiene formation, but does not possess centers able to form I. At ∼400°, this phase can be transformed, in flow of reacting mixt., to B-phase and in air to α-VOPO4 (for a P-V ratio 1.02) or to a mixt. of B-phase and α-VOPO4 (for a P-V ratio (1.13). The catalysts with B-phase or the mixt. of B-phase and α-VOPO4 are both selective in I formation, but the former in a wider range of temps. α-VOPO4 is also selective in I formation but at lower temps. and with lower yields than in the case of B-phase. At the temp. at which the B-phase is active the α-VOPO4 is no more selective; at this temp., it is partially reduced to B-phase during reaction. β-VOPO4 is not selective in I formation, but only in Me vinyl ketone formation. This phase is less reducible to B-phase than α-VOPO4; one of the causes of the deactivation of P-V catalysts can be attributed to the formation of β-VOPO4 by transformation of α-VOPO4. [on SciFinder(R)]Pubblicazioni consigliate
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