Study of the mobility of lattice oxygen in complex oxide catalysts for partial oxidation of propylene to acrolein

Architecture of industrial Bi-Mo-Co-Fe-K-O propene oxidation catalysts

“…The substantial reduction of Fe 3+ to Fe 2+ , which also agrees with early studies ( 26 , 27 ), together with the unreduced Mo 6+ centers (fig. S6) indicates that the electrons obtained at BiMoO sites move through the bulk to accumulate at Fe 2+ centers in the Fe 2 Mo 3 O 12 /β-FeMoO 4 domains.…”

“…1D ) ( 25 ). The formation of Fe 2+ with a larger ionic radius of 78 pm (versus 65 pm for Fe 3+ ) induced transformation of Fe 2 Mo 3 O 12 to β-FeMoO 4 ( 26 ) that was indicated by XRD analysis (table S6) showing a large decrease of Fe 2 Mo 3 O 12 from 29 to 7% accompanied by an increase of β-Co 0.7 Fe 0.3 MoO 4 component from 53 to 71%. We note that β-FeMoO 4 is formally assigned to β-Co 0.7 Fe 0.3 MoO 4 in the XRD analysis because the two phases are isostructural with similar cationic radii (Fe 2+ , 78 pm and Co 2+ , 75 pm; both octahedral).…”

Study of the local structure and oxidation state of iron in complex oxide catalysts for propylene ammoxidation

“…To achieve high performance on the Fe-Mo-Bi catalyst, the balance between Fe 3+ and Fe 2+ should be kept close to that in the initial state, which is known to have the highest catalytic activity and selectivity. 47 Our experiment demonstrated (Fig. 1) that the initial state of iron molybdate, Fe 2 (MoO 4 ) 3 , has decomposed significantly for all catalyst samples from S5 through S48.…”