Study of molybdenyl, vanadyl and mixed ammonium vanadyl salts of [PMo12O40]3− as oxidation catalysts

Catalytic selective oxidation of isobutane over Csx(NH4)3−xHPMo11VO40mixed salts

“…It was explained by the fact that the MoO 3 species issued from the partial decomposition of Keggin anions (band at 595 cm −1 ) were partially reduced to MoO 2 by isobutane under reaction conditions. 7,21 Since the intensity of the 629 cm −1 band increased with the decrease in the Cs loading, this supports the hypothesis that the introduction of Cs stabilizes the Keggin structure under the reaction conditions.…”

Effect of vanadyl species in Keggin-type heteropoly catalysts in selective oxidation of methacrolein to methacrylic acid

“…This finding suggests that HPA was partially decomposed during reaction with VO(C 2 O 4 ). After calcination at 350°C for 12 h, HPA was partially decomposed to Keggin structure fragments [16]. HPAV, VHPA, and HVOPA were also partially decomposed during calcination, which cause the decrease of some split peaks [ …”

“…Marchal-Roch et al synthesized H 3Àx (VO) x PMo 12 O 40 and (NH 4 ) 3À2x (VO) x PMo 12 O 40 as catalysts for oxidation dehydrogenation of isobutyric acid to MAA. Vanadyl species act as counterions and can improve isobutyric acid conversion and MAA selectivity [16]. In the work of Bayer et al, vanadyl salts of H 3 PMo 12 O 40 and H 4 PMo 11 VO 40 were prepared for oxidation of isobutyric acid.…”

Methacrylic Acid: Not a Mere Product But Activator in the Catalytic Oxidation of Methacrolein?

“…We sometimes observed formation of XRD pattern that may be attributed to Fm " 3m symmetry after impregnation of Cs 2 H 2 PVMo 11 O 40 in MAA at ambient conditions. This symmetry is typical e.g., to H 3-2x [VO] x PMo 12 O 40 [12], suggesting that MAA pretreatment can lead to the removal of vanadyl ions to the secondary structure. Unfortunately, appearance of Fm " 3m patterns was not well reproducible upon MAA treatment of different Cs 2 H 2 PVMo 11 O 40 samples.…”