Molybdenum–vanadium–antimony mixed oxide catalyst for isobutane partial oxidation synthesized using magneto hydrodynamic forces
•Weak permanent magnetic fields alter chemical activity of metal-oxide particles.•Magneto-hydrodynamic (MHD) treatment alters oxidation behavior of α-Sb2O3.•MHD Sb–V–Mo catalyst outperforms reference in isobutane partial oxidation.
A peculiar effect was observed that the oxidation behavior of antimony oxide prepared in presence of a weak permanent magnetic field is changed. Reactivity of α-Sb2O3 (senarmontite) toward oxidation is significantly enhanced after recirculating its suspension in a magneto hydrodynamic (MHD) system. This inspired the MHD synthesis of a molybdenum–vanadium–antimony mixed oxide with superior catalytic activity for selective partial oxidation of isobutane. Traditionally these mixed oxides are synthesized via sol–gel processes involving complexing agents and/or costly alkoxides. Here a new convenient way is presented to synthesize Mo–V–Sb mixed oxide catalysts departing from senarmontite (α-Sb2O3), ammonium heptamolybdate and ammonium vanadate. The MHD treated mixed oxide prepared from suspensions of Sb2O3 with Mo and V salts was evaluated in isobutane partial oxidation and compared with conventionally prepared catalysts. Improved performance was observed for MHD catalysts, with a peak methacrolein selectivity of 40% and decreased COx selectivity as compared to a reference ‘slurry-type’ catalyst. Although the MHD synthesis mechanism cannot yet be explained on a molecular level, it represents significant scientific and economical potential. This report is intended as an invitation to assist in formulating a molecular mechanism capable of explaining these observations.
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Journal: Applied Catalysis A: General - Volume 474, 22 March 2014, Pages 18–25