Characterization and evaluation of MoVTeNb mixed metal oxide catalysts fabricated via hydrothermal process with ultrasonic pretreatment for propane partial oxidation

Mo1.00VxTe0.20Nb0.16On (x=0.35–0.50x=0.35–0.50) mixed-metal oxide catalysts were synthesized through ultrasonic and hydrothermal treatments. Both TeO2 and H6TeO6 were used as tellurium sources. The enhanced dispersion of TeO2 by ultrasonic treatment is crucial for obtaining an active and selective MoVTeNbO catalyst for acrylic acid (AA) formation from propane oxidation. The TeO2-derived Mo1.00VxTe0.20Nb0.16On (x=0.35–0.41x=0.35–0.41) are superior to their H6TeO6-derived counterparts; propane conversion and AA selectivity over the Mo1.00V0.41Te0.20Nb0.16On is 55% and 60 mol% at 380 °C, respectively, giving an AA formation rate of 22.3 μmol g−1 min−1. Based on the physicochemical properties of the catalysts, we propose that the ultrasonic treatment can give rise to (i) enhanced presence of the orthorhombic Te2M20M20O57 (M=MoM=Mo, V, Nb) and hexagonal Te0.33MO3.33 (M=MoM=Mo, V, Nb) phases, (ii) surface enrichment of Te, (iii) enhanced reactivity of lattice oxygen, (iv) an increase in MoOTe and VOTe entities, and (v) better isolation of active sites.