One-Pot Synthesis\nof Mixed-Phase MoVTeNbO<sub><i>x</i></sub> Catalysts for\nSelective Oxidation of Propane to\nAcrylic Acid

One-pot hydrothermal synthesis assisted by sodium citrate\nand citric\nacid is developed to fabricate mixed-phased MoVTeNbO<sub><i>x</i></sub> catalysts with different phase compositions for selective\noxidation of propane to acrylic acid. Structures of various catalysts\nare comprehensively characterized. Interfacial interactions occur\namong the M1 and M2 phases of mixed-phase MoVTeNbO<sub><i>x</i></sub> catalysts to exert synergistic effects on the selective production\nof acrylic acid. Various mixed-phase MoVTeNbO<sub><i>x</i></sub> catalysts exhibit the same type of active site on the M1-phase\ncomponent, with a significantly enhanced ability to adsorb and activate\npropane. The propane conversion increases linearly with the density\nof surface site for propane adsorption, while the propene selectivity\nincreases linearly with the density of surface site for propene adsorption.\nAmong the synthesized catalysts, a MoVTeNbO<sub><i>x</i></sub> catalyst composed of 35.3 wt % M1 phase, 19.2 wt % M2 phase,\nand 45.7 wt % amorphous phase exhibits the largest density of active\nsite and consequently the best catalytic performance with 38.9% propane\nconversion and 71.2% acrylic acid selectivity at 380 °C.