Sol–Gel Synthesis of Bismuth Molybdate Catalysts for the Selective Oxidation of Propylene to Acrolein: Influence of pH Value and Theoretical Molar Atomic Ratio

Different bismuth molybdate catalysts for the selective oxidation of propylene to acrolein were prepared by the sol–gel method, starting from bismuth nitrate, ammonium molybdate, and citric acid. The influence of pH value and theoretical molar Bi/Mo atomic ratio on the complexation and gelation is surveyed using IR spectroscopy, X-ray diffraction, and BET. Their catalytic activities for the conversion propylene to acrolein are examined.