This invention provides a method for preparing the selective oxidation catalyst FeMo@ZSM-22. The method includes: preparing a
mixed metal salt solution by dissolving soluble
molybdate and
soluble iron salt; ultrasonically dispersing ZSM-22
molecular sieve powder in deionized water to obtain a
molecular sieve suspension; slowly adding the
mixed metal salt solution dropwise to the
molecular sieve suspension under rapid stirring, and adding a precipitant to adjust the pH to 2.0-5.0; and obtaining the FeMo@ZSM-22 catalyst after
microwave aging, washing,
drying, and
calcination. This invention incorporates ZSM-22 molecular
sieve in situ during the co-
precipitation synthesis of the FeMo catalyst, achieving a high degree of
synergy between the
redox sites (FeMo) and the weakly acidic sites (ZSM-22) at the nanoscale. The resulting catalyst is used for the direct selective oxidation of
dimethyl ether to
formaldehyde, not only overcoming the seesaw effect between activity and selectivity in traditional pure
metal oxide catalysts, but also exhibiting extremely low preparation cost, good long-term anti-coking stability, and promising prospects for large-scale industrial production.