Preparation method and application of nitrogen-doped magnetic manganese ferrite catalyst

The invention discloses a preparation method and application of a nitrogen-doped magnetic manganese ferrite catalyst, and the preparation method comprises the following steps: adding Mn (NO3) 2 and Fe (NO3) 3 into distilled water, stirring until Mn (NO3) 2 and Fe (NO3) 3 are completely dissolved into a red solution, adding a polyacid gelatinizing agent containing secondary hydroxyl, and continuously stirring to form dark red to black sol; heating the sol to 60-80 DEG C under stirring, adding an ammonia coagulant, continuously stirring until the sol is coagulated into orange or dark red gel, drying to obtain dry gel, heating to 425-475 DEG C in a heating furnace, calcining to obtain dark red powder, mixing and grinding the dark red powder with a nitrogen source until the dark red powder and the nitrogen source are completely and uniformly mixed, putting the mixture into a reaction furnace, heating to 425-475 DEG C in a nitrogen atmosphere, continuously calcining for 3-6 hours, and cooling to room temperature t