TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The layered compound is montmorillonite, kaolin, water stone or brucite; the oxidizing agent is ammonium persulfate, hydrogen peroxide, potassium hypermanganate and ferric chloride; and the inert gas is nitrogen or argon. Preferred Process: The preparation comprises weighing montmorillonite and phenylamine at mass ratio 1:1, dispersing montmorillonite in deionized water, stirring for 5 hours with ultrasound, forming montmorillonite suspension with 0.05 g/ml mass concentration, controlling volume of ethanol to volume ratio of montmorillonite and ethanol at 1:0.5-1, dissolving phenylamine in ethanol, adding montmorillonite suspension, stirring at 20 degrees C for 30 hours, and forming phenylamine intercalation montmorillonite suspension; controlling volume of sulfuric acid or hydrochloric acid at volume ratio of phenylamine intercalation montmorillonite suspension and sulfuric acid at 1:0.3, weighing oxidizing agent to mass ratio of phenylamine and ammonium persulfate at 1:1, dissolving in deionized water to form ammonium persulfate solution with 0.5 g/ml mass concentration, adding sulfuric acid in phenylamine intercalation layered suspension, stirring for 2 hours, adding ammonium persulfate solution in suspension with 0.5 ml/minute, stirring at 5 degrees C for 20 hours, filtering by vacuum, washing with deionized water for three times and washing with absolute ethyl alcohol for three times, drying at 60 degrees C for 24 hours, grinding and obtaining montmorillonite interlayer polyaniline; putting montmorillonite inter-layer polyaniline in tube furnace, feeding nitrogen with 100 ml/minute of flowing speed for 0.8 hour, maintaining flowing speed of nitrogen, heating with 10 degrees C/minute, heating tube furnace at 150 degrees C for 3 hours, heating at 900 degrees C for 3 hours, cooling to room temperature, grinding, and obtaining layered compound inter-layer nitrogen mixed graphene; and weighing hydrofluoric acid to 1:2 of the mass ratio of montmorillonite and hydrofluoric acid, dispersing montmorillonite inter-layer nitrogen mixed graphene in ethanol, stirring for 5 hours with ultrasound, forming montmorillonite inter-layer nitrogen mixed graphene suspension with 0.5 g/ml concentration, adding hydrofluoric acid in montmorillonite inter-layer nitrogen mixed graphene suspension slowly, stirring for 15 hours with ultrasound, filtering, washing with deionized water for three times and washing with absolute ethyl alcohol for three times, drying at 60 degrees C for 24 hours, grinding and obtaining nitrogen mixed graphene catalyst.