▎ 摘　　要

NOVELTY - The method involves mixing graphene oxide dispersion with aqueous ammonia and hydrothermally obtaining three-dimensional nitrogen-doped graphene, immersing 3DNG in Co salt solution, freeze-drying and pyrolyzing the impregnated product to prepare Co/3DNG. The cobalt salt is cobalt acetate tetrahydrate, cobalt(II) nitrate hexahydrate, cobalt chloride hexahydrate or cobalt sulfate heptahydrate. The impregnation refers to adding deionized water and absolute ethanol to the cobalt salt in sequence and stirring thoroughly, and immersing the 3DNG in the solution and leaving the solution to stand still. The freeze-drying refers to freezing the impregnated product to -25 degrees C, and cooling down to -80 degrees . The high temperature cracking refers to heating and keeping the freeze-dried product in a nitrogen (N2) atmosphere. USE - Preparation method of three-dimensional nitrogen-doped graphene-supported cobalt nanoparticle (Co/3DNG) catalyst used to catalyze the oxidation of lignin and model compounds (all claimed) in field of catalyst preparation and biomass conversion. ADVANTAGE - The method is used to catalyze the oxidation and depolymerization of lignin and the beta O4 model compound, and the catalyst exhibits excellent catalytic activity and selectivity without adding any inorganic base. The method adopts the hydrothermal-impregnation-cracking method, and the Co/3DNG catalyst can be prepared simply and quickly. The conversion rate of the lignin beta -O-4 model compound 2-phenoxy-1-phenylethanol is as high as 97% without the addition of any alkali. The yield of the main product phenol is 97%, and the selectivity is 100%. The Co/3DNG catalyst has good magnetic properties, and can be directly recycled and reused by using magnets. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a Co-3DNG catalyst; and (2) an application of Co-3DNG catalyst used to catalyze the oxidation of lignin and model compounds, which involves heating Co-3DNG catalyst, lignin or lignin model compound and methanol under high pressure in an oxygen environment to achieve catalytic oxidation. DESCRIPTION OF DRAWING(S) - The drawing shows a X-ray diffraction pattern of Co-3DNG. (Drawing includes non-English language text)