Preparation method of size-controllable Au-C high-selectivity oxidation catalyst

The invention discloses a preparation method of a size-controllable Au-C high-selectivity oxidation catalyst. The preparation method comprises the following steps: preparing one or a mixture of more than one of tannic acid, polyvinylpyrrolidone, polyvinyl alcohol, hexadecyl trimethyl ammonium bromide and polyethylene glycol as a protective agent, reducing a gold precursor into uniform spherical particles with the size range of 2-20 nm through a reducing agent, and anchoring 0.5-5.0 wt% of gold particles on the surface of a carbon material through immobilization, wherein the carbon material comprises one or a mixture of more than one of activated carbon, carbon nanotubes, graphene oxide, carbon nanofibers and the like. By adopting the Au-C catalyst, under the conditions of normal pressure with oxygen circulation at 40-90 DEG C or connection with an oxygen ball, the conversion rate of benzaldehyde prepared by oxidizing benzyl alcohol can reach 87% and the selectivity of benzaldehyde reaches 83% or above, and th