Method for preparing dimethyl disulfide by virtue of methanthiol sulfidization method

The invention provides a method for preparing dimethyl disulfide by virtue of a methanthiol sulfidization method. The method comprises the specific steps of filling a tower-type reactor with a solid catalyst and then filling the tower-type reactor with a mixed solution containing dimethyl disulfide, dimethyl trisulfide and dimethyl polysulfide, keeping the solid catalyst to be immersed in the solution inside the tower, spraying powdery sulfur into the solution and continuously introducing impure methanthiol gas from the bottom of the tower-type reactor; enabling the produced hydrogen sulfide gas to return inside a thiol reactor by virtue of the tower top and synthesizing methanthiol from thiol and methanol, extracting a mixture of dimethyl disulfide, dimethyl trisulfide and dimethyl polysulfide, rectifying to obtain dimethyl disulfide, further introducing a mixed solution of byproducts dimethyl trisulfide, dimethyl polysulfide and a small amount of dimethyl disulfide into the tower-type reactor to complete the circular reaction. The conversion rate of sulfur can be not less than 99.0%, the content of bottom product dimethyl polysulfide is 0.5%-1% (in mass percentage) and the purity of dimethyl disulfide by virtue of primary rectification is not more than 99.5%.