Preparation method of sodium 2-naphthalenesulfonate

The invention discloses a preparation method of sodium 2-naphthalenesulfonate. The preparation method comprises following steps: 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, and sodium sulfite are subjected to neutralization reaction so as to obtain two naphthalene sulfonic acid sodium solid compounds; the two naphthalene sulfonic acid sodium solid compounds are introduced into a reactor with a stirring device, water is added until sodium 2-naphthalenesulfonate saturation states are achieved at a set temperature, solid sodium hydroxide is added with stirring slowly so as to obtain asolid liquid mixture containing precipitated crystals; the solid liquid mixture is cooled to room temperature, and is subjected to crystallization, filtering, and washing so as to obtain a filter cake containing sodium 2-naphthalenesulfonate and a filtrate containing sodium 1-naphthalenesulfonate; the filtrate is subjected to evaporative concentration until a sodium hydroxide aqueous solution with a desolvation concentra