Method of double solvents, benzene substitutive rectification for separating c9 aromatics

This invention discloses a method for separating C9 aromatic hydrocarbons by double-solvent extraction and rectification. The method comprises: (1) pre-fractionating C9 aromatic hydrocarbon mixture, and collecting the rich fraction containing mesitylene and o-methyl ethyl benzene; (2) introducing the rich fraction into the middle of a double-solvent extraction-rectification column, introducing high-boiling-point solvent from the top of the column and low-boiling-point solvent from the bottom of the column, and extracting to obtain mixed fractions containing mesitylene and the low-boiling-point solvent at the top of the column and mixed fractions containing o-methyl ethyl benzene and the high-boiling-point solvent at the bottom of the column; (3) separating the mixed fractions in a solvent recovery column to obtain mesitylene and o-methyl ethyl benzene products, discharging, and recycling the solvents. The method significantly expands the relative volatility between trimethyl benzene and o-methyl ethyl benzene by using high-boiling-point and low-boiling-point solvents.