The invention provides a method for increasing yield of 5-sulfoisophthalic acid for synthesis of a ternary
monomer. The method comprises the following steps: feeding, filling
nitrogen, performing a first-stage heating reaction, performing a second-stage heating reaction, adding remaining
oleum, performing a third-stage heating reaction, and performing a negative pressure reaction. The method has the beneficial effects that the reaction time is shortened, and the
reaction temperature is lowered; compared with the existing production process, the maximum
reaction temperature is lowered by 30 DEGC, and the sulfonation reaction cycle is shortened by 2 hours; the loss of
sulfur trioxide is reduced, the cost is reduced, and the
economic benefits of the ternary
monomer product can be increased;the amount of
oleum is reduced, which is 5% less than that in the current process dosage, and the amount of alkali used in the subsequent
neutralization process can be reduced by more than 5%, at thesame time, the reaction time of the
neutralization process is shortened, the amount of cooling water is reduced, and the energy saving effect is remarkable; and the yield of 5-sulfoisophthalic acid isincreased.