Method and apparatus for producing dicyanobenzene

An apparatus for producing dicyanobenzene comprising:

• (1) absorption means for contacting a xylene-ammoxidation reaction gas comprising dicyanobenzene obtained by ammoxidation of xylene with an organic solvent so as to obtain a dicyanobenzene-absorbing solution comprising the organic solvent in which the dicyanobenzene is dissolved;
• (2) extraction means for contacting the dicyanobenzene-absorbing solution with a basic aqueous solution comprising one or more salts selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium carbamate so as to extract a water-soluble salt formed by neutralization reaction between carboxylic acid in the dicyanobenzene-absorbing solution and a base in the basic aqueous solution into an aqueous phase;
• (3) liquid-liquid separation means for separating a mixture of the dicyanobenzene-absorbing solution and the basic aqueous solution sent from the extraction means into an organic phase and an aqueous phase;
• (4) degassing means for decomposing one or more salts selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium carbamate contained in the organic phase sent from the liquid-liquid separation means, so as to separate the one or more salts from the organic phase;
• and
• (5) low-boiling-point compound separation means for distilling the organic phase sent from the degassing means to separate components contained in the organic phase and having a boiling point lower than that of the dicyanobenzene, from the organic phase so as to obtain the dicyanobenzene.