System and method for producing diester-based composition

A system for producing a diester-based composition, the system comprising:

• a first reactor to an N-th reactor connected in series in which an esterification reaction of dicarboxylic acid and alcohol is performed;
• and
• a reflux unit connected to the first reactor and selectively separating unreacted alcohol from a mixed gas generated during the esterification reaction and then refluxing the separated unreacted alcohol to the first reactor, wherein the reflux unit includes:
• 1) A reflux column for receiving the mixed gas and unreacted alcohol in a liquid state from the first reactor and then transferring the mixed gas to a condenser and the unreacted alcohol in a liquid state to the first reactor;
• 2) the condenser for condensing the mixed gas;
• and
• 3) a layer separator for separating alcohol and water from a condensate passed through the condenser, wherein the layer separator discharges a water layer and allows an alcohol layer to be recovered,
• wherein:
• one or more reactors selected among a second reactor to the N-th reactor are additionally connected to the reflux unit;
• and
• N is an integer of 2 to 10,
• wherein the reflux unit further comprises:
• 4) a pre-condenser directly connected to the reflux column and condensing a portion of unreacted alcohol in the mixed gas;
• and
• 5) a gas-liquid separation device directly connected to the pre-condenser and receiving the mixed gas and the unreacted alcohol in a liquid state and then transferring the mixed gas to the condenser and the unreacted alcohol in a liquid state to the reflux column,
• wherein the alcohol layer recovered through the layer separator is transferred to the gas-liquid separation device.