PROCESS FOR RECOVERING ACROLEIN OR PROPIONALDEHYDE FROM DILUTE AQUEOUS STREAM

PROBLEM TO BE SOLVED: To provide a method for purifying acrolein or propionaldehyde. SOLUTION: This method for purifying the acrolein or propionaldehyde comprises the following steps. (1) feeding a dilute aqueous solution comprising the acrolein or propionaldehyde and light-boiling point impurities, (2) providing a single column distillation system comprising a distillation column having a top condenser, a crude product feed inlet attached onto the distillation column, a distillation site for the light-boiling point impurities above the crude product feed inlet, a liquid side-draw take-off outlet for recovering purified acrolein or propinaldehyde located between the crude product feed inlet and distillation site for the light-boiling point impurities and a distillation site for heavy impurities below the crude product feed inlet, (3) introducing the dilute aqueous solution through the crude product feed inlet into the distillation column and distilling the dilute aqueous solution and (4) recovering the purified acrolein or propionaldehyde through the liquid side-draw take-off outlet.