Method for preparation of aldehyde

A method for preparing an aldehyde, comprising:

• supplying a reactant comprising a syngas and an olefin to a reactor and reacting them in the presence of a catalyst to obtain a reaction product comprising an aldehyde;
• supplying the reaction product to a first flash drum, performing gas-liquid separation, and supplying a liquid separated product comprising an unreacted olefin, the catalyst, and the aldehyde to a vaporization part comprising a vaporizer;
• vaporizing the liquid separated product in the vaporization part to separate a vapor stream comprising the unreacted olefin and the aldehyde, and a liquid stream comprising the catalyst;
• supplying the vapor stream to a second flash drum to separate an upper discharge stream from the second flash drum comprising the unreacted olefin, and a lower discharge stream from the second flash drum comprising the aldehyde;
• and
• supplying the upper discharge stream from the second flash drum to one or more flash drums, and supplying the lower discharge stream from the second flash drum to a distillation tower and performing distillation to obtain the aldehyde from a lower discharge stream from the distillation tower,
• wherein a ratio of an operating temperature (° C.) of the vaporizer to a reaction temperature (° C.) of the reactor is 1.1 to 1.9.