Method for preparing acrylic acid

A method for preparing an acrylic acid, the method comprising:

• bringing a mixed gas including an acrylic acid into contact with water in an absorption tower to obtain an acrylic acid solution including the acrylic acid;
• performing crystallization of the acrylic acid by a process including a multistage crystallization process in which two or more crystallization units each including a crystallizer and a solid-liquid separator are connected in series,
• introducing the acrylic acid solution to the crystallizer of a first stage crystallization unit of the two or more crystallization units;
• crystallizing the acrylic acid, which is included in the acrylic acid solution introduced to the crystallizer in each stage, in the crystallizer in each stage to obtain a suspension including an acrylic acid crystal, and supplying the suspension to a solid-liquid separator in each stage;
• solid-liquid separating the suspension in the solid-liquid separator in each stage to obtain a concentrated acrylic acid solution and a mother liquor;
• dividing the mother liquor into a first mother liquor stream and a second mother liquor stream, circulating the first mother liquor stream to the crystallizer in a prior-stage prior to a stage to which the solid-liquid separator from which the mother liquor is separated belongs or to the absorption tower, and circulating the second mother liquor stream to the crystallizer in the stage to which the solid-liquid separator from which the mother liquor is separated belongs;
• introducing the concentrated acrylic acid solution to the crystallizer in an after-stage after a stage to which the solid-liquid separator from which the concentrated acrylic acid solution is separated belongs;
• and
• obtaining a purified acrylic acid from the solid-liquid separator of the crystallization unit in the last stage of the two or more crystallization units.