Method for preparing isopropyl alcohol

A method for preparing isopropyl alcohol, the method comprising:

• supplying a feed including isopropyl alcohol, water, a first light by-product, a second light by-product, and a heavy by-product to a first column provided with a first reboiler;
• separating the first light by-product from an upper discharge stream of the first column;
• supplying a lower discharge stream of the first column including the isopropyl alcohol, water, the second light by-product, and the heavy by-product to a second column provided with a second reboiler, and separating the lower discharge stream of the first column into an upper discharge stream of the second column including the second light by-product, a first side discharge stream of the second column including a mixture of the isopropyl alcohol and water, a second side discharge stream of the second column including the heavy by-product, and a lower discharge stream of the second column including the water, respectively;
• supplying the first side discharge stream of the second column including the mixture of isopropyl alcohol and water to a third column which is divided into a first region, a second region, and an upper region by a separation wall and provided with a layer separator on the upper portion, and performing azeotropic distillation in the presence of an azeotropic agent;
• and
• obtaining isopropyl alcohol from a lower discharge stream of the first region of the third column,
• wherein the upper discharge stream of the third column is heat exchanged with one or more of the lower discharge stream of the first column and the lower discharge stream of the second column through one or more of the first reboiler and the second reboiler.