(613c) Deep Dehydration of Organic Solvents by Pressure Swing Adsorption

Deep dehydration of organic solvents by PSA (pressure swing adsorption) has been studied using pilot plants. PSA had been applied commonly for the separation of oxygen and nitrogen from air and for the purification of hydrogen. JGC applied the PSA technology to the deep dehydration of organic solvents which form azeotropes with water. In general, azeotropic or extractive distillation had been applied to dehydration of organic solvents forming such azeotropes. However, its difficulty in operation and high energy consumption have always been major problems. By applying PSA to the dehydration of such organic solvents, low energy consumption and easy operation can be expected.

Although PSA is applied for the dehydration of bioethanol at present, the water content of dehydrated ethanol is usually several thousand ppm. We have been investigating the PSA operation conditions to obtain deeply-dehydrated ethanol. Ethanol containing less than 100 ppm of water can be obtained under the proper conditions, continuously and stably.

It was also found that PSA dehydration can be applied to other organic solvents, such as methanol, t-buthanol, tetrahydrofuran, and 2-propanol.

JGC had achieved completion of the engineering, procurement, and construction for six PSA commercial plants. The oldest one has been operating for 9 years without any major trouble and without any need to change the adsorbent. At present, the construction of larger scale commercial plants is being planned.