Electrochemical Reaction of Alcohols in Subcritical Water

We have been studying electrolysis of organic compounds in subcritical water as a waste treatment technology and molecular conversion technology. Organic molecules can be converted to innocuous compounds, such as carbon dioxide, water, and hydrogen by electrolysis under hydrothermal condition.

In this study, we have applied the hydrothermal electrolysis to reactions of alcohols, such as butanol, ethylene glycol, and glycerol. Batch type and continuous flow-type reactors were used in order to reveal the main reaction pathways of organic compounds containing hydroxyl group in the electrolysis in subcritical water to predict reaction feature of biomass-related compounds such as saccharides.

As a result, it was found that 1-butanol was converted into butylaldehyde and butyric acid via partial oxidation at 250 C and 1 - 3 A of DC current while no oxidation products was observed without electrical current loading at identical conditions. As a gas phase product, hydrogen was generated according to electorchemical reaction. Glycerol which has two primary hydroxyl groups and one secondary one was treated in dilute alkaline solution at 240-280 C. The experimental results showed that glycerol was converted into lactic acid, glycolaldehyde, and formic acid. As a gas product, only hydrogen was obtained. The yield and selectivity of lactic acid was lower than the reaction in concentrated alkali solution at 300 C.