Application of nonthermal atmospheric-pressure plasma irradiation as a new method for noncatalytic liquid-phase selective oxidation of polyhydric alcohols

Abstract

We have developed a new liquid-phase noncatalytic selective oxidation of polyhydric alcohols such as glycerol. This method involves the use of a nonthermal atmospheric-pressure plasma instead of precious-metal catalysts. We found that noncatalytic selective oxidation of glycerol achieved a conversion comparable to that achieved by gold-catalyzed oxidation, and the desired glyceric acid, which is a pharmaceutical raw material, was obtained. When the solution pH was changed from strongly alkaline to neutral, the main reaction switched from the one that occurs in the presence of gold catalysts to the one that occurs in the presence of platinum catalysts. These results suggest that the reactive oxygen species generated by nonthermal atmospheric-pressure plasma irradiation vary depending on the solution pH.