Selective Production of Glycolic Acid and Dihydroxyacetone From Glycerol Under Non-Thermal Plasma in Liquid Phase.

Valorising crude glycerol, a major by-product of biodiesel production, is essential for advancing a circular chemical economy. Traditional methods of oxidising crude glycerol to produce value-added chemicals such as glycolic acid (GcA) and dihydroxyacetone (DHA) typically require noble metal catalysts and energy-intensive conditions. Herein, we present a catalyst-free, non-thermal plasma (NTP) process that operates in the liquid phase at ambient temperature and pressure. This novel approach enables the selective oxidation of glycerol into GcA and DHA without the need for added reagents or catalysts. With a deposited power of 9.6 W and short residence time, 100% selectivity towards GcA was achieved with 7% glycerol conversion. Extending the treatment time to 60 min increased glycerol conversion to 35%, with selectivities of 58% for GcA and 36% for DHA. These results highlight the potential of liquid-phase NTP as a sustainable and efficient method for upgrading crude glycerol under mild conditions.