Photocatalytic conversion of glycerol to dihydroxyacetone

Abstract

This work was carried out to convert glycerol to value-added compounds in liquid phase over TiO₂-based photocatalyst. The investigated parameters were catalyst dosage (1-3 g/L), H₂O₂ concentration (0.3-1.5 mol/L), UV light intensity (1.1-4.7 mW/cm²), reaction time (4-8 h) and electron acceptor types (O₂ and H₂O₂). It was found that TiO₂ in anatase phase can achieved the glycerol conversion of around 71.42% at catalyst dosage of 3 g/L, H₂O₂ concentration of 1.5 mol/L, UV light intensity 4.7 mW/cm² and reaction time 8 h. The addition of monometallic (bismuth, platinum, palladium, and gold) and bimetallic (gold-bismuth, gold-platinum, and gold-palladium) on TiO₂ can enhance the photocatalytic activity for glycerol conversion to value-added compounds. Among all studied photocatalysts, the AuPd/TiO₂ with 3 wt.% of each metal promoted the highest glycerol conversion up to 98.75% at 24 h of reaction time and using O₂ as electron acceptor and provided the yield of glyceraldehyde, dihydroxyacetone, hydroxypyruvic acid, glyceric acid, glycolic acid, formaldehyde and glycolaldehyde of 16.35, 7.47, 8.45, 1.69, 21.92, 22.94 and 6.03%, respectively. In addition, it was found that the defective TiO₂ photocatalyst, which was successfully synthesized through solution plasma process can promote the glycerol conversion to value-added compounds. It gave the glycerol conversion of around 58.49% at 24 h of reaction time and using O₂ as electron acceptor and provided the yield of glyceraldehyde, dihydroxyacetone, hydroxypyruvic acid, glycolic acid, formaldehyde and glycolaldehyde of 4.85, 3.32, 2.11, 2.15, 26.61 and 39.15%, respectively.