The selective oxidation of glycerol over metal-free photocatalysts: insights into the solvent effect on catalytic efficiency and product distribution

Selective oxidation of glycerol to high value-added derivatives is a promising biomass conversion pathway, but the related reaction mechanism, in particular the solvent effect, is rarely studied. In this work, O-doped g-C3N4 was used as a metal-free catalyst to catalyze the selective oxidation of glycerol in different solvents. It was found that solvents can affect both catalytic efficiency and product distribution. A series of controlled experiments and theoretical calculation were applied to attest that the difference in interaction between glycerol and catalysts in different solvents is the main factor: competitive adsorption and hydrogen bond network from water inhibit the adsorption and activation of glycerol on the catalyst surface and reduce the conversion efficiency, while in acetonitrile, the stronger adsorption makes the oxidation reaction continue to yield esters. Two reaction routes in different solvents over O-doped g-C3N4 are proposed for the first time, which is helpful for people to better understand the related reaction mechanism.

Automated summary

This study investigated the selective oxidation of glycerol using O-doped g-C3N4 catalyst in different solvents and found that solvents play a crucial role in affecting catalytic efficiency and product distribution. The interaction between glycerol and catalysts in different solvents was identified as the main factor influencing the conversion efficiency, with water inhibiting adsorption and activation of glycerol on the catalyst surface, while acetonitrile promoting ester production. The proposed reaction routes over O-doped g-C3N4 in different solvents provide insights into the related reaction mechanism.