Towards valorization of glycerol and molasses: Carbon-based catalysts from molasses for the synthesis of acetins.

Abstract

Crude sugarcane molasses (SCM) was successfully applied for the first time as a bio-feedstock for producing biochar catalysts for glycerol upgrading. Preparation methods were developed, including partial or hydrothermal carbonization (abbr. PC and HTC) and chemical activation. After functionalization with -SO₃H groups, the catalysts were tested for the esterification of glycerol to acetins. The materials varied in their textural and chemical features, particularly in the -SO₃H content, giving the single-step PC method a distinct advantage. The best catalyst yielded approximately 74 % of di- and tri-acetins with 97 % glycerol conversion within only 2 h of the reaction and demonstrated great stability over three consecutive cycles. The formation of the desired TA product was correlated with the concentration of -SO₃H groups. Despite being non-porous, the most active PC catalyst possessed a compact structure with a high abundance and easy accessibility of -SO₃H, COOH, and -OH groups on its surface.