Green Synthesis of Furfural Acetone by Solvent-Free Aldol Condensation of Furfural with Acetone over La₂O₃–MgO Mixed Oxide Catalyst

Abstract

Conversion of biomass, whether fresh or waste, into valuable chemicals and intermediates will be very useful to reduce dependence on fossil feedstock. Furfural is a biomass-derived chemical which can be valorized. Furfural acetone (FAc) is used as an intermediate in fine chemical industries and produced by using polluting homogeneous basic catalysts. In the current study, La–Mg mixed oxide (MO) catalysts with various mole ratios were prepared by hydrothermal (H) and combustion (C) methods for the preparation of FAc. It was found that moderate to strong basicity of the La1Mg3MO-H catalyst prepared by the hydrothermal method vis-à-vis La₁Mg₃MO-C helps to attain a highly selective cross-aldol condensation reaction of furfural with acetone. In the current reaction process, high conversion of furfural (96%) and high selectivity of FAc (98%) were achieved after 7 h of reaction time. The catalyst was well characterized by various analytical orthogonal techniques such as FTIR, DCS-TGA, SEM-EDX, BET, TPD, and XRD. A solvent-free reaction engineering approach was adopted to eliminate the undesired byproducts, and also, the use of hazardous solvents was avoided. A kinetic model based on the proposed reaction mechanism was developed, which follows the LHHW mechanism with weak adsorption of all species. The activation energy of the cross-aldol condensation of furfural with acetone was found to be 12.11 kcal/mol.