Mutual Valorization of 5-Hydroxymethylfurfural and Glycerol into Valuable Diol Monomers with Solid Acid Catalysts

Biomass platform molecules such as glycerol and 5-hydroxymethylfurfural have been valorized into diol monomers by acetalization reaction in the presence of tridirectional large pore zeolites (HY and Beta), a laminar zeolite (ITQ-2) and a mesoporous aluminosilicate (MCM-41), and a conventional homogeneous acid catalyst (p-toluenesulfonic acid). The influence of the solvent polarity, pore structure, hydrophobic character, and acidity of the catalyst on the activity and selectivity to 5-hydroxymethylfurfural (HMF) glyceryl acetals has been studied. Results showed that, while the homogeneous catalyst mainly promotes polymerization reactions, tridirectional zeolites are more active catalysts but less selective and deactivate more rapidly than mesoporous MCM-41 and delaminated two-dimensional zeolites. ITQ-2 and MCM-41 catalysts with smaller confinement effects, easy diffusion, and adequate surface polarity provide high yield (98%) and selectivity (100%) to the target compound. These catalysts are stable and allow regeneration and reuse.