Batch and Continuous-Flow Preparation of Biomass-Derived Furfural Acetals over a TiO2 Nanoparticle-Exfoliated Montmorillonite Composite Catalyst

Furfural acetals with high octane value, high calorific value and high oxidation resistance are considered promising biofuels or fuel precursors with huge potential demand. However, there are few studies on efficient scalable catalyst systems, including continuous-flow catalyst systems, for their preparation. In this work, TiO2 nanoparticles supported on exfoliated montmorillonite, with strong Lewis acid sites and abundant accessible Bronsted acid sites, is used to catalyze the acetalization reactions of biomass-derived furfural and alcohols. Low dosage of the catalyst made the reaction reach equilibrium in a very short time (TOF=690-1305 min(-1)) at room temperature with the acetal as the only product. In continuous-flow reactions, the catalyst showed a stable product output with conversion close to that for the batch reaction with a short catalyst-reactant contact time of 150 s. Contrast experiments revealed that both Lewis and Bronsted acid sites on the catalyst were indispensable for maximizing the catalytic performance, and simultaneously activating both furfural and alcohol on the adjacent Lewis and Bronsted acid sites was proposed to be responsible for the high catalytic performance.

Automated summary

In this study, TiO2 nanoparticles supported on exfoliated montmorillonite were used as catalysts to efficiently catalyze the acetalization reactions of biomass-derived furfural and alcohols. The catalyst achieved equilibrium in a short time with high catalytic performance, showing stable product output in continuous-flow reactions. Both Lewis and Bronsted acid sites on the catalyst were essential for maximizing the catalytic performance by simultaneously activating both furfural and alcohol.