Synergistic Effect of Acidic-Basic Features of Copper-Doped Layered Double Hydroxides Nanocatalysts in Valorization of Biomass-Derived Furfural to Biofuels.

Valorization of biomass-derived chemicals into high-quality compounds and biofuels is enormously fundamental to diminish dependence on fossil-based resources. Furfural is a bio-based valuable compound which can be proficiently upgraded to 4-(2-furyl)-3-buten-2-one (FAc) and 1,4-pentadiene-3-one, 1,5-di-2-furanyl (F2Ac) via aldol condensation of furfural with acetone. In the present work, efficient Cu-doped MgAl layered double hydroxides (LDH) nanocatalysts are fabricated by coprecipitation and are exploited for furfural conversion to obtained FAc and F2Ac. The structure-activity relationship is scrutinized by characterizing fresh and spent nanocatalysts via numerous techniques. The good correlation between the amount of weak acidic-weak basic catalytic sites and nanocatalysts performance is established. The superior performance of Cu-0.1 nanocatalyst (Cu-content = 1.85 wt%) in aldol condensation is attributed to the presence of optimum weak acidic sites (0.21 mmol g-1) and weak basic sites (0.36 mmol g-1), synergistic acidic-basic effect, nano-sized Cu(OH)2 nanoparticles (1.6 nm), high BET surface area (181 m2 g-1), and mesoporous architecture of material. Cu-0.1 nanocatalyst delivered 98% FAc selectivity with 100% furfural conversion at 85 °C. Furthermore, at 100 °C, the nanocatalyst gives 55% F2Ac selectivity with 73% furfural conversion. The catalyst displays good recyclability (7 recycles) and stability. Plausible mechanistic pathway for transformation of furfural to FAc and F2Ac is proposed.