A promising approach to transform levulinic acid into γ-valerolactone using niobic acid photocatalyst and the accumulated electron transfer technique

The photocatalytic production of gamma-valerolactone (GVL) from levulinic acid (LA) was performed using the UV assisted accumulated electron transfer technique. For this purpose, a commercial niobic acid (HY-340) produced by Companhia Brasileira Metalurgia e Mineralurgia (CBMM) was used as photocatalyst. HY-340 showed higher efficiency in ethanol (a hole scavenger) and additional contact time with the substrate (48 h in the dark) after the reaction under UV light. Longer illumination time leads to the conversion of by-products to GVL with maximum selectivity of 44.7 %. Electron paramagnetic resonance (EPR) measurements allied with the spin trapping method indicated the reduction process occurs through the transfer of H center dot. Finally, O-2 pulse titration was developed to quantify the electrons accumulated in the HY-340 conduction band. From this experiment, a significant TOF value was calculated to 3.3 x 10(-6) s(-1) considering that experiments were conducted at room temperature and ambient pressure.