Boosting levulinic acid hydrogenation to value-added 1,4-pentanediol using microwave-assisted gold catalysis

Microwave (MW) -assisted levulinic acid (LA) hydrogenation has been performed over two gold catalysts (commercial 1 wt% Au/TiO2 by AUROlite™ and 2.5 wt% Au/ZrO2, prepared using deposition-precipitation). MW-assisted LA hydrogenation was carried out in water and in solvent-free conditions via (i) H-transfer and (ii) molecular H2. Au/TiO2 promoted complete LA conversion and the further reduction of the produced GVL to 1,4-pentanediol (1,4-PDO) in the presence of 50 bar H2 at 150 °C (4-hour reaction). Interestingly, selectivity to 1,4-PDO was complete at 200 °C. Extended characterisation highlighted the cooperative role played by the gold nanoparticles and the support, onto which activated hydrogen atoms spillover to react with LA. This results in the remarkable activity of Au/TiO2. Both catalysts showed structural and morphological stability under reaction conditions. It was possible to reactivate the Au/TiO2 catalyst by MW-assisted oxidation, paving the way for catalyst recycling directly inside the MW reactor.

Microwave (MW) -assisted levulinic acid (LA) hydrogenation has been performed over two gold catalysts (commercial 1 wt% Au/TiO2 by AUROlite (TM) and 2.5 wt% Au/ZrO2, prepared using deposition-precipitation). MW-assisted LA hydrogenation was carried out in water and in solvent-free conditions via (i) H-transfer and (ii) molecular H-2. Au/TiO2 promoted complete LA conversion and the further reduction of the produced GVL to 1,4-pentanediol (1,4-PDO) in the presence of 50 bar H-2 at 150 degrees C (4-hour reaction). Interestingly, selectivity to 1,4-PDO was complete at 200 degrees C. Extended characterisation highlighted the cooperative role played by the gold nanoparticles and the support, onto which activated hydrogen atoms spillover to react with LA. This results in the remarkable activity of Au/TiO2. Both catalysts showed structural and morphological stability under reaction conditions. It was possible to reactivate the Au/TiO2 catalyst by MW-assisted oxidation, paving the way for catalyst recycling directly inside the MW reactor. (C) 2019 Elsevier Inc. All rights reserved.