Minimizing Energy Demand in the Conversion of LevulinicAcid to ‑Valerolactone via Photothermal Catalysis UsingRaney Ni

Abstract

The valorization of lignocellulosic wastes emerges as a prime strategy tomitigate the global carbon footprint. Among the multiple biomass derivatives, -valerolactone is particularly attractive as precursor of high-value chemicals,biofuel, green solvent or perfumery. -Valerolactone can be synthesizedthrough a hydrogenation reaction from levulinic acid, obtained from cellulose.However, the high energy requirements of this synthetic pathway havehindered its industrial viability. To drastically reduce the reaction energyrequirements, here a novel synthetic strategy, based onsolvothermal-photothermal processes using cost-effective Raney-Ni asphotothermal catalyst, is proposed. First, the use of hydrogen gas is avoidedby selecting isopropanol as a safer and greener H-source. Second, aphotothermocatalytic process is used to minimize the reaction temperatureand time with respect to conventional reactions. This approach exploits thebroadband optical absorption of the Raney®-Ni, due to its highly dampedplasmonic behavior, to achieve fast and efficient catalyst heating inside thereactor. The photothermal reaction required less than 2 h and just 132 °C toreach over 95% conversion, thereby drastically reducing the reaction time andenergy consumption compared to conventional reactions. Importantly, theseconditions granted high catalyst reusability. This solvothermal-photothermalapproach could offer a sustainable alternative for the industrial production of -valerolactone.