One-pot levulinic acid production from rice straw by acid hydrolysis in deep eutectic solvent

Levulinic acid is a useful chemical platform derived from lignocellulose, which is applied in many applications such as solvents, fuels and pharmaceuticals. The natural structure of lignocellulose is recalcitrant to access cellulose and upgrade to levulinic acid. Here we showed that a combination of rice straw dissolution in carboxylic acid-based deep eutectic solvent (DES) and acid hydrolysis enabled rice straw conversion into levulinic acid. Among carboxylic acid-based DESs (choline chloride-acetic acid, choline chloride-oxalic acid, choline chloride-malonic acid and choline chloride-succinic acid), choline chloride-Oxalic acid DES potentially dissolved rice straw (100 °C for 2 h) and converted the dissolved cellulose to levulinic acid (52%) by HCl at mild condition (120 °C at 10 h and atmospheric pressure). Our approach is superior to conventional processes for levulinic acid production, such as no separation of intermediates (glucose and HMF), mild condition and inexpensive DES cost, making the one-pot process efficient and economically.