In Situ Carbonic Acid from CO2: A Green Acid for Highly Effective Conversion of Cellulose in the Presence of Lewis acid

Converting cellulose to renewable energies and chemicals is the most promising and sustainable route to solving the crisis of fossil fuel resources. Up to now, however, it is still a big challenge to effectively transform recalcitrant cellulose into targeted compounds. For the first time, this study proposes a new and highly effective catalysis system with a synergy effect to convert cellulose into formic acid and levulinic acid simultaneously by using in situ carbonic acid from CO2 as a green acid in the presence of CrCl3. The synergy effect of in situ carbonic acid and CrCl3 could highly effectively hydrolyze cellulose to glucose, isomerize glucose to fructose, dehydrate fructose to HMF, and rehydrate HMF to formic acid and levulinic acid in a one-pot way. Here, 49% formic acid and 32% levulinic acid could be obtained from cellulose at a moderate condition. Our results demonstrated that this new catalysis system is comparable to other catalysis systems, and in situ carbonic acid can be used as a low-cost acid to replace mineral acids such as H2SO4, HCl, and H3PO4 and organic acids such as C6H6O3S, H2C2O4, and Cl3CCOOH to constitute novel, highly effective, low-cost, and less environmental impact catalysis systems for producing formic acid and levulinic acid from cellulose.