Production of levoglucosenone and 5-hydroxymethylfurfural from cellulose in polar aprotic solvent-water mixtures

We demonstrate a process to produce levoglucosenone (LGO) and 5-hydroxymethylfurfural (HMF) from cellulose in up to 65% carbon yield using sulfuric acid as catalyst and a solvent consisting of a mixture of tetrahydrofuran (THF) with water. In pure THF, LGO is the major product of cellulose dehydration, passing through levoglucosan as an intermediate. Increasing the water content (up to 5 wt%) results in HMF as the major product. HMF is formed both by glucose dehydration and direct dehydration of LGA. The maximum combined yield of LGO and HMF (similar to 65 carbon%) is achieved in the presence of 1-2.5 wt% H2O, such that comparable amounts of these two co-products are formed. THF gave the highest total yields of LGO and HMF among the solvents investigated in this study (i.e., THF, diglyme, tetraglyme, gamma-valerolactone (GVL), cyclopentyl methyl ether (CPME), 1,4-dioxane, and dimethyl sulfoxide (DMSO)). Furthermore, the rate of LGO and HMF degradation in THF was lower than in the other solvents. LGO/HMF yields increased with increased strength of the acid catalyst (H2SO4 > H3PO4 > HCOOH), and HMF was produced more selectively than LGO in the presence of hydrochloric acid. Techno-economic analysis for LGO and HMF production from cellulose shows that the lowest LGO/HMF production costs are less than $3.00 per kg and occur at a cellulose loading and water content of 2-3% and 1.5-2.5% respectively.