Two-Stage Fractionation and Fiber Production of Lignocellulosic Biomass for Liquid Fuels and Chemicals

In the current study, a simple two-step fractionation process was developed for utilization of hardwood biomass without forming troublesome sticky lignin condensation products. The four product streams generated are a hemicellulose extract, a lignin extract, separated wood fibers (pulp) and wood fiber bundles (rejects). All four product streams can be further utilized for production of transportation fuel, chemicals, and biomaterials. The optimum fractionation conditions for mixed southern hardwood chips are the following: extraction with 10 g/L formic acid (FA) at 160 °C for 90 min followed by extraction with 50% (w/w) EtOH at 80 °C for 90 min. The yield of pulp and reject fibers that are produced from the FA and EtOH pre-extracted wood chips by mechanical action are 38% and 28%, respectively. Cellulose to glucose conversion yield of the FA treated wood, as well as that of the final pulp and fiber bundles by enzymes, are strongly improved compared to that of the original hardwood chips.