Rapid liquefaction of lignocellulosic waste by using ethylene carbonate

Cyclic carbonates were selected as novel liquefying reagents in order to establish a rapid liquefaction technique converting lignocellulosic waste into useful chemicals. Lignocellulosic materials such as wood and cellulose were liquefied using ethylene carbonate (EC) or propylene carbonate (PC) in the presence of acid catalyst at elevated temperature (120–150°C). Very rapid and complete liquefaction occurred in the EC-liquefaction of cellulose and white birch (hardwood). The rate of the EC-liquefaction of cellulose was approximately 10 times faster than that of current polyhydric alcohol liquefaction. Conversely, liquefaction was not accomplished due to the formation of insoluble lignin derivatives when applied to softwood (Japanese cedar and Japanese cypress). Satisfactory liquefaction is dependent on the type of lignin, i.e. hardwood lignin or softwood lignin. This problem was solved by blending ethyleneglycol (EG) with EC. 13C-NMR revealed that the EC liquefaction products from cellulose include levulinic acid compounds, which also results from EG liquefaction of cellulose.