Cypress Liquefaction in a Water/Methanol Mixture: Effect of Solvent Ratio on Products Distribution and Characterization of Products

The effect of mixed solvents (water/methanol) on product yields obtained from cypress liquefaction and characterization of products was investigated at 180–300 °C. Results showed that the mixed solvents markedly enhanced the bio-oil yield as compared with pure water and pure methanol. The highest bio-oil yield of 46.7% was obtained in a mixed solvent with the ratio of 5/5 at 280 °C. Hemicelluloses decomposition preceded lignin and cellulose in all tested solvents and lignin was almost totally transformed after liquefaction at 280 °C in pure water. Water had the best effect on the conversion of cellulose as compared with other mixed solvents and methanol tests. The compositions of bio-oils were strongly different depending on the ratios of water/methanol. The higher heating value of solid residues obtained from mixed solvent tests at 280 and 300 °C were 24.7–29.7 MJ/kg, indicating that it would be suitable for combustion as solid fuel.