Difference between revisions of "Hydrothermal processing"

A hydrothermal process is usually performed in water at 250-374°C under a pressure of 4-22 MPa. The process can also be carried out under self-generated pressure. The hydrothermal process is divided into two reaction conditions, namely subcritical and supercritical water conditions. These two conditions are determined by the critical point of water (i.e., 374°C and 22.1 MPa). Subcritical water is classified below the critical point at a 100-374°C temperature range and under sufficient pressure to remain liquid. Supercritical water occurs when the temperature is above 374°C and the pressure is above 22.1 MPa. The decomposition steps of biomass during the hydrothermal process can be summarized as follows: at approximately 100°C, the water-soluble portion of the biomsas disperses into water, and hydrolysis takes place above 150°C. Meanwhile, biomass polymers (i.e., cellulose and hemicellulose) disintegrate into heir monomeric chains. At approximately 300°C and 10 MPa, liquefaction occurs and bio-oil is obtained.