Production of Heavy Oils with High Caloric Values by Direct Liquefaction of Woody Biomass in Sub/Near-critical Water

Direct liquefaction of a woody biomass (Jack pine sawdust) in sub/near-critical water without and with catalysts (alkaline earth and iron ions) has been investigated at temperatures of 280–380 °C. Heavy oils with a high caloric value of 30–35 MJ/kg (much greater than that of the crude wood sample used) were obtained, along with water soluble oils with a caloric value of 19–25 MJ/kg. The yields of heavy oil and total oil products tended to maximize in the temperature range of 280–340 °C for all the liquefaction operations regardless of the presence of a catalyst or the type of catalyst. All the catalysts tested, i.e., Ca(OH)2, Ba(OH)2, and FeSO4, were found effective for enhancing the formation of heavy oil products at 280–340 °C, while they significantly promoted the formation of gas and water at >340 °C. The yield of heavy oil in the operation at 300 °C for 30 min was improved significantly from around 30% without catalyst to greater than 45% by Ba(OH)2. The maximum yield of total oil products reached 51...