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 degrees 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 degrees 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 degrees C, while they significantly promoted the formation of gas and water at > 340 degrees C. The yield of heavy oil in the operation at 300 degrees 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% in the operation without catalyst, while it increased to about 65% with Ca(OH)(2) at 300 degrees C. The, GC/MS measurements for the heavy oil products revealed that the oils contain mainly carboxylic acids, phenolic compounds and derivatives, and long-chain alkanes.