Monday, May 5, 2008 - 8:30 AM
3-02
Autoxidative delignification of woody biomass in ethanol and enzymatic saccharification of the resulting pulp
Although the wet oxidation and the solvolysis are representative pretreatment and delignification methods for the production of ethanol from woody biomass, the attempt of combining these two processes has been scarcely made so far probably from the fear of explosion. In reality, ethanol is readily autoxidized under relatively mild conditions, and diethyl acetal, ethyl acetate, methane, carbon monoxide, hydrogen, carbon dioxide and so on are formed, while this oxidation is suppressed to some extent in the presence of antioxidants such as lignin, lignin model compounds, or lignin containing materials, and the antioxidants themselves are preferably oxidized to carbon dioxide. Based on this fact, the selective delignification of pulverized woody biomass is now achieved by its autoxidation in ethanol under pressure of oxygen or air at 130-160°C.
When 1g of pulverized spruce (0.25-0.42mm) was treated with either oxygen or air at the initial pressure of 1 or 5MPa respectively in 10mL of ethanol at 150°C for 16h, 0.64-0.65g of pale yellow pulp containing 3.5% of lignin was obtained. Its similar oxidation but in water led to its carbonization, probably because of the much smaller solubility of oxygen in water than in ethanol or the lack of autoxidation itself. Enzymatic saccharification of the resulting pulp with 10FPU of acremonium cellulase at 4% loading for 120h gave 0.46g of monosaccharides: 56% yield of glucose and mannose based on the dry spruce.
When 1g of pulverized spruce (0.25-0.42mm) was treated with either oxygen or air at the initial pressure of 1 or 5MPa respectively in 10mL of ethanol at 150°C for 16h, 0.64-0.65g of pale yellow pulp containing 3.5% of lignin was obtained. Its similar oxidation but in water led to its carbonization, probably because of the much smaller solubility of oxygen in water than in ethanol or the lack of autoxidation itself. Enzymatic saccharification of the resulting pulp with 10FPU of acremonium cellulase at 4% loading for 120h gave 0.46g of monosaccharides: 56% yield of glucose and mannose based on the dry spruce.
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