| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2004: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
Cellulosic biomass is the most important biomass resource on the earth. Introduction of the effective utilization method of cellulosic biomass as low molecular-weight (MW) chemicals as well as energy resources is important to establish the future sustainable society. This research project is related to the useful low MW chemical production from cellulosic biomass through controlled pvrolysis.
Pyrolysis is a fundamental basis of thermochemical conversion processes such as carbonization, dry distillation, gasification and fast pyrolysis to from bio-oil. Cellulosic biomass is highly reactive under these conversion conditions, but products are usually obtained as a very complex mixture including gaseous, liquid and solid products. So, isolation of the low MW chemicals from these mixtures is difficult and economically unfeasible. We study the pyrolysis mechanism of cellulosic biomass on molecular basis to establish the more selective conversion method through controlled pyrolysis. As for cel
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lulose, ring-opening polymerization of levoglucosan (1,6-anhydro-β-D-glucopyranose), the primary product from cellulose pyrolysis, has been suggested as a key reaction which governs the product selectivity between low MW products and solid carbonized products. Indeed, pyrolysis of cellulose in sulfolane (a solvent for levogludosan) is a quite useful condition to form low MW products selectively without forming solid carbonized products.
Catalytic effects of sulfuric acid or polyphosphoric acid on the products selectivity were studied in sulfolnae. As a result, these acidic catalysts were quite useful for production of levoglucosenone (〜42%) and furfurals (〜36%) (optimized yields from cellulose). The conversion mechanism was also clarified. In the mechanism, the conversion : levoglucosenone→furufurals was found to require water. This information is very useful to control the product selectivity between levoglucosenone and furfurals : levoglucosenone was preferentially obtained under distillation conditions, while selectivity of furufurals substantially increased under steam-distillation conditions.
Some new conditions which lead to the controlled pyrolysis of cellulose were also discovered. Boric acid substantially stabilized the low MW sugar molecule as pyrolytic products. Some aromatic compounds were discovered as stabilizing agent of the surface molecule of the crystalline cellulose. From our previous study, cellulose pyrolysis has been suggested to start from such surface molecule due to the lower stabilization energy than the inner molecule. So, these new conditions are expected to be effective in controlling the product selectivity in cellulose pyrolysis. Less
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