| Summary: | 碩士 === 義守大學 === 化學工程學系暨生物技術與化學工程研究所 === 104 === Hemicellulose and cellulose often co-exist in the plant cell walls. Hemicellulose is formed by different pentose and hexose, comprising xylose, arabinose and galactose. The purpose is to promote the value of bio-mass energy by gasification of hemicellulose in supercritical water to recover higher-valued gaseous products. In this study, using xylose as a model compound of hemicellulose, investigates the main parameters and operating conditions for the gasification of xylose in supercritical water, and attempts to find the optimal reaction conditions.
All experiments use a 16-ml batch reactor. The main operating parameters include: temperatures 400-600 ∘C, reactor pressures 50-250 bar, reactant concentrations 0.05-0.3 M. The product gas is analyzed using a GC-TCD, and is found to consist mainly of hydrogen, carbon monoxide, methane, carbon dioxide, ethylene and ethane. The results show that gas yield ranges between 4.73-77.27 m mol/g, with a maximum of 77.27 m mol/g (600 ∘C, 100 bar). HHV range between 185-446 kJ/mol, with a maximum of 446 kJ/mol (575 ∘C, 100 bar). Energy yield range between 0.056-1.766 kJ/kJ, with a maximum of 1.766 kJ/kJ (600 ∘C, 100 bar). Some energy yields exceed one or even approaches two, because in addition to the gasification of xylose itself, water is also involved in the gasification reactions. The results showed that xylose gasifies reasonably well in supercritical water, since under proper conditions, it is almost completely transformed into gas products.
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