| Summary: | 碩士 === 國立成功大學 === 環境工程學系 === 104 === A. Confusa hardwood, which is available locally in Taiwan, was torrefied under oxidative and non- oxidative conditions at varying temperatures from 240 to 320°C. Also, the wood was treated with bio-solution, NOE-7F, and the effects were analyzed. Solid yield, enhancement factor of HHV, energy yield and energy- mass- co-benefit index (EMCI) of the final solid products were calculated to better characterize the biomass torrefaction. Thermogravimetry analysis and derivative thermogravimetry analysis (TGA ＆ DTG), high resolution scanning electron microscope (HR-SEM), and high resolution gas chromatography/ high resolution mass spectrometry (HRGC/HRMS) analyze the products of the torrefaction process.
Weight and atomic ratios of H/C and O/C ratios were shown to decrease with increasing temperatures under both oxidative and non- oxidative atmospheres, moderately less in oxidative atmospheres. The addition of the NOE-7F lowered H/C and O/C ratios more uniformly. A lower solid yield was obtained with increasing temperature under oxidative and non-oxidative conditions. For the addition of the bio-solution, it decreased by 43.1% and 41.3% and in the absence of bio-solution by 45.8% and 44%, respectively. The enhancement factor of HHV increased with increasing temperature, with slight inflection point occurring at 300°C for untreated hardwood. The enhancement factor of HHV was 1.6 and 1.4 for non-oxidative and oxidative atmospheres, respectively. Under oxidative condition, the EMCI for untreated hardwood was highest (26.9) at 300°C and for treated hardwood was at (22.4) at 280°C.
HR-SEM images captured at the highest (320°C) and lowest (240°C) temperatures showed a more pronounced thermal degradation under oxidative conditions exhibited by the presence of more tubular shape structures with smoother walls, in the presence of NOE-7F. Results of thermogravimetry analysis showed that the decomposition of cellulose lowers from 0.757 wt%/°C (360 °C) to 0.67 wt%/°C (342 °C) in the presence of bio-solution, under non-oxidative and oxidative conditions, respectively. Compounds detected in the liquid fraction via HRGC/HRMS analysis were phenol (1), 2-methoxyphenol (2), 4-methylphenol (3), 2,6-dimethoxyphenol (4), 2-methoxy-4-methylphenol (5), 4-ethyl-2-methoxyphenol (6), 1,2,3-trimethoxybenzene (7), Guaiacol (8), Furfural (9), 3,4,5 Trimethoxytoluene (10), 4-hydroxy-3-methoxyphenyl acetone (11), 1,2 benzenediol (12) and 8-Nonenoic acid(13).
The kinetic analysis identified the non-isothermal torrefaction of A. Confusa hardwood to be pseudo -first order. When considering the addition of NOE-7F, the activation energy for decomposition of hemicellulose was decreased by 9.6% and 10.5% for non-oxidative and oxidative atmospheres, respectively. On the other hand, the activation energy for decomposition of cellulose was decreased by 3.1% and 4.4% for non-oxidative and oxidative atmospheres, respectively. This shows that addition of NOE-7F results in lower activation energy, especially for non-oxidative conditions.
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