摘要
为了研究玉米秸秆水热炭化过程及固体目标产物特性的演变规律,在高温高压反应釜中,进行反应温度为180-290℃、停留时间为8 h的水热炭化实验研究。研究发现,随反应温度的升高,玉米秸秆固体水热焦产率从180℃时的71%逐渐下降至290℃时的36%,而C质量分数从玉米秸秆原料中的44.86%增加至72.36%,O质量分数从原料中的44.2%下降至15.36%,明显提高了其能量密度。至290℃时,水热焦的H/C和O/C原子比分别为0.88和0.16,接近于煤的H/C和O/C原子比,高位热值高达29.79 MJ/kg。水热焦中特征官能团随温度升高而减少,而C=C、C=O和芳香特征峰红外吸收逐渐增强,同时热重分析表明水热焦热稳定性逐渐提高。元素组成和傅里叶红外光谱分析表明玉米秸秆经水热炭化处理,低于230℃时主要经历脱水和脱羧反应,而高于230℃以后,以缩聚反应和芳香化为主。
Corn stover is a major agricultural waste,it is abundantly available across China,and its annual production was about 200 million tons in recent years. However,there were limited reports on hydrothermal carbonization of corn stover in the past few years. Thus,corn stover was chosen as the precursor for hydrothermal conversation of the present work. To explore the hydrothermal carbonization process of corn stover and chemical,energetic properties of hydrochar,corn stover was hydrothermally treated at different reaction temperatures from 180℃ to 290℃ for 8h. The results showed that with the increase of reaction temperature,the hydrochar yield was reduced from 71% at 180℃ to 36% at 290℃,and the carbon content of hydrochars was increased from 44. 86% of feedstock to 72. 36% at 290℃.Simultaneously,when the reaction temperature was increased,the oxygen content of hydrochars was obviously decreased,which was reduced from 44. 2% of feedstock to 15. 36% at 290℃,thus energy density of hydrochars was clearly increased. When the reaction temperature was up to 290℃,the hydrochar exhibited coal-like oxygen / carbon and hydrogen / carbon atomic ratios,and the higher heating value reached 29. 79 MJ / kg. Compared with the feedstock,functional group of hydrochars was decreased when the reaction temperature was enhanced. However,the characteristic peaks of C=C,C=O and aromatic functional group in Fourier transform infrared（ FTIR） spectra were strengthened. The thermal stability of hydrochars was also increased in thermogravimetry（ TG） analysis. Elemental components and FTIR analyses suggested that corn stover during hydrothermal carbonization mainly underwent dehydrationand decarboxylation reactions when the operating temperature was below 230℃,however,the process was governed primarily by condensation polymerization and aromatization when the temperature was above 230℃.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2016年第4期180-185,共6页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(51206194)
河南省高等学校青年骨干教师项目(2013GGJS-115)
郑州市科技攻关计划项目(153PKJGG130)
关键词
玉米秸秆
水热炭化
傅里叶红外光谱
热重分析
corn stover
hydrothermal carbonization
Fourier transform infrared spectra
thermogravimetry analysis
