Influence of steam pretreatment on coal composition and devolatilization
Influence of steam pretreatment on coal composition and devolatilization
复制标题
DOI：
10.1021/ef00014a017
复制
发表时间：
1989-03
期刊：
影响因子：
5.3
通讯作者：
M. R. Khan;Wei-yin Chen;E. Suuberg
中科院分区：
文献类型：
--
作者：
M. R. Khan;Wei-yin Chen;E. Suuberg
先前的研究表明，用蒸汽预处理煤可以提高煤热解过程中的液体产率。本研究的目的是表征经过蒸汽和氦气处理的煤，以更好地了解预处理对热解产率和成分的影响。预处理的样品在快速和慢速加热反应器中热解。使用以下表征技术来分析产物：元素分析、傅里叶变换红外光谱、气相色谱/质谱和交叉偏振/魔角旋转13C核磁共振光谱。这项研究表明，低阶煤的蒸汽处理降低了煤中甲氧基、酚类、脂肪族羰基和羧基的浓度。低阶煤经过蒸汽处理后，总氧浓度显着降低，而高阶煤的氧含量没有变化，甚至更高。经过蒸汽预处理后，酚类是所用水中的主要成分。蒸汽预处理增加了 Wyodak 煤的芳香度。蒸汽处理并没有提高任何煤的真空热解的总挥发物产率。低阶煤在蒸汽处理后快速热解时焦油产量增加，但这些增加似乎是以总挥发物产量为代价的。当蒸汽处理的煤以缓慢的加热速率脱挥发分时，无论是低阶煤还是高阶煤，都没有观察到焦油产量的增加。
Previous studies have shown that pretreating coal with steam can enhance the liquid yields during coal pyrolysis. The objective of this research was to characterize steam-and helium-treated coals to better understand the effects of pretreatment on pyrolysis-produced yield and composition. Pretreated samples were pyrolyzed in rapid and slow heating rate reactors. The following charac-terization techniques were used to analyze the products: elemental analysis, Fourier transform infrared spectroscopy, gas chromatography/mass spectrometry, and cross-polarization/magic-angle-spinning 13C nuclear magnetic resonance spectroscopy. This research demonstrated that steam treatment of a low-rank coal reduces the concentration of methoxy, phenolic, and aliphatic carbonyl and carboxyl groups in the coal. The low-rank coal showed significant reductions in total oxygen concentration after steam treatment, but the high-rank coals showed unchanged or even higher oxygen content. After steam pretreatment, phenols were the major components found in the water used. Pretreatment with steam increased the aromaticity of Wyodak coal. Steam treatment did not enhance total volatile yields from vacuum pyrolysis for any of the coals. Low-rank coals showed increases in tar yields when pyrolyzed at a rapid rate after steam treatment, but these increases seemed to be at the expense of total volatilesyield. When steam-treated coal was devolatilized at a slow heating rate, no increase in tar yield was observed for either a low-or a high-rank coal.