吡啶预处理抑制煤热解过程中交联反应的研究

Suppressing cross-linking reactions during pyrolysis of lignite pretreated by pyridine

采用吡啶蒸气、吡啶溶液两种溶胀方式对伊泰褐煤进行了预处理,用热重结合在线质谱仪考察了两种处理方式对煤热解过程中交联反应的抑制效果。结果表明,两种预处理方法对煤热解过程的交联反应都有不同程度的抑制,但其作用温度和机理不同。吡啶蒸气预处理可能通过与煤形成N—OH氢键、断开煤本身含氧官能团之间的氢键,从而在400℃以前抑制煤本身含氧官能团之间的氢键交联反应;吡啶溶液预处理主要是通过改变煤的结构,减少煤小分子同大分子网络结构之间缔合,提高氢的传递效率等因素来抑制小分子同煤大分子网络结构及其热解过程中间碎片之间的交联反应。

A Chinese lignite Yitai （YT） was pretreated by pyridine vapor and pyridine solvent. The effects of the treatments on the pyrolysis behavior of the pretreated coals were studied by thermogravimetric mass spectrometry （TG-MS）. The results showed that both treatments could suppress the cross-linking reactions （CLRs） during pyrolysis of the treated coal, but the suppressing temperature range and mechanism were different. Some inherent hydrogen bonds （HBs） in the coal were broken by pyridine vapor treatment and new stronger N--OH HBs were formed. Thus, low temperature CLRs （ below 400 ℃ ） that were related to the hydrogen-bonded COOH--COOH and COOH--OH were suppressed. However, pyridine solvent pretreatment influenced the pyrolysis behavior by reducing the association interactions between the low molecular weight compounds and macromolecular network, thus, relaxing the three-dimensional network of coal and enhancing the transmission efficiency of hydrogen in coal.