Quantitative Analyses of Chemical Structural Change and Gas Generation Profile of Coal upon Heating toward Gaining New Insights for Coal Pyrolysis Chemistry
Quantitative Analyses of Chemical Structural Change and Gas Generation Profile of Coal upon Heating toward Gaining New Insights for Coal Pyrolysis Chemistry
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DOI：
10.2355/isijinternational.isijint-2018-816
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发表时间：
2019-01-01
影响因子：
1.8
通讯作者：
Norinaga, Koyo
中科院分区：
文献类型：
--
作者：
Fukuoka, Tetsuya;Takeda, Norihiro;Norinaga, Koyo
煤在热解过程中，伴随着气体的释放，煤的化学结构发生了演化变化。焦炭的化学结构变化和气体生成特征对焦炭的粘结性和强度、粒度等物理性能有重要影响。然而，固体焦的挥发分分析和结构分析大多是单独进行的，很难将两者联合收割机结合起来，从机理水平上对煤的热分解过程有定量的认识。在这项研究中，同时分析了热处理的煤的固体化学结构和气体生成剖面进行了两种煤，在同一条件下热解。采用四极杆质谱仪和光谱方法（NMR和FT-IR）进行在线气体分析，分别用于定量评价气体形成特性和固体化学结构。对所获得的信息进行了综合分析，为煤热解机理提供了新的认识。本文提出了一种定量分析煤热解过程中可转移氢的方法。它包括芳族簇生长，羟基的分解，以及氢气和热解水释放到气相中的定量评估。所提出的方法表明，在热解过程中表现出可塑性的烟煤具有3.5 mol/kg-煤的可转移氢，而次烟煤（非粘结性煤）的可转移氢的量在高达500 ℃的热解过程中为1.3 mol/kg-煤。
Chemical structure of coal is evolutionary changed during pyrolysis that accompanies gas release. The chemical structural change and gas formation profiles play important roles in determining caking property and physical properties such as strength and size of the resultant coke. However, analyses of volatile components and structural analysis of solid char have been mostly performed individually, and it is difficult to combine both and to obtain quantitative understanding on the thermal decomposition of coal at mechanistic level. In this study, simultaneous analyses of solid chemical structures of the heat treated coals and gas formation profiles were conducted for two kinds of coals that were pyrolyzed at an identical condition. On-line gas analysis with a quadrupole mass spectrometer and spectroscopic methods (NMR and FT-IR) were employed for quantitative evaluation of gas formation characteristics and solid chemical structure, respectively. The information obtained were then integrated to acquire new insight for coal pyrolysis mechanism. Here an approach to quantify the transferable hydrogen that contributes to stabilize radicals formed in pyrolyzing coal was proposed. It includes the quantitative assessment of aromatic cluster growth, decomposition of hydroxyls, and releases of hydrogen and pyrolytic water into gas phase. The proposed approach suggested that a bituminous coal that exhibits plasticity during pyrolysis had 3.5 mol/kg-coal transferable hydrogen, whereas the amount of transferable hydrogen of the sub-bituminous coal, a non-caking coal, was 1.3 mol/kg-coal, during pyrolysis up to 500 degrees C.