Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part VII. Raman spectroscopic study on the changes in char structure during the catalytic gasification in air
Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part VII. Raman spectroscopic study on the changes in char structure during the catalytic gasification in air
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DOI：
10.1016/j.fuel.2006.01.011
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发表时间：
2006-07-01
期刊：
影响因子：
7.4
通讯作者：
Li, Chun-Zhu
中科院分区：
文献类型：
--
作者：
Li, Xiaojiang;Hayashi, Jun-ichiro;Li, Chun-Zhu
FT-IR/拉曼光谱已被用于识别维多利亚褐煤焦在400℃空气中气化过程中的结构特征。拉曼光谱的反卷积使我们能够确定焦中与O-2发生优先反应的主要结构位点。Na和Ca催化剂的存在改变了碳和O-2之间的反应途径。在没有催化剂的情况下，煤焦在气化过程中形成的含o官能团与芳香族结构密切相关，因而容易使芳香族结构松动。非催化气化是缓慢的，并且发生在一些特定的位点上(特别是富含sp(3)或sp（2)-sp(3)混合物），分布在整个焦炭中。在催化剂（Na或Ca）的存在下，含o的官能团在整个炭中与主芳族结构不紧密结合。催化气化反应被定位在与催化剂相关的位点上。较小的芳环体系的优先去除和交联结构在催化剂存在下的持续存在意味着较大的芳环体系越来越集中，柔韧性小，影响了催化剂的分散。(C) 2006 Elsevier Ltd版权所有。
FT-IR/Raman spectroscopies have been used to identify the structural features of Victorian brown coal chars during the gasification in air at 400 degrees C. The deconvolution of the Raman spectra has allowed us to identify the main structural sites in char where preferential reaction with O-2 takes place. The presence of Na and Ca catalysts is shown to alter the reaction pathways between char and O-2. In the absence of a catalyst, the O-containing functional groups formed in char during gasification were closely associated with the aromatic structure and thus tended to loosen the aromatic structure. The non-catalysed gasification was slow and took place on some specific (especially sp(3)-rich or sp(2)-sp(3) mixture) sites distributed throughout the char. In the presence of a catalyst (Na or Ca), the O-containing functional groups were not closely associated with the main aromatic structure throughout the char. The catalytic gasification reactions were localised on the sites associated with the catalysts. The preferential removal of smaller aromatic ring systems and the persistence of cross-linking structures in the presence of a catalyst mean that the large aromatic ring systems were increasingly concentrated with little flexibility, affecting the dispersion of catalyst. (C) 2006 Elsevier Ltd. All rights reserved.