神府煤热解的结构变化及煤焦加氢反应性研究

Structural changes of Shenfu coal in pyrolysis and hydrogasification reactivity of the char

将煤加氢过程分解为原煤热解和焦加氢两个过程,在固定床反应器内研究了煤热解和焦加氢反应。采用红外气体分析仪、拉曼光谱仪和X射线衍射仪,分析研究了煤热解过程中气体组分含量与煤焦微观结构变化的相互关系以及煤焦微观结构对其加氢反应特性的影响。结果表明,热解温度对煤焦的微观结构和加氢反应性有较大影响,400-800℃,随着温度升高,煤焦拉曼分峰面积比A_(D1)/A_G、A_(D2)/A_G、A_(D3)/A_G、A_(D4)/A_G均上升,A_G/A_(All)减小。800-900℃,A_G/A_(All)增大,无序碳的相对含量增加,石墨化进程明显。煤焦的XRD分析与拉曼光谱分析结果一致。400-800℃,随着温度升高,煤焦中碳结构晶面间距d_(002)先增加后减小,堆垛高度L_(002)增加,晶面间距与堆垛高度比d_(002)/L_(002)减小,煤焦中石墨碳结构的含量增加。800-900℃,d_(002)减小,L_(002)明显增大。采用拉曼分峰比(aA_(D1/G)+bA_(D2/G)+cA_(D3)/G+dA_(D4/G))与加氢反应性特征参数τ_(0.5)进行线性拟合,得到代表碳微晶结构加氢反应性的拟合因子,且拟合因子越大,相应碳微晶的加氢反应性越好。

Coal hydrogasification,divided into coal pyrolysis and char hydrogasification,was studied in a fixed bed reactor. FT-IR gas analyzer,Laser Raman analyzer and XRD were applied to analyze the relationship betw een gas production component of coal pyrolysis and microstructure change of char,and the influence of microstructure change of char on char hydrogasification reactivity. The results show that pyrolysis temperature has an obvious effect on microstructure and hydrogasification reactivity of char. With rising temperature,the ratios of Raman band area AD1/AG,AD2/AG,AD3/AG,AD4/AGgradually rises,and the ratio of AG/AAlldecreases within400-800 ℃ and increases within 800-900 ℃. It indicates that graphitization process of char is obviously emerged due to the increase of relative amount of disordered carbon in pyrolysis. The results of XRD analysis are in accordance with those of Raman analysis. The interplanar crystal spacing d002 increases within 400-800 ℃. d002 decreases and L002 increases sharply within 800-900 ℃. By fitting the Raman area ratio formula（ aAD1/G＋bAD2/G＋cAD3/G＋ dAD4/G） with hydrogasification reactivity（ τ0.5）,the obtained factor represents the hydrogasification reactivity of carbon microcrystal. The factor is bigger,and the reactivity of carbon microcrystal is better.