逐级酸处理对锡盟褐煤的结构及热解特性的影响

为了探讨高硫褐煤提质利用中酸洗处理对煤质特性的影响,以内蒙古锡盟褐煤为研究对象,依次用HF、HNO₃和HCl的酸溶液进行预处理,对原煤及其酸处理样品进行了傅里叶变换红外光谱的煤结构表征、程序升温差热-热重实验的煤热解特性研究及其反应过程的动力学分析。结果表明,HF处理对煤样的结构影响不大,HNO₃的处理明显改变了HF处理后煤样中有机质的结构,HCl处理又使HNO₃处理引起的煤样中脂肪基团CH₃的吸收峰强度变化减弱;逐级酸处理对锡盟褐煤的热解特性存在一定的影响,HF和HNO₃处理对褐煤的热解反应性具有促进作用,HCl处理对其热解反应性的影响不大。动力学分析显示,不同过程酸预处理对褐煤热解过程的影响不能单独采用热解过程的总包反应活化能进行描述,热解活化能不仅与指前因子存在着补偿效应,也与热解阶段的失重量存在一定的关联。

Effect of fractional step acid treatment process on the structure and pyrolysis characteristics of Ximeng brown coal

To investigate the effects of acid pretreatment on the structure and pyrolysis performance of brown coal with high sulfur content,the brown coal from Ximeng,Inner Mongolia was selected,and leached by HF,HNO3 and HCl solution step by step.The pyrolysis performance and structure characteristics of Ximeng raw coal and different acid treatment coal samples were studied in detail by means of thermal gravimetric analysis and FT-IR technique,and the pyrolysis kinetics was also analyzed.The results show that the structure of coal sample is not significantly affected by the HF treatment process,but an obvious organic structure change is found in the coal samples further treated by HNO3 solution.The intensity variation of absorption peaks of aliphatic groups CH3 caused by HNO3 is weakened by the HCl treatment process.The pyrolysis performance of Ximeng brown coal can be changed by the fractional step acid treatment.HF and HNO3 treatment processes promote the reactivity of coal pyrolysis,and the further treatment of HCl solution only has a slight influence.The kinetics analysis of coal pyrolysis reveals that the effect of different acid treatments on the pyrolysis characteristics of Ximeng brown coal can not be described only by the apparent activation energy of pyrolysis reaction.There is a compensation effect between pyrolysis activation energy and pre-exponential factor,besides,the pyrolysis activation energy relates to the weight loss of coal pyrolysis.