低阶煤快速干馏焦油渣中的煤沥青提取及其表征

Extraction and characterization of coal pitch from tar residue of rapid distillation of low rank coal

高品质煤沥青是制备炭材料的优质原料,从低阶煤快速干馏焦油渣(DDTR)中提取高品质煤沥青对提高低阶煤的清洁、高附加值利用具有重要意义,而煤沥青分子结构信息的准确获取则可有效指导其高附加值利用。为了回收DDTR中的富碳有机物(煤沥青),分别以洗油(WO)、四氢呋喃(THF)和正丁醇(BA)作为溶剂对DDTR进行萃取后得到WOS、THFS和BAS共3种煤沥青。结合煤沥青的工业分析、元素分析结果,通过傅里叶变换红外光谱(FTIR)结合分峰拟合、核磁共振氢谱(1 H-NMR)、气相色谱联用质谱(GC-MS)、热重分析(TGA)和热重红外联用(TG-FTIR),分别对3种煤沥青的基团组成、芳香性、分子结构、热解行为和氧化行为进行详细研究。结果表明:煤沥青的芳香性和分子量是影响软化点(SP)、结焦值(CV)、甲苯不溶物(TI)和热解行为的重要因素,且呈正相关。其中,WOS的着火点较高且氧化过程强烈,适合氧化改性,而THFS则相反。萃取得到的3种煤沥青几乎都不含喹啉不溶物(QI)且芳香性指数(f_(a))均大于0.70,属于高品质的煤沥青。

High quality coal pitch is a high quality raw material for the preparation of carbon materials.The extraction of high quality coal pitch from tar residue of rapid distillationof low rank coal(DDTR)is of great significance to improve the clean and high added value utilization of low-rank coal,and the accurate acquisition of molecular structure information of coal pitch can effectively guide its high added value utilization.In order to recycle the carbon-rich organic matter(coal pitch)from DDTR,three kinds of coal pitches named as WOS,THFS and BAS have been obtained by the extraction of DDTR with the washing oil(WO),tetrahydrofuran(THF)and n-butanol(BA)as the solvents,respectively.Combined with the results of proximate analysis and elemental analysis of coal pitch,Fourier transform infrared spectroscopy(FTIR)combined with curve-fitted analysis,hydrogen nuclear magnetic resonance spectroscopy(1 H-NMR),gas chromatography-mass spectrometry(GC-MS),thermogravimetric analysis(TGA)and thermogravimetric infrared(TG-FTIR)were adopted.The group composition,aromaticity,molecular structure,pyrolysis behavior and oxidation behavior of the three coal pitches were studied in detail.The results show that the aromaticity and molecular weight of coal pitch are the important factors affecting softening point(SP),coking value(CV),toluene insoluble(TI)and pyrolysis behavior,they are positively correlated.WOS has a high ignition point and intense oxidation process,which is suitable for oxidative modification,while THFS is the opposite.The three kinds of coal pitches are almost contain no quinoline insoluble(QI)and the aromatic index(f a)is greater than 0.70,which can be classified as high quality coal pitch.