净化沥青的傅里叶变换红外光谱分峰拟合定量分析

Quantitative Analysis of Refined Pitches by Curve-Fitting of Fourier Transform Infrared Spectroscopy Spectrum

高温煤焦油沥青是人造炭材料的优质原料。为了获得高品质人造炭材料,必须对原料沥青进行净化处理,使得净化沥青具有合理的分子量分布、较高芳香缩合度和适宜的脂肪族侧链结构,炭化后才能生成易于石墨化的趋于规整的碳微晶结构。分别以中温沥青和热聚合改性沥青为原料,采用两种净化分离处理方法,得到四种净化沥青(RP-1, RP-2, RP-3和RP-4)。以四种净化沥青的傅里叶变换红外光谱数据为基础,结合分峰拟合数学方法,准确获得了净化沥青的芳香性指数(Iar)、支链化指数(CH_3/CH_2)、 OH官能团的存在形式及分布情况和其他基础官能团含量。由分析研究结果可知,四种净化沥青均具有较大的芳香缩合度。RP-3芳香性指数高达0.90,芳香缩合度最高。RP-4支链化指数仅为0.07,脂肪族侧链数量较多、碳链较长。四种净化沥青中OH官能团存在形式有明显不同。研究结果将为人造炭/石墨材料的原料优选提供理论支持。

High temperature coal tar pitch is a kind of high quality raw material to produce carbon materials.However,coal tar pitches without refining treatment was not suitable to produce such high quality carbon materials.Actually,refining treatment is an important way to adjust the molecular weight distribution,aromatic structure,and aliphatic side chain structure of coal tar pitch.Refining treatment is a precondition to produce carbon materials which is easy to graphitize with coal tar pitch as the raw material.In this study,four kinds of refined pitches numbered as RP-1,RP-2,RP-3 and RP-4 have been obtained by two kinds of preparation methods with the medium pitch and modified pitch as the raw materials,respectively.The refined pitches have been studied by Fourier Transform infrared spectroscopy(FTIR)and curve-fitting analysis in order to gain additional information on the comparation of these four refined pitches.The curve-fitted data provide quantitative evidence of aromaticity(Iar),length of aliphatic chain(CH 3/CH 2),distribution of OH groups,and oxygen-containing functional groups with different refined pitches.The results have showed that:these four kinds of refined pitches has a larger aromatic condensation degree.RP-3 has the highest aromaticity index of 0.9.RP-4 has the Index of the branched chain of 0.07,which means that RP-4 have a long aliphatic chain.The distribution of OH groups in refined pitches was significantly different.The results can provide a theoretical support for the selected raw materials in the preparation of carbon/graphite materials.