低阶煤的热解萃取处理是低阶煤高附加值利用的有效方法之一, 开展低阶煤热萃取物的热解特性研究, 对低阶煤清洁、 高效转化具有重要意义。 采用热重分析与红外光谱联用(TG-FTIR)技术, 结合分峰拟合数学方法, 开展褐煤热萃取物(CPW)热解过程活化能与热解逸出气分子结构参数的关联性探索。 以CPW为研究对象, 采用非等温动力学方法开展热解动力学研究, 运用无模式函数法(Flynn-Wall-Ozawa法和Kissinger-Akahira-Sunose法)计算CPW不同转化率(α)下的活化能(Ea), 得到热解过程(0.20≤α≤0.80)的活化能介于94.04和177.40 kJ·mol-1范围之内, 平均活化能为130.01 kJ·mol-1, Ea的大小随转化率提高而增加; 采用PeakFit软件对不同α下热解逸出气红外光谱的四个区域(700~900, 1 100~1 800, 2 800~3 000和3 000~3 100 cm-1)进行分峰拟合, 获得CPW热解逸出气分子中官能团信息和各官能团相对含量, 引入六种结构参数(I1~I6)用来描述逸出气的分子结构, 探索CPW在转化率为0.20≤α≤0.80范围内的热解活化能与各结构参数之间的关联性。 研究结果表明: CPW各热解阶段的活化能与相应的I1(支链化程度)、 I2(含氧量)、 I3(芳香性指数)、 I4(芳环五元取代)、 I5(三、 四元取代)及I6(二元取代)等六种分子结构参数密切相关, 且热解活化能与I1, I3和I6三种参数呈现良好的线性关系(拟合后R2分别为0.903 4, 0.744 7和0.803 1); 对同一转化率下热解活化能Ea与逸出气的六种分子结构参数整体进行线性回归分析, 得到结构参数模型为Ea=124.91-88.75I1-318.84I2-19.19I3+40.29I4-14.28I5+1 272.33I6(R2高达0.999 9)。 基于热重红外联用技术, 剖析CPW的热解Ea与热解逸出气官能团变化规律, 深入了解CPW在热解过程中的演变规律, 有助于明晰CPW的热解过程和热转化行为, 为褐煤的高附加值利用提供一定理论依据。

Pyrolysis extraction was one of the effective ways of high value-added utilization of low-rank coal. It was significant to clarify the pyrolysis characteristics of a thermal extraction for clean and efficient conversion of low-rank coal. The relationship between pyrolysis activation energy and the molecular structure of escaped gas in Lignite extract (CPW) has been researched by the technology of a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR) and the method of peak fitting. In this work, the CPW has been used as the raw material, and the non-isothermal kinetics of CPW was studied by the TG method. Under the condition of equal conversion rate without considering the reaction mechanism, the pyrolytic activation energy (Ea) of CPW was calculated and analyzed using the Flynn-Wall-Ozawa method and Kissinger-Akahira-Sunose method. The results indicated: that the pyrolytic activation energies of CPW ranged from 94.04 to 177.40 kJ·mol-1 when the conversion rate (α) was between 0.2 and 0.8, and the average value of activation energy was 130.01 kJ·mol-1. Moreover, with the increase conversion rate, activation energy also increased. The Peak Fit software was used to perform peak fitting of the infrared spectra of CPW in four regions of 700~900, 1 100~1 800, 2 800~3 000 and 3 000~3 100 cm-1 to achieve the fine structure information about various functional groups. In addition, six molecular structure parameters (I1~I6) were introduced to characterize the relationship between molecular structure and pyrolysis activation energy of CPW when the conversion rate was 0.20≤α≤0.80. The results showed that: It is closely related to molecular structure and pyrolysis activation energy of CPW during the different reaction stages. It showed a good linear relationship between the pyrolysis activation energy and molecular structure parameters, including the degree of branching (I1), aromaticity index (I3), degree of substitute (I6), and the linearity R2 is 0.903 4, 0.744 7 and 0.803 1, respectively. The six molecular structure parameters and pyrolysis activation energy (Ea) were analyzed by linear regression at the same conversion rate. The fitting relationship model between the Ea of CPW and the molecular structure indexes was shown as follows: Ea=124.91-88.75I1-318.84I2-19.19I3+40.29I4-14.28I5+1 272.33I6 (R2 up to 0.999 9). Based on the TG-FTIR experiment, the molecular structure parameters and pyrolysis activation energy of CPW were analyzed, which helped to clarify the pyrolysis process and thermal conversion behavior of CPW. They provided the certain theoretical basis for the high value-added utilization of lignite.