褐煤热萃取物的热解特性与热解产物分子结构关联性研究  

Study on the Correlation Between Pyrolysis Characteristics and Molecular Structure of Lignite Thermal Extract

作　　者：闫立东[1] 朱亚明[1] 程俊霞[1] 高丽娟[1] 白永辉 赵雪飞[1] YAN Li-dong;ZHU Ya-ming;CHENG Jun-xia;GAO Li-juan;BAI Yong-hui;ZHAO Xue-fei(College of Chemical Engineering,University of Science and Technology Liaoning,Anshan 114051,China;State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering,Ningxia University,Yinchuan 750021,China)

机构地区：[1]辽宁科技大学化学工程学院,辽宁鞍山114051 [2]宁夏大学省部共建煤炭高效利用与绿色化工国家重点实验室,宁夏银川750021

出　　处：《光谱学与光谱分析》2023年第3期962-968,共7页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(U1361126);辽宁省自然科学基金项目(2021-MS-306,2021-BS-245);辽宁省教育厅基金项目(2020LNQN03,LJKZ0309);省部共建煤炭高效利用与绿色化工国家重点实验室开放课题(2022-K41);辽宁科技大学优秀青年基金项目(2021YQ06)资助。

摘　　要：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(E_(a)),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),E_(a)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(I_(1)~I_(6))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I_(1)(支链化程度)、I_(2)(含氧量)、I_(3)(芳香性指数)、I_(4)(芳环五元取代)、I_(5)(三、四元取代)及I_(6)(二元取代)等六种分子结构参数密切相关,且热解活化能与I_(1),I_(3)和I_(6)三种参数呈现良好的线性关系(拟合后R^(2)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E_(a)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E_(a)=124.91-88.75I_(1)-318.84I_(2)-19.19I_(3)+40.29I_(4)-14.28I_(5)+1 272.33I_(6)(R^(2)高达0.999 9)。基于热重红外联用技术,剖析CPW的热解E_(a)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(E_(a)) 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(I_(1)~I_(6)) 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(I_(1)), aromaticity index(I_(3)), degree of substitute(I_(6)), and the linearity R^(2) is 0.903 4, 0.

关 键 词：热解萃取 FTIR分峰拟合 分子结构参数 热解特性 

分 类 号：TQ522.65[化学工程—煤化学工程]