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基于量子化学计算的煤低温氧化放热强度 被引量:1

Exothermicity of coal during low temperature oxidation process based on quantum chemical calculation
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摘要 煤分子结构是影响煤氧化放热特性的根本原因。以水峪(SY)烟煤为研究对象,采用量子化学计算与工业和元素分析、傅里叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)、程序升温、差示扫描量热等相结合的方法,构建并优化SY煤的三维分子模型,并对煤的低温氧化放热强度进行研究。研究成果如下:SY煤的变质程度较高,其中碳元素主要以四取代的芳香烃和环烷烃形式存在,氮和硫元素主要以具有芳香性的吡咯和噻吩形式存在;碳氧官能团中醚氧键(C—O)、羰基(C=O)和羧基(COO—)的比例约为1.5∶1∶1.5,煤中氢键主要以羟基自缔合氢键为主。构建SY煤三维层状结构模型的分子式为C_(203)H_(140)O_(18)N_(2),分子量为2 893.01,确定煤低温氧化过程中的6种活性基团分别为:■;在煤的低温氧化阶段,前3种活性基团未发生开环反应,主要生成环己酮和H_(2)O,后3种活性基团可发生多步反应至最终产物为CO和CO_(2)。基团发生彻底氧化反应生成CO和CO_(2)的反应热分别为ΔH_(2)=-591.88 kJ/mol、ΔH_(3)=-7_(18).10 kJ/mol,未发生彻底氧化反应的最小反应热为ΔH_(min)=-366.99 kJ/mol,最大反应热为ΔH_(max)=-535.07 kJ/mol;结合耗氧速率、CO产生速率和CO_(2)产生速率,可计算得到SY煤在不同低温氧化阶段的放热强度,与差示扫描量热实验所得放热强度相比,计算值和实验值基本一致,说明采用量子化学方法计算煤放热强度的可行性。 The molecular structure is the fundamental factor affecting the oxidation exothermic properties of coal.Shuiyu(SY)bituminous coal was characterized by the combination of quantum chemical calculation,proximate and ultimate analysis,fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),and temperature programmed and differential scanning calorimetry experiment.The three-dimensional molecular model of SY coal was constructed and optimized,and the low-temperature oxidation exothermicity of coal was studied.The results were as follows:the metamorphism degree of SY coal was high,in which the carbon elements mainly existed in the form of tetra-substituted aromatics and cycloparaffin,and the nitrogen and sulfur elements mainly existed in the form of aromatic pyrrole and thiophene.The ratios of ether-oxygen bond(C-O),carbonyl group(C=O)and carboxyl group(COO-)in the carbon-oxygen functional groups were about 1.5∶1∶1.5,and the hydrogen bonds in coal were mainly self-associated by hy-droxyl.The molecular formula of SY coal three-dimensional layered structure model was defined as C_(203)H_(140)O_(18)N_(2)(mo-lecular weight is 2893.01),during the low-temperature oxidation process,the six active groups in coal were determined as:■,respectively.In the low-temperature oxidation stage of coal,the first three active groups did not occur ring-opening reaction,and mainly generated cyclohexanone and H_(2)O,while the last three active groups underwent multi-step reactions and the final products were CO and CO_(2).During the above oxidation reaction,the reaction heats of the complete oxidation reaction to generate CO and CO_(2) were ΔH_(2)=−591.88 kJ/mol and ΔH_(3)=−7_(18).10 kJ/mol,while the minimum reaction heat of the incomplete oxidation reaction was ΔH_(max)=−366.99 kJ/mol,and the maximum reaction heat was ΔH_(max)=−535.07 kJ/mol.Combined with the O_(2) con-sumption rate,CO generation rate and CO_(2) generation rate,the exothermicity of SY coal in different low-temperature ox-idation stages could be calculated.Compared with the exothermicity measured by differential scanning calorimetry experi-ment,the calculated value was basically consistent with the experimental value.It indicates the feasibility of using quantum chemistry method to calculate the exothermicity of coal.
作者 高飞 白企慧 贾喆 滕弋非 李应迪 GAO Fei;BAI Qihui;JIA Zhe;TENG Yifei;LI Yingdi(School of Safety Science and Engineering,Liaoning Technical University,Huludao125100,China;Key Laboratory of Mine Thermodynamic Disasters and Control of Ministry of Education,Liaoning Technical University,Huludao 125100,China)
出处 《煤炭学报》 EI CAS CSCD 北大核心 2023年第9期3428-3440,共13页 Journal of China Coal Society
基金 国家自然科学基金面上资助项目(51874161)。
关键词 放热强度 低温氧化 煤结构 量子化学计算 活性基团 exothermicity low-temperature oxidation coal structure quantum chemistry calculation active group
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