低变质煤结构分析及其与热解焦油产率关联性研究

Structure analysis of low rank coal and its correlation with pyrolysis tar yield

通过元素分析仪和固体13C-NMR检测6种不同低阶煤的组成和结构,采用Peak-fit软件对13C-NMR谱图进行分峰拟合并半定量计算煤样中各类型有机碳含量,由Matlab数学软件分析了影响焦油产率的有机碳结构类型。结果表明:①WCW、PLQ、JJM、TCG、HG和HF煤样中亚甲基碳分别占总脂碳含量的34.41%、34.29%、34.01%、44.78%、41.62%和49.94%,说明煤样结构中脂肪碳中亚甲基碳含量较多,脂链数N均小于9,说明连接在短链上的支链,主要以脂环侧链形式存在;②HF煤样的平均亚甲基碳数Cn=2.13,其余均小于2,WCW最小,仅为1.05,说明脂肪族以短链为主,链长一般在1~3个碳;③影响煤焦油产率的关键因素为亚甲基碳(I2)、带质子芳碳(I4)和烷链支链化度(I7)为辅助因素;二元组合I2和I4表现出良好的线性关系,三元组合I2、I5(酚羟基或醚氧连碳)和I7与焦油产率的关联性最大,其Radj^2=0.992;④不同煤样中镜质组含量从26.10%增至82.10%,易断裂桥键数n与脱氢含量WH分别从5.37增至8.17、3.24增加到5.92,交联桥键数P 0越小,交联反应程度越低,易断裂桥键数n和脱氢含量WH越大,交联桥键数P 0越小,焦油特征指数X tar越大,对焦油生成过程越有利。

The composition and structure of six different low-rank coal samples were determined via elemental analyzer and solid 13 C-NMR apparatus.The Peak-fit software was used to analyze the 13 C-NMR spectrum to semi-quantitatively calculate the ratio of different types of organic carbon in coal samples,and the influence of organic carbon types on tar yield was investigated by Matlab mathematical software.The results show that:(1)The content of methylene carbon in WCW,PLQ,JJM,TCG,HG and HF coal samples accounts for 34.41%,34.29%,34.01%,44.78%,41.62% and 49.94% of the total lipid carbon content,respectively.The content of methylene carbon in aliphatic carbon in coal sample structure is high,and the number of aliphatic chain N is less than 9,which indicates that the branched chain connected on the short chain mainly exists in the form of the alicyclic side chain.(2)The average methylene carbon number of HF coal sample is Cn=2.13,the rest are less than 2,WCW is the smallest,only 1.05,indicating that aliphatic group is mainly short chain and the chain length is generally 1-3 carbon.(3)Methylene carbon(I2)is the key factor that controls the coal tar yield,while proton aromatic carbon(I4)and proton with alkyl chain branched degree(I7)are as auxiliary factors.Binary combination of I2 and I4 show a good linear relationship with tar yield.The three-element composition of I2,I5(phenolic hydroxyl or ether oxygen carbon)and I7 has the greatest relevance of coal tar yield,and its Radj^2 is 0.992.(4)The vitrinite content in different coal samples increases from 26.10% to 82.10%,the number of fragile bridge bonds n and the dehydrogenation content WH increases from 5.37 to 8.17,3.24 to 5.92.The results show that the smaller the number of crosslinked bridge bonds P0 is,the lower the degree of crosslinked reaction is,the higher the number of brittle bridge bonds n and the dehydrogenation content WH is,the smaller the number of crosslinked bridge bonds P0 is,and the greater the tar characteristic index X tar is,and the more favorable the tar generation process is.