瘦煤化学结构表征及分子模型构建

Chemical structure characterization and molecular model construction of lean coal

为了高效清洁利用高阶煤,以瘦煤为研究对象,通过X射线光电子能谱(XPS)和固体核磁共振碳谱(^(13)C NMR)实验表征方法对瘦煤的元素赋存形态以及碳原子结构进行了表征分析,构建了瘦煤大分子模型,并对其进行结构优化。结果表明:瘦煤分子的芳香结构由1个萘、8个蒽、1个四连苯、1个芘、2个吡啶、2个吡咯以及1个噻吩构成;含氧结构包括2个环内氧接脂碳,2个氧取代芳碳以及1个羰基碳;脂肪烃则由2个脂甲基、3个芳甲基、2个亚甲基以及4个次甲基组成;最终构建的瘦煤大分子模型为C_(200)H1_(40)O_(5)N_(4)S;初始模型经优化后,煤分子的价电能和非键能都有所下降,但最终模型中煤分子的价电子能比非键能要高,是总能量的主要部分;从煤表面对不同气体所能提供的吸附空间角度来讲,煤中CO_(2)气体的吸附优势要强于CH_(4)气体。

In order to utilize high-rank coal efficiently and cleanly,based on Shanxi lean coal,this paper explores the molecular structure characteristics of lean coal and constructs a molecular model of lean coal.In this paper,X-ray photoelectron spectroscopy(XPS)and solid-state nuclear magnetic resonance carbon spectroscopy(^(13)C NMR)were used to characterize and analyze the element occurrence and carbon atom structure of lean coal,and a macromolecular model of lean coal was constructed and optimized.The results showed that the molecular aromatic structure of lean coal was composed of 1 naphthalene,8 anthracene,1 tetraphenylene,1 pyrene,2 pyridine,2 pyrrole and 1 thiophene.The oxygen-containing structure includes two intramolecular oxygenbonded aliphatic carbons,two oxygen-substituted aromatic carbons and one carbonyl carbon.Aliphatic hydrocarbons are composed of 2 fatty methyl groups,3 aromatic methyl groups,2 methylene groups and 4 methylene groups.The final macromolecular model of lean coal is C_(200)H1_(40)O_(5)N_(4)S.After the initial model was optimized,the valence energy and non-bond energy of coal molecules decreased,but the valence electron energy of coal molecules in the final model was higher than that of non-bond energy,which was the main part of the total energy.Therefore,from the point of view of the adsorption space that the surface of lean coal can provide for gas,the adsorption advantage of CO_(2)gas in lean coal is stronger than CH_(4) gas.