【作者】 马延平；

【导师】 曾凡桂；

【作者基本信息】 太原理工大学 ， 矿产普查与勘探， 2012， 硕士

【摘要】 煤中非共价键作用的研究可以看出,煤分子之间及其与溶剂间的非共价键作用具有一个显著的特征：非共价键广泛存在且分子间的作用具有选择性。从超分子化学角度,可以认为这些结构为超分子实体,它们具有超分子结构的基本特征,如确定的结构和构象。同时煤在Cdaf=87%,Vdaf=29%,R0m=1.3%出现第二次煤化作用跃变,伴随着此次跃变,煤萃取率达到最大值。因此要想认识第二次煤化作用和萃取之间的关系,则必须深入认识煤的微观结构。近年来计算机辅助分子设计(Computer-Aided Molecular Design, CAMD)技术在煤大分子结构研究中的广泛应用,不但可以方便的构建某一特定煤的大分子结构模型,而且还可以了解其三维立体结构,同时在分子力学、分子动力学和量子化学等研究的基础上,认识煤的微观结构参数,以及不同变质程度煤在微观结构上的差异性。因此,本文以柳林3#镜煤吡啶抽提残煤(柳林3#原煤的Cdaf=88.18%,Vdaf=25.49%,R0m=1.294%)和抽提沥青质为研究对象,采用13C CP/MAS NMR和XPS对其结构分析,获得残煤和沥青质的结构特征,构建计算13C CP/MAS NMR计算谱图能够与实验谱图较好吻合的模型。在此基础上应用分子力学和分子动力学方法构建了煤的超分子结构。主要结论如下：1柳林3#残煤结构中芳香碳原子主要以蒽的形式存在。脂肪碳以很短的侧链形式存在,在结构中起到联接芳香结构单元的作用。氧主要是以酚羟基和醚氧键的形式存在,同时还有羰基。2沥青质的芳香部分主要以萘和蒽的形式存在,脂肪侧链很长,氧主要以酚羟基的形式存在,同时存在少量的羰基和羧基。3稳定的柳林3#残煤大分子结构能量按其大小排序依次为范德华能、键扭转能、键角能与键伸缩能。在该结构模型中,芳环之间的平行排列所占比例很小,这可能是煤在镜质组反射率1.3%左右发生物理化学性质转折的结构因素所致。通过添加周期性边界条件得到该煤的密度为1.22g/cm3。量子化学半经验方法(AM1)模拟结果表明：脂肪侧链中的C-C键较长,因而活性较高；边缘碳原子带有较多的负电荷,而芳香碳原子所带电荷较少,稳定性高。沥青质结构中芳环之间的平行排列在该结构模型中所占比例较小,通过添加周期性边界条件得到其密度为1.15g/cm3。4由于沥青质和残煤组合形式的不同,导致超分子中的平行构型所占比例各异。沥青质+沥青质和残煤+残煤组合的结构模型显得紧凑,而沥青质+沥青质+残煤+残煤结构中平行构型所占比例少,可见沥青质的存在对柳林3#煤超分子的构型存在影响。超分子形成过程的模拟结果表明,其主要作用力是芳香层片之间的相互作用。此外,超分子形成过程的识别现象还受脂肪侧链等的影响,这些脂肪支链可以起到空间排斥和范德华力相互吸引的作用,进而影响到超分子的形成过程；在沥青质中出现的脂肪侧链会影响到超分子的大小,进而影响其密度的大小；芳香层片之间的相互作用强,同时脂肪侧链的干扰少,超分子的形成过程就相对容易。脂肪侧链影响了氢键的数目以及其它具有方向性作用力的大小。5非共价键能在分子构型中起到了至关重要的作用,尤以范德华力最为显著；极性基团形成的静电能较范德华力小,表明极化作用并非超分子形成的关键因素。价键能的组成分析可以发现键扭转能最大,其次为键角能,而键反转能最小,这是因为在能量最小化构型中键的扭转和键角的变化是煤大分子具有立体构型的基础。不同组合超分子识别过程中,静电能的变化不是很明显,可能是由于超分子的形成不受静电力的影响所致。6应用XRD分析得到柳林3#原煤构型中d002、La和Lc的平均值分别为3.50A、12.30A和12.40A,与理论模拟超分子构型得到的3.5A、11.435A和12.20A基本吻合。7根据柳林3#原煤的抽提率(9.93%),在建立柳林3#超分子构型时保持残煤和沥青质分子1：5的比例,研究表明沥青质和残煤的相对位置会影响到超分子构型,超分子构型中不但出现了芳香层片之间平行构型,还出现了垂直构型。更多还原

【Abstract】 By the non-covalent research in coal, the interaction between coal molecule and solvent has a significant characterization that not only non-covalent interaction exists, but also the recognition interaction can be found. In terms of the supramolecular chemistry, these structures can be seen as supramolecular entity. They have the basic features of the supramolecuar structure, such as the fixed structure and configuration. The second coalification jump occurs on the condition of Cdat=87%,Vdaf=29%,Rm0=1.3%. With this coalification, the coal in this rank has the highest extraction. So in order to understand the relation between extraction and the second coalification, it is essential to insight into the microscopic structure of the coal.In recent years, computer-aided molecular design (CAMD) technology has been widely used in the coal macromolecular structure. It not only can easily build the model of a particular coal macromolecular structure, but also understand their three-dimensional structure. The microstructure parameters of the coal and the microstructure difference of different ranks coal also can be understood on the basis of reseach of molecular mechanics, molecular dynamics and quantum chemistry. Therefore, the pyridine extracted residue of vitrain from Linlin3#(Cdaf=88.18%,Vdaf=25.49%,Rm0=1-31%) and extraction are the objects of study. The coal samples are studied by13C CP/MAS NMR and XPS analysis. Macromolecular structure models are constructed based on the results of proximate and ultimate analysis.13C chemical shift of macromolecular structure is calculated by ACD/CNMR predictor, and the structure is corrected according to the calculation results. Finally the macromolecular structure which is consistent with the experimental results is gotten. On the basis of the two models, the supramolecule is constructed. The main conclusions are as follows:1In the LLR model, aromatic structure units are dominated by anthracene; Aliphatic C atoms exist in the form of side-chain, it connects the aromatic structure; O atoms mainly exist in the form of-OH and-O-, which contain a small amount of C=O.2In the asphaltenes, aromatic structure units are dominated by naphthalene and anthracene; Aliphatic C atoms exist in the form of side-chain, which are very long. Oxygen exists in the form of phenolic hydroxyl; meanwhile there is a small amount of carbonyl and carboxyl.3The order of main energy for stable LLR model is van der waals energy> torsion energy> angle energy>bond energy. The simulation results also showed the aromatic layer structure tend to be parallel occupies a small proportion, this may be the structure factors that the physical and chemical properties of the coal whose vitrinite reflectance is1.3%take a new turn. LLR density is1.22g/cm3by enclosing coal model into the (PBC) periodical boundary condition. Semi-empirical quantum chemistry methods (AM1) simulation indicates that the C-C bonds adjacent to aliphatic side chain C atoms exhibit a higher activity and terminal C atoms have more negative charge, which therefore prone to undergo oxidation reactions while aromatic C atoms are characterized by fewer charges and very high stability. Also in the asphaltenes model, the aromatic layer structure tend to be parallel occupies a small proportion, and its density is1.15g/cm3.4Due to the difference of the combination of the residual coal and asphaltenes, the aromatic layer structure has different proportion in the supramolecular structure. In particular, the model (asphaltenes+asphaltenes+residual coal+residual coal) is disorganized, while the model (asphaltenes+asphaltenes and residual coal+residual coal) is terse. So the presence of the asphaltenes effects the Linlin3#supramolecular configuration. The molecular mechanical calculations of the supramolecular model show that the main drive interaction in the supramolecualr formation is the attraction between the aromatic planes. The molecular recognition is completed with the contribution from other atomic groups present in the molecule, such as the alkyl branches. These alkyl groups contribute to the formation of the supramolecular formation through the combined effect the steric repulsion and the van der Waals attraction. The side-chain in the asphaltenes affects the size of the supramolecular model and its density. The strong interaction between the aromatic layer of the two molecules and less interference of the aliphatic side-chain causes the supramolecular formation process easy relatively. It was also found that the alkyl branches limit the number of available active sites for H-bonding and other directional interactions.5The non-covalent bond in the molecular conformation plays a very important role, especially the Van der Waals force. In the medium-rank coal, the Van der Waals force is the driving interaction in the supramolecular formation. The electrostatic contribution arising mainly from the polar groups is small in all cases, showing that polarity does not seem to play an important role in the formation.6By the XRD analysis, the average values of the d002, La and Lc is3.50A,12.30A and12.40A, which are consistent with the theoretical result (3.5A,11.435A and12.20A).7Due to the etraction rate of9.93%in Liulin3#raw coal, the raw coal consists of five residual coal molecules and one asphaltene. The relative of the residual coal molecules and asphaltene affects the formation of the supramolecualr structure, besides the perpendicular geometry can be found.更多还原