【作者】 李保民；

【导师】 魏贤勇；

【作者基本信息】 中国矿业大学 ， 化学工艺， 2008， 博士

【摘要】 水和甲醇是极性溶剂,在一定的温度下可溶解煤中的小分子极性化合物,而且在酸催化下可选择性地断裂煤骨架结构中的共价键,这对于认识煤结构与从煤中提取组分较单一的化学品都具有较重要的意义。以水和甲醇为溶剂,采用常压萃取和固体超强酸催化解聚的方法,以GC/MS和FTIR为分析手段,研究了4种中低变质煤的萃取率和萃取物组成。水的常压萃取结果表明:随着煤变质程度的降低,萃取率增加,而且含氧化合物含量增加;萃取物成分较简单,主要有4大类,分别为含杂原子化合物,芳烃,长链烯烃和长链烷烃,含氧化合物和长链烷烃占萃取物总量的绝大部分;水能够破坏煤大分子交联结构中的氢键并在一定程度上催化其中醚键的断裂反应;萃取物中有一定量的非极性化合物,这可能是溶到水中极性有机物和非极性有机物的分子间的相互作用的结果;由于水对煤的浸润性不强,不容易进入微孔和网络结构,因此,水溶出的是以游离态存在的部分小分子。甲醇对煤的浸润性强于水,溶剂分子易于接近煤表面或煤结构的大孔表面而进入微孔和网络结构。因此,甲醇的常压萃取有以下特点:萃取物中芳烃成分增加,酚类成分和烯烃化合物的含量也有所增加,长链烷烃含量较少。由此说明,煤结构中作为小分子的流动相中的芳烃和烯烃化合物主要存在于煤的微孔结构中,长链烷烃主要游离于煤或大孔表面,较少地居于微孔之中。所合成的超强酸SO₄^2-/ZrO₂（SZ）对所选煤模型化合物具有较高的催化活性;采用SZ催化煤解聚得到组分较单一且含量较高的酚类成分。酚是一种合成有机高聚物的单体。因此,这是一种从煤中获取单组分化学品的很好的方法。SZ催化煤解聚萃取物的种类和含量与煤种有关,变质程度低、含氧量高的煤种可获得高含量的酚类化合物。煤解聚产物中应有更大分子量的酚、酸和酯类化合物,但由于GC/MS检测范围的限制而没有被检测出来。极性溶剂能够溶解煤结构中以流动相存在的极性和非极性物质。极性物质的溶出是因为极性溶剂破坏了煤中原结构中的部分氢键;非极性物质的溶出可能是溶解到水中的极性有机物和煤中的非极性有机物的分子间的相互作用的结果。SZ催化煤解聚得到组分较单一且含量较高的酚类成分,这说明所研究煤样的煤大分子网络结构中存在较丰富的醚键和酯键,固体超强酸催化煤解聚是获得酚的有效手段。更多还原

【Abstract】 Water and methanol are polar solvents which can dissolve micromolecular polar compounds in coal at certain temperature and selectively break the covalent bonds of coal structure with the catalysis of certain acid, which is of great importance in both understanding of coal structure and extracting of relatively simply composed chemicals from coal. Taking water and methanol as solvents respectively and employing methods of extraction under normal atmosphere and super solid acidic catalyst depolymerization via analytical means of GC/MS and FTIR, we studied the extraction rate and composition of extracts from four medium and low ranks of coals.Results of extraction under normal atmosphere with water as solvent indicate that the lower the coal rank, the higher the extraction rate as well as the percentage of oxygenated chemicals. The extracts are simple, mainly including four major kinds of compounds, namely, heteroatom and aromatic compounds, long-chain alkane and alkene compounds, among which oxygenated chemicals and long-chain alkane compounds account for the majority. Water can break the hydrogen bond of the network structure inside coal macromolecules and can catalyze to fracture the ether bond to some extent. Interaction between the hydrated polar organic and non-polar organic possibly leads to a certain amount of non-polar compounds in the extracts. Since water has a ralatively low infiltrating rate to coal, it is not easy to enter the millipore and network structure. Thus what water can dissolve is part of micro- molecules at free state.Methanol has higher infiltrating rate to coal than water, so its molecule can readily approach coal surface or macro pore surface of coal structure before entering the millipore and network structure. Extraction under normal atmosphere with methanol as solvent is therefore characterized by the following features: aromatics take up a greater part among the extracts, which is also the case in phenols and olefin compounds while long-chain alkanes account for relatively low proportion. This shows that small-molecular aromatics and olefin compounds of the coal structure in the mobile phase mainly exist in the microporous parts of the coal, while the long-chain alkenes dissociates on the surface of the coal or the macroporous parts but seldom in the millipore.The synthesized super solid acidic catalyst SO₄^2-/ZrO₂（SZ） has a relatively high catalytic activity to the selected coal model preparaed. With catalysis of SZ, the coal was depolymerized to single composed phenolic compounds in high amount, which is a kind of monomer that can be used to synthesize organic polymer. The above method is therefore a good way to get single composed chemicals from coal. The type and quantity of the catalytical depolymerization extracts by solid super acid SZ are related to the type of coal. Higher yields of phenolic compounds can be obtained from low ranked and highly oxygenated coal. Phenols, acid and ester derivatives of larger molecular weight should have been detected in the depolymerized products without the restrictions of GC/MS detection range.Polar solvents can dissolve the polar and non-polar material in mobile phase in the coal structure. That cracking of part of hydrogen bond of the original coal structure owning to strong polar solvents is respossible for the dissolvement of the polar material, while the dissolvement of the non-polar material is a result of interaction between the polar organic and non-polar organic molecules that are dissolved in water. Super solid acid can be used to catalyse coal depolymerization to get single composed and the high amount of phenolic compounds. This implies that coal macromolecules network structure is rich for ether and ester bond and resorting to solid super acid to catalyzed coal depolymerization is an effective approach to obtain phenolic compounds.更多还原