Study On The Rule Of Composition And Structure Of Organic Small Molecules And Volatiles Of Macromolecules In All-rank Coals

To research the exsisting forms and distribution of small molecules in structure model of coals and the relationship between macromolecules and small molecules, twelve different degree samples, ranged from lignite to anthracite, were extracted by soxhlet, then the small molecules were analyzed by GC/MS, and the macromolecules were pyrolyzed and analyzed by TG-GC/MS. The result shows that:Lignites have the highest extraction rate(9.80%~12.10%), anthracite has the lowest(0.07%), and bituminous is the middle(2.00%~7.20%). The small molecules analyzed by GC/MS consist of n-alkanes, aromatic and oxygen-containing heteroatom compounds. N-alkanes mainly exist in low and middle rank bituminous, and it is most in lignite and low-rank bituminous; Aromatic mainly exist in bituminous, and it is concentrated in middle-rank coal. In addition, there is almost nothing texted in high-rank bituminous and anthracite. N-alkane distribution is gradually narrowed with coal dgree, and the number of highest carbon n-alkane is lower and lower. The number of fused rings of aromatic is from 2 to 5. It is first from large to small and then in the opposite with the coal degree. The theory of small molecules three forms, free state, microporous embedded state, network embedded state, adopts in all-rank coals.The pyrolytic volatiles of all-rank coals after 380 oC come from the macromolecules. And there are alkanes, olefins, heteroatom compounds, monocyclic and bicyclic aromatics as well as their alkyl substitution. Alkanes are most, secondly are aromatics and olefins, the least are heteroatom compounds moreover they only appear before 440 oC, but the others appear before 610 oC.There is some similarity brtween small molecues and pyrolytic volatiles of macromolecules on composition and Structure, but it’s not exactly the same. For example, the n-alkane distribution of the former is wider than that of the latter, and the number of fused rings of aromatic of the former is more than that of the latter, the last, the structure of heteroatom compounds of the former is more complex than that of the latter. But the relationship between them and coal degree is the same. It contains that the n-alkane and heteroatom compounds mainly distribute in lignites and low-rank bituminous, but the aromatic mainly distribute in middle-rank bituminous.