Solvent Extraction Of Shenfu Coal And Study On Pyrolysis Characteristics Of Its Model Compounds

In this paper,Shenfu coal as the research object,using methanol,acetone,toluene and tetrahydrofuran(THF)four solvents,through Soxhlet and ultrasonic two ways to extract Shenfu coal small molecules.The extract and the residue were analyzed by FT-IR,GC/MS and TG-DTG.The structure and composition of the extract and the residue were studied,and the differences of the extracts were compared.The effects of extraction process on the pyrolysis behavior of coal and the activation energy of coal and raffinate were investigated.Finally,Py-GC-MS was used to study pyrolysis of four model compounds(Anthracene/ 3,5-dimethylbenzoic acid/ 4-aminophenol/ P-octylphenol)and the distribution of the products was detected online.The results show:(1)Shenfu coal using four kinds of solvents through Soxhlet and ultrasonic extraction of the extraction rate of the order of order: THF> acetone> methanol> toluene.The optimum ultrasonic extraction conditions were as follows: power 250 W,extraction time 2.0h.The effect of extraction on the extraction rate varies depending on the solvent,but in general Soxhlet extraction> Ultrasonic assisted extraction.(2)The functional groups in the residue are roughly the same,indicating that the macromolecule skeleton of coal is not destroyed.The four solvent extracts consist essentially of aliphatic,aromatic and heteroatom compounds.The aliphatic hydrocarbons are mainly C10~C24 n-alkanes,aromatic hydrocarbons are mainly alkyl-substituted benzene and naphthalene,heteroatom compounds are mainly oxygen-containing compounds.Ultrasonic extracts have more aliphatic hydrocarbons than Soxhlet extract,while Soxhlet extracts have more aromatic hydrocarbons than ultrasonic extraction.(3)The results show that the activation energy of the eight kinds of raffinate in the active phase of pyrolysis is lower than that of the raw coal.The activation energy of Soxhlet residue is larger than that of ultrasonic extraction,and the activation energy has a certain correlation with their extraction rate.(4)From the rapid pyrolysis of coal model compounds,anthracene is not cleaved at heating,but only a small amount of benzene ring rearrangement occurs,and the proportion of rearrangement increases with increasing temperature;The warming reaction helps the activation of the amino group during the pyrolysis of the oxygencontaining functional groups.The chain-like aliphatic hydrocarbon structure is a lively structure in weakly viscous coal,which is rich in pyrolysis reaction.With the increase of pyrolysis temperature,the type of product increases greatly,and the long chain is more active than short chain.