Characteristics of heteroatomic structural portions in soluble organics from coal liquefaction residue

Coal liquefaction residue is a typical solid waste in coal chemical industry. However,the coal liquefaction residue is of high content of soluble organics and rich in condensed aromatic structure,thereby is considered to be the valuable heavy carbon resources. In this study,the isometric methanol/toluene mixed solvent was used to extract soluble organics from coal liquefaction residue by the ultrasonic-Soxhlet synergetic extraction at mild condition,based on the good solubility of coal liquefaction residue in organic solvents. Then the soluble organics was oxidized according to sequential ruthenium ion catalyzed oxidation,combined with gas chromatography/mass spectrometry analysis,the molecular structural characteristics of heteroatomic structure units in soluble organics were revealed,thereby to provide supporting information for its clean conversion and higher valuable utilization. Among the CLR-soluble organics(CLR-SO)from coal liquefaction residue,the heteroatom species in acid compounds containing heteroatom are mainly oxygen,nitrogen and sulfur,and the functional groups are methoxy,carbonyl,ether bridge bond,nitro,amino,acetonitrile,indole,phenazine,thiocarbonyl,etc. In addition,esters containing nitrogen,sulfur,fluorine and other heteroatoms were also detected. In addition to oxygen-containing compounds,other heteroatom compounds appear in the oxidation products 3. Heteroatom structure exists in the macromolecular framework of CLR-SO,which is protected by the electron cloud of the surrounding aromatic rings during the oxidation process,preferentially oxidizes the aromatic ring structure around the molecular framework of CLR-SO. In addition to acids and esters,other compounds containing heteroatoms were also detected in the oxidation products of CLR-SO,which were mainly distributed in the oxidation products 3 and oxidation products 4,and most of them were found in the oxidation products 4. In addition,heteroatoms such as chlorine and fluorine were detected in the molecular framework of CLR-SO in the form of covalent bonds. In summary,in this paper,through step-by-step selective oxidation,the molecular structure of organic matter is stripped layer by layer,more structural unit fragments are obtained,and the heteroatomic structure information in CLR is enriched.