Study On The Co-thermal Dissolution Of Shenfu Coal With Lignin And Related Model Compounds

In this thesis, the behaviors of co-thermal dissolution of Shenfu(SF) coal and lignin were studied. The influence of temperature, solvent, and addition ratio of lignin on co-thermal dissolution were disscussed. Simultaneously, the thermolysis behaviors of coal-related model compounds were investigated, and various analyses and characterizations of co-thermal dissolution soluble fractions, residue and thermolysis products were performed.The results show that the co-thermal dissolution yield of SF coal and lignin increased with the increase of extraction temperature until to 360℃. Further rising the temperature to 380℃, the thermal dissolution yield significantly decreased. With the temperature rising, the thermolysis can be intensified, thus the co-thermal dissolution yield increased. Futher increasing the temperature, the thermal condensation reaction of radical fragments occurs, and heavy products are formed, which hardly dissolved in solvents, resulting in the decrease of the co-thermal dissolution yield.CMNO is a more effective thermal dissolution solvent than 1–MN. When the co-thermal dissolution of SF coal and lignin were conducted at a mixed ratio 1:1 by mass, the highest co-thermal dissolution yields of SF coal and lignin were 73.8% in 1-MN, and 77.0% in CMNO, respectively. Since CMNO is a polar solvent, it can break the strong cross- links in the coal, which the non-polar solvent 1-MN can’t dissociate, resulting in the increase of the thermal dissolution yield. The thermal dissolution process had an obviously de-ashing effect, almost all of the ash was transferred into the residue. Co-thermal dissolution of SF coal and lignin shows that there exists synergistic effect, which is the function of temperature.The synchronous fluorescence spectrometry analysis showed that the main structural units of the co-thermal dissolution soluble fractions mainly contained low rings aromatic hydrocarbon structure, such as monocyclic ring, bicyclic ring and tricyclic ring and also little aliphatic hydrocarbon structure. From the IR analysis of different co-thermal dissolution soluble fractions and residues, it showed that the compositions of co-thermal dissolution soluble fractions were greatly impacted by the solvent characteristics, thermal dissolution temperature. The dissolution of oxygen containing functional groups increased with the polarity of solvent increasing or the thermal dissolution temperature rising, and more aromatic structures dissolved in the solvent.The thermolysis performance of coal-related model compounds of different bond energy is quite different. Benzyl phenyl ether easily thermolysis, benzyl ether is next, dibenzyl has a little difficult to thermolysis, but diphenyl ether does not thermolysis. When the reaction temperature is 390℃, addition 10% of the lignin can promote the thermolysis of dibenzyl to increase the conversion, improved by 3.5%. But it is no effect to Diphenyl ether, which needs high temperature to thermolysis. When addition of small amount of phenol in the thermal dissolution of SF coal, it was found that phenol had a little promoting effect for the thermal dissolution of SF coal.