Study On Catalytic Thermal Dissolution Of Xilinguole Lignite And Hydro-liquefaction Of The Thermal Dissolution Soluble Fraction

In this dissertation,the effects of different temperature,catalysts and solvents on the thermal dissolution(TD)properties of Xilinguole(XLGL)lignite were studied.The effect of BF₃/SBA-15 catalyst on the TD properties of XLGL lignite under different solvents was emphatically investigated.The structure of thermal dissolution soluble fractions(TDSFs)was analyzed and characterized.The effects of different liquefaction reaction temperature and catalysts on hydroliquefaction properties of different TDSFs were probed.The catalytic hydrogenation and liquefaction properties of Ni-Mo-S/Al₂O₃catalysts to different TDSFs were especially focused,and the liquefaction products were characterized and analyzed.The results suggest that the four catalysts all have a certain promoting effect on the TD of XLGL lignite,and the catalytic activity is in order of BF₃/SBA-15>Fe S+S>SO₄^2-/Zr O₂=Fe₂O₃.At 360?,the TD yield of BF₃/SBA-15 was the highest,and the TD yields of CMNO,1-MN+10%CH₃OH and 1-MN were 39.5%,58.6%and 28.6%,which were higher of 17.1%,16.4%and 12.7%than those without catalyst respectively.The results suggested that the catalyst could improve TD activity of coal.It was found out that CMNO contained indoles and other polar components which could break the weak cross-linking bonds in coal,and CH₃OH in 1-MN could produce alcohololysis reaction with coal.Catalysts can promote the two kinds of reactions,resulting in the increase of the TD yield obviously.On the other hand,1-MN is a non-polar solvent,and the TD is mainly controled temperature,resulting in its relatively lower TD yield.The TDSF obtained with 1-MN+10%CH₃OH and BF₃/SBA-15 catalytic TD at360?gave the highest yield of liquefied oil(CHS)as 33.1%after catalytic hydrogenation under Ni-Mo-S/Al₂O₃ with cyclohexane as solvent at 360?.This is because the aromatic condensation degree of this TDSF is lower and the aliphatic hydrocarbon content is higher,which is benifical for the hydro-liquefaction of TDSF.CHSs were dominated by 1?2 ring aromatic compounds.The content of saturated cycloalkanes in CHS obtained by liquefaction of TDSF at 320?was 6.12%,which was slightly higher than that of 5.07%in CHS obtained by liquefaction of TDSF at 360?.The hydroliquefaction performance of TDSF was affected by the acidity and hydrogenation activity of the catalyst.The hydroliquefaction activity of three catalysts used were in the order Ni-Mo-S/Al₂O₃>Ni/ZSM-5>Cu-Ni/Al₂O₃.Temperature has a great influence on hydro-liquefaction of TDSF.In the presence of catalyst Ni-Mo-S/Al₂O₃and tetrahydronaphthalene as hydrogen donor solvent,the yield of CHS increased gradually with the increase of the liquefaction temperature from 280?to 400?,and the maximum was 60.4%obtained at 400?.This suggests that the increase of temperature is benifical for the breaking of some covalent bonds such as the C-C bridge bonds in the structure of TDSF,resulting in the decomposition of TI and TS converting to small molecular oil.The content of saturated cycloalkanes in CHS decreased with the increase of liquefaction temperature,and the maximal content of saturated cycloalkanes in CHS was 13.5%obtained at 280?,suggesting that low temperature hydrogenation is favorable to saturate hydrogenation of aromatics.Therefore the hydro-liquefaction of TDSF at low temperature can be used to produce the potential jet fuel.