Study On Co-liquefaction Of Xilinguole Lignite And Biomass

The behaviors of liquefaction of Xilinguole lignite using water as solvent were studied in this thesis.The effects of solvents,hydrogen sources,blending ratio of biomass,catalysts and other conditions on the co-liquefaction properties of lignite with biomasses were investigated,and the liquefaction products were characterized.The results showed that under the present experimental conditions,the maximum liquefaction conversion and oil+gas yield were 76.76% and 50.94% respectively when the liquefaction of lignite was carried out with THN as solvent,suggesting that Xilinguole lignite had a higher liquefaction activity.The liquefaction performances were different at different reaction conditions when water was used as solvent.The optimal liquefaction conditions were obtained as 420℃,60 min,5% K2CO3 catalyst(mass fraction to lignite),and the initial pressure of CO 2MPa.The liquefaction conversion and oil+gas yield were 53.70% and 48.29% respectively when liquefaction carried out under this optimal condition.When the co-liquefactions of Xilinguole lignite with lignin were carried out at 360℃,the liquefaction conversion and oil yield were increased as the increasing of the addition ratio of lignin.When using ethanol/formic acid as solvent,the oil yield of co-liquefaction was 37.68%,which increased 6.38% compared to that of solvent ethanol.The liquefaction performance was better for formic acid as an in-situ hydrogen donor than that for H2.When the catalyst was reduced ore(prepared by in-situ hydrogen reduction),the catalytic performance was more active at 400℃ than that at 360℃.At 360℃,the reduced ore catalyst had no significant effect on the liquefaction conversion,but the oil yield increased to 8.49%.There was hardly synergistic effect to be observed in the co-liquefaction.At 400℃,the reduced ore displayed higher catalytic activity,the co-liquefaction conversion and oil yield increased 10.44% and 14.22% respectively than those at 360℃.Comparing with theoretical calculated values,the liquefaction conversion and oil yield increased 12.48% and 6.56% respectively,suggesting that there existed synergistic effect in the co-liquefaction at 400℃ with the reduced ore catalyst.In addition,the catalytic performance of the reduced ore was much better than that of the raw ore.In the case of co-liquefaction of Xilinguole lignite with corn stalk without catalyst carried out at 360℃,the highest oil yield(43.95%)was obtained at ethanol/formic acid system and lignite/corn stalk ratio 1:1.Under K2CO3 catalyst,the oil yield increased abviously,and synergistic effect was observed by the increase of oil yield compared to the theoretical calculated value.When the reduced ore was used as catalyst,the catalytic liquefaction performance was better at high temperature.At 360℃,the oil yield increased 9.20% by the reduced ore compared to without catalyst,but synergistic effect was not observed in the case.At 400℃,the liquefaction conversion and oil yield increased 10.76% and 10.92% respectively under the reduced ore compared to those of no catalyst use state.Compared with theoretical calculated values,the liquefaction conversion and oil yield increased 6.92% and 5.45% respectively,suggesting that there existed synergistic effect in the case,and the reduced ore was more active under higher temperature 400℃.Characterization of liquefied products suggested that the addition of biomass in the liquefaction of lignite promoted the break of weak bonds and pyrolysis of coal,and increased the amounts of light constituents in the co-liquefaction oil.It can also promot more coal components converting into co-liquefaction oil,suggesting that addition of biomass can promote the liquefaction of lignite.