Study On The Catalytic Hydrogenation Of Lignite And Related Model Compounds

To investigate the hydrocracking mechanism of bridge bond in low rank coal from the molecular level is the theory foundation for the efficient utilization and controllable transformation of low rank coal. In this paper, the model compounds related to structure of low rank coals were used to study the hydrocracking mechanism of、-O-O、C-C, and bridge bond. The interaction between C-O and-C- bridge bond during the liquefaction was also investigated. The effects of reaction temperature, liquefaction atmosphere, hydrogen donor solvent and catalyst type on the hydro-liquefaction behaviors of lignin were studied. The liquefaction products obtained from the liquefaction of lignin were analyzed by GC-MS. Finally the co-liquefaction behaviors of different coal with lignite witch contains large number of weak bonds were studied.The experimental results show that, in the conditions of 400 oC, 5 Mpa initial hydrogen pressure and 1h reaction times, C-O bridge bond is much easier cleavage than C-C bridge bond. The hydrocracking activities of four types of bridge bonds follow the order:-C-O- >-O-O- >-C-C- >-C-. It is discovered that the addition of DBE can promote the conversion of DPM. Ni/AC and Ni-Mo/AC catalyst show high activities for the conversion of DPM, when Ni/AC or Ni-Mo/AC catalysts were added into the mixture system of DBE and DPM, DPM’s conversion rate was increased by 40%~50%, but the ratio of DBE/DPM had no significant effect on the products distribution. THN plays a role of hydrogen donor solvent during the liquefaction, THN hydrogenation properties were strengthened in the presence of catalyst. Catalyst can promote the activity for hydrogenation of model compounds, and the different activity compounds have different catalytic properties.It was found that lignin conversion rate was first increased with temperature and then decreased. the conversion rate reached the highest at 400 oC(conversion rate was 83%),,H2 has little effect on enhancing the conversion rate of wood. The addition of THN can significantly improve the conversion rate of lignin(Increased by 23%). Hydro-liquefaction conversion of lignin was obviously promoted by Ni/ZSM-5, lignin hydro-liquefaction of conversion rate reached to 83.17% When Ni loading of Ni/ZSM-5 was 10%. The liquefaction of lignin conversion from liquid oil fractions were analyzed by GC-MS, found that the product is mainly the alkyl substituted compounds, and a small amount of substituted phenols.It was found that different ratio of Shengli(SL) lignite and lignin co-liquefaction showed a trend of increaseing on the total conversion rate, liquefaction conversion rate was higher than the theoretical value by 9.1%, when Shengli lignite and lignin ratio was 1:1. When the ratio of Shengli lignite and Xiaosong(PS) meager lean coal co-liquefaction rate was 1:5, 1:1 and 5:1, experiment results showed that the three kind of proportion of total conversion rate was higher than the theoretical value. The total conversion rate was 12% higher than the theoretical value when the ratio of Shengli lignite and Xiaosong meager lean coal was 5:1, the formation of HS was also promoted. When Shengli lignite and subbituminous(SF) coal ratio was 1:5, 1:1 and 5:1, co-liquefaction experiment results showed that the three kind of ratio had no effect on the total conversion rate, it also had no effect on Generation of HS. When Shengli lignite and Datun(QM) coal ratio was 1:5, 1:1 and 5:1, co-liquefaction experiment results showed that the three kind of ratio had a certain effect on the total conversion rate, The conversion rate increased by 5%, it also had no effect on Generation of HS.