Study On The Kinetics Of Shenfu Coal And Its Thermal Dissolution Soluble Fractions Liquefaction

The effects of different temperatures and solvents on thermal dissolution(TD) of Shenfu(SF) coal were studied in this thesis, and the TD behavior of SF coal was investigated. Then the kinetics of SF coal and TD soluble fractions(TDSFs) liquefaction catalyzed by Ni-Mo-S-Al2O3 were also studied. In addition, the TDSFs, TD insoluble fractions and the liquefied products were characterized by FTIR and elemental analyses.The results showed that the TD process could deash effectively, the TDSFs were nearly ashless. When 1–methylnaphthalene(1–MN), which is a non-polar solvent was used as extraction solvent at the temperature 320 to 360℃, the TD soluble yield(TDSY) of SF coal increased with the TD temperatures rising. The maximum TDSY was got at 360℃. Further increasing the temperature, the TDSY decreased contrarily. It is because the pyrolysis of SF coal begin at 360℃, resulting to the TDSY getting to the maximum. However, at higher temperature 380℃, the condensation reactions take place, leading to the TDSY decreased.The TDSY obviously increased when methanol(MT) was added into 1-MN at 360℃, and the TDSY was 67%. This is due to the alcoholysis reaction occurred between MT and –OH groups in coal structure. The TDSY with CMNO was higher up to 8% than that with 1-MN at 360℃, because CMNO is a mixed polar solvent, it can break the cross-linking structure of coal macromolecule associated by –OH groups, making the TDSY to be increased.The kinetic models of SF coal and TDSFs liquefaction catalyzed by Ni-Mo-S-Al2O3 were set up in this thesis, the models included reciprocal transformation between coal, preasphaltene(PA), asphaltene(AS) and oil in the process, the models integrated such as the series reactions, parallel reactions and regressive reactions. Based on the SF coal and TDSF liquefaction kinetic model set up, the activation energies of SF coal calculated ranged from 125 kJ/mol to 244 kJ/mol, while the activation energies of 1-MN 360℃ TDSFs were 63-135 kJ/mol. It indicated that the TDSFs had higher liquefaction activity than raw coal When MT was added into 1-MN, the activation energies of the obtained TDSFs were 79-146 kJ·mol-1, they were higher than that without MT, it indicated that the liquefaction activity of TDSFs decressed with MT added. For TDSFs from different temperatures, the reaction rate constants of the TDSFs from lower temperature were faster,and the activation energies were lower, it indicated that the TDSFs from lower temperature had higher liquefaction activity than the TDSFs from higher temperature.The SF coal and TDSFs liquefaction models set up in this thesis were proved to be reasonable, FTIR of liquefied products obtained from SF coal and TDSFs liquefaction catalyzed by Ni-Mo-S-Al2O3 at different temperatures. The results showed that there existed obvious regressive reactions at higher liquefaction temperatures. Comparing the reaction processes of the SF coal liquefaction and TDSFs liquefaction, it was found that the mechanisms of SF coal and TDSFs liquefaction catalyzed by Ni-Mo-S-Al2O3 were different. At higher temperature, there existed the condensation reactions of preasphaltene and asphaltene to coke in SF coal liquefaction process, this reactions nearly appeared in TDSFs liquefaction process.The liquefaction products of TDSFs contained more aliphatic groups such as –CH3,-CH2, less Oxygen-containing functional groups, but the liquefaction products of coal contained more aromatic groups, this was the main reason which leading to the difference of liquefaction activity.