Effect Of Hydrothermal And Solvent Swelling Treatment And Iron Catalysts On The Liquefaction Of Shenhua Coal

At present it has been a main research issue to improve the liquefaction reactivity of coal to moderate the liquefaction conditions and increase the oil yield. In this paper, the experiments were carried out in an autoclave to investigate the effects of pretreatment by 1-Butyl-3-Methyl-Imidazolium Tetrafluoroborate ([BMIM][BF4]), 1-Butyll-3-Methyl-Imidazolium trifluoromethanesulfonate([BMIM][TFO]) and some other solvents on direct liquefaction of Shenhua coal as well as the iron, sulfur role in the process of liquefaction.TG/DTG curves show that Shenhua coal exhibits its maximum weight loss rate at about 430℃, and the existance of Fe catalyst increases the weight loss of SH coal pyrolysis from 35% to 60% and widen its major decomposition range. Addition of Fe in coal during the thermal treatment is benefit to break the hydrogen bond and other non-covalent bonds. Fe can also restrains regressive reaction occurs from oil.Results of The thermal and hydrothermal pretreatments of Shenhua coal change the cross-linking structure of Shenhua coal, especially the strength and distribution of non-covalent bonds such as hydrogen bond. The conversion increased by 2% after thermal treatment at 250℃due to the formation of new non-covalent and covalent bond cross link in the process of thermal treatment under higher temperature, in which the devolatilization and the pyrolysis occur obviously. Solvent swollen coals have much lower pyrolysis activation energies than raw coal. The liquefaction conversion of NMP swollen coal enhanced 10.8%. [BMIM][BF4] can effectively promote the reactivity of coal by changing the coal structure after thermal and swelling treatment. Much more light liquid products can be obtained at less severe liquefaction condition when [BMIM][BF4] serves as solvent or catalyst.The major role of the iron in coal liquefaction is promoting the formation of activated hydrogen and increasing the oil yield and coal conversion. The main sources of activated hydrogen include thermal and catalytic cracking of solvent and H2. The major transfer approach of activated hydrogen is from molecular hydrogen to solvent and then from solvent to coal. Sulfue has significantly positive effect on the liquefaction process. Addition of sulfur is helpful for converting heavy product to oil. Sulfur has also a favorable role in supplying more activated hydrogen from gas to liquid products.