Experimental Research On The Catalytic Hydrogenation Of Shenfu Long Flame Coal

Low-rank coal refers to lignite,low metamorphic bituminous coal(long flame coal,non-caking coal and weak caking coal).Low-rank coal reserves are abundant,accounting for 55% of national coal resources.At the same time,most low-rank coals have the characteristics of low ash,low sulfur.However,they are not currently used as conventional coking coal because they are not or weakly caking.Even in the presence of strong caking coal,the blending ratio generally does not exceed 5%.Therefore,improving the caking property of low-rank coal through experimental methods as coking coal can not only ease the shortage of coking coal and promote high-value utilization of low-rank coal.In this paper,different initial hydrogen pressure,reaction time and reaction temperature and co-catalyzed hydrogenation of long-flame coal and biomass were carried out in batch high-pressure reactors.The solvent extraction,TD-DTG,infrared analysis,GC-MS,and electron paramagnetic resonance were used to characterize the structure of the modified coal,and the mechanism of hydrogenation and thickening of long-flame coal was analyzed.The main results obtained are as follows:1.At a reaction temperature of 370 ℃ and an initial hydrogen pressure of 4 MPa,after 50 minutes of catalytic hydrogenation of longflame coal,the structure of the coal changed significantly.The oxygencontaining functional groups such as-OH,C-O,and COO-in the coal,and alkyl side chains and bridges decreased.The reduction of the bond structure reduces the formation of the cross-linked structure of the coal molecules and increases the fluidity of the coal molecules.The caking property of the long flame coal is significantly improved,and the caking index of the modified coal is increased from 0 to 78.There is a linear relationship between the modified coal caking property and the sum of the asphaltene and pre-asphaltene yields.2.The catalyst can promote the depolymerization of coal molecules and improve the coal conversion,the asphaltene and oil yield.By calculating the hydrogen consumption under a nitrogen atmosphere,the catalyst can promote the hydrogen transfer from tetralin to the coal molecules;the main role of the catalyst is to improve The activation of hydrogen in hydrogen,and the total hydrogen consumption in the reaction from the amount of tetralin and hydrogen are equal.3.Compared with long flame coal hydrogenation alone,cohydrogenation of biomass and long flame coal can improve long-flame coal caking property under mild conditions.The addition of biomass can reduce the initial pyrolysis temperature of long-flame coal and increase the maximum thermal weight loss rate.The difference in the content of lignin in biomass is responsible for the different caking-increasing effects.The phenoxy groups produced by lignin attack coal molecules and increase the degree of coal depolymerization in the reaction,and then the hydrogen radicals from the biomass and the solvent and hydrogen stabilizes coal free radicals,thereby increasing the asphaltene and pre-asphaltene contents of the modified coal.Thermogravimetric experiments of long-flame coal,pine sawdust,long-flame coal,and pine sawdust mixtures have found that there is a synergy between long-flame coal and pine sawdust during pyrolysis.At 360 ℃,3 MPa,pine sawdust,and 1:1 reaction conditions,the long flame coal caking index increased from 0 to 80.4.The mechanism of hydrogen transfer during the catalytic hydrogenation of long flame coal was experimentally studied.The results showed that hydrogen in tetralin was easier to stabilize radicals than hydrogen without catalyst addition,therefore the main path of hydrogen transfer was from tetralin to coal molecules;after adding a catalyst,hydrogen is more likely to stabilize coal radicals to form light components than tetralin,and tetralin inhibits the transfer of hydrogen in hydrogen and the coal molecules depolymerization,coal radicals preferentially absorb highly active hydrogen in the radical reaction,therefore the hydrogen transfer path is directly from hydrogen to coal molecules.5.By analyzing the sem images of coke obtained under the same reaction conditions and different amounts of modified coal,it is known that as the proportion of modified coal gradually increases,the cell structure on the coke surface develops well.The porous structure on the coke surface forms it is related to the escape of volatile substances in coal during carbonization.During the carbonization process,the modified coal is equivalent to a thermal binder,and the long-flame coal and the modified coal undergo pyrolysis fusion.The softened and molten binder is adsorbed on the surface of the long-flame coal,and the formed colloid aggregates the coal particles.