Study On Desulfurization Of Coking Coal And Changes Of Properties

In this paper, desulfurization of inorganic sulfur in XY1# by Fe2(SO4)3 and organic sulfur in XY2# by microwave chemistry method was studied. Properties changes of caking index and pyrolysis behavior were investigated after desulfurization as well. The result shows that pyrite of coal can be removed effectively by Fe2(SO4)3. The removal of pyritic sulfur could be inhanced by increasing concentration of Fe2(SO4)3, increasing reaction temperature, prolonging reaction time or decreasing particle size of coal.67.43% of pyritic sulfur can be removed under the optimal condition of this article. Microwave irradiation combined with NaOH treatment has a better effect on organic sulfur desulfurization of XY2# when compared with other chemical additives or single treatment respectively, which could remove 66.40% of organic sulfur in XY2#. The organic sulfur removal could be improved by prolonging reaction time, increasing microwave power, rising the ratio of solution to coal. With the increase of the concentration of NaOH, the removal of organic sulfur increased at first and then decreased, reached the maximum at 2.5mol/L. Caking index increased from 76.24 to 82.57, reaches the standard of "SCI"-strong caking index coal, the desulfurization rate reaches 11.01 %when added asphalt additives.The content of hydrogen increased slightly while carbon, ash and volatile decreased for XY1# after treatment; only oxydgen in XY2# increased because of oxidation during desulfurization. The maximum weight loss rate of XY2# still corresponded to 500℃ but maximum weight loss rate decreased from1.03%/min to 0.91%/min after treatment for pyrolysis analysis. FTIR shows intensity of peaks corresponding to pyrite in XY1# and that of organic sulfur in XY2$ decreased obviously. XPS shows 82.76% of thioalcohol and thioether, 67.74% of sulfone,32.76% of sulfoxide and 11.90% of thiophene in XY2# were removed, respectively.The sulfur removal sequence of different model compounds under the optimized desulfurization condition for coal as follows:Diphenyl disulfide≈n-Octadecylmercaptan> Diphenylsulfone> Dibenzothiophene. Sulfur in 1-Octanethiol could be removed by γ-FeOOH and desulfurization rate is proportion to molar ratio. XRD shows that γ-FeOOH turned into FeS and Fe3O4 after desulfurization.