Effects Of Metal Ions On The Release Of Sulfur-Containing Gases During Pyrolysis Of Model Compounds And Coal

With the development of social economy,a serie of environmental problems were caused during the process of exploitation and utilization of middle and high sulfur coal.More and more attention has been paid to the coal pyrolysis,as it can be used as a single pre-combustion pretreatment process in improving coal utilization efficiency and pollutant control.To a certain extent,the directional migration of sulfur in coal can be realized by the co-pyrolysis of coal and additives.In this paper,the effects of metal ions on the release of sulfur-containing gases from model compounds and coal pyrolysis are studied,which can provide the basic theoretical basis for the comprehensive utilization of middle-high sulfur coal and the effective control of sulfur-containing pollutants.In this study,at first,Py-GC technology was used to quantitatively investigate the effects of different ion species and concentrations on the release of sulfur-containing gases during pyrolysis of sulfur-containing model compounds.Then,Fe³⁺was selected as the additive,and its influence on the release of sulfur-containing gases during pyrolysis of model compounds was qualitatively analyzed by Py-MS.On this basis,three coal samples with different types of sulfur content were selected to investigate the effects of internal ash in coal and the Fe³⁺additive on the release of sulfur-containing gases.The main conclusions are drawn as follows:?1?Different ion species have different effects on the release of sulfur-containing gases during pyrolysis of model compounds.Compared with K⁺,Na⁺and Ba²⁺,the effect of Fe³⁺is very stronger and more affected by ion concentration.?2?Under the same atmosphere,the temperature range of sulfur-containing gas release during pyrolysis of different sulfur-containing model compounds is different,which is related to the stability of the model compound structure.Compared with DS,the aromatic sulphur in PS and the thiophene sulphur in 2-MT are more difficult to decompose under Ar and CO₂ atmospheres.?3?Fe³⁺is more favorable for the maximum temperature of COS and SO₂ release peak to move towards lower temperature during pyrolysis of these three model compounds under 3%O₂-Ar atmosphere.With the increasing of ion concentration,their release tendency increases.?4?The main release forms of sulfur-containing gases in coal pyrolysis under different atmospheres are different.Under Ar atmosphere,the amount of H₂S release is the most significant,while COS release increasing in the CO₂ atmosphere and mainly SO₂ in the 3%O₂-Ar atmosphere.?5?For the release of the main sulfur-containing gases in different atmospheres,the deash process is beneficial for the maximum temperatures of release peaks to move to the lower temperatures.?6?Under Ar and CO₂ atmospheres,Fe³⁺can intrigue the maximum temperature of H₂S release peak to move to the higher temperature.COS and SO₂ release behavior is greatly affected by coal type.In the 3%O₂-Ar atmosphere,there is no significant H₂S release.For COS and SO₂,Fe³⁺can cause their maximum peak temperatures to decrease.In addition,Fe³⁺is beneficial for the decomposition of sulfur compounds in coal at lower temperatures.