Effects Of Metal Oxides And Composite Angents On Sulfur Fixation During Coal Pyrolysis And Char Combusition

In this paper,pyrolysis-chromatography?Py-GC?and microcomputer-based sulfur analyzer were used to study the effects of metal oxides and calcium-based composite sulfur-fixing agents on the sulfurization fixation and H₂S,COS,SO₂emission during Yangquan and Ordos raw coals pyrolysis and their chars combustion.In addition,the detailed sulfur forms in coals and their chars were obtained by XPS analysis.The main conclusions are obtained as following:CaO,CuO,Fe₂O₃ all have strong sulfur-fixing effects during coal pyrolysis,resulting in the higher sulfur-fixing ratios compared with raw coal,as they can significantly reduce the H₂S release of the main sulfur-containing gases during pyrolysis.K₂CO₃ and Na₂CO₃ can inhibit the reaction of CaO and H₂S,so the sulfur-fixing ratios during coal pyrolysis are decreased.CaS is more stable than CuS and FeS,so the sulfur fixation ratios of chars with CaO are higher during combustion.During the char combustion,CuO,Fe₂O₃ can promote SO₂ emission,while composite calcium-based sulfur-fixing agents with both K₂CO₃ and Na₂CO₃ significantly can reduce SO₂ release.Thus,these composite calcium-based sulfur-fixing agents have higher sulfur fixation ratios during char combustion compared with single CaO.In addition,the effects of these single metal oxides or composite calcium-based sulfur-fixing agents also on these deashed coals are same with their raw coals.By XPS analysis,Yangquan coal mainly contains organic thiophene sulfurs,while pyrite in Erdos coal.The form of inorganic sulfurs in the chars with single CaO or composite calcium-based sulfur-fixing agents is mainly CaS,and the proportion of sulfides in total sulfurs is about 66%-72%.The organic sulfur form is mainly stable thiophenes.