The Distribution Of Sulfur In Xinyu Coal And Sulfur Migration Behavior In Coal Microwave Desulfurization Process

The removal of sulfur from coal,especially the organic sulfur not make any critical progress,has been a thorny problem in the clean and efficient utilization of coal.Although part of organic sulfur could be removed by microwave with assistant,this method only confined to the macro test and the migration of organic sulfur is not clear,which hinders people to further study the mechanism of microwave desulfurization.Therefore,in this paper,the migration behavior of sulfur-containing compounds in coal was investigated through analyzing the basis properties of solid,liquid and gas before and after coal desulfurization with FT-IR,XANES,XPS Gas Chromatography and Liquid Chromatography analysis instruments,and the organic sulfur in coal has been simplified to several coal-like organ sulfur model compounds for microwave combined additives desulfurization tests.After analysis on the solid,liquid and gas products before and after microwave desulfurization,it is found that the main types of organic sulfur in XinYu coal existed in the form of mercaptan,thioether,thiophene,and a small number of sulfoxide and sulfone.As results of XPS,Thiophene accounted for 71.41% of the total amount of organic sulfur in XinYu coal,mercaptan and thioether accounted for 26.53%,and the content of sulfoxide and sulfone was only about 2.05%.So in this article,the benzyl mercaptan,diphenyl disulfide and dibenzothiophene were selected as the model compound of mercaptan,sulfur ether and thiophene for microwave with assistant test.It is discovered that the sulfur content in coal samples hardly decreased under the microwave radiation,which verifies that the microwave energy alone is not enough to break the sulfur containing bond in coal.Nevertheless,the desulfurization rate can reach 26.9% and 37.8% respectively under the condition of microwave combined additive?NaOH,HAc: H₂O₂?.Under the condition of oxide additives?HAc: H₂O₂?,organic sulfur in coal samples was more easily removed than that with inalkaline additives?NaOH?.The reduce content of mercaptan and thioether was the most,34.28%.But the content of thiophene decreased less,and the content of sulfoxide and sulfone increased by 6.12%.For gaseous products,CS₂ and H₂ S were detected under both two kinds of additives,while COS was detected only under the condition of oxide additive,and SO₂ was detected under the molten alkali.And liquid products existed in the form of sulfate,carboxylic or sulfonic acid.During microwave desulfurization tests of model loading with the benzyl mercaptan,diphenyl disulfide and dibenzothiophene under microwave combined additives tests,in alkaline condition,the relative content of benzyl mercaptan decreased by 54.86%,the relative content of sulfoxide and sulfone,inorganic sulfur respectively increase by 18.15% and 36.71%,respectively;In oxide additives condition,the decreasing relative content of benzyl mercaptan and inorganic sulfur was more 4.07% and 24.49% respectively than the condition of alkaline additives,while the increasing relative content of sulfoxide and sulfone was more 28.75%.Under two kinds of additives,the model loading with benzyl mercaptan and diphenyl disulfide was oxidized into oxidation state.However,the content of model loading with benzothiophene changed into sulfoxide and sulfone was less than mercaptan and thioether,which suggests that the structure of thiophene in coal is more stable than those of mercaptan and thiophene.As a result from model compounds,it can be inferred that sorts of C-S,S-S and S-H bonds in coal was broken,and might be oxidized into sulfoxide and sulfone.