Theoretical And Experimental Study On Organic Sulfur Removal In High Sulfur Coal

As the main energy of our country,coal is essential in the economic development of our country.However,the pollution produced by coal combustion is also contrary to the strategy of green sustainable development advocated nowadays.Therefore,the sulfur components in coal,especially the removal of organic sulfur,have always been the focus of research.With the development of computer and related software,quantum chemical calculation is widely used in coal desulfurization.After analyzing the composition of coal,the thermal effect of microwave and the analysis of non thermal effect,we explored the sulfur compounds based on quantum chemistry,and simplified the microwave field into electric field,and analyzed the response of organic sulfur in coal under the action of microwave.This paper takes Shanxi Xinyu coal as the research object,through the analysis of group separation and XPS experiment: the relative content of organic sulfur in“clean coal > heavy component > dense medium Component > loose medium component”decreased,and complex degree of organic sulfur in reduction in Xinyu coal.Through the analysis of soluble solution,it is concluded that the organic sulfur models in coal are as follows: 3 thiophene sulfur,4 thiol thioether sulphur and 5 kinds of sulfoxide sulfur,and by analyzing the insoluble matter,3 macromolecular structure models were built: the structural model of coal lightweight group,the structural model of coal sparse medium group and the structural model of coal sparse heavy group.By means of thermogravimetric analysis of similar structure small molecule compounds,it is found that the initiation temperature of sulfoether,sulfoxide sulphur and thiophenic sulfur increases gradually.The thermo fracture temperature of thiophene is the lowest,the temperature of thiophene is the highest,in the three kind of sulfur compounds.For similar structures,when the S atom is directly related to the aryl radical,the conjugate effect is formed between the S atom and the aryl radical,which makes the bond breaking temperature increase.In order to proving the non-thermal effect of microwave,the experiment of Raman spectra and tetraphenyl thiophene at the same temperature were carried out in this thesis,and the molecular structure changes at the same temperature,which provesthe existence of the non thermal effect.By studying the tangent value of the complex permittivity and the loss angle tangent of the three compounds in 2GHz~18GHz microwave,it is concluded that the response of sulfoether and sulfonide sulphur to thiophenic sulfur is greater than that of thiophenic sulfur,indicating that this sulfoether and sulfonide sulphur is easier to remove.Finally,the quantum chemistry of organic sulfur model compounds in coal was studied in the Dmol3 module of Material Studio software.By adding different electric fields,it is found that the C-S bonds of thiophene,thioether and sulfonyl compounds will grow longer with the increase of external electric field,and the dipole moment will also increase.All these indicate that the polarity of the model containing sulfur is increased under the effect of applied electricity,and the C-S and S-S bonds will break first.By analyzing the calculation results of the structural model of coal sparse medium group in macromolecular structure model,we find that the bond length of C-S bond in molecular structure is longer than other chemical bonds,while bond level is smaller than other chemical bonds.Therefore,it can be obtained that the bond energy of C-S bond is smaller in the structural model of the coal thinning medium,thus providing a theoretical basis for the removal of organic sulfur from the microscopic angle.