Study On The Mercaptan And Thioether From Coking Coal Response To Microwave Irradiation

The shortage of resources and a lot of organic sulfur in coking coal will directly affect the yield and quality of coke, steel and other products. The organic sulfur in coal is complex and difficult to effective removal.Making the sulfur bonds rupture is the foundation of the microwave desulfurization. The occurrence form of organic sulfur in coal is the key to removal of it. In this paper, chemical group components of the coking coal from Xinyu, Shanxi province were separated by solvent extraction. On the basis of forms and distribution of the organic sulfur components in coal, the model compounds were screened out and synthetized for studying the response laws of microwave irradiation. The influence of the non-thermal effect of microwave on desulfurization reaction was investigated by the modern analytical techniques and quantum chemistry calculation. The mechanism of coal desulfurization by microwave was analysed. We hope the result of this study can provide the basic information and theoretical foundation for the microwave desulfurization. The main results of this work are as follows: 1. The occurrence forms of sulfur in Xinyu coking coalThe main occurrence of sulfur in Xinyu coking coal is pyrite, thioethers/thiols, thiophenes, sulfones and sulfoxides respectively, and the ratios of different types of organic sulfur has no much difference. The organic sulfur ratio is closer to 90% of the total sulfur in Xinyu refined coal and mainly exists in the form of macromo-lecular structure.2. Preparation of the model compounds The small molecule mercaptan and thioether compounds with different structure were screened out. The higher molecular weight of mercaptan, dicarbonyl thioether and p-thioketone compounds with different aromatic carbon ratio were synthesized, and the structures were confirmed by FT-IR,1HNMR and 13CNMR.3. The electromagnetic response characteristics of the coal sample and model compoundsElectromagnetic response characteristics of the thiol/thioether compounds exhibit significant dependence on the measurement frequencies, sulfur content and molecular structure. (1) The larger the sulfur content is, the larger is ε’,sulfur- containing bonds obviously increased the microwave polarization response ability of the thiols/thioethers with different structure.(2) Studies have shown that optimum activation frequencies varied for different kinds of sulfur atoms. (3) For thioether, the higher is the aromatic carbon ratio, the larger is value peak and corresponding frequency of the ε’. (4) Microwave mainly takes the form of nonthermal effect on the mercaptan and thioether compounds. All effects considered, The optimum activation frequency of thiols/thioethers under microwave radiation should be the range of 0.5 to 2GHz.4. Effect of microwave non-thermal effect on the structural characteristics of organosulfur compoundsThe C-S bond of thiols/thioethers is the active point of the chemical reaction. Microwave nonthermal effect can change the intramolecular charge and bond energy distribution, reduce the energy gap, affect the vibration strength of polar groups and activate compounds indirectly. But nonthermal effect does not destroy the original chemical bond and not produce new chemical bond.5. Experimental study on microwave desulfurization of coking coalThe organic sulfur of thiols/thioethers can be removed efficiently under the together action of the microwave thermal and non-thermal effect. Using HNO3 and microwave pretreatment can obviously improve oxidative desulfuization, and the desulfurizing ratio of organic sulfur from Xinyu coking coal reach to 28.5% under the best conditions.