| Coal on the one hand is the main provider of energy, on the other hand is also a major source of environmental pollutions. Poly-generation coal gasification technology is currently the primary means of clean use of coal with high efficiency. High temperature gas purification involves removing of dust, toxic substances (such as Na, K and other alkali metals; HCl, HF and other gases), and desulfurization (90% of H2S). High temperature gas desulfurization is one of the key technologies. Desulfurization at high temperature can be used to recover and reuse gas sensible heat, reduce possibility of the catalyst poisoning and improve the catalytic efficiency and catalyst life. The coal gas desulfurization technology at high temperature became one of the promising research fields of energy.Gas desulfurization can be carried out by wet and dry desulfurization. Although the traditional wet desulfurization has high desulfurization performance, the solvent liquid can not be used at high temperature. Dry desulfurization is suitable for high-temperature, but catalyst activity is not high and unable to adapt to the large volumes of coal gasification process. The paper combined the advantages of wet and dry desulfurization, establishs high-temperature wet oxidation of hydrogen sulfide desulfurization process. The Fe-based ionic liquid (Fe-IL) was synthesized directly by mixing 1:2 molar ratio of 1-butyl-3-methylimidazolium (BmimCl) and FeCl3·6H2O at room temperature in this paper. From TG of Fe-IL, of the Fe-based ionic liquids the decomposition temperature is about 350℃; From Raman spectra of Fe-IL, the Fe-based ionic liquids can maintain their phyisiochemical characteristics below 220℃, it provides an atternative to develop wet oxidation desulfurization at high temperature; From cyclic voltammetry curves of Fe-IL, the Fe(III)/Fe(II) iron pairs of the Fe-based ionic liquids present good redox reversibility even the Fe-based ionic liquids were treaded in the range of 105℃-200℃, which provides a fundmental basis for the Fe-based ionic liquids to be recycled and reused.Based on high thermal stability and reversible redox properties, wet desulfurization process of hydrogen sulfide at high temperature was constructed in this paper. The effects of the flow and concentration of hydrogen sulfide, and reaction temperature on the desulfurization performances were investigated. The product sulfur was characterized by XRD, Raman, TG, DSC and elemental analysis. It is found that the sulfur capacity of Fe-IL is about 13 times at 180℃(3.92 g/L) than at 50℃(0.32g/L). The reaction temperature imposed greater influence on desulfurization performances. The desulfurization efficiency increased by about 64% while the reaction temperature increased from 105℃to 180℃. There was not a IR peak of S-O band at 1622cm-1 observed, which implied that there were not by-products of SO42\S2O32\SO32- produced in this regeneration process. The XRD and FT-Raman spectrum of the product sulfur showed that the product was rhombic sulfur. The oxidation desulfurization reaction of Fe-based ionic liquids was zero order irreversible reaction with the activation energy of 26.82kJ/mol.Therefore, this paper presents wet oxidation of desulfurization new technology at high temperature with an intergrated advantage of high temperature dry desulfurization and with high efficiency wet desulfurization. During the desulfurization process, there were not any pH regulation needed in desulfurization and by-products produced in this regeneration process. It could be expected to be used as a green wet oxidation of desulfurization at high temperature in chemical engineering and environmental engineering. |
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