Study On Desulfurization Performance Of Triethylamine Iron Based Ionic Liquid Binary Compound System

In the process of coal gasification,90%of the inorganic sulfide contained in the raw gas will be converted to hydrogen sulfide（H₂S）.H₂S is an acidic,toxic,colorless substance with pungent odor of rotten eggs,and also a strong neurotoxic.When H₂S concentration in the environment reaches a certain value,it can cause inflammation or immediate death in the body.H₂S in the air pollutes the atmosphere,contributes to the greenhouse effect and destroys the ozone layer.In the industrial production process,the presence of H₂S will deactivate the catalyst,reduce the production volume of the target product and increase the cost consumption.Therefore,it is necessary to remove H₂S from the environment and industry.Desulfurization technology is mainly divided into dry desulfurization and wet desulfurization.Among the wet desulfurization,the wet oxidation method based on iron has been widely studied and applied due to its advantages such as cheap raw materials,large desulfurization amount and simple process.However,this method has disadvantages such as desulfurizer being easily diluted and more by-products.In order to solve these shortcomings,this paper takes advantage of the characteristics of ionic liquid vapor pressure,the structure of anion and anion adjustment,triethylamine hydrochloride（Et₃NHCl）as cationic,anhydrous ferric chloride（Fe Cl₃）as anion synthesis of triethylamine iron base（x Et₃NHCl·Fe Cl₃）ionic liquid with different salt and iron ratio x,as a desulfurizer for desulfurization.Then the synthesized ionic liquid was characterized by IR,Raman and thermogravimetric analysis.Through infrared characterization,it is found that the characteristic peak of N-H bond appears at the wavelength of 3385 cm^-1,and the characteristic peak of hydrogen bond between N-H bond in Et₃NHCl and Cl in Fe Cl₃ appears at the wavelength of 3130 cm^-1.Raman spectroscopy showed that the Fe Cl₄^-molecular group structure of the synthesized x Et₃NHCl·Fe Cl₃ ionic liquid appeared at the wavelength of 333 cm^-1.The thermogravimetric analysis shows that the ionic liquid x Et₃NHCl·Fe Cl₃ has good thermal stability below 200℃,and almost does not lose weight.After a series of characterization,the density,viscosity and solubility of x Et₃NHCl FeCl₃ were measured in this paper.Density and viscosity experiments show that when the temperature is 333.15 K,the density decreases with the increase of x,and the viscosity increases with the increase of x.The solubility experiment showed that the total solubility of the system decreased with the increase of temperature,increased with the increase of pressure,first increased and then decreased with the increase of x.RETM model was used to fit the solubility data,and Henry’s coefficient（H）and chemical equilibrium constant（K）were obtained by fitting.The effects of temperature,pressure,salt to iron ratio x and other factors on H and K were discussed.It was found that the physical absorption was the main part of the absorption process.With the increase of pressure,the physical absorption increased significantly,while the chemical absorption increased slowly.The viscosity of xEt₃NHCl·FeCl₃ ionic liquid is high,and the method of compound solvent is used to reduce its viscosity in this paper.With desulfurization rate as the dependent variable,on the basis of selecting the optimal salt-to-iron ratio x=1.5,six solvents of DMAC,DMF,DMEE,DMI,MDEA and DEAE were selected to compound with 1.5Et₃NHCl·Fe Cl₃ ionic liquid.The optimal compound solvent of DMAC and the optimal complex ratio of 5:1 were selected.Then the effects of experimental temperature and gas velocity on the desulfurization performance of the optimal complex were studied.It provides the research basis for industrial desulfurization process of ionic liquid widely used.