Study On The Solubilization Control Of Iron Salt In Organic Phase And Its Oxidative Desulfurization

In the petrochemical,biological gas process,natural gas extraction and waste treatment process,will produce or release toxic gas hydrogen sulfide,with a wide range of concentrations.Aqueous phase wet oxidation desulfurization technology,such as Lo-cat process,can almost independently purify all concentrations of hydrogen sulfide,and high desulfurization efficiency.But the aqueous phase system needs to constantly adjust the pH,and desulfurization agent easily degraded.Therefore,it was proposed non-aqueous wet oxidation desulfurization technology,both with water phase wet desulfurization advantages,but also to avoid the existence of a series of problems caused by water.However,the solubility of the inorganic iron salt in the organic solvent is too low,and the desulfurization can not effectively remove hydrogen sulfide.Therefore,on the basis of this,the relationship between environmental conditions,solvent composition and iron salt morphology with the amount of dissolved iron salts in the organic phase is explored to further improve the desulfurization performance.The solubility of FeCl3 in DMAC,DMF,TBP and NMP increased with the increase of temperature,and the desulfurization performance was also improved.The solubility of FeCl3 in TBP is most affected by temperature,iron salt concentration increased by about 10 times from 20? to 80?,reaching 0.1760 mol·L-1.However,the solubility of FeCl3 in DMAC is the highest under different temperature conditions,and the concentration of FeCl3 is 0.5741 mol·L-1 at 80?.Although the temperature change can be more obvious to improve the solubility of iron salts,but the corresponding desulfurization performance is poor,and the need to maintain the corresponding desulfurization process in the dissolved temperature,can not meet our needs.In the experiment,the effects of the latent solvents were investigated.The addition of the latent solvent methanol and ethanol to DMAC-FeCl3 was carried out.By changing the composition and properties of the solvent to improve the iron salt solubility,the DMAC and alcohol volume ratio of 9:1,and the solubility of iron salt was increased by about 6 times.When methanol was used as the latent solvent,it reached 0.7232 mol·L-1,and when ethanol was latent solvent,it reached 0.7811 mol·L-1.The amount of dissolved is higher than the sum of the two solvents,and the synergistic effect is obtained.10 mL desulfurization agent in the 10000 ppm hydrogen sulfide concentration stable desulfurization for more than 50 min.However,there is a serious flaw in the system for the rapid loss of desulfurization.It was found that 1-butyl-3-methylchloroimidazole(BmimCl)and triethylamine(Et3NHCl)were able to form a stable organic iron salt with FeCl3.The two iron salts were able to dissolve with DMAC in any proportion,significantly increased desulfurization agent iron salt concentration,up to 3.55 mol·L-1.When the proportion of organic iron salt and DMAC is more than 20:4,10 mL desulfurizer can stabilize desulfurization for more than 200min at the concentration of 10,000 ppm hydrogen sulfide,and the sulfur capacity is about 8 g·L-1,which is much higher than the cosolvency process.When the ratio continues to increase,the desulfurization performance decreases with the decrease of iron salt concentration,but it can still achieve the purpose of desulfurization,and its viscosity will decrease with the increase of DMAC ratio.The regeneration performance of the two kinds of solubilizing systems was good,and the regeneration performance was determined by oxygen and sulfur ratio.The BmimFeCl4-DMAC system was 8.15 m3·kg-1 and the Et3NHFeCl4-DMAC system was 30.42 m2·kg-1.The IR of the two systems before and after desulfurization showed that the two were chemically stable.Through the comparative analysis of physical and chemical parameters and electrochemical experiments,BmimCl is superior to Et3NHCl,The new desulfurizer based on the BmimCl with high electrochemical activity,low viscosity and fast regeneration rate.Through the tail gas TOC,the two system solvent loss is slow,within the acceptable range,much lower than the cosolvency system.