Abstract:

Hydrogen sulfide removal by catalytic oxidative method with chelated iron has the advantages of high efficiency, simple operation, and recyclable sulfur resources. At the same time, there are also problems such as slow regeneration of desulfurization liquid, ligand degradation, and difficult separation of sulfur products. In this study, ethylene diamine tetraacetic acid (EDTA) was used as the organic ligand to complex Fe³⁺ for the absorption and oxidation of hydrogen sulfide while oxygen was used in the regeneration of ferrous ion to ferric ion. The effects of different factors on the desulfurization were investigated and the system was optimized. The results showed that the system achieved a maximum hydrogen sulfide removal efficiency of 99.99% when the Fe(Ⅲ) was 0.09mol/L and the molar ratio of EDTA to Fe(Ⅲ) ([L ^n-]/[Fe³⁺]) was 1.4 at pH=9. X-ray diffraction, X-ray photoelectron spectroscopy and energy dispersive spectroscopy detection confirmed that the solid product was mainly elemental sulfur. The scanning electron microscope and particle size analysis exhibited that the PEG600 was beneficial to particle growth and agglomeration, causing the size distribution increasing from 10—100nm to 100—1000nm. Meanwhile, the addition of PEG600 improved the production of elemental sulfur over 90%. PEG600 also reduced the degradation efficiency of EDTA which was less than 10% after six cycling experiments. Ni(Ⅱ) in the desulfurization solution facilitated the regeneration of Fe(Ⅲ). The regeneration time was shortened from 60min to 20min when the molar concentration of Ni(Ⅱ) was 5% of Fe(Ⅲ) which promoted the oxygen utilization.

Key words: hydrogen sulfide, gas, iron chelates, selectivity

摘要：

络合铁法去除H₂S具有效率高、操作简单、可回收硫资源等优点，同时也存在脱硫液再生缓慢、配体降解以及硫黄产物不易分离等问题。本研究以乙二胺四乙酸（EDTA）为有机配体络合Fe³⁺用于H₂S的吸收氧化，以氧气为氧化剂再生脱硫液，考察不同因素对脱硫效果的影响并优化体系。结果表明，在Fe(Ⅲ)浓度为0.09mol/L、EDTA与Fe(Ⅲ)摩尔比[L ^n-]/[Fe³⁺]为1.4、pH=9时，H₂S去除率高达99.99%。X射线衍射仪、X射线光电子能谱和能量色散光谱结果证明固体产物主要为硫单质，扫描电子显微镜及粒度分析结果表明PEG600能促进产物硫的增大与团聚，产物颗粒粒径由10~100nm增加至100~1000nm。通过计算产率可得PEG600能增加硫的产率至90%以上。同时，PEG600抑制了EDTA的降解，6次循环实验后，EDTA的降解率不到10%。脱硫液中加入Ni(Ⅱ)可促进Fe(Ⅲ)的再生，当Ni(Ⅱ)的摩尔浓度为 Fe(Ⅲ)的5%时，再生时间由60min缩短至20min，氧气利用率提高。

关键词: 硫化氢, 气体, 络合铁, 选择性