氯化咪唑铁基离子液体的物化性能及脱硫机理

采用变温拉曼光谱、红外光谱探针及XRD等现代分析技术研究疏水性氯化咪唑铁基离子液体的酸性特征及循环热稳定性，结果表明，氯化咪唑铁基离子液体可以在不超过240 ℃的条件下循环使用；具有Bronsted酸和Lewis酸的共同特点；Fe³⁺/Fe²⁺离子对具有很好的氧化还原可逆性，可以在酸性条件下直接氧化硫化氢脱硫，所得硫磺产物属于单斜晶系；升高温度可以显著提高其硫容和脱硫效率。由此，以氯化咪唑铁基离子液体为酸性脱硫液的非水相湿法氧化脱硫机理是活性成分Fe³⁺氧化硫化氢生成单质硫磺并转化成还原态Fe²⁺，经氧气氧化再生后Fe²⁺回到氧化态Fe³⁺。上述脱硫过程不需添加辅助试剂和调控pH。

Physicochemical properties of iron based chloride imidazole ionic liquid and wet desulfurization mechanism of hydrogen sulfide

The hydrophobic iron based chloride imidazole ionic liquid(ICIL) was reported to be used as desulfurizing agent.In order to explore the relationship between its structure and the desulfurization performance of hydrogen sulfide,variable temperature FT Raman spectroscopy,FT IR probe and XRD were used to investigate its acidity,recycle thermostability,and desulfurization mechanism.The results indicate that ICIL’s recycle operation temperature is less than 240 ℃;moreover,ICIL is not only Bronsted acid and also Lewis acid with high redox reversibility of Fe3+/Fe2+ionic pairs,which can oxidize hydrogen sulfide to sulfur directly and produce monoclinic sulfur;the sulfur capacity and desulfurization performance of ICIL can be improved significantly with increasing reaction temperature.The FT IR spectroscopic probe with pyridine explores that the non aqueous wet oxidation desulfurization process by ICIL is carried out by two steps:firstly,Fe3+in ICIL oxidizes hydrogen sulfide to sulfur and is transferred to Fe2+,and then Fe2+ is oxidized by oxygen and backed to Fe3+.Importantly,the above desulfurization process is performed without any addition of chemical additives and pH adjustment.