N-杂环离子液体液固相变吸收SO2

Liquid-solid phase change absorption of SO2 by N-heterocyclic ionic liquid

采用不同N含量及碱性的六元N-杂环三级胺与不同酸性的有机羧酸直接中和制备了一系列离子液体,并将其用于SO2的捕集,发现制得的部分离子液体可液固相变吸收SO2。通过探究不同N-杂环离子液体对SO2的吸收负载量,发现离子液体的SO2吸收性能受阳离子N含量以及阴、阳离子的pKa共同影响。采用XRD、FTIR、元素分析、单晶衍射等表征手段对1,3,5-三甲基六氢-1,3,5-三嗪乙酸盐离子液体相变吸收SO2的产物进行分析,单晶解析发现固体吸收产物为甲胺基甲磺酸,并进一步推测了该离子液体吸收SO2的反应过程与相变机理,反应过程先是1,3,5-三甲基六氢-1,3,5-三嗪在酸性条件下分解成亚甲基甲胺,然后由于SO2的亲核作用,导致亚甲基甲胺碳氮双键的断裂和产物碳硫单键的形成。

A serial of ionic liquids were prepared by direct neutralization of six-membered N-heterocyclic tertiary amine with different nitrogen contents and alkaline using organic carboxylic acids with different acidities.The ionic liquids were then used for SO2 capture and some of them showed the phase change absorption behavior.By exploring the SO2 absorption capacity using different N-heterocyclic ionic liquids,we found that the SO2 absorption is affected by the cationic nitrogen content of ionic liquids as well as the pKavalue of the anions and cations.Using XRD,FTIR,elemental analysis and single crystal diffraction,we analyzed the phase change products of SO2 absorption by 1,3,5-trimethylhexahydro-1,3,5-triazine acetate ionic liquid,and the solid absorption product was found to be methylaminomethanesulfonic acid.It is further speculated that 1,3,5-trimethylhexahydro-1,3,5-triazine is first decomposed into methylene methylamine under acidic conditions,and then,due to the nucleophilic attack of SO2,the carbon-nitrogen double bond in methylene methylamine is broken with the formation of the carbon-sulfur single bond.