Study On Novel Deep Eutectic Solvents For Absorption Of SO₂

With the development of native industry,China’s coal consumption grows up continuously,and the environmental pollution of SO₂ from coal-fired flue gas（CFFG）are becoming sharply serious.The common CFFG desulfurization method has some disadvantages of low operation efficiency,low utilization rate of sulfur resources,and the secondary pollution of desulfurization byproducts.Deep eutectic solvents（DESs）and ionic liquids（ILs）are researched for application of SO₂ gas recovery due to the advantages of high vapor pressures,good thermochemical stabilities and reversible absorption capacities of SO₂,which are very promising SO₂ absorbents.In this thesis,a series of new DESs Emim X-EPy Y where X and Y were either Cl^?or Br^?were designed and synthesized with two common ILs as raw materials integrating the advantages of ILs and DESs.These liquid DESs was prepared by mechanical mixing the two ILs Emim X and EPy Y which were solid at room temperature according to certain molar ratios.This method broadened the application range of solid ILs and the selection range of raw materials of DESs.The thermal stability of the prepared DESs was analyzed.The effects of absorption temperature,SO₂ partial pressure,gas flow rate,and absorbent moisture content on the SO₂absorption capacity of DESs were systematically investigated.The formation of DESs and the absorption process of SO₂ were explored by IR and H NMR spectra.And the effect and mechanism of Cl^?and Br^?on the comprehensive performance of Emim X-EPy Y were studied.The results showed that the decomposition temperatures of six as-prepared DESs were above 218oC,and they could efficiently and reversibly absorb SO₂.Especially,at20oC,1.0 and 0.1 atm,the SO₂capacity of Emim Cl-EPy Cl（1:1）reached 1.383 and0.777 g SO₂/g DES,respectively,higher than the corresponding results of all reported SO₂ absorbent.Under the conditions of 90°C and 1.0 atm N₂ purging,the SO₂desorption rates of DESs were above 97.0%,and the absorption performance remained stably after five cycles of SO₂ absorption/desorption.The results of IR and H NMR spectra showed that Emim X-EPy Y were joined with two hydrogen bonds,in which the two components of Emim X and EPy Y were hydrogen bond donors and acceptors for each other.The mechanism of SO₂ absorption by Emim X-EPy Y is physical function.The increase of Cl element content in Emim X-EPy Y is conducive to improving the absorption capacity of SO₂,and the increase of Br element content is conducive to improving the thermal stability of the absorbent and the absorption rate of SO₂.Overall,new DESs prepared with two conventional ILs in this thesis exhibit the great SO₂ absorption capacity and thermal stability.The research idea has reference value for the advanced development of DESs.This kind of DESs is the SO₂absorbent with good application prospects.