阴离子功能化大孔树脂用于二氧化硫的多位点高效捕集（英文）

Ultra-High SO_2 Capture by Anion-Functionalized Resins through Multiple-Site Adsorption

提出了一种针对大孔树脂阴离子功能化的新策略并合成了一系列阴离子功能化大孔树脂[IRA-900][An],在20℃和101.3 kPa的吸附条件下实现了对SO_2的超高吸附容量(>10 mmol·g-1)。和常规唑基阴离子功能化大孔树脂相比,聚咪唑基硼酸阴离子功能化的大孔树脂[IRA-900][B(Im)_4]在低压条件下仍然展现了卓越的SO_2捕集能力。吸附实验发现,[IRA-900][B(Im)_4]在10.13 kPa和20℃的低压环境中能够保持10.62 mmol·g-1的超高SO_2吸附量。通过红外谱学研究以及密度泛函理论(DFT)计算来进行吸附机理探究,发现聚唑基硼酸阴离子[B(Im)_4]具有独特的正四面体构型,从而打破了阴离子上N负位点之间的电子流动和共轭效应。在[IRA-900][B(Im)_4]捕集SO_2过程中,阴离子连续和SO_2分子发生化学相互作用时,吸附焓变无明显下降。因此,一个[B(Im)_4]阴离子能够提供四个有效的作用位点和SO_2发生化学吸附作用,从而在低压条件下,[IRA-900][B(Im)_4]仍然实现了超高的SO_2捕集能力。此外,我们对阴离子功能化大孔树脂[IRA-900][B(Im)_4]在低压条件下对SO_2吸附的循环稳定性做了探究。结果发现,在20℃和10.13 kPa的吸附环境中以及70℃的脱附条件下,[IRA-900][B(Im)_4]展现了良好的循环稳定性,具有极大的工业应用价值。最后,这种阴离子功能化的策略以及多位点捕集方法对实现烟气环境中SO_2的高效捕集开拓了新的思路。

The anion-functionalization strategy has been proposed and applied for the synthesis of macro-porous resins [IRA-900][An], thus realizing anultra-high SO2 adsorption capacity （〉10 mmol-g^-1） at 101.3 kPa and 20℃. Compared with the normal azole-based anion-functionalized resins, the poly（imidazolyl）borate anion-functionalized resin [IRA-900][B（Im）4] exhibited an outstanding adsorption capacity at low SO2 partial pressures （10.62 mmol.g^-1 at 20℃ and 10.13 kPa）. From the results of the IR spectrum investigation and DFT calculations, the multiple-site adsorption mechanism was verified. On account of the unique tetrahedral configuration of [B（im）4], the conjugation and electronic communication between the electronegative nitrogen atoms were disrupted, making them behave as local reactive sites. Therefore, at least four electronegative nitrogen atoms could be provided by one [B（im）4] to react with SO2 without evident adsorption enthalpy deterioration （from -50.6 kJ.mol^-1 to -37.2 kJ.mol^-1） during the continuous SO2 capture; this was responsible for the ultra-high SO2 adsorption capacity achieved by [IRA-900][B（Im）4] at low partial pressures. Moreover, the thermal stability and reversibility of [IRA-900][B（Im）4] for SO2 capture and desorption were investigated. Six cycles where the adsorption was carried out at 20℃ and 10.13 kPa and the regeneration was performed at 70℃ demonstrated the adequate reversibility of [IRA-900][B（Im）4] for SO2 capture, showing the resin＇s great potential for industrial desulfurization. Thus, the anion-functionalization strategy and multiple-site adsorption behavior provide new perspectives to realize effective SO2 capture from flue gas.