Xiamen Key Laboratory of Terrigenous Environmental Pollution Treatment and Ecological Remediation,Department of Chemistry, Huaqiao University

固-液相变吸收剂在CO2负荷调控下可发生相变形成固体产物,具有易分离、操作简便的优势,但现有体系大多需有机分相剂调控才能发生固液相变,存在分相剂易挥发损耗、富液黏度大等瓶颈。本研究构建了异氟尔酮二胺(IPDA)-水二元固-液相变吸收体系,无需分相剂,水相溶液吸收CO2后即可发生固液相变。研究表明,1.00mol·L-1IPDA水溶液在313.15K下饱和吸收负荷高达0.85molCO2·mol-1,吸收产物为白色晶体粉末且富集在溶液下层,富液体积占总溶液体积的43.60%,而CO2富集率达93.98%,此时,上层贫相黏度为1.08mPa·s。富相固体产物分离熔融后在393.15K温度条件下解吸60min,再生效率为98.31%。经5次循环吸收-解吸,再生容量仍保持初始容量的80%以上,具有良好的重复利用性。13C核磁共振(NMR)表征分析表明,IPDA与CO2反应生成IPDA-氨基甲酸盐与碳酸氢盐,大多聚集在富相中,仅少量氨基甲酸盐溶于贫相中。解吸完成后,样品未见CO2产物峰,进一步证明了IPDA-H2O可完全解吸。量子化学计算证明,吸收前IPDA与水偶极矩接近,极性相近可互溶,吸收后形成的产物偶极矩低、极性小,产物间的分子内氢键高于产物和水的氢键,产物晶格能增加。因此,产物从溶液中析出,无需分相剂调控,即可在水中发生固液相变。

Solid-liquid biphasic absorbents offer the advantages of easy separation and operation due tothe formation of a solid phase after CO2 capture, which can be separated by static precipitation. Howev⁃er, most existing absorbents require organic phase separators to regulate phase transition, leading to is⁃sues including volatile loss of phase separators and high viscosity of the rich liquid phase. In this study,a novel amine -water binary solid -liquid biphasic absorbent was developed. This absorbent exhibitssolid-liquid phase change behavior without the need for an organic phase separator after CO2 absorptionin the aqueous solution. Absorption experiments showed that the total absorption capacity of IPDA-H2Ocould reach 0.85 mol CO2·mol-1 at a concentration of 1.00 mol·L-1 and an absorption temperature of313.15 K. After reaching saturation, CO2 was concentrated in the lower solid phase, which accountedfor 43.60% of the total solution volume and contained 93.98% of the total absorption loading. The CO2-lean phase had a low viscosity of 1.08 mPa·s. After being hot-melted, the solid products were regen⁃erated at 393.15 K for 60 min, with a regeneration efficiency of 98.31%. Even after 5 absorption anddesorption cycles, the regeneration capacity remained above 80% of its initial capacity, indicating goodregeneration stability. 13C NMR spectra showed that most of the IPDA-carbamate and its decompositionproduct, bicarbonate, were concentrated in the rich solid phase, while a small amount ofunprecipitated carbamate and water were present in the lean phase. 13C NMR spectra indicated that CO2was almost completely released from IPDA-H2O, demonstrating the system′s excellent absorption-de⁃sorption performance. Quantum chemical calculations revealed that IPDA and H2O had similar dipolemoments before CO2 absorption, indicating similar polarity and high mutual solubility. After absorption,the dipole moment of the products decreased. Additionally, the intramolecular hydrogen bonding withinthe products was found to be stronger than the bonding between the product and water. This increase inthe product′s lattice energy drives the precipitation of the product carbamate, resulting in a solid-liquidphase transition.

国家自然科学基金资助项目(22278168,22276064)

龙青海,王琛,龚娟娟,等.异氟尔酮二胺-水二元固-液相变吸收剂捕集CO2机制[J].能源环境保护,2024,38(3):91-99.

LONG Qinghai, WANG Chen, GONG Juanjuan, et al. Mechanism of CO2 capture into isophorone diamine-waterbinary solid-liquid biphasic absorbent[J]. Energy Environmental Protection, 2024, 38(3): 91-99.