四乙烯五胺修饰介孔硅胶吸附CO2性能的研究

采用浸渍法将四乙烯五胺(TEPA)负载到介孔硅胶(SG)上,制备了一系列胺功能化的CO₂吸附材料(TEPA-SG).利用傅里叶变换红外光谱(FT-IR)、热重分析(TGA)和N₂吸脱附等分析方法对样品进行了表征,并在固定床反应器中考察了TEPA负载量、吸附温度对CO₂吸附性能的影响,同时通过添加不同质量分数的聚乙二醇(PEG)考察了羟基对吸附性能及再生性能的促进作用.结果表明,当TEPA负载量为40%(质量分数)、吸附温度为70 ℃时,TEPA-SG的吸附量高达2.21 mmol/g;PEG的加入改变了氨基与CO₂的相互作用机理,当TEPA与PEG的质量比为3:1,总负载量为40%时,CO₂的吸附量为2.70 mmol/g,且经过10次吸脱附循环实验后,CO₂吸附量仍保持在2.66 mmol/g,表现出较好的循环稳定性.Clausius-Clapeyron方程计算得该过程的等量吸附热为30~40 kJ/mol,且随吸附量的增大等量吸附热逐渐减小,表明TEPA30/PEG10-SG吸附剂表面存在能量不均匀性.

Study on CO2 adsorption properties of tetraethylenepentamine modified mesoporous silica gel

A novel tetraethylenepentamine (TEPA) modified mesoporous silica gel (SG) sorbent (TEPA-SG) for CO₂ capture was prepared by the wet impregnation method. The prepared samples were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), and N₂ adsorption-desorption technologies. Meanwhile, the effects of TEPA loadings and adsorption temperatures on the adsorption capacity were investigated in a self-assembled fixed bed reactor. Different weight percentages of polyethylene glycol (PEG) were added to TEPA-SG to study the promoting effect of hydroxyl groups on the adsorption capacity and regenerability. The results show that the SG modified by 40% TEPA has a maximum adsorption capacity of 2.21 mmol/g at 70 ℃ and atmospheric pressure. Moreover, the adsorption capacity increases to 2.70 mmol/g by adding a desirable amount of PEG, and after ten cyclic adsorption-desorption tests, the adsorption capacity is maintained at 2.66 mmol/g, demonstrating that as-prepared TEPA and PEG modified sorbent displays an excellent regenerability. In addition, the isosteric heat of adsorption based on the Clasius-Clapeyron equation approaches 30~40 kJ/mol, and decreases gradually with increasing the adsorption capacity, indicating that the surface of TEPA30/PEG10-SG sorbent shows an energetic heterogeneity.