四乙烯五胺修饰介孔硅胶吸附CO_2性能的研究

Study on CO_2 adsorption properties of tetraethylenepentamine modified mesoporous silica gel

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 k J/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。

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 adsorptiondesorption technologies. Meanw hile,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 to2. 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 ClasiusClapeyron equation approaches 30 - 40 k J/mol,and decreases gradually with increasing the adsorption capacity,indicating that the surface of TEPA30/PEG10-SG sorbent shows an energetic heterogeneity.