改性碳纳米管常温下吸附分离低浓度CO2

采用浸渍法将四乙烯五胺(TEPA)和三乙烯四胺(TETA)负载至碳纳米管(CNTs)上,得到一种固态胺吸附剂CNTs-TEPA和CNTs-TETA,用以吸附低浓度下的CO2.利用扫描电镜(SEM)、透射电镜(TEM)、傅里叶红外(FTIR)光谱、N2物理吸附脱附、元素分析和热重分析(TGA)等方法表征样品.结果表明:CNTs-TEPA和CNTs-TETA形态并未发生变化,仍保留CNTs规整有序的孔道结构,但样品的比表面积和孔容都显著减小.在常温条件下,CNTs-TEPA和CNTs-TETA的CO2吸附量与CNTs相比有显著提高,同时,在胺浸渍质量相同的情况下,改性后的CNTs-TEPA效果优于CNTs-TETA.温度从20℃升至30℃,CNTs-TEPA和CNTs-TETA的CO2吸附量分别从126.7、101.2mg·g-1升至139.3、110.4mg·g-1.CNTs的吸附量随着温度的增加变化不明显.最后,采用Suyadal和Yasyerli两种模型对CO2的动态吸附穿透曲线进行拟合,结果说明Yasyerli模型对CNTs、CNTs-TEPA和CNTs-TETA的CO2吸附过程的拟合程度更高.

Adsorption of Low Concentration CO2 by Modified Carbon Nanotubes under Ambient Temperature

Solid amine adsorbents for low concentration CO 2 removal were developed using carbon nanotubes(CNTs)impregnated with tetraethylenepentamine(TEPA)and triethylenetetramine(TETA).The adsorbents were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier-transform infrared spectroscopy(FITR),N 2 adsorption/desorption,elemental analysis and thermogravimetric analysis(TGA).After impregnation,the shapes,fundamental channels and pore structures of the adsorbents were unchanged.However,the surface area and pore volume decreased.The adsorption behavior toward low concentration CO 2 was investigated in a fixed-bed column.The results indicated that the adsorption capacity was enhanced substantially by modification.The CO 2 adsorption capacity of CNTs-TEPA was higher than that of CNTs-TETA with the same amount of amine loading.The adsorption capacity increased steadily from 126.7 to 139.3 mg·g-1 for CNTs-TEPA and from 101.2 to 110.4 mg·g-1 for CNTs-TETA as the temperature increased from 20 to 30℃.The adsorption capacity of the raw CNTs experienced a modest increase,but began to decrease gradually with further temperature increases.Suyadal and Yasyerli deactivation models were applied to investigate the experimental breakthrough curves of raw and modified CNTs.It was concluded that the Yasyerli deactivation model is more appropriate to analyze the breakthrough curves of CO 2 adsorption on solid amine adsorbents.