聚乙烯亚胺改性MCM-48的制备及其CO_2吸附性能的研究

Modification of MCM-48 with Polyethyleneimine and Its Performance for CO_2 Adsorption

以聚乙烯亚胺(PEI)为氨基改性剂,采用浸渍法对介孔分子筛MCM-48进行改性,利用X射线衍射、低温N2吸附/脱附和热重分析法等手段考察了改性前后样品的结构特征以及热稳定性,并采用静态体积法考察了298K和348K下CO2的吸附行为。结果表明,经过PEI改性后,MCM-48样品的结构特征得到了很好地保持,改性后样品的比表面积和孔体积随着PEI负载量的增加而显著下降。在348K下,PEI改性MCM-48样品对CO2吸附量随着PEI负载量的增加而显著提高,当PEI负载量达到60%(w)时,所得吸附剂在348K和105Pa下对CO2的吸附量从改性前的0.36mmol/g提高到3.13mmol/g。稳定性实验表明,PEI改性介孔MCM-48材料重复使用6次,对CO2吸附容量无明显下降。表明PEI改性MCM-48材料作为CO2吸附剂具有广阔应用前景。

A nanoporous materials(MCM-48-PEI) prepared by modification of the mcsoporous molecular sieve MCM-48 with polyethyleneimine(PEI) using wet impregnation method. These PEI -loaded MCM -48 materials were characterized by X-ray powder diffraction (XRD) ,N2 adsorption/desorption measurements and thermal gravimetric analysis (TGA) to investigate their textural properties before and after PEI-modification. CO2 adsorption was tested by volumetric adsorption isotherm equipment at 298K and 348K. The results showed that all PEI-loaded MCM-48 materials still remained the inlact structure after modification with PEI. The surface area and total pore volume of PEI-loaded MCM-48 materials decreased with increasing PEI loading.With increasing PEI loading,the CO2 adsorption capacity significantly improved at 348K. In the CO2 partial pressure of 1 atm. at 348K,the CO2 adsorption ca pacity of MCM-48 increased from 0. 36 mmol·g-1 to 3.13 mmoi·g-1 after loading 60%(wt) PEI. The CO2 adsorption capacities of MCM-48-PEI decreased little after six adsorption-desorption cycle,which indicated that MCM-48-PEI materials had good adsorption ability.All these experiments reveal that MCM-48-PEI can be used as a po tentially adsorbent for CO2.