Polyethyleneimine-Modified Amorphous Silica for the Selective Adsorption of CO2/N2 at High Temperatures

Cheng Li; Xiaoqing Wang; Anjie Yang; Peng Chen; Tianxiang Zhao; Fei Liu

doi:10.1021/acsomega.1c04743

Polyethyleneimine-Modified Amorphous Silica for the Selective Adsorption of CO₂/N₂ at High Temperatures

ACS Omega. 2021 Dec 14;6(51):35389-35397. doi: 10.1021/acsomega.1c04743. eCollection 2021 Dec 28.

Authors

Cheng Li¹, Xiaoqing Wang¹, Anjie Yang¹, Peng Chen¹, Tianxiang Zhao¹, Fei Liu¹

Affiliation

¹ Key Laboratory of Green Chemical and Clean Energy Technology, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, P. R. China.

Abstract

Mechanochemistry is very attractive as an efficient, solvent-free, and simplified technique for the preparation of composite adsorbents. Here, a series of polyethyleneimine (PEI)-modified SiO₂ adsorbents were prepared via mechanical ball milling for selective adsorption of CO₂ at high temperatures. The structural properties of these adsorbents were characterized by XRD, SEM, TGA, FTIR, and N₂ adsorption-desorption. This method can better disperse the PEI evenly in the SiO₂ as well as maintain the porous structure of the adsorbents by comparing with the impregnated adsorbents. These adsorbents presented appreciable performance in separating CO₂ at high temperatures, and the CO₂ adsorption capacity of PEI(70%)/SiO₂ is up to 2.47 mmol/g at 70 °C and 1.5 bar, which is significantly higher than that of the same type of CO₂ adsorbent reported in the literature. Furthermore, the adsorbent of PEI(70%)/SiO₂ provided an ideally infinite selectivity for CO₂/N₂ (15:85) at 70 °C. These results showed that mechanical grinding methods are a simple and effective approach to producing amine-modified silica composite adsorbents.