Enhanced CO2 Adsorption over Silica-Supported Tetraethylenepentamine Sorbents Doped with Alkanolamines or Alcohols

Abstract

Silica-supported tetraethylenepentamine (TEPA/SiO2) sorbents for CO2 adsorption were prepared by incipient impregnation method, in which porous silica was loaded with TEPA and alkanolamines or alcohols as dopants. Both CO2 adsorption capacity and amine utilization efficiency of these sorbents were evaluated in a self-assembled fixed-bed reactor. The results show that the introduction of alkanolamines or alcohols, especially those with higher amine and hydroxyl densities, into TEPA/SiO2 notably improves their CO2 adsorption performance. The maximum CO2 adsorption capacity (4.14 mmol/g) was obtained over a doped TEPA/SiO2 loaded with 30% TEPA and 30% diethanolamine. The interaction between hydroxyl and amino groups, leading to the improved dispersion of TEPA phase on the surface of SiO2, was investigated by N2 adsorption–desorption measurements, scanning electron microscopy, and X-ray photoelectron spectroscopy. The calculation based on density functional theory shows that the existence of the hydroxyl grou...