Development of hybrid amine-functionalized MCM-41 sorbents for CO2 capture

• A novel MCM-41 sorbent was synthesized by both grafting and impregnation method.
• New formed network facilitated the dispersion of TEPA and the diffusion of CO2.
• Effects of amine loadings, temperature and flow rate on CO2 sorption were studied.
• The sorbent exhibited excellent cyclic regenerability and thermal stability.

In consideration of the increasing warming trends worldwide, the development of highly efficient CO2 adsorbents becomes of vital importance. In this paper, a novel hybrid 3-aminopropyltrimethoxysilane (APTS) and tetraethylenepentamine (TEPA) modified MCM-41 sorbent was synthesized by a two-step method. APTS was first grafted onto the MCM-41, and then TEPA was impregnated. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and N2 adsorption–desorption techniques. CO2 adsorption–desorption experiments were performed in a self-assembled fixed bed reactor under ambient pressure. The effects of hybrid amine loadings, adsorption temperatures, and influent velocities on CO2 sorption were investigated. Among the composites synthesized, MCM-41 modified with 30 wt.% APTS and 40 wt.% TEPA (MCM-41-APTS30%–TEPA40%) showed maximum adsorption capacity of 3.50 mmol-CO2/g-sorbent. The MCM-41-APTS30%–TEPA40% sorbent exhibited well cyclic regenerability after ten adsorption–desorption cycles. Further, the adsorption kinetics of MCM-41 and MCM-41-APTS30%–TEPA40% were studied. CO2 adsorption was a two-stage process, and the Avrami model could fit well with the experimental data of MCM-41-APTS30%–TEPA40%.