A Simple Strategy to Improve PEI Dispersion on MCM-48 with Long-Alkyl Chains Template for Efficient CO₂ Adsorption

Polyethylenimine (PEI) impregnated MCM-48 samples without calcination (MCM-48-W) whose pores are covered with cetyltrimethylammonium bromide (CTAB with long-alkyl chains) were verified to be more efficient CO₂ adsorbents than PEI impregnated conventional MCM-48 samples. The samples were characterized by thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), nitrogen adsorption-desorption, and Fourier transform infrared spectroscopy (FTIR) analysis. Also, CO₂ adsorption behaviors including adsorption capacity, adsorption thermodynamics, and adsorbent stability were studied to reveal the CO₂ adsorption performance on as-synthesized PEI supported materials. The experimental results indicated that the CO₂ adsorption and amine efficiency of MCM-48-W were always higher than those of conventional MCM-48 samples at the same PEI loading. MCM-48-W impregnated with 40 wt % PEI (MCM-48-W(40)) exhibited 2.59 mmol·g^-1 of CO₂ adsorption capacity (6.9 mmol CO₂/g PEI), the highest amine efficiency ever reported for MCM-48 impregnated PEI in pure CO₂, which may be because the existence of long-alkyl chains improved the dispersion of PEI loading. We presented a simple strategy with the advantages of less consumption of PEI and omission of the calcination step for the improvement of PEI dispersion on MCM-48 with long-alkyl chains template for high efficiency CO₂ adsorption.