CO₂ Adsorption by Amine-Functionalized MCM-41: A Comparison between Impregnation and Grafting Modification Methods

Abstract

Modifications by impregnation and grafting are commonly used for the preparation of amine-functionalized MCM-41. A comprehensive evaluation of the advantages and disadvantages of the two methods was performed in this work. MCM-41 was synthesized by the hydrothermal method, setting the amine-loading mass fraction at 40, 50, and 60 wt %. Three amine-modified adsorbents were prepared by impregnating polyethylenimine (PEI), and the three other adsorbents were prepared by grafting 3-aminopropyltriethoxysilane (APTS) onto MCM-41. The as-prepared adsorbents were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and N2 adsorption–desorption techniques. CO2 adsorption capacities were measured, and the experimental data were fitted with adsorption kinetic models. The cyclic stability of the adsorbents prepared by the two kinds of amine-modified methods was compared using the cyclic adsorption–desorption experiments. The characterization results showed that the target adsorbents were prepared successfully. The thermal stability of the adsorbents modified by grafting was better than the thermal stability of the adsorbents modified by the impregnation. Maximum CO2 adsorption capacities of 3.53 mmol g–1 (50% PEI–MCM-41) and 2.41 mmol g–1 (50% APTS–MCM-41) could be reached at 25 °C and 1 atm, which were 4.7 and 3.2 times greater than that of MCM-41. The Avrami model fitted the experimental data well, indicating a variety of interactions between the adsorbents and CO2. CO2 adsorption capacity after 5 adsorption–desorption cycles decreased by 14.22 and 5.19% for the adsorbents prepared by impregnation and grafting, respectively. It was concluded that MCM-41 modified by impregnation and grafting followed the same kinetic model. The absorbents modified by impregnation showed higher CO2 adsorption capacity and amine-loading efficiency, while those prepared by grafting had better thermal and cyclic stabilities.

Surface modification of biomaterials based on cocoa shell with improved nitrate and Cr(vi) removal

“…45 The peaks at 1572 cm À1 , 1302 cm À1 and 1100 cm À1 corresponding to the bending of amino groups (N-H) from PEI were also visible in the spectrum of CS-T-PEI. 34,46 These results clearly indicate that the macromolecular chains of PEI were successfully impregnated to the CS-T surface. Aer acidic treatment, the increase of the peak intensity at 3320 cm À1 was associated to the stretching vibration of NH 3 + whereas the peaks at 1730, 1648 and 1450 cm À1 were assigned to the symmetric and asymmetric stretching vibration of N-H. 37 To ensure the proper graing of dendrimers and identify any interaction that occurred during processing, the treated and untreated adsorbents were analyzed chemically by XPS.…”

Radiation-initiated high strength chitosan/lithium sulfonate double network hydrogel/aerogel with porosity and stability for efficient CO2 capture

“…14 However, the conventional methods of graing and impregnation to introduce CO 2 -philic groups usually has negative inuences on surface area and may result in a decrease in CO 2 absorption capacity. 15 Possible strategy to overcome the shortcoming is utilizing porous polymer with high specic surface area and physicochemical stability as the matrix and then introducing CO 2 -philic groups. 16 Hydrogels are a series of functional materials with high water content and three dimensional crosslinked hydrophilic networks.…”

Recent Advances in the Preparation and Applications of Organo‐functionalized Porous Materials

“…On the other hand, different amine‐functionalized MCM‐41 materials synthesized in‐situ ,[154c] and ex‐situ methods were explored for CO 2 adsorption. It was evident that adsorbents prepared by a grafting method showed higher stability, whereas sample prepared by impregnation method showed better adsorption capacity . Further, CO 2 capture capacity of functionalized SBA‐15 and MCM‐41 are compared based on 100 research papers published on this field using 15 inputs (support properties, amine properties, preparation method and operational variables).…”