CO2 Capture by the Amine-modified Mesoporous Materials
ABSTRACT Novel CO2 adsorbents were prepared by grafting two different aminosilanes on mesoporous silica MCM-41 and SBA-15. The properties of the mesoporous materials before and after surface modification were investigated by powder X-ray diffraction (XRD) pattern, solid-state 29Si nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectra, and measurements of N2 adsorption and desorption isothermal, which confirmed that aminosilanes were grafted on the surface of the channels in the mesoporous materials. Thermogravimetry analysis (TGA) evaluated the amount of grafted amine to be about 1.5–2.9 mmol·g−1. The CO2 adsorption capacity of MCM-41 increased from 0.67 mmol·g−1 to 2.20 mmol·g−1 after AEAPMDS (N-β-(aminoethyl)-γ-aminopropyl dimethoxy methylsilane) modification (p=101 kPa) at room temperature. The studies of the mechanism of CO2 adsorption suggested that there were two main contributions to the increase: the chemical adsorption based on the active sites of amine groups and the capillary condensation caused by the nano-scale channels of the mesoporous materials.
- Adsorption Science & Technology - ADSORPT SCI TECHNOL. 01/2009; 27(6):593-602.
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ABSTRACT: Mesoporous MCM-41, MCM-48 and SBA-15 were synthesized using Rice husk ash (RHA) as the silica source and their defective Si-OH sites were functionalized by 3-chloropropyltrimethoxysilane (CPTMS) which was subsequently grafted with amine compounds, Tris(2-aminoethyl)amine (TREN) and Tetraethylenepentamine (TEPA). X-ray powder diffraction (XRD) and BET results of the parent mesoporous silica suggested their closeness of structural properties to those obtained from conventional silica sources. CO(2) adsorption of branched amine TREN and straight chain amine TEPA at 25, 50 and 75 degrees C was obtained by Thermogravimetric Analyser (TGA) at atmospheric pressure. TREN grafted mesoporous silica showed 7% of CO(2) adsorption while TEPA grafted mesoporous silicas showed less CO(2) adsorption, which is due to the presence of isolated amine groups in TREN. TREN grafted mesoporous silicas were also observed to be selective towards CO(2), thermally stable and recyclable. The order of CO(2) adsorption with respect to amount of amine grafting was observed to be MCM-48/TREN>MCM-41/TREN>SBA-15/TREN.Journal of hazardous materials 10/2009; 175(1-3):928-38. · 4.14 Impact Factor
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ABSTRACT: The capture of carbon dioxide was carried out using MCM-41 and SBA-15 as adsorbents. These mesoporous materials were synthesized by the hydrothermal method, and subsequently functionalized with the di-iso-propylamine (DIPA). Then, they were characterized by XRD, BET, and TG/DTG. The X-ray diffraction patterns of the synthesized samples showed the characteristic peaks of MCM-41 and SBA-15, indicating that the structures of these materials were obtained. The functionalized samples presented a decrease of the intensities of these peaks, suggesting a decreasing in the structural organization of the material; however, the mesoporous structure was preserved. For the adsorption capacity measurements, the materials were previously saturated with carbon dioxide at 75°C, and then desorbed in a thermobalance in the temperature range of 25–900°C, under helium atmosphere. Desorption tests showed that the functionalized MCM-41 presented a weight loss of 7.5wt%, against 5.9wt% for SBA-15. The obtained values indicate that these nanostructured materials can be used as adsorbent for carbon dioxide capture. KeywordsAdsorption of carbon dioxide–Mesoporous materials–Functionalization–ThermogravimetryJournal of Thermal Analysis and Calorimetry 01/2011; 106(3):779-782. · 1.98 Impact Factor