CO₂ Adsorption on the N- and P-Modified Mesoporous Silicas

Area of Science:

• Materials Science
• Chemistry
• Environmental Science

Background:

• Mesoporous silica materials like SBA-15 and MCM-48 are widely studied for adsorption applications.
• Functionalization of these materials can enhance their properties for specific targets.
• Carbon dioxide (CO2) capture remains a critical challenge in mitigating climate change.

Purpose of the Study:

• To functionalize SBA-15 and MCM-48 mesoporous silicas with N- and P-containing groups.
• To investigate the CO2 adsorption capacity of the modified silica materials.
• To evaluate the stability and reusability of the functionalized adsorbents.

Main Methods:

• Post-synthesis modification of SBA-15 and MCM-48 using (3-aminopropyl)triethoxysilane (APTES).
• Characterization using multinuclear NMR, FTIR spectroscopy, thermogravimetric analysis, nitrogen physisorption, and UV-Vis spectroscopy.
• Dynamic CO2 adsorption/desorption measurements at 40 °C.

Main Results:

• Successful grafting of aldimine and aminophosphonate derivatives onto the silica pore surfaces.
• Enhanced CO2 adsorption capacities were observed for the modified silicas compared to the pristine materials.
• MCM-48 functionalized with Schiff base residues achieved a CO2 adsorption capacity of 4.60 mmol/g.
• NMR spectroscopy confirmed the presence of physically captured CO2.
• Modified silicas exhibited good stability with only a 5% decrease in adsorption capacity over three cycles.

Conclusions:

• Functionalization of SBA-15 and MCM-48 with APTES derivatives significantly enhances CO2 adsorption.
• The Schiff base functionalized MCM-48 demonstrates promising performance for CO2 capture.
• The modified materials show good reusability, making them suitable for practical applications.