Optimization of CO₂ Adsorption on Solid-Supported Amines and Thermal Regeneration Mode Comparison

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Solid-supported amines are crucial for carbon dioxide (CO2) capture.
• Optimizing adsorbent properties is key to improving CO2 adsorption efficiency.
• Understanding the impact of support characteristics and flue gas components is vital for practical CO2 capture systems.

Purpose of the Study:

• To evaluate the CO2 adsorption performance of tetraethylenepentamine (TEPA) impregnated on five commercial porous supports.
• To investigate the influence of support texture, TEPA loading, and flue gas components (H2O, SO2, NO) on CO2 adsorption.
• To assess the thermal stability and compare regeneration modes (linear vs. step) for solid-supported amines.

Main Methods:

• Impregnation of five commercial porous supports (mesoporous alumina, montmorillonite, silica gel, porous resin, MCM-41) with TEPA.
• CO2 adsorption performance evaluation using a fixed-bed reactor coupled with mass spectrometry.
• Analysis of support texture, TEPA loading, thermal stability (thermogravimetry), and regeneration efficiency.

Main Results:

• CO2 adsorption capacity correlated with adsorbent support texture, with mesoporous supports showing higher performance (>370 mg/g CO2 per unit TEPA).
• Optimal TEPA loading was primarily influenced by pore volume.
• Water (H2O) enhanced CO2 adsorption, while sulfur dioxide (SO2) inhibited it due to irreversible binding; nitrogen oxides (NO) had minimal effect.
• TEPA exhibited a main weight loss peak at 513 K.
• Step regeneration required 37 K lower temperature and yielded a 20% larger desorption peak area compared to linear regeneration.

Conclusions:

• Mesoporous supports facilitate uniform TEPA loading and enhance CO2 adsorption.
• Flue gas components significantly impact adsorption, with H2O being beneficial and SO2 detrimental.
• Step regeneration is a more energy-efficient and effective method for solid-supported amine regeneration in practical CO2 capture applications.