Exfoliated vermiculite nanosheets supporting tetraethylenepentamine for CO2 capture

Abstract

CO2 capture is a critical process to reduce CO2 emission into the atmosphere. Here we report a novel and inexpensive composite adsorbent for capturing CO2. The composite was prepared by supporting tetraethylenepentamine (TEPA) onto exfoliated vermiculite (E-VER) nanosheets using wet-impregnation and freeze-drying methods. Vermiculite, as a cheap and natural abundant clay, was delaminated into ultrathin nanosheets via liquid-phase exfoliation. The negatively charged E-VER has exposed surfaces and a large surface area, which is ideal for supporting TEPA with the desired loading. It was found out that the TEPA loading has a crucial impact on the pore structures, surface areas, and the CO2 adsorption capacities. E-VER-TEPA-2% with a TEPA loading of 2% demonstrates the optimal performance for CO2 capture, showing a CO2 adsorption capacity of 29.5 ​mmol/g at 45 ​bar and 25 ​°C and 22.6 ​mmol/g at 40 ​bar and 75 ​°C. The E-VER/TEPA composites are compressible, a volumetric capacity of 29.93 ​mmol/cm3 was obtained for E-VER-TEPA-2% at 45 ​bar and 25 ​°C after being compressed at 20 ​MPa. Furthermore, E-VER/TEPA composites exhibited excellent cyclic stability over six cycles and long-time heat-treatment.

Keywords

• Exfoliation
• Two-dimensional materials
• Composites
• CO2 capture
• Clay