Silica-incorporated crosslinked poly(ethylenimine) adsorbents for CO2 capture: Mitigating diffusion resistance and improving liquid water stability

Amine-supported materials have been extensively studied as economically viable adsorbents for CO 2 capture. Nevertheless, their water tolerance and the costs associated with support materials remain challenging. This study aims at developing water-stable amine-based CO 2 adsorbents through epoxy-crosslinking of PEI with or without incorporation of G10 silica. It was demonstrated that CO 2 adsorption capacity, water stability, and amine efficiency of crosslinked PEI can be improved by incorporating silica particles. Addition of 10 wt% G10 silica with respect to PEI during the crosslinking process at a 2.5% epoxide-to-amine molar ratio (100–G10@CPEI–2.5) led to a material with a CO 2 uptake of 3.01 mmol/g in the presence of 15% CO 2 /N 2 at 75 °C, representing a 33% increase compared to its G10-free counterpart (CPEI–2.5). Moreover, a CO 2 uptake of 4.18 mmol/g was obtained for 100–G10@CPEI–2.5 at 75 °C with 50% relative humidity. Notably, incorporation of G10 in CPEI–2.5 not only enhanced the PEI efficiency (mmol CO 2 /g PEI) but also improved its stability upon prolonged exposure to liquid water (up to 10 days), maintaining 87.5% of its initial CO 2 adsorption performance. Furthermore, cyclic CO 2 adsorption–desorption of 100–G10@CPEI–2.5 demonstrated excellent stability, retaining 96.1% of its initial capacity after 100 cycles under dry conditions, while its H 2 O/CO 2 co-adsorption capacity remained stable throughout all cycles in the presence of 15% CO 2 /N 2 with 50% RH.