Alginate-derived solid-liquid hybrid structured adsorbent for CO₂ capture

The development of highly stable structured solid amine adsorbent is crucial for the large-scale deployment of CO₂ capture systems. Here, we report a structured solid amine adsorbent using the solid-liquid hybrid wrapping method, wherein a suspension of tetraethylenepentamine (TEPA) and ZSM-22 support is encapsulated within a calcium alginate film through freeze-drying. The textural properties of the structured adsorbents (SA@S/T_X) were investigated using scanning electron microscopy, N₂ adsorption-desorption, Fourier transform infrared spectroscopy, and thermal gravimetric analyzer. The CO₂ adsorption capacity of SA@S/T_X displayed an initial increase followed by a decrease with increasing TEPA loading, and the adsorption rate exhibited a similar trend according to the pseudo-first-order model. The maximum adsorption capacity and adsorption rate (k) were observed to be 2.22 mmol/g and 0.98 min⁻¹ (under conditions of pure CO₂, 1 atm and 25 °C), respectively, at a TEPA content of 0.5. In addition, SA@S/T_X exhibited good regeneration stability with a low loss in capacity of 10.8 % during 30 cycle of CO₂ adsorption–desorption tests, and high thermal stability with a low amine loss of 2.0 % under conditions of 100 °C and 12 h. These results demonstrate that the solid–liquid hybrid wrapping method effectively shapes the powdered adsorbent while significantly reducing TEPA volatilization, offering a possibility for the industrial applications of solid amine adsorbents.