Composite Sorbents Based on Carbon Nanotubes and K2CO3 for CO2 Capture from Ambient Air

K2CO3-containing sorbents supported on carbon nanotubes (CNT) were prepared via one-pot extrusion molding and heat treatment. The porous CNTs were mixed with a water-isopropyl alcohol solution of potassium acetate (CH3COOK) and extruded by a plunger extruder. After drying in air, extrudates were calcined at 500 degrees C in argon to obtain the sorbents with a K2CO3 weight content in a range of 13.1-44.8 wt %. Samples were characterized using various techniques (scanning electron microscopy (SEM), X-ray diffraction (XRD), and low-temperature nitrogen adsorption) and were tested in the process of carbon dioxide capture from ambient air. The sorbent with 44.8 wt % K2CO3 demonstrated the promising dynamic CO2-sorption capacity (up to 8.9 wt %) under temperature-swing adsorption (TSA) cycle conditions. Taking into account that the sorbents need a relatively low temperature for regeneration (150 degrees C) while demonstrating high CO2-sorption capacity in the sequence of TSA cycles, these sorbents may be of interest for direct air capture applications.