Carbonate-bicarbonate looping was tested for direct CO2 capture from air using a composite sorbent K2CO3/Y2O3. The phase composition, the porous structure and the texture of the composite sorbent were characterized by means of X-ray diffraction, mercury intrusion and scanning electron microscopy methods. The thermal properties of the sorbent were additionally studied by X-ray diffraction in situ and thermogravimetry methods. CO2 absorption from air and desorption experiments were performed in a continuous-flow system. The effect of regeneration temperature on CO2 uptake was investigated. It was shown that CO2 absorption uptake from air is about 28 mg (CO2)/g in temperature swing absorption cycles within regeneration temperature range of 150-250 degrees C. However, the increase of the regeneration temperature up to 300 degrees C results in gradual decrease of the absorption uptake down to 10 mg (CO2)/g. The XRD pattern of the cycled sample contains a set of reflections that cannot be assigned to any known potassium-or yttrium-containing crystalline phase. The new phase, which is thermally stable up to 460 degrees C, accumulates potassium ions and is, probably, responsible for the sorbent capacity decay. (C) 2013 Elsevier Ltd. All rights reserved.