Direct CO2 capture from ambient air using K2CO3/Al2O3 composite sorbent

A composite sorbent K2CO3/γ-Al2O3 was synthesized and tested for direct carbon dioxide capture from ambient air. Composition and structure of the composite were characterized by means of atomic absorption spectroscopy, low-temperature nitrogen adsorption, X-ray diffraction and transmission electron microscopy, differential scanning calorimetry and thermogravimetry methods. CO2 absorption from air and desorption experiments were performed in a continuous-flow system. The effect of temperature on thermal regeneration of the composite was investigated. It was shown that stable CO2 absorption capacity of 4.0-4.9 wt.% can be obtained in cycles with regeneration temperature of 250-300 °C. The composite sorbent demonstrated a great stability of its CO2 absorption characteristics, therefore it should be considered as a promising material for direct carbon dioxide capture from air. The total energy required for air-borne CO2 capture and its subsequent methanation was assessed.