Synthesis and Performance of Zr(OH)n(CO3)m–ZnO Composite Adsorbent for CO2 Capture and Concentration from Air in Closed Environments

The features of the formation of the porous structure of a Zr(OH)n(CO3)m–ZnO composite adsorbent, as well as its thermal and sorption properties with respect to CO2, have been studied in relation to life-support systems for closed environments. It has been established that the amorphous micro-mesoporous structure of the material is formed during the synthesis of the adsorbent at the hydrothermal treatment stage as a result of the hydrolysis of zirconium hydroxycarbonate. The specific surface area and micropore volume of the material increase almost a hundredfold compared with the initial zirconium hydroxycarbonate and amount to 298 m2/g and 0.120 cm3/g, respectively. Zinc oxide acts as a stabilizing additive that mitigates the degradation of the porous structure of Zr(OH)n(CO3)m and of the adsorbent as a whole upon its contact with water vapor during operation, particularly during regeneration. The material exhibited a high sorption capacity for carbon dioxide under dynamic conditions (of the order of 9–11.5 L/L at a CO2 content in the air mixture equal to 0.4–1.0%) and stability over long-term resource testing (4600 adsorption–desorption cycles), which makes it possible to recommend it for CO2 capture and for the air revitalization of space complexes.