Formation and stability of the porous structure of the adsorbent based on Zr(OH)4 for absorption of CO2 from the atmosphere of isolated objects

The development of effective adsorbents for carbon dioxide capture from various gas environments is an extremely urgent task today. The features of the formation of the porous structure of the Zr(OH)4-ZnO composite adsorbent, as well as its sorption properties with respect to CO2, are studied. It is established that the micro-mesoporous structure of the material is due to the presence of zirconium hydroxide, which is formed during the synthesis of the adsorbent mainly at the stage of hydrothermal treatment as a result of hydrolysis of zirconium hydroxycarbonate under the action of water vapor. The specific surface area and micropore volume of the Zr(OH)4-ZnO adsorbent granulated by extrusion vary in the range of 279 – 322 m2/g and 0.119 – 0.131 cm3/g, respectively, which is almost two orders of magnitude greater than these parameters for the original material. Zinc oxide is a stabilizing additive that prevents degradation of the porous structure of zirconium hydroxide and the adsorbent as a whole when it comes into contact with water vapor during synthesis and operation (at the regeneration stage). The material has demonstrated high sorption capacity for carbon dioxide under dynamic conditions (about 7.5 l CO2/l adsorbent) and stability over 4600 adsorption-desorption cycles, which allows it to be recommended for absorbing CO2 from the atmosphere of space complexes.