CO2 adsorption by organohydrotalcites at low temperatures and high pressure

Abstract

• CO 2 -adsorption organohydrotalcites at 0 °C and 35 °C and up to 35 atm was studied. • Sample HT-TDD-C adsorbed 176.66 mg of CO 2 ·g −1 at 0 °C and 35.00 atm. • 1.34 g of calcined HT needed to reduce the amount of CO 2 in 1 m 3 of air to preindustrial level. • New CO 2 capture materials available for use in CCU technologies. In this study, the maximum CO 2 -capture capacities of two families of organohydrotalcites, with intercalated dodecyl sulphate or tetradecanedioate anions in their uncalcined and calcined states, were studied. Adsorption conditions with high CO 2 gas pressures (up to 35 atm) and low temperatures (0 °C and 35 °C) were tested. The calcined Mg-Al hydrotalcite with tetradecanedioate anion had the highest CO 2 -adsorption capacity (176.66 mg·g −1 at 0 °C), which was 24.4% higher than the best results obtained with the calcined Mg-Al hydrotalcites with carbonate. Approximately, 1.34 g of calcined hydrotalcite was necessary to reduce the amount of CO 2 in 1 m 3 of air to the preindustrial level. A thorough characterisation of the surfaces and structures of the samples was performed using different techniques. The CO 2 adsorption process was modelled using different mathematical equations: Langmuir, Freundlich, Sips, Toth, Dubinin-Radushkevich, and Temkin. The adsorption nature of the hydrotalcites enables us to achieve adsorption–desorption cycles by simply changing the CO 2 pressure conditions. These results may contribute to the development of new CO 2 capture materials for use in carbon capture and use technologies and for the mitigation of greenhouse gas emissions.