Mitigation of CO2 emissions by hydrotalcites of Mg3Al-CO3 at 0 °C and high pressure

Abstract

This work shows the maximum CO2 capture capacity, using CO2 isotherms at 0, 20 and 30 °C and pressures of up to 35 atm, of four adsorbents with different particle size distribution and different pore size distribution: two hydrotalcites of Mg3Al-CO3, one synthesized in laboratory (C1) and another commercial (C2) and two calcined (C1 500 and C2 500) obtained from C1 and C2 by calcination at 500 °C for 2 h, respectively. The maximum capture capacities were obtained for samples calcined (CLDH), 98.16 mg·g−1 for C2 500 sample and 142.02 mg·g−1 for sample C1 500, both at 0 °C and 34.28 atm. The capture capacity of the C2 500 sample was the least influenced by temperature changes, which could be related to the porous structure of the samples. Consequently, for applications that are carried out between 0 and 30 °C, the best sample will be C2 500. Previously the samples were characterized by X-ray diffraction, transmission and scanning electron microscopy, thermogravimetric and thermo-differential analysis, particle size distribution and pore size distribution by N2 adsorption isotherms. The CO2 adsorption isotherms data were adjusted to the Freundlich, Langmuir, Dubinin-Radushkevich y Temkin models. These two last models confirmed that the nature for CO2 adsorption was physical. In short, this work showed the usefulness of calcined hydrotalcite as a CO2 adsorbent, using low temperature (0 °C) and high pressure (34.28 atm) as working conditions.