Thermal stability and CO₂ adsorption–desorption performance of synthetic hectorite and its CeO₂/NiO nanocomposites

Abstract

Understanding the properties of clay minerals is crucial for developing efficient adsorbent and catalytic materials, creating new options for carbon capture technologies (CCT). This study investigates for the first time the thermal stability of synthetic hectorite (Hec), a smectite clay mineral, aiming to prepare nanocomposites containing CeO₂ and NiO nanoparticles as promising material for carbon capture technologies. Hectorite was thermally treated at 540 °C, 740 °C, and 800 °C, with physicochemical analyses (XRD, Raman, FTIR, SEM) identifying 540 °C as the optimal temperature for incorporating CeO₂ and NiO catalytic species (CS) without disrupting the intrinsic smectite structure. Additionally, the introduced CS, enhanced the thermal stability of hectorite as confirmed by TGA/DSC. CO 2 adsorption measurements at 35 °C revealed that pure Hec exhibited the highest adsorption capacity of 1231 μmol g −1 and retained 51% of the gas during desorption with N 2 , underscoring its potential for carbon capture and storage. In contrast the pure hec calcined at 540 °C, adsorbed 912 μmol g −1 , while the nanocomposites Hec_Ce, Hec_Ni, and Hec_CeNi showed values around 800 μmol g −1 , with Hec_CeNi achieving the highest retention (65%), which may be associated with oxygen vacancies in the ceria structure. These results highlight synthetic clay-based materials as promising, cost-effective candidates for advanced CCT applications, with added potential for CO₂ conversion in presence of catalytic species.