Montmorillonite-supported Pd⁰, Fe⁰, Cu⁰ and Ag⁰ nanoparticles: Properties and affinity towards CO₂

Highlights: • Purification and modification of montmorillonite. • Dispersion and immobilization of metallic nanoparticles within NaMt layers. • Changes of the distance between the minerals clay layers. • Applications of NaMt-M-NPs adsorbents for adsorption of CO₂. - Abstract: This study reports the carbon dioxide (CO₂) adsorption on montmorillonite (NaMt) incorporating Cu⁰, Fe⁰, Pd⁰ and Ag⁰ as metallic nanoparticles (MNPs). The changes in structural, textural, morphological and adsorption properties of the resulting materials (NaMt-MNPs) were investigated. Electron microscopy and X-ray diffraction showed that dispersion of fine MNPs occurs mainly within the interlayer space of NaMt, producing a slight structure expansion. This was accompanied by a visible enhancement of the affinity towards CO₂, as supported by thermal programmed desorption measurements. NaMt-MNPs displayed high CO₂ retention capacity (CRC) of ca. 657 μmol/g for NaMt-Cu as compared to NaMt. This was explained in terms of increased number of available adsorption sites due to enlarged interlayer spaces caused by MNP insertion. The differences in CO₂ adsorption capacities clearly demonstrate the key role of MNPs in improving the surface properties and adsorption capacity. The results reported herein open new prospects for clay supported metal nanoparticles as efficient adsorbents for CO₂.