Study on Pore Distribution and Formation Rule of Sepiolite Mineral Nanomaterials

Abstract

Theoretical research and specific surface area analysis of nitrogen adsorption indicated that a lot of structural micropores exist in sepiolite minerals fibers. However, the microporous size, existing form, and the distribution relationship between microporous structures were not proved yet. In this paper, the section TEM samples of nanofibers were prepared on the basis of the metal embedding and cutting technique, and the inner structure of sepiolite nanofibers was observed by TEM. The results showed that sepiolite fibers have multiplayer structure similar to concentric circles, and many micropores with the size of about 2-5 nm are normal and parallel to the c-axis. The reason for the previously mentioned phenomenon was explained by using BET analysis and X-ray diffraction analysis results.

Low temperature conversion of levulinic acid into γ-valerolactone using Zn to generate hydrogen from water and nickel catalysts supported on sepiolite

“…1C) showed that the average pore diameter was around 4 nm, which was coherent with previously reported data for this type of clay. 48,49 No appreciable differences were observed in the prole of the support and the supported nickel catalysts. Regarding to the pore distribution of the Ni supported catalysts (Fig.…”

“…Finally, the sepiolite free Ni catalyst had a low surface area of only 7 m 2 g À1 , being this value close to that obtained by others authors in bulk Ni catalysts. 48,49 Fig . 2 shows XRD patterns of the Ni-based catalysts and their NiO precursors before and aer the reduction step.…”

Ni Supported on Natural Clays as a Catalyst for the Transformation of Levulinic Acid into γ-Valerolactone without the Addition of Molecular Hydrogen

“…As it is well known, if sepiolite is heat treated structural modifications due to the loss of water molecules are observed. Preisinger [72] reported that the loss of the bound H2O leads to a phase change during which the structure is folded by rotation of the phyllosilicate ribbons. These ribbons rotate around an axis through the Si-O-Si corner bonds which link the ribbons (Figure 2B).…”

Adsorption of phenanthrene by stevensite and sepiolite

“…The dimensions of the channels are ∼0.4 nm × 1.08 nm (Fig. 4b) (Helmy & de Bussetti, 2008;Suárez & Romero, 2012;Tang et al, 2012) whereas the size of the PHE molecule is 1 nm in aqueous solution (Huang et al, 1996). Thus, accommodation of the PHE molecule in the sepiolite channels might be hampered because of size.…”