Active Iron Sites of Disordered Mesoporous Silica Catalyst FeKIL-2 in the Oxidation of Volatile Organic Compounds (VOC).

Iron-functionalized disordered mesoporous silica (FeKIL-2) is a promising, environmentally friendly, cost-effective and highly efficient catalyst for the elimination of volatile organic compounds (VOCs) from polluted air via catalytic oxidation. In this study, we investigated the type of catalytically active iron sites for different iron concentrations in FeKIL-2 catalysts using advanced characterization of the local environment of iron atoms by a combination of X-ray Absorption Spectroscopy Techniques (XANES, EXAFS) and Atomic-Resolution Scanning Transmission Electron Microscopy (AR STEM). We found that the molar ratio Fe/Si ≤ 0.

Spectroscopic evidence for the structure directing role of the solvent in the synthesis of two iron carboxylates.

Crystal engineering: The synthesis of the known compounds MIL-100(Fe) and MIL-45(Fe) is characterized by spectroscopy. The products are obtained under identical conditions by varying the solvent from pure water to a mixture of water and acetone. The starting solution, the gel, and the final reaction product were characterized by X-ray absorption spectroscopy (see picture).

Understanding (6)Li MAS NMR spectra of Li(2)MSiO(4) materials (M = Mn, Fe, Zn).

Analysis of (6)Li MAS NMR spectra of several lithium transition-metal orthosilicates (Li(2)MSiO(4), M = Mn, Fe, Zn) improved the understanding of the relation between the spectral parameters and the structural characteristics of the materials. It was shown that for manganese- and iron-containing materials the width of the (6)Li spinning-sideband powder patterns can be roughly related to the arrangement of the transition-metal cations within the first cation coordination sphere around lithium. In mixed zinc-manganese lithium orthosilicates the (6)Li isotropic shift depends on the number of Li-O-Mn bonds, in which a particular lithium site is involved.