Herstellung von Metalloxid-Nanopartikeln aus Alkali-Metallaten in organischen Lösungsmitteln

The present invention relates to a method for producing metal or metalloid oxide nano particles of the general formula (I), wherein M\ a, and b have the following meanings: M1 metal or metalloid selected from the groups 1 to 15 of the periodic table of elements (IUPAC) of the lanthanides, actinides, and mixtures thereof, a 1 - 4, and b 1 - 4, wherein a and b are selected \u3cbr/\u3ebased on the oxidation number of M1 such that the compound of the general formula (I) has a neutral charge, comprising the following steps: (A) preparing a solution or dispersion of at least one compound of the general formula (II), wherein M1 has the above meaning, and M2, x, y, z, and n have the following meanings: M2 alkali or alkaline earth metal or mixtures 2 thereof, x 0.5 - 6.30, y 0.5 - 6, z 0.5 - 4, and n O - 12, wherein x, y, and z are selected based on the oxidation numbers of M1 and M2 such that the at least one compound of the of the general formula (II) present in the reaction mixture from step (A) with at least one acidic ion exchanger by adding the at least one ion exchanger to the reaction mixture, in order to obtain the metal or metalloid nanoparticles of the general formula (I), and (C) separating the at least on acidic ion exchanger from the reaction mixture

Structure of Cs0.5_{0.5}[Nb2.5_{2.5}W2.5_{2.5}O14_{14}] analysed by focal-series reconstruction and crystallographic image processing

The structure of the oxygen sub-lattice in Cs0.5[Nb2.5W2.5O14] is investigated for the first time by advanced electron-optical methods. Since Cs0.5[Nb2.5W2.5O14] resembles the crystal structure of the so-called M1 phase of Mo–V–Nb–Te–O, which is the best catalyst for the selective oxidation of propane to acrylic acid, the structure analysis of the oxygen sub-lattice can contribute substantially to a better understanding of this catalytic process. The so far only partially known structure of the complex metal oxide Cs0.5[Nb2.5W2.5O14] is investigated by combining modern methods of high-resolution transmission electron microscopy with crystallographic image processing techniques. Average atom positions in the a–b plane are determined from the phase of the exit-plane wave function, which was numerically reconstructed from a focal series of spherical-aberration-corrected electron micrographs. The experimentally determined atom positions agree well with a structure model obtained by first-principles calculations for the underlying M5O14 (M = Nb, W) framework. Moreover, several deviations from the periodic structure, which may influence the catalytic properties of the structurally similar M1 phase, are observed. The obtained results demonstrate that aberration-corrected high-resolution transmission electron microscopy is a reliable alternative for the analysis of periodic structures, in particular when traditional methods for crystallographic structure determination like XRD or neutron diffraction cannot be applied