Thin layers of pure TiO 2 and TiO 2 doped by different amounts of Fe 2 O 3 have been prepared by the sol–gel method with tetraisopropyl orthotitanate and Fe(NO 3)3. Physico-chemical properties of catalysts were characterized by BET Adsorption, x-ray Diffraction (XRD), FE-SEM, as well as Raman and UV-Vis spectroscopy. The photocatalytic activity of the obtained materials was investigated in the reaction of complete oxidation of p-xylene in gas phase under the radiation of UV (λ=365 nm) and LED (λ=470 nm) lamps. It has been found that the particle size of all samples was distributed in the range 20–30 nm. The content of the rutile phase in Fe-doped TiO 2 samples varied in the range 6.8 to 41.8% depending on the Fe content. Iron oxide doped into TiO 2 enables the photon absorbing zone of TiO 2 to extend from UV towards visible waves as well as to reduce its band gap energy from 3.2 to 2.67 eV. Photocatalytic activities of the TiO 2 samples modified by Fe 3+ have been found to be higher than those of pure TiO 2 by about 2.5 times.

Simply mixing the complex [{RuCl2(1,3,5‐C6H3iPr3)}2] (1) with PCy3 is sufficient to generate a catalyst suitable for highly efficient atom‐transfer radical addition and polymerization reactions at exceptionally low temperatures (see scheme). The steric congestion at the metal caused by the bulky ligands is thought to be essential for the reactivity of the catalyst.

The use of a tetrafunctional epoxy‐based additive to modify the molecular structure of poly(ethylene terephthalate) (PET) was investigated with the aim of producing PET foams by an extrusion process. The molecular structure analysis and shear and elongation rheological characterization showed that branched PET is obtained for 0.2, 0.3 and 0.4 wt% of a tetrafunctional epoxy additive. Gel permeation chromatography (GPC) analysis led to the conclusion that a randomly branched structure is obtained, the structure being independent of the modifier concentration. The evolution of shear and extensional behavior as a function of molecular weight (Mw), degree of branching, and molecular weight distribution (MWD) were studied, and it is shown that an increase in the degree of branching and Mw and the broadening of the MWD induce an increase in Newtonian viscosity, relaxation time, flow activation energy and transient extensional viscosity, while the shear thinning onset and the Hencky strain at the fiber break decrease markedly.

Abstract:The bimetallic ruthenium complex [(1,3,5-i-Pr 3 C 6 H 3 )Ru(m-Cl) 3 RuCl(C 2 H 4 )(PCy 3 )] has been synthesized by reaction of [(1,3,5-i-Pr 3 C 6 H 3 )RuCl 2 )] 2 with one equivalent of PCy 3 in the presence of ethylene. It can be used as a catalyst precursor for the controlled atom transfer radical polymerization of methacrylates at 35 8C. The resulting polymers show low polydispersities.Keywords: acrylates; bimetallic complex; polymerization; radical reaction; ruthenium Starting with seminal publications in the mid 1990s, [1] transition metal-catalyzed atom transfer radical polymerizations (ATRP) have become ubiquitous in modern macromolecular chemistry.[2] For most applications, Cu(I) complexes with amine-based ligands are used as the catalysts.[3] Nevertheless, there are a number of other transition metals which are known to catalyze ATRP reactions.[2] Among those, ruthenium complexes are of special interest because some of them were found to display very high activities. [4,5] In continuation of our efforts to develop new catalysts for ruthenium-catalyzed radical reactions, [5a,6] we have recently described the homobimetallic complex [(cymene)Ru(m-Cl) 3 RuCl(C 2 H 4 )(PCy 3 )] (1). [7] This complex shows an outstanding catalytic activity in atom transfer radical addition (ATRA) reactions. Since ATRP and ATRA are mechanistically closely related, [2] we were interested to see whether complex 1 can also be used for the controlled polymerization of acrylates. Unfortunately, complex 1 showed a very limited solubility in the monomer-toluene starting mixtures. We therefore investigated possibilities to increase the solubility of complex 1. A modification of the p-ligand appeared to be a suitable strategy because the catalytically relevant RuCl 2 (C 2 H 4 )(PCy 3 ) fragment would not be directly affected. Consequently, the well-soluble dimer [(1,3,5-i-Pr 3 C 6 H 3 )RuCl 2 ] 2 (2) [8] was chosen as the starting material. When a solution of complex 2 in isooctane was heated to 50 8C with one equivalent of PCy 3 in the presence of an atmosphere of ethylene, the desired bimetallic complex 3 was formed (Scheme 1). The product precipitates from solution and can be isolated by filtration (yield: 90%).The new complex was comprehensively characterized by 1 H and 13 C NMR spectroscopy, elemental analysis and single-crystal X-ray crystallography. The 13 C NMR spectrum of 3 in CD 2 Cl 2 showed two signals of equal intensity for the methyl groups of the i-Pr 3 C 6 H 3 p-ligand. This can be explained by the fact that complex 3 is chiral and configurationally stable on the NMR time scale. The methyl groups are thus diastereotopic. In the 1 H NMR spectrum, however, the difference between the two CH 3 groups was not resolved and only one doublet was observed at d ¼ 1.39 ppm. In order to avoid partial dissociation of the labile ethylene ligand, all spectra were recorded under an atmosphere of C 2 H 4 . Analysis of complex 3 by X-ray crystallography confirmed the expected dinuclear structure with three chloro bridges (Fi...

In this investigation, the thin film of degussa P25 was obtained by dip coating method and calcined at 450 °C for 2 h (P25-450-2) and used as photocatalyst for gas-phase photooxidation of xylene. The physico-chemical properties of calcined P25-450-2 powder was studied by the methods of BET adsorption, XRD, FTIR, UV–vis, Raman spectroscopies, SEM, TEM, carbon dioxide temperature-programmed desorption . The thickness of the film was determined on the Alpha Step IQ KLA—Ctencor equipment and the point of zero charge (PZC) of the sample was determined by salt addition method. P25-450-2, having a band gap of 3.155 eV, is advisable to use UV lamps in photocatalytic reactions. The kinetics of gas-phase photooxidation of xylene reaction on the thin films of P25-450-2 under UV illumination was studied using a gradientless flow circulating system at atmospheric pressure and 40 °C. The obtained results showed that the kinetics of the given reaction should be written by fractional equations describing the dependence of the reaction rate on the concentration of adsorbed molecules of xylene and oxygen, dissociative adsorbed water vapor, and also on the total intensity of light. The reaction was proposed to follow the Langmuir-Hinshelwood mechanism.