PdIn/Al2O3 Intermetallic Catalyst: Structure and Catalytic Characteristics in Selective Hydrogenation of Acetylene

Kinetics and Catalysis - The structure and catalytic characteristics of a bimetallic catalyst containing Pd1In1 nanoparticles deposited on the surface of γ-Al2O3 were studied. The formation of...     

Production of Pure Aqueous 13C‐Hyperpolarized Acetate by Heterogeneous Parahydrogen‐Induced Polarization

A supported metal catalyst was designed, characterized, and tested for aqueous phase heterogeneous hydrogenation of vinyl acetate with parahydrogen to produce ¹³C‐hyperpolarized ethyl acetate for potential biomedical applications. The Rh/TiO₂ catalyst with a metal loading of 23.2 wt % produced strongly hyperpolarized ¹³C‐enriched ethyl acetate‐1‐¹³C detected at 9.4 T. An approximately 14‐fold ¹³C signal enhancement was detected using circa 50 % parahydrogen gas without taking into account relaxation losses before and after polarization transfer by magnetic field cycling from nascent parahydrogen‐derived protons to ¹³C nuclei. This first observation of ¹³C PHIP‐hyperpolarized products over a supported metal catalyst in an aqueous medium opens up new possibilities for production of catalyst‐free aqueous solutions of nontoxic hyperpolarized contrast agents for a wide range of biomolecules amenable to the parahydrogen induced polarization by side arm hydrogenation (PHIP‐SAH) approach.     

Cobalt-containing catalysts based on Al2O3 for the oxidative destruction of organic dyes in the aqueous phase

Kinetics and Catalysis - Alumina-based cobalt-containing catalysts have been synthesized for the oxidation of organic dyes with hydrogen peroxide in the aqueous phase. According to X-ray...     

LaMn1 – xFexO3 (x = 0–1) Perovskites in Methane and Carbon Monoxide Oxidation Reactions

Kinetics and Catalysis - The LaMn1 – xFexO3 (х = 0–1) perovskites were prepared by the Pechini route and characterized by X-ray diffraction analysis, HR TEM, XPS, and BET. Their...     

Stability of the (0001) surface of the Bi<Subscript>2</Subscript>Se<Subscript>3</Subscript> topological insulator

The inertness of the cleaved (0001) surface of a Bi₂Se₃ single crystal to oxidation has been demonstrated using X-ray photoelectron spectroscopy, as well as atomic-force and scanning tunneling microscopy and spectroscopy. No intrinsic bismuth and selenium oxides are formed on the surface after a month of storage in air. Atomically flat surfaces with macroscopic sizes (∼1 cm²) and rms roughness less than 0.1 nm have been prepared, and (1 × 1)-(0001) Bi₂Se₃ atomic structure has been resolved. The tunneling conductance measurements have shown that the energy dependence of the surface density of states is quasilinear in the band gap of Bi₂Se₃.     

Side‐chain functionalized liquid crystalline polymers and blends, 6. Phase behavior,structure and magnetic properties of Cu(II) containing liquid crystalline ionomers

The new series of the LC ionomers containing copper ions has been obtained and their phase behavior has been studied. It was shown that at low metal ion concentrations in the LC ionomers (˜2 mol‐%) the induction of the SmA phase is observed. An increase in the copper ion concentration is accompanied by a slight rise in clearing and glass transition temperatures. The magnetic properties of LC ionomers were studied at the first time. It was shown that LC ionomers are antiferromagneties with a strong exchange interaction J = 174–178 cm^–1. Temperature dependencies of the magnetic moment and the magnetic anisotropy are adequately described in the framework of the 1‐D‐Heisenberg linear‐chain model.     

Atomic and Electronic Structure of SiOx Films Obtained with Hydrogen Electron Cyclotron Resonance Plasma

Journal of Experimental and Theoretical Physics - The silicon oxide thin films obtained by thermal SiO2 treatment in hydrogen electron cyclotron resonance plasma at various exposure times are...     

Correlation between magnetic properties and molecular structure of some metallo-mesogens

The behaviour of a large number of paramagnetic metallo-mesogenic molecules with Cu and VO in different mesophases in a magnetic field was investigated by EPR techniques and magnetic susceptibility measurements. The investigation of the angular dependence of the EPR spectra enabled conclusions to be reached concerning the molecular orientation in the external magnetic field. Temperature dependence magnetic susceptibility measurements were carried out in order to obtain information about the overall susceptibility anisotropy. The good agreement between experimental results and calculated data based on the known increment scheme is obvious. It is shown that the direction of orientation of the molecules in a magnetic field is predetermined by the sum of the anisotropy of the phenyl ring and the chelate core in the molecular structure.     

Effect of the Structure of Carbon Nanofibers on the State of an Active Component and on the Catalytic Properties of Pd/C Catalysts in the Selective Hydrogenation of 1,3-Butadiene

The state of highly dispersed palladium particles supported on filamentous carbon was studied using high-resolution electron microscopy, XPS, and X-ray diffraction analysis. Three types of filamentous carbon were used, in which the basal planes of graphite were arranged along, across, and at an angle to the nanofiber axis. The amount of supported palladium was 0.25–5.8 wt %. The structure of the carbon support was found to affect the properties of the active component. Highly dispersed palladium particles exhibited the strongest interaction with a carbon surface formed by the butt ends of graphite (002) layers. This interaction resulted in electron transfer from the metal to the support and in the stabilization of palladium in the most dispersed state. A change in the properties of palladium particles caused a change in the catalytic properties of Pd/C catalysts in the reaction of selective 1,3-butadiene hydrogenation to butenes. The strong interaction of Pd²⁺ with the butt ends of graphite resulted in the stabilization of palladium in an ionic state. An increase in the fraction of Pd²⁺ in the catalysts was responsible for a decrease in both the overall activity and selectivity of Pd/C catalysts in the reaction of 1,3-butadiene hydrogenation to butenes.