A. A. Vedenyapin

Separation of copper and bichromate ions by complex methods

Separation of Cu2+ and Cr2O72− has been studied by electrodialysis combined with preliminary adsorption on bentonite. The influence of concentration, pH, and electric current on the degree of desalination has been studied. The optimum conditions for almost complete separation of the ions studied have been found. Real galvanic sewage has been examined by this method.

Electrocatalysis on microdeposits of palladium on vitreous carbon, deposited at different potentials

The potential at which Pd is deposited on vitreous carbon has a strong influence on the activity of the catalyst in the cathodic evolution of H2 and the electrohydrogenation of acetophenone. The most effective catalyst is Pd deposited at E=0.6 V.

ADSORPTION OF PD, NI, AND CU IONS ON ANODE-OXIDIZED CARBON FIBER MATERIALS

The anodic oxidation of the carbon felt Carbonetcalon results in the formation of surface defects which serve as centers of strong adsorption of PdII, NiII, and CuII ions. The electrochemical reduction of adsorbed ions makes it possible to obtain metallic catalysts, which undergo multiple redox cycles without loss of metal. The catalysts are characterized by high dispersity of the reduced phase, high adsorption capacity with respect to hydrogen, and 100% selectivity in hydrogenation of acetophenone.

Ligand effect in dissymmetric Cu-Ru and Cu-Pd catalysts

ConclusionsFor Raney Cu-Ru and Cu-Pd catalysts non-additive changes in the strength of the catalyst-hydrogen bond and in the catalytic activity and enantioselectivity were found to occur with changing composition, indicating the presence of a ligand effect in these systems.

Study of the formation of copper-nickel asymmetric catalysts

Conclusions1.The catalytic properties of CNC depend on the conditions of preparation. The simultaneous formation of Cu and Ni and their alloy occurs during the-reduction process of CNC.2.The appearance of a cluster effect is observed for the enantioselective hydrogenation on CNC.

Electrohydrogenation of ethyl acetoacetate on a modified nickel catalyst

ConclusionsThe enantioselective electrohydrogenation of ethyl acetoacetate in the region of the anodic and cathodic potentials of the Ni electrode-catalyst, in relation to the reversible hydrogen electrode, proceeds with the enantioselectivity of ∼10%.

Phase composition of skeletal copper-ruthenium catalysts and absorption of hydrogen on them

1. n nSkeletal copper-ruthenium catalysts are composed of copper, ruthenium, bayerite, and gibbsite phases. n n n n n2. n nThe change curves of the copper-ruthenium catalysts were taken, and from them were determined the specific surface areas of the ruthenium phases and the average size of the ruthenium crystallites. n n n n n3. n nA complex relationship was found to exist between the dispersity of ruthenium and its amount in a mixed catalyst.

Mechanism of modifying skeletal copper catalyst for asymmetric hydrogenation

1. n nCopper tartrate complexes that partially go into solution are formed on the surface of a copper catalyst when skeletal copper is modified with (2R,3R)-(+)-tartaric acid. n n n n n2. n nThe character of the modifier-catalyst bond is close to the character of the modifier-metal bond in the corresponding complex.

Kinetics and mechanism of hydrogenation of C=O group in acetoacetic ester on skeletal copper catalyst

1. n nThe kinetics of the hydrogenation of acetoacetic ester on skeletal copper catalyst in the liquid phase was studied. The observed reaction rate is strongly dependent on the hydrogen pressure and the temperature. n n n n n2. n nA scheme was proposed for the progress of the studied reaction along three routes.

Effect of size of ruthenium crystallites in Ru/SiO2 catalyst on its catalytic and asymmetrizing activity

1. n nA study was made of the asymmetrizing activity of asymmetric Ru/SiO2 catalyst samples that had been modified with (+)-tartaric acid in the liquid-phase hydrogenation of ethyl acetoacetate. n n n n n2. n nThe sample that contains Ru as crystallites with a size of 45 A has the highest asymmetrizing activity. n n n n n3. n nTaking into consideration the characteristics of asymmetric hydrogenation, an explanation was offered for the observed experimental data.