Sergey V. Volkov

Methane oxidative carbonylation catalyzed by rhodium chalcogen halides over carbon supports

Abstract Gas phase carbonylation of methane is studied in the presence of molecular oxygen over pure carbon carriers and carbon supported rhodium chalcogen halides. Activated carbons and fullerene blacks have been used as carbon supports. XPS and IR-spectroscopy data show the formation of rhodium chalcogen halides in solids prepared by different methods. We have found that the productivity of acetic acid by carbon supported rhodium chalcogen halides depends strongly on the carbon carrier and the method of the catalyst preparation. Namely, the catalyst with highest productivity for the acetic acid is prepared by synthesizing the rhodium chalcogen halide over the carbon support followed by thermal destruction. We have also found that rhodium chalcogen halides over activated carbons are more active compared with fullerene supported catalysts.

Carbon-loaded porous materials produced from fine-particle silica

Carbon-loaded porous materials have been produced by modifying inorganic matrices with pyrolytic carbon prepared via polystyrene carbonization at 750°C in an argon atmosphere. The matrices have been produced from silica particles about 80 nm in size, and polystyrene has been introduced either via impregnation or using polystyrene solutions as dispersion media in the fabrication of the composites. The structure and state of the carbon formed in pores of the composites have been studied by x-ray photoelectron spectroscopy and transmission electron microscopy. The results demonstrate that the pyrolytic carbon has the form of nanotubes or segmented nanospheres.

New Cluster-Type Rhodium Selenochlorides in Oxidative Carbonylation of Methane

New rhodium selenochlorides Rh4Se16Cl10 and Rh4Se18Cl10 whose structure is based on the cluster “cubane” [Rh4(μ3-Se)4] and products of their thermal transformations were obtained. The catalytic properties of the compounds on various carbon and silica supports in oxidative carbonylation of methane in the gas phase and their dependence on the catalyst preparation technique, type of support, and size of its nanopores were analyzed.

Chemical conversions of rhodium selenochloride Rh2Se9Cl6

Rhodium selenochloride Rh2Se9Cl6 (1) reacts with aqueous solutions of KCN and CsCl and 4-cyanopyridine (4-CNPy) to give complexes KCs2Rh(CN)6 (2) and RhCl3(4-CNPy)3 (3). According to X-ray diffraction data, 2 and 3 have mononuclear structures in which the rhodium atoms are in the oxidation state III and six-coordinate environment. Reactions 1 with CN-containing ligands lead to complete displacement of selenium-containing ligands from the rhodium coordination sphere.

Porous inorganic materials modified with pyrolytic carbon producted from polystyrene

Microporous materials were obtained by pyrocarbon modification of matrices based on a highly dispersed silicon dioxide. The modification involved polystyrene carbonization at 400 and 700°C in an argon flow. The possibility was elucidated of varying the properties of porous materials (density, porosity, sorption of organic solvents, and compression strength) by varying the way of introduction of polystyrene solutions into the matrix and their concentrations.

Purification of rhodium-plating electrolytes to remove nonferrous metal impurities

Optimal conditions were determined for purification of sulfate rhodium-plating electrolyte to remove ions of iron(III) and nonferrous metals. Electrochemical and chemical purification techniques were developed.

Chemical transformation of cluster osmium thioselenochloride Os3S7SeCl8

The binuclear osmium complex Os3S7SeCl8 was prepared by the reaction of cluster chalcogen chloride K6Os2S2O6(CN)8 with an aqueous KCN solution. In the complex, the distance between the osmium atoms is 2.85 Å, and they are linked by μ-SO22− bridges with the OsSOs angle of 75.9°. The osmium coordination number is 6. In the reaction with CN− ligands under study, the individual fragments of the structure are retained; however, the trinuclear cluster skeleton of Os3S7SeCl8 is destroyed.