L. N. Chukhlomina

Catalytic oxidation of phenol in the presence of iron-containing composites based on silicon and boron nitrides

Sorption and catalytic activities of iron-containing composites based on silicon and boron nitrides in purification of aqueous solutions to remove phenol under ozonation and UV irradiation in the presence of oxalic acid and hydrogen peroxide additives was studied.

Preparation of Si3N4–ZrO2 ceramic composites by self-propagating high-temperature synthesis

Results are provided for a study of Si3N4–ZrO2 composite ceramic material preparation by self-propagating high-temperature synthesis from ferrosilicon and zirconium concentrate. It is noted that as a result of high-temperature dissociation of ZrSiO4 silicon dioxide is nitrided with formation of silicon oxynitride and it is condensed in surface layers of a specimen in the form of filamentary crystals.

Features of the formation of silver nanoparticles on the silicon nitride surface

Special features of the formation of particles of a silver-containing catalyst phase on a silicon nitride surface in relation to the mode of the active component deposition were studied. The influence of a redox medium of the catalytic reaction of the ethylene glycol selective oxidation to glyoxal on the final composition and structure of silver catalysts was studied.

Use of Si-N-Fe and B-N-Fe Compositions for Formaldehyde Degradation in Combined Heterogeneous and Homogeneous Catalytic Processes

The catalytic activity of B-N-Fe and Si-N-Fe compositions toward formaldehyde degradation in aqueous solutions by ozonation and UV irradiation was examined in relation to the time of exposure, phase composition and weight of the catalyst, and amount of oxalic acid added. The conditions for complete degradation of formaldehyde were determined, and high workability of the composites was demonstrated. The application of the catalysts in drinking water treatment to remove formaldehyde was tested.

Analysis of the sorption and catalytic activity of a B-N-Fe composite in water purification to remove oxalic acid

Sorption and catalytic activity of composites based on nitrogenized ferroalloys of boron in purification of aqueous solutions to remove oxalic acid in separate and joint exposure to UV radiation and ozone with and without addition of hydrogen peroxide was studied. The materials were produced by self-propagating high-temperature synthesis. X-ray diffraction analysis and IR spectroscopy were used to determine the presence of hydrated iron oxalate in a composite material upon its contact with a contaminant. The conditions in which the organic contaminant is completely degraded were found.

Metal-ceramic composites prepared under combustion conditions and their catalytic activity in dye degradation

Composites based on boron, silicon, and chromium nitrides and on Sialon were prepared with the aim of using them in photocatalytic degradation of dyes for wastewater treatment. The surface parameters, elemental and phase composition, and morphology and size of particles of the materials were evaluated. The activity of the composites in decolorization of dye solutions under the conditions of generation of photoactive systems (Ruff-Fenton, ferrioxalate, peroxide-ferrioxalate) was studied. The highest degree of dye degradation is reached when using composites based on boron nitride, which is due to the combination of the photoadsorption and photooxidation.

Structural-phase and morphological characteristics of silver catalysts on modified ceramic supports for selective oxidation of alcohols

New ceramic materials based on silicon nitride and obtained by self-propagating high-temperature (SPHT) synthesis were investigated. The Si3N4 materials modified with Zr and Al compounds were used as supports for silver-containing catalysts of selective oxidation of ethyleneglycol into glyoxal. The procedure for the synthesis of supported silver-containing catalysts affected the structural and morphological states of the active component before and after the catalytic reaction.

Combustion of the Fe-Si alloy in nitrogen gas

Combustion of the Fe-Si alloy in nitrogen gas was explored. The combustion was found to proceed in an autooscillating mode. Upon addition of nitrided ferrosilicon, magnesium fluoride, or ammonium chloride into a green mixture, the process becomes steady-state, while the extent of nitriding attains its maximum value. The phase composition and morphology of the product were found to depend on reaction conditions. The products formed in the presence of ferrosilicon or magnesium fluoride were found to largely contain columnar, platelike, and whiskerlike β-Si3N4 crystals (≥95%), while those in the presence of ammonium chloride contain silicon nitride with a granular structure and elevated content of the α-phase (<80%). Acid enrichment of combustion products was used to obtain silicon nitride with a Fe content of 0.01–0.1 wt %.

Use of composites based on boron nitride in combined photocatalytic process for generation of hydrogen and degradation of soluble organic substances

Possibility of using composites based on boron nitride in combined photocatalytic processes for degradation of soluble organic substances and generation of hydrogen was examined. The hydrogen evolution rate and output capacity of the composites under study in release of hydrogen from aqueous solutions of formic and oxalic acids and hydrazine under irradiation with visible and UV light were evaluated. It is shown that the highest efficiency of generation of molecular hydrogen is achieved in photodecomposition of hydrazine and oxalic acid with a composite whose phase composition includes iron and a set of semiconductor carbides (Fe3C, MgC2, Al4C3, SiC).

Nitride-based materials SHS-produced from ferroalloys: II. Silicon nitride as a support for Ag-Containing catalysts for partial oxidation of ethylene glycol

Ag-containing catalytic systems immobilized on SHS-produced and acid-leached Si3N4 supports showed good service parameters in partial oxidation of ethylene glycol to glyoxal. Compared to similar catalytic systems on aluminosilicate supports, our catalysts exhibit more uniform distribution of active centers over support surface, narrow size distribution of Ag particles, higher chemical resistance, and lower carbon deposition.