D. F. Kondakov

Synthesis of complex hydroxo salts of magnesium, nickel, cobalt, aluminum, and bismuth and oxide catalysts on their base

Synthesis methods have been developed for the precursors of oxide catalysts that include the combination of magnesium nickel cobalt aluminum hydroxocarbonate, with a layered hydrotalcite-type structure and decavanadate and paramolybdate ions in the anion layers, and bismuth hydroxocarbonate. On the base of these precursors, multicomponent oxide catalysts have been manufactured for the oxidative dehydrogenation (OD) of light alkanes. Some of these catalysts showed high selectivities and high product yields in the conversion of ethane to ethylene.

Chromium, vanadium, molybdenum, tungsten, magnesium, and aluminum hydrotalcite hydroxo salts and oxide catalysts on their base

A method is developed for the synthesis of chromium-containing catalysts for the oxidative dehydrogenation (ODH) of alkanes, comprising the precipitation, from nitrate solutions, of mixtures of isomorphic hydrotalcite-type magnesium aluminum and magnesium chromium hydroxocarbonates and the incorporation of oxovanadate, oxomolybdate, and oxotungstate ions by means of anion exchange and subsequent heat treatment. A series of oxide catalyst samples with progressively more complex compositions were prepared: Mg-Al, V-Mg-Al, V-Mo-Mg-Al, Cr-V-Mg-Al, Cr-V-Mo-Mg-Al, and Cr-V-Mo-W-Mg-Al. The catalytic properties of these complex oxides in the ODH of ethane and propane are improved with progressively complex compositions. Chromium-containing catalysts have higher selectivities and provide higher conversions compared to state-of-the-art iron- and nickel-containing oxides.

Magnesium iron aluminum hydroxosalts and oxide catalysts for oxidative dehydrogenation of alkanes and alcohols

Methods are developed for the synthesis of precursors for oxide catalysts containing iron hydroxocarbonate and magnesium aluminum hydroxocarbonate with hydrotalcite-type layered structure and decavanadate and paramolybdate ions in anionic interlayers. These precursors are used to synthesize oxide catalysts for oxidative dehydrogenation of alcohols and alkanes with high selectivity and good yields of the desired product in conversion of ethane to ethylene and alcohols to carbonyl compounds.

Study of metal extraction in high-frequency vibration mini-columns

The prospects of high-frequency vibration mini-columns for use as models for studying the extraction recovery and separation of metals are demonstrated.

Textural and structural characteristics of phosphorites from the Polpinsky deposit

The textural and structural characteristics of phosphorites from the Polpinsky deposit have been determined. These raw materials are shown to be of siliceous polymineral type and consist mostly of α-quartz, hydroxycarbonate apatite, montmorillonite, and bonschtedtite. The modification dynamics of chemical composition and the textural characteristics (specific surface, pore volume, and pore diameter) of the solid upon the acid decomposition of a phosphorite sample from Polpinsky deposit have been studied. The α-quartz in phosphorites is shown to not experience crystal-structural alterations upon acid decomposition; its pore size does not inhibit the extraction of acid-soluble components, including calcium and phosphorus, from the bulk.

Morphology of calcium carbonate prepared via homogeneous synthesis

The morphology of calcium carbonate prepared via homogeneous synthesis from carbonate–chloride solutions was studied. The precipitates were investigated by scanning electron microscopy (SEM) and Xray diffraction. The effects of the ratio between the chloride and carbonate components of a solution on the morphology, crystal structure, and particle size of precipitated calcium carbonate were illustrated.

Synthesis of basic yttrium nitrate

The reaction between yttrium nitrate and potassium hydroxide solutions was conducted at 25 and 50°C and at the boiling point of the reaction mixture, and the reaction products were studied. The Schreinemakers method, X-ray diffraction and crystal-optical analyses, IR spectroscopy, and electron microscopy demonstrated that X-ray amorphous yttrium hydroxide Y(OH)3 and basic yttrium nitrate Y(OH)2.5(NO3)0.5 · H2O are formed at 25 and 50°C as a poorly crystallized precipitate depending on the ratio between the initial reagents. Keeping the reaction products at the boiling temperature gives rise to a well-crystallized sample of basic yttrium nitrate.

Samarium-containing catalysts of oxidative dehydrogenation of alkanes

A method was developed for introducing samarium into Mg-Al hydrotalcites, which are precursors of oxide catalysts for oxidative dehydrogenation of alkanes. Samples of oxide catalysts were synthesized that contained samarium oxide and also various combinations of magnesium, aluminum, chromium, vanadium, molybdenum, and niobium oxides. The catalytic properties of the produced catalysts were studied in the oxidative dehydrogenation of ethane, propane, and isobutane. Addition of samarium to some of the multicenter catalysts under study was found to increase the selectivity and the yield of target products.

Composition of Lean Apatite Ores from the Laokai Deposits

X-ray powder diffraction and X-ray fluorescence analyses of lean apatite ores from the Laokai deposits were performed. The test sample was divided into 11 fractions, each being analyzed for phosphorus and the major associated impurities. The chemical composition of the lean apatite was found to be virtually independent of particle size, thereby the primary beneficiation of the raw material being excluded.

Behavior of Impurities of Polpino Phosphorites in Acid Extraction

The phase composition of phosphorites from the Polpino deposit (Bryansk oblast, Russia) is studied. The phosphorites are shown to be highly likely to contain α-quartz, phosphate substance, and clay mineral phases, in addition to the two major phases. The textural characteristics of Polpino phosphorites are determined as dependent on the temperature of preliminary heat treatment. The behavior of impurities upon hydrochloric acid decomposition of Polpino phosphorites is investigated. Iron and aluminum impurities are found to not interfere with the acid extraction of the phosphate substance.