A physico-chemical study of iron-chromium-molybdenum catalysts

In the study of the Fe_1–xCr_xMo_1·5O₆ system by X-ray, IR and Mössbauer methods the formation of solid state substitution solutions has been detected, which possess similar catalytic properties in methanol oxidation.

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, , Fe_1–xMo_1·5O₆ , .

     

Physico-chemical properties of silica-supported vanadium oxide catalysts

- . TiO₂ ZnO. - CO₂ H₂O. — .

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The effect of visible light on propane and n-butane oxidation has been sutied on a seires of metal oxides. TiO₂ and ZnO have been found to exert a photocatalytic effect. On TiO₂, propane and n-butane are oxidized to CO₂ and H₂O. On ZnO as catalyst, partial oxidation products, aldehydes and ketones, are formed.

     

Development of phase composition for mixed Ni?Cu chromite catalysts. Conversions under calcination

IR spectroscopic and X-ray studies of variations in the composition of Ni, Cu and (Ni+Cu) ammonium chromates under thermal treatment show that the Ni–Cr system consists of spinel and NiO, and Cu–Cr systems consist of the spinel CuCr₂O₄ only. In mixed Ni–Cu–Cr systems part of Ni- and Cu-containing components remain independent and part of them form common Ni+Cu phases.

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Ni-, Cu- (Ni+Cu)- . , Ni–Cr NiO, Cu–Cr — CuCr₂O₄. Ni–Cu–Cr Ni- Cu- , Ni+Cu .

     

Optimization of conditions for synthesizing sulfonated hydrazides of benzoic and benzenesulfonic acids

The kinetic relationships of arenesulfonation of benzoic and benzenesulfonic acid hydrazides were studied. Based on the data obtained, the conditions for synthesizing these products were optimized. The synthesis can be performed using aqueous-organic solvents containing 2-propanol, 1,4-dioxane, or tetrahydrofuran as nonaqueous component. The thermal stability of benzenesulfohydrazide and its sulfonation product was compared on the basis of data of gas chromatography–mass spectrometry. The fragmentation pathways of the reactants and target product, sulfonated benzenesulfohydrazide, were suggested.     

Comparison of the Reactivities of Tyrosine–Proline-Based Dipeptides toward Acylation with Nitrophenyl Benzoates

Russian Journal of Organic Chemistry - The reactivities of the L-Tyr–L-Pro dipeptide and its analog with a hydroxymethyl group instead of carboxy group in the proline moiety were compared by...     

Determination of Indicator Congeners of Polychlorinated Biphenyls in Water at Ultratrace Levels by Gas Chromatography–Tandem Mass Spectrometry

Journal of Analytical Chemistry - We validated a procedure for the determination of indicator congeners (ICs) of polychlorinated biphenyls (PCBs) (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) in...     

Reactivity of Tyrosyl–Proline toward Benzoylation in Aqueous 1,4-Dioxane

Russian Journal of Organic Chemistry - The kinetics of the reaction of L-tyrosyl-L-proline (Tyr–Pro) with di- and trinitrophenyl benzoates in aqueous 1,4-dioxane (40 wt % of water) were...     

Gas-phase autoignition of a spherical volume of fuel in an oxidative medium

A mathematical model of the ignition of unmixed of fuel and oxidizer (a finite spherical volume of fuel surrounded by an infinite oxidizer medium) was developed. The regularities of the autoignition of this system were examined. It was demonstrated that the temperature maximum arising at the fuel-oxidizer interface propagates with increasing amplitude and velocity toward the center of the spherical volume and that the time it takes to attain the maximum temperature (below the autoignition threshold) and the ignition delay time (above the threshold) depend on the parameter δ nonmonotonically, more specifically, exhibit well-pronounced maxima     

Thermal explosion in a batch reactor charged with a liquid–solid heterogeneous system

The characteristics of a thermal explosion in an ideal mixing batch reactor charged with a liquid–solid heterogeneous system are studied. The reactor initially contains both phases. The solid reagent dissolves and reacts in the liquid phase. A strong dependence of the critical value of the Semenov parameter on the dimensionless time of complete dissolution of the solid reagent is established. It is shown that, at short times of complete dissolution, the critical value of the Semenov parameter is practically independent on this time, and the thermal explosion occurs as in a homogeneous system, according to Semenov theory. The heterogeneous properties of the reaction system manifest themselves only at long times of complete dissolution.