On the mechanism of chlorobenzene hydrolysis over Cu promoted lanthanum phosphate

The reaction mechanism of chlorobenzene hydrolysis to produce phenol over Cu promoted lanthanum phosphate has been studied taking into account a parallel reaction through which benzene is formed. There is a competition for the adsorption sites between the reactants and the reaction products.

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, , , . .

     

Redistribution kinetics of isotope molecules due to reversible bimolecular reactions with several atomic channels

Isotope kinetic equations for reversible bimolecular reactions describe the rearrangement of atoms in activated complexes. It has been established from the model reaction CH₄+HCH₃+H₂ that the isotopic homoexchange of methane via two atomic channels is given by one set of equations with different sets of parameters.

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- . CH₄+HCH₃+H₂ , .

     

Enhancement of H2- and retardation of O2-adsorption during O2?H2 titration cycles on Pt?Al2O3 catalyst surfaces

The title effects can be eliminated if the slow bleeding of H₂ from freshly reduced CuO-towers (often used as O₂-getters in purifying N₂ carrier gas) can be avoided, then H₂–O₂ titrations of Pt surfaces give consistent values from almost the first titration. Water injected at 25 °C also hardly affects the titer values.

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H₂ O₂ , H₂ CuO ( O₂ N₂ — -). H₂–O₂ Pt . , 25° C, .

     

Kinetics of oxidative sulfonation of butylamine in the presence of CuCl2

Kinetic regularities of butylamine sulfonation to N, N-dibutylsulfamide in the presence of copper(II) chloride have been studied. Reaction mechanism involves the formation of Cu(II) amine complexes, their subsequent interaction with SO₂ and the redox decomposition of an intermediate to final products.

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N-N- (II). Cu(II), SO₂ - .

     

Kinetics of SO2 oxidation on K2S2O7?V2O5 catalyst in non-steady conditions

Studies of SO₂ oxidation on a molten component of vanadium catalysts in non-steadystate conditions indicates that the kinetics agree fairly well with an oxidation-reduction mechanism. In the low temperature range (<790 K) tetravalent vanadium can be partially crystallized.

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. , - . ( 790 ) .

     

Partial oxidation of methane on Cr2O3/Al2O3

The oxidation of methane on supported chromia was studied at temperatures varying between 423 and 743 K and CH₄/O₂ ratios between 1 and 9 in a differential reactor. The main reaction products observed were carbon monoxide and formaldehyde. The rates of reaction obey a power law expression.

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, 423 743 CH₄/O₂ 1 9, . . .

     

Stopped-flow study of the oxidation of ascorbic acid by the oxo-bridged trinuclear ruthenium complex [(NH3)5RuORu(NH3)4 ORu(NH3)5]7+

The kinetics of the oxidation of ascorbic acid by [(NH₃)₅RuORu(NH₃)₄ORu(NH₃)₅]⁷⁺ has been studied by the stopped-flow method. The activation parameters have been calculated and a possible mechanism is suggested.

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[(NH₃)₅RuORu(NH₃)₄ORu·(NH₃)₅]⁷⁺ . .

     

The compound Rh[HN((CH2)3P(C6H5)2)2]Cl in a hydrogenation reaction

The tridentate chelate ligand bis(diphenylphosphinopropyl) amine and its title complex were prepared and characterized by³¹P n.m.r. and other spectroscopic data. Its activation energy E_A for hydrogenation of cyclohexene is 52.3 kJ mol^–1.

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³¹P. 52,3 /.

     

Stereoselectivity observed in cross metathesis of cis- and trans-2-butene with 1-butene over Re2O7/Al2O3 catalyst

Cross metathesis of cis- and trans-2-butene with 1-butene was studied over Re₂O₇/Al₂O₃ catalyst in a recirculation system at 313 K. Formation of ethylene and hexenes was inhibited by 2-butenes; formation of propene and pentene proceeded without induction from trans- and with induction from cis-2-butene and 1-butene. Selective formation of trans-2-pentene was observed from trans-2-butene, but no such selectivity was characteristic for cis-isomers.

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- -2- 1- Re₂O₇/Al₂O₃ 313 . 2-; - -2- 1-. -2 -2-, , - .

     

Studies of vanadium catalysts for sulfur dioxide oxidation by51V-NMR

Studies of the⁵¹V-NMR spectra of a series of industrial catalysts and systems modelling the active catalyst component indicate that the catalyst composition depends on the preparation method and during thermal treatment the support interacts with the active component. The local environment of vanadium is being formed in the process of catalytic reactions.

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⁵¹V , -I-4, , : KVO₃, KVO₃–SiO₂, KVO₃–K₂SO₄ , , . .

     

Decomposition of dimethyl sulfide in the presence of Al2O3, and catalyst deactivation

The catalytic decomposition of dimethyl sulfide has been studied over the temperature range of 400–500 °C. The main reaction products are methylmercaptane, H₂S and methane. Catalyst deactivation is due to its coking during the reaction. The possibility of oxidative catalyst regeneration at 550 °C has been shown.

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400–500°C. , . , . 550°C.

     

Catalytic oxidative hydrolysis of H2PO2? anions in the presence of RhCl3

Kinetics of H₂ evolution in the RhCl₃–NaH₂PO₂–HCl–H₂O system has been studied. As found by³¹P NMR, Rh(I) complexes with the Rh–P(OH)₂O^– bond are formed and play the role of catalysts in the subsequent H₂ evolution reaction.

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H₂ RhCl₃–NaH₂PO₂–HCl–H₂O. ³¹P Rh(I) Rh–P(OH)₂O^–, H₂.

     

Catalysts for metathesis of olefins, prepared by anchoring of MoO2(acac)2 to Al2O3

New highly active catalysts for metathesis of olefins were obtained through the interaction of bis(acetylacetonato)dioxymolybdenum(VI) with surface OH groups of -Al₂O₃ and subsequent reduction in H₂ or CO.

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()(VI) OH -Al₂O₃ H₂ CO .

     

Synthesis and studies of catalysts prepared by supporting Hf(CH2Ph)4 on SiO2 and Al2O3

Catalysts prepared by supporting Hf(CH₂Ph)₄ on silica and alumina were studied. Their catalytic activity in ethylene polymerization was shown to increase considerably upon heating in hydrogen. IR spectroscopic studies of catalysts heated in hydrogen show the formation of surface Hf hydrides.

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, Hf (CH₂Ph)₄ . , . .

     

Catalysts for selective hydrogenation of conjugated dienes into olefins in the presence of PdCl2 complexes

Complexes of PdCl₂ with amines or pyridine reduced by (iso-Bu)₂ AlH are shown to be catalytically active in the selective hydrogenation of conjugated dienes into olefins in aromatic media. The promoting effect of H₂O and O₂ has been established.

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PdCl₂ , (-Bu)₂ AlH, . H₂O O₂.

     

Mass-spectrometric analysis of SO3 in SO2 oxidation over vanadium catalysts

The detailed composition of the reaction mixture and, in particular, SO₃ concentration, in SO₂ oxidation over vanadium catalysts, have been determined experimentally. Both oxidized and reduced catalysts were shown to absorb a considerable amount of SO₃, the desorption rate of SO₃ being lower than that of its adsorption.

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, , . , , SO₃, .

     

Studies on catalytically active surface compounds, IX. Formation of O2? radicals on VCl4/SiO2 catalysts

The conditions for the formation of O ₂ ^– on VCl₄/SiO₂ catalysts have been investigated. It is shown that thermal vacuum treatment (TVT) of unhydrolyzed catalysts leads to partial hydrolysis of the surface vanadium complex caused by the silanol groups of the support. The ability of the catalysts to generate O ₂ ^– radicals was found to depend on the degree of hydrolysis caused by thermal vacuum treatment.

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O ₂ ^– VCl₄/SiO₂. , , . , O ₂ ^– , .

     

IR study of interaction of propylene at CoO-MgO and CoO-MoO3-MgO surfaces

IR spectra of propylene adsorbed in CoO-MgO and CoO-MgO-MoO₃ solid solutions show that a surface -complex with Co²⁺ ions is formed, strongly bonded in the former case and weakly in the latter. Thus, introduction of Mo strongly modifies the catalytic properties of Co²⁺ active centers. In the presence of oxygen, allylic species, aldehyde and carboxylate complexes appear.

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, CoO-MgO CoO-MgO-MoO₃ - Co²⁺, . , Mo Co²⁺. - .

     

Hydrogenolysis of n-butane on low-loaded Rh/TiO2. II. Catalysts obtained by impregnation

The activity in n-butane hydrogenolysis of Rh/TiO₂ (0.6 wt. % Rh) catalysts propared by impregnation and reduced at different heating rates is reported. The catalyst reduced at 5 K/min is ten times more active than that reduced at 20 K/min, despite the fact that the dispersion values are similar in both cases.

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Rh/TiO₂ (0,6 . % Rh), qv , -. , 5 /, , 20 /, , .

     

Effect of pressure on the rate of n-heptane conversion on Pt/Al2O3 catalysts

The effect of pressure on the rates of product formation in n-heptane conversion on Pt/Al₂O₃ has been studied at 490 °C over the pressure range of 10–50 atm. It has been shown that the rate of isomerization is practically independent of pressure, and the dependence of the rates of dehydrocyclization and hydrocracking on pressure is described by simple kinetic equations. The reaction order of dehydrocyclization with respect to hydrogen tends to –2.0 at high pressures.

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- 10–50 490°C. , , . –2,0.