Trapping adsorption of carbon monoxide located between carbon dioxide adsorbed on magnesium oxide

Carbon monoxide adsorbed on MgO is strongly trapped by the adsorbed carbon dioxide, increasing the heat of adsorption from 85.4 to 184.1 kJ/mol. The trapped CO is thought to be captured by two or three adsorbed CO₂ and becomes less active to react with oxygen.

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, MgO, , 85,4 184,1 /. , CO CO₂ .

     

Spectroscopic study of silver state in CaO

Electron spectra of the oxidized states of silver (Ag²⁺) in CaO have been identified by comparison of ESR and diffuse reflectance electron spectra.

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Ag²⁺ CaO .

     

Quantum-chemical examination of the factors rule in terms of simplest cluster calculation approaches

CNDO/BW examination of the factors rule in terms of the cluster approach has revealed its validity not only for the adsorption energy and the frequency shift of the stretching vibrations in the formation of hydrogen bonds but also for the variations of the hydrogen atom charge and the OH bond length.

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CNDO/BW . () , OH .

     

Kinetics and mechanism of ketone-bisulfite addition reaction in aqueous solution

The kinetics of the addition of bisulfite to acetone has been studied by the polarographic technique. The specific rate increases with pH and hence the reaction is probably base catalyzed. Mechanisms have been suggested for the reaction in the presence and absence of added base.

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- . pH, , , . .

     

Reactions between ammonium sulphate and metal oxides (metal=Cr,Mn and Fe) and thermal decomposition of the products

The reactions between ammonium sulphate and three metal oxides (Cr₂O₃, MnO₂ and Fe₂O₃) were studied. It was confirmed by X-ray diffraction and chemical analysis that stable reaction intermediates were formed consecutively in the course of the reactions.These were (NH₄)₃M(SO₄)₃ and NH₄M(SO₄)₂ for Cr₂O₃ and Fe₂O₃ and (NH₄)₂Mn₂(SO₄)₃ for MnO₂. The thermal decompositions of these intermediates and of the metal sulphates were carried out. The contracting-volume equation was valid for the decomposition of all the intermediates. The Arrhenius parameters were determined.

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Zusammenfassung Es wurden die Reaktionen zwischen Ammoniumsulfat und drei Metalloxiden (Cr₂O₃, MnO₂ und Fe₂O₃) untersucht. Durch Röntgendiffraktion und chemische Analyse wurde bestätigt, dass im Verlaufe der Reaktion stabile Zwischenprodukte gebildet werden. Es handelt sich dabei um (NH₄)₃M(SO₄)₃ und NH₄M(SO₄)₂ im Falle von Cr₂O₃ und Fe₂O₃ und um (NH₄)₂Mn₂(SO₄)₃ im Falle von MnO₂. Diese Zwischenprodukte und die Metallsulfate wurden thermisch zersetzt. Die Volumenkontraktionsgleichung war für die Zersetzung all dieser Zwischenprodukte gültig. Die Arrheniusparameter wurden bestimmt.

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Cr₂O₃, MnO₂ Fe₂O₃. , . , (NH₄)₃M(SO₄)₃ NH₄M(SO₄)₂, (NH₄)₂Mn₂(SO₄)₃. . . .

     

Surface transformations of copper oxidation catalysts

Photoelectron spectra of Cu₂Mo₃O₁₀ catalysts in different conditions of catalytic propylene oxidation show that in an oxidizing atmosphere reversible surface reconstruction takes place, directing the reaction to selective oxidation to acrolein, whereas in reducing atmosphere total oxidation takes place.

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Cu₂Mo₃O₁₃, , . .

     

Relationship between catalytic activity and π-electron density

A correlation between the activity of unsaturated esters of ,-carboxylic acids and ,-unsaturated ketones and the -electron density of hydrogenated bonds has been found.

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,- , ,- - .

     

Methanol conversion to hydrocarbons and dimethyl ether on decationized zeolite T

Methanol transformations over the hydrogen forms of zeolite T (32%–76% decationization and 13%–32% dealumination) during contact with methanol vapor was studied at 200°–400°C. The catalysts used show a high activity in methanol conversion into light hydrocarbons and dimethyl ether but over a short period.

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T (32–16% 13–32% ) 200–400°C. , .

     

X-ray study of palladium catalysts. Influence of thermal treatment in hydrogen on the phase composition

The thermal treatment of Pd catalysts in a reducing atmosphere of hydrogen leads to interaction of supported metal and support to form solid solutions.

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, .

     

Dilution effect on catalytic pyrolysis of hydrocarbons

It is shown that unlike thermal pyrolysis, the rate of catalytic pyrolysis is greatly affected by dilution of hydrocarbons with inert gases. The nature of this effect has been analyzed.

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, . .

     

State of copper ions, bond energy of oxygen and catalytic properties in hydrogen oxidation for a copper-magnesium system

The bond energy of surface oxygen in a copper-magnesium catalyst and its reactivity are shown to be greatly dependent on the structure of the nearer environment of copper ions. For catalysts prepared at low temperatures (773 K) this structure changes from a symmetrical square planar in CuO to an octahedral with various degrees of axial distortion depending on the copper content.

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, . , (773 ), CuO .

     

Enantioselective hydrogenation on heterogeneous metal catalysts

The rate of formation of the excess of one enantiomeric product in the enantioselective hydrogenation of ethyl acetoacetate (EAA) and acetylacetone (acac) on a Raney copper catalyst modified with chiral aminoacids (AmA) correlates with the formation constants of the mixed complexes [CU EAA AmA] and [Cu acac AmA].

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() - () , () [Cu··] [Cu··].

     

Infrared spectroscopic study of the adsoprtion of methacrylates on aerosil

The type and ratio of the attached groups was measured by FT-IR spectroscopy for the adsorption of three methacrylates. The adsorption enthalpies can be determined from a correlation with infrared frequency shifts.

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--. -.

     

Selective dehydrogenation of tetralin on zeolites

The dehydrogenation of tetralin on two zeolite catalysts has been studied, the experiments were planned statistically according to the Orthogonal Central Composite Design. In order to determine the influence of coke deposits, the time-on-stream theory of catalyst decay is applied too.

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. . .

     

Study of distribution of elements in the depth of V?P?Co catalyst grain

It has been shown that addition of cobalt to a vanadium-phosphorus oxide catalyst increases the P/V molar ratio on the surface, the surface acidity and the selectivity of butane oxidation. It has been established that in the V–P–Co–O catalyst the probability of the removal of phosphorus from the surface is markedly reduced.

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, , . , V–P–Co–O .

     

Physico-chemical properties of iron-tin mixed oxide catalysts in cyclohexane oxidation

The state of mixed iron-tin oxide catalysts with a variable ratio of their metallic components has been studied by Mössbauer and ESCA spectroscopy. The results are compared with the activity of these catalysts in cyclohexane oxidation.

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- . .

     

Influence of the preparation method of precipitated Fe?Mn catalysts on their properties in CO hydrogenation

Studies of the properties of precipitated Fe–Mn catalysts in CO hydrogenation have revealed that samples precipitated from iron and manganese nitrates by sodium carbonate are more selective to olefins than those precipitated by ammonia. Difference in the catalytic properties is due to the different phase compositions of the catalysts.

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CO , . , , , , . .

     

Hexadiene formation during decomposition of 2-propanol over Ca?P?O catalysts

Hexadiene formation from 2-propanol was investigated in view of acid-base properties of Ca–P–O catalysts with the Ca/P atomic ratio varying from 1.5 to 5.0. The catalytic activity in hexadiene formation increased up to a maximum at Ca/P=2.0, having almost the same amount of weak acidic sites as weak basic sites, and decreased with futher increase in Ca/P ratio.

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2- - Ca–P–O Ca/P, 1,5 5,0. , Ca/P=2, , Ca/P.

     

Hydrocarbon hydrogenolysis on nickel-tin catalysts

Hydrogenolysis of ethane, n-hexane and cyclohexane has been studied on nickel-kieselguhr catalysts modified by organic and inorganic compounds of tin. Tin additives decrease nickel reactivity with respect to C–C dissociation, which is ascribed to the formation of surface intermetallides on the catalyst.

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, - - , . . C–C .

     

Decomposition of alkanethiols to dialkyl sulfides and hydrogen sulfide

Disproportionation of thiol to sulfide and H₂S takes place on catalysts of various composition, the most active being those with paired acid-base centers. On these catalysts at 200–400°C methanethiol is quantitatively converted to dimethyl sulfide. Disproportionation of ethanethiol and particularly of 2-propanethiol is accompanied by the decomposition of sulfides formed and initial thiols to produce olefins and H₂S.

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H₂S , - . 200–400°C . 2- H₂S.