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.

---

, 423 743 CH₄/O₂ 1 9, . . .

     

Acid-base properties of Al2O3/MgO oxides, V. Decomposition of diacetonealcohol

The activity of MgO–Al₂O₃ mixed oxides in the decomposition of diacetonealcohol was studied using a micro slurry reactor, which allowed pretreatment of the catalyst in situ. The rate constant was used to characterize the strength of the basic surface sites. A reaction order of one and a decrease of the rate constant from MgO to Al₂O₃ was observed.

---

MgO–Al₂O₃ . , . . MgO Al₂O₃.

     

Isomerization and secondary metathesis of 2-butenes over a MoO3/Al2O3 catalyst

Transformation of cis- and trans-2-butene at 40°C was investigated over a MoO₃/A₂O₃ catalyst reduced with hydrogen and subjected to different pretreatments. Isomerization is accelerated by hydrogen preadsorbed either at low or high temperatures. The cometathesis of 2-butenes with the 1-butene intermediate, however, is enhanced only by hydrogen preadsorbed at low and suppressed by hydrogen adsorbed at high temperatures.

---

- -2- 40°C MoO₃/Al₂O₃, . , , . 2- 1- , ; , .

     

Electroconductivity changes of Na-modified TiO2 and Pt/TiO2 films

Electrolytic supporting of metallic sodium on the surface of TiO₂ and Pt/TiO₂ films is shown to change significantly the Fermi level of the semiconductor substrate already at small concentrations of sodium. The steady-state catalytic activity changes only at high concentrations of supported sodium, varying the chemical composition of the active phase. The contact process does not play any significant role in the catalytic process.

---

, TiO₂ Pt/TiO₂ . , . .

     

Determination of metal dispersity of Pd/SiO2 catalysts by transmission electron microscopy and H2?O2 chemisorption

Dispersity of palladium for a series of Pd/SiO₂ catalysts has been determined by TEM and H₂–O₂ chemisorption. The mean crystallite dimensions obtained by these methods have been compared. Assuming O/Pd_s to be 0.6 for Pd crystallites larger than 9 nm, good agreement has been observed between the results of the two experimental methods.

---

Pd/SiO₂ H₂–O₂. , . O/Pd_s0.6, Pd 9 , .

     

Chemisorption of H2, O2 and CO on bimetallic catalysts Rh?Ag/Al2O3

Comparison of adsorptive properties of Rh–Al₂O₃ catalysts in relation to H₂, O₂ and CO as adsorbates points to different surface interactions between the adsorbates and metallic surface of the catalysts. The differences may result from the changing composition of bimetal surface in relation to the catalyst composition and/or from the changing stoichiometry of surface interactions of the adsorbates.

---

H₂, O₂ CO Rh–Ag/Al₂O₃ . , , () .

     

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.

---

. , - . ( 790 ) .

     

Kinetics of Co?Mo/Al2O3 catalyst reduction

According to kinetic studies on the reduction of commercial Co–Mo/Al₂O₃ and model catalysts in H₂ at 523–773 K, the kinetic curves for the reduction process have been determined. The reduction rate is shown to be higher for the commercial catalyst. Activation energies E_act for the reduction of several forms of Mo and Co in Co–Mo/Al₂O₃ catalysts are presented.

---

H₂ 523–773 . , : Mo Co .

     

Role of tellurium in the oxidation of 1-butene on Te-doped CdMoO4

New active and selective catalysts were prepared by adding different quantities of Te to CdMoO₄. These were already selective at low Te levels, but the one with a Cd/Te/Mo ratio of 1/1/1 was specific for butadiene. The catalytic behavior of the Cd–Te–Mo–O system has been correlated mainly with the CdTeMoO₆ phase in the region rich in Te and with the CdMoO₄ phase with Te as dopant in the region poor in Te.

---

Te CdMoO₄. Te, CdTeMo=111 . Cd–Te–Mo–O CdTeMoO₆ Te, CdMoO₄ Te , Te.

     

Kinetics and mechanism of OsO4 catalyzed oxidation of chalcones by Ce4 in aqueous acetic sulfuric acid media

Kinetics of OsO₄ catalyzed oxidation of chalcones by Ce⁴⁺ has been studied in aqueous acetic-sulfuric acid medium in the temperature range 313 to 338 K. The order in [oxidant] is zero while the order with respect to [substrate] and [catalyst] are each fractional. The rate of the reaction decreased with increase in percentage of acetic acid while [H⁺] had practically no effect on the rate The rates of various substituted chalcones (with substituents in the phenyl. ring attached to the moiety) are in the orderp-CH₃>m-CH₃>H>p-Cl>m-Cl>m-NO₂>p-NO₂. A mechanism in which formation of a cyclic ester between chalcone and OsO₄ in a fast step followed by its decomposition in a rate-determining step is envisaged.

---

Ce⁴⁺, OsO₄, - 313–338 . —, —. , [H⁺] . ( , : -CH₃>-CH₃>H>-Cl>-NO₂>-NO₂. , OsO₄ , , .

     

Catalytic properties of Cu(Acac)2 anchored to shock-compressed MgO and MgF2 supports

Catalytic properties of Cu(Acac)₂ anchored to shock-compressed MgO and MgF₂ in model reactions of hydrogenation and isomerization of heptene-1 have been studied. It is shown that by changing the defect structure of the support via shock treatment at various temperatures, the activity and selectivity of metal complex catalysts can be affected.

---

Cu(Acac)₂, MgO MgF₂ -1. , , , .

     

Effect of reduction of bismuth molybdate Bi2(MoO4)3 on its activity in isomerization of butene-1 to butenes-2

The reduction of bismuth molybdate Bi₂(MoO₄)₃ by hydrogen increases its activity in isomerization of butene-1 to butenes-2 due to the activation effect of oxygen vacancies.

---

Bi₂(MoO₄)₃ -І -2, .

     

CO oxidation over CuCr/Al2O3 catalysts in presence of SO2

Poisoning of variously prepared CuCr/Al₂O₃ catalysts having different compositions by sulfur dioxide has been studied. Comparative values for a decrease in the catalyst activities have been obtained.

---

CO .

     

Effect of rare earth ions on the catalytic activity of Ln2MnNiO6 perovskites

Abstract A series of rare earth transition metal perovskites has been synthesized and the catalytic activity tested for 2-propanol decomposition. The effect of rare earth ions on the catalytic activity can been understood from the correlations obtained between the physico-chemical properties and the catalytic activity of the perovskites.

---

, , 2-. , - .

     

Structure, activity and selectivity of V2O5-TiO2 catalysts for o-xylene conversion

The formation of needle shaped crystallites of V₆O₁₃ at low V concentrations on V₂O₅-anatase coated catalysts explains the low selectivity for phthalic anhydride during o-xylene oxidation. The (010) plane of V-oxide, most active for selective oxidation of o-xylene, is not accessible and the contact of this plane with the anatase faces promotes the anatase-rutile transformation and the incorporation and blocking of V⁴⁺ ions.

---

V₆O₁₃ V , V₂O₅-, -. (010) , -, , - V⁺⁴.

     

Acid behavior of SiO2?Al2O3 mixed oxides

Surface acidity of a series of silica-alumina mixed oxides have been investigated by IR-spectroscopy and catalytic measurements. Pure alumina was the most active catalyst in the conversion of butan-1-ol, but the E1 part in the reaction increased with increasing SiO₂ content. It was concluded that the number of acidic sites increased with increasing Al₂O₃ content, while the strength of the acidic sites with the silica content.

---

- . -I-, E1 SiO₂. , Al₂O₃, - .

     

Comparison of the sulfurization of CoMoK/Al2O3 catalyst with H2S and CS2

Only H₂S consumption and H₂O formation was found in the sulfurization of CoMoK/Al₂O₃ water gas shift catalyst with H₂S/H₂, but CO₂ was formed first, then CH₄, H₂O and H₂S appeared in the later part of TPS with CS₂/H₂. Carbon deposition on the catalyst during the sulfurization with CS₂/H₂ caused a lower activity than the catalyst sulfurized with H₂S but could be removed in the run of WGS reaction.

---

, CoMoK/Al₂O₃, H₂S/H₂ H₂S H₂O, CS₂/H₂ CO₂ CH₄, H₂O H₂S. CS₂/H₂ H₂S, , .

     

Methane synthesis from CO/H2O mixture on supported nickel catalysts, II. Surface species in CO?H2 and CO?D2O interaction by IR spectroscopy

The species resulting in CO, CO+H₂ or CO+D₂O adsorption on supported Ni catalysts were followed by IR spectroscopy and their role in methane synthesis mechanism is discussed.

---

- , CO, CO+H₂ CO+D₂O . .

     

Mechanism of competitive oxidation and H-D exchange of cyclohexane in the PtII?PtIV?Cl??D2O?D2SO4 system

The results of kinetic studies on competitive oxidation and H-D exchange of cyclohexane in the Pt^II–Pt^IV–Cl^––D₂O–D₂SO₄ system involving variations in the concentrations of D⁺, Cl^– and Pt^II, are in agreement with two possible mechanisms involving the formation of a common intermediate alkyl-platinum complex.

---

H/D Pt^II–Pt^IV–Cl^––D₂O–D₂SO₄ D⁺, Cl^–, Pt^II , - .

     

Infrared spectra of nitric oxide adsorbed on photoreduced V/SiO2 catalyst

Studies of the IR spectra of surface species produced via NO adsorption on selectively photoreduced V/SiO₂ catalysts indicate that at low coverages NO is adsorbed on V³⁺ ions to form strongly bonded mononitrosyl species V³⁺...... NO. With increasing NO coverage, V³⁺ is oxidized to V⁴⁺, which is accompanied by the appearance of gaseous N₂O and weak adsorption of NO on V⁴⁺.

---

- , NO V/SiO₂ . , V³⁺ NO V³⁺... NO. V³⁺ V⁴⁺, N₂O NO V⁴⁺.