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.

---

[(NH₃)₅RuORu(NH₃)₄ORu·(NH₃)₅]⁷⁺ . .

     

Catalysts for metathesis of olefins obtained through [Mo3O4(C2O4)3 (H2O)3]2? coordinated to γ-Al2O3

New highly active catalysts for the metathesis of olefins have been obtained through the interaction of [Mo₃O₄ (C₂O₄)₃ (H₂O)₃]^2– anion with Al₂O₃ surface and further activation in H₂ or CO atmosphere.

---

[Mo₃O₄ (C₂O₄)₃ (H₂O)₃]^2– Al₂O₃ H₂ CO .

     

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.

---

³¹P. 52,3 /.

     

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.

---

()(VI) OH -Al₂O₃ H₂ CO .

     

Hydrogen pressure dependence of the reaction of neopentane with hydrogen over Pd/SiO2 and Pt/SiO2 catalysts

H₂ pressure influences in different ways the reaction rates of neopentane conversion over Pd/SiO₂ and Pt/SiO₂ catalysts. It seems that on Pt/SiO₂ both isomerization and hydrogenolysis involve a common surface intermediate (probably an adalkyl), whereas on Pd/SiO₂ the hydrogenolysis goes via more dehydrogenated species than those involved in isomerization.

---

H₂ Pt/SiO₂ Pd/SiO₂. , Pt/SiO₂ (, ), Pd/SiO₂ , .

     

Reforming type Pt/Al2O3 catalyst prepared from [(CH3)3PtX]4 complexes by thermal decomposition

Pt/Al₂O₃ catalysts with good reforming activity were prepared from [(CH₃)₃PtX]₄ (X=Cl, Br, I) complexes and tested in pulse and continuous-flow reactors in n-hexane dehydrocyclization. It has been demonstrated that [(CH₃)₃PtX]₄ complexes are excellent precursors of supported platinum catalysts.

---

Pt/Al₂O₃ [(CH₃)₃ PtX]₄ (X=Cl, Br, I) -. , [(CH₃)₃PtX]₄ .

     

An IR study of the Ziegler system Co(acad)3/Mg(n-butyl)2 in THF

Applying IR spectroscopy for studying the Ziegler system Co(acac)₃/Mg(Bu)₂ (Bu=n-butyl) in tetrahydrofuran, it could be shown that the following reactions take place: reduction of cobalt (III), exchange of the acetylacetonate groups and their interaction with Mg(Bu)₂.

---

Co(acac)₃/Mg(Bu)₂ (Bu=-) - , (III), Mg(Bu)₂.

     

High-temperature reduction of SO2 by methane at various CH4/SO2 ratios

The character of the effect of initial reaction mixture and temperature on the selectivity of catalytic reduction of sulfur dioxide by methane in the presence of oxygen has been studied.

---

.

     

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.

---

, Hf (CH₂Ph)₄ . , . .

     

On the deactivation of Fe2O3?MoO3/SiO2 catalysts in the oxidation of methanol to formaldehyde

The deactivation behavior of Fe₂O₃–MoO₃/SiO₂ catalysts with different Fe₂O₃+MoO₃ content in the oxidation of methanol to formaldehyde is investigated. A simplified reaction-deactivation kinetic model is presented and used to compare and discuss the different behaviors.

---

Fe₂O₃–MoO₃/SiO₂ Fe₂O₃+MoO₃ . : -.

     

Formation mechanism and structure of compounds catalytically active in propylene dimerization and formed in Pd(acac)2?PR3?BF3OEt2 systems

The interaction between the components of catalytic Pd(acac)₂–PR₃–BF₃OEt₂ systems dimerizing propylene to linear hexenes with 59 % selectivity, has been studied by UV and¹H NMR spectroscopy methods. Formation mechanism of catalytically active [R₃P–Pd–H]⁺BF ₄ ^– compounds is suggested.

---

, ¹ Pd(acac)₂–PR₃–BF₃OEt₂, 59%, [R₃P–Pd–H]⁺BF ₄ ^– .

     

CO hydration over catalysts prepared via supporting Fe3(CO)12 and (NEt4)2[Fe2Mn(CO)12] on oxide supports

A comparison of the properties of iron-containing catalysts prepared through carbonyl clusters Fe₃(CO)₁₂ and (NEt₄)₂[Fe₂Mn(CO)₁₂] and iron and manganese nitrates in CO hydration indicates that the addition of Mn incorporated in (NEt₄)₂[Fe₂Mn(CO)₁₂] decreases the methane yield and increases the portion of higher hydrocarbons.

---

, Fe(CO)₁₂ (NEt₄)₂[Fe₂Mn(CO)₁₂] , CO. Mn (NEt₄)₂[Fe₂Mn(CO)₁₂] .

     

Preparation of a Ru/Al2O3 catalyst from Ru3(CO)12 infrared and XPS study

A supported ruthenium catalyst on alumina prepared from Ru₃(CO)₁₂ has been studied by infrared and X-ray photoelectron spectroscopy (XPS). The triatomic cluster is retained on the support but breaks down at 150°C. Complete elimination of the carbonyl groups requires heating at 350°C under vacuum. XPS studies show that the decomposed catalyst does not change on further reduction in H₂ at 400°C. The ruthenium atoms remain trapped within the pores of the support.

---

Al₂O₃, Ru₃(CO)₁₂, (XPS). , 150°C . 350°C . XPS , H₂ 400°C . .

     

Decomposition of N2O over CuxMg1?xAl2O4 catalysts

The results show that there is not difference between the catalytic activities of two series of Cu_xMg_1–xAl₂O₄ catalysts, despite a small but significant difference in cation distribution. The activity is mainly affected by the presence of CuO.

---

, , , , - Cu_XMg_1–XAl₂O₄. CuO.

     

Peculiarities of propylene metathesis over catalysts prepared by anchoring of Mo(V) oxalate to γ-Al2O3

Propylene metathesis over catalysts prepared by coordination of Mo(V) oxalate to -Al₂O₃ has been studied.

---

, (V) -Al₂O₃.

     

Catalytic activity of the Al2O3?Cr2O3?Fe2O3 system II. Influence of nitrogen bases on hydrocarbon aromatization

The physico-chemical properties of the Al₂O₃–Cr₂O₃–Fe₂O₃ catalyst system have been correlated with n-hexane dehydrocyclization. Using a poisoning technique, the ionic and radical steps of the reaction have been determined.

---

- Al₂O₃–Cr₂O₃–Fe₂O₃ -. , .

     

Some spectroscopic and freezing point depression measurements on the homogeneous hydrogenation catalyst CoH3(PPh3)3

NMR, EPR and freezing point depression (FPD) experiments were performed on solutions of the homogeneous hydrogenation catalyst CoH₃(PPh₃)₃. The results of these measurements show that the compound has a dynamic structure on the NMR time scale at room temperature and that it is slightly dissociated into bisphosphine species and free phosphine. FPD and¹H-NMR measurements indicate that one Et₂O molecule is present per catalyst molecule.

---

, () CoH₃(PPh₃)₃. , , . H¹- , Et₂O.

     

Thermal activation of Al2O3 supported MoO3 and WO3 metathesis catalysts

Alumina-supported MoO₃ and WO₃ catalysts were activated for the metathesis of propene by thermal treatment in Ar. Temperatures up to 1140 K are required for catalysts with low metal contents. These exhibit the highest specific activities though they are known to be highly resistant to reduction. It is proposed that the active sites are formed from Mo(VI) and W(VI) species under the conditions employed.

---

MoO₃ WO₃, Al₂O₃, . 1140 . , , . , , Mo W.

     

Effect of iron on the behavior of Fe2O3?MoO3/SiO2 ammoxidation catalysts

Catalytic ammoxidation of propylene was studied using Fe₂O₃–MoO₃/SiO₂ catalysts, which have been prepared following a special method. Interaction of ammonia with the catalysts was studied by means of IR spectroscopy and gravimetrically using a McBain balance. Introduction of iron into MoO₃/SiO₂ catalysts modifies acidic as well as redox properties.

---

Fe₂O₃–MoO₃/SiO₂ . . - . MoO₃/SiO₂ , .

     

Infrared studies of CO2(CO)8 adsorption on zeolites Y

Co₂(CO)₈ sublimed onto the surface of HY, CeY, CoY and two dealuminated forms of NaY zeolite is converted at room temperature to Co₄(CO)₁₂ and other surfacebound cobalt carbonyl species. The reaction proceeds in a different way on each of the above zeolites, depending also on their pretreatment.

---

Co₂(CO)₈, HY, CeY, CoY NaY, Co₄(CO)₁₂ - . - .