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1.
Photobromination of SiH4 under uv-irradiation at various wavelengths has been studied. Rate constants for the elementary reactions Br(2P3/2)+SiH4HBr+SiH3 (k=3.2×10–11 exp(–21.8±2.5)/RT, cm3/s) and Br* (2P1/2)+SiH4HBr+SiH3 (k*=(3±1)×10–13 cm3/s) have been determined in the temperature range from 300 to 415 K.
- . Br(2P3/2)+SiH4HBr+SiH3, k=3,2×10–11 exp (–21,8±2,5)/RT 3/ Br*(2P1/2)+SiH4HBr+SiH3, k*=(3±1)×10–13 3/ 300–415 K.
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2.
Data on the radical non-chain mechanism of ascorbic acid oxidation by molecular oxygen catalyzed by Co2+, Ni2+, Mn2+ and Zn2+ ions are reported.
Co2+, Ni2+, Mn2+ Zn2+.
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3.
XRD, isothermal and temperature-programmed reduction (TPR) experiments were carried out with SiO2, SiO2–Al2O3 and -Al2O3 supported catalysts. Molybdena is in a more disperse state on supports containing more alumina and it is more reducible on SiO2–Al2O3 than on SiO2 or -Al2O3. TPR curves were shown to reflect connections between reduction kinetics and dispersity.
-, , SiO2, SiO2–Al2O3 -Al2O3. , , SiO2–Al2O3 SiO2 -Al2O3. .
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4.
Supported SnO2/SiO2 catalysts have been prepared by the reaction of the surface hydroxy groups of silica gel and gas phase tin chloride (PS method). The catalytic properties have been examined in the reaction of 2-propanol to show the effect of VPS cycles on the amount and nature of the active sites.
SnO2/SiO2 . 2- VPS .
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5.
Chemisorption of H2S on Al2O3, Al2O3–Cl and Pt/Al2O3–Cl has been studied by gravimetry and IR spectroscopy. The influence of the amount of Cl on the H2S adsorption equilibrium value and the nature of the adsorption sites at low and high coverages are discussed.
H2S Al2O3, Al2O3–Cl Pt/Al2O3–Cl . Cl H2S, .
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6.
The kinetics of Fe3+ and Cu2+ sorption from sulfate salt solutions by fibrous polyampholite have been studied.
Fe3+ Cu2+ , .
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7.
An increase of the reduction temperature of a Ni/CeO2 solid results in a continuous decrease of the catalytic activity toward C2H6 hydrogenolysis and of the quantity of adsorbed H2. O2 treatments with subsequent reduction at low temperature restore a part of the initial properties. This behavior, typical of a strong metal support interaction, is similar to that of Ni/TiO2, Ni/SiO2 and Ni/ZrO2 solids and shows that the SMSI phenomenon is general.
Ni/CeO2 C2H6 H2. . , (), Ni/TiO2, Ni/SiO2 Ni/ZrO2 , .
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8.
Relative oxidation rate constants of several normal, iso-, cyclo-and methylcycloalkanes have been measured in Cl2–H2O and Cl2–Hg2+–H2O solutions at 343K. The selectivity of C–H bond dissociation in both systems is the same. HOCl is assumed to be the active species for the two systems.
Cl2–H2O Cl2–Hg2+–H2O 343 , -,- ; C–H . , HOCl.
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9.
Mössbauer spectroscopic studies of the state of Pt–Sn catalyst for hydrocarbon conversion supported on prechlorinated -Al2O3 indicate that, unlike nonchlorinated Al2O3, this system is much more reduced and besides Pt3Sn–PtSn2, its surface contains sigfificant amounts of Sn(II) and Sn(IV) chlorides bonded to the surface.
Pt–Sn , -Al2O3. , Al2O3, Pt–Sn Pt3Sn–PtSn2 Sn(II) (IV), .
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10.
The hydrocondensation of CO2 and CO with and without added MeOH, HCHO and (CH3)2CHOH has been studied on CuO/ZnO contact masses in a static reactor at different pressures and reaction times.
CO2 CO MeOH, HCHO (CH3)2CHOH CuO/ZnO .
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11.
Cyclohexane is oxidized by air oxygen in CH2Cl2 solution to yield cyclohexanol, cyclohexanone and cyclohexyl chloride when irradiated by light (>310 nm) in the presence of (Bu4N)2CrO4 or (Bu3SnO)2CrO2. The addition of PhIO greatly accelerates the reaction and increases the yield of products. The reaction mixture contains neither cyclohexanol nor cyclohexanone when the photoreaction in the presence of the Cr(VI)–PhIO system is carried out in argon atmosphere. Hence neither iodosylbenzene nor oxochromium compounds can be oxygen atom donors in alkane oxygenation. The accelerating effect of iodosylbenzene may be due to the enhanced oxidizing power of photo-excited oxochromium species when coordinated to iodosylbenzene.
CH2Cl2 , , (>310 ) (Bu4N)2CrO4 (Bu3SnO)2CrO2. PhIO . Cr(VI)–PhIO , , . , ( ) . .
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12.
Systems V2O5–KHSO4 and V2O5–K2SO4 have been studied by the51V NMR method. The first system demonstrates the same states of vanadium as the previously studied V2O5–K2S2O7, in this system a compound with an equimolar ratio of components has been found. In V2O5–K2SO4 the state of vanadium differs from the above systems and the formation of a compound with V/K=4 is observed.
51V KHSO4–V2O5 K2SO4–V2O5. , K2S2O7–V2O5, . K2SO4–V2O5 V/K4.
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13.
Thermal decomposition of 10-molybdo-2-vanadosilicic heteropolyacid has been studied by29Si and51V-NMR method.29Si-NMR MAS spectra of solid samples indicate that the HPA begins to decompose at T<300°C and the decomposition is complete at 300–400°C.
29Si 51V Si–Mo-V () 12- . 29Si MAS , 300°C 300–400°C.
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14.
Diffuse reflectance spectroscopy of supported CuO–TiO2 catalysts have revealed that, depending on the CuO content and the calcination temperature, either Cu2+ ions incorporated into the TiO2 lattice, or surface oxide clusters, primary oxide aggregates and CuO1+X phase bonded to the support by Ti–O–Cu bridges, are formed.
, CuO–TiO2 Cu2+, TiO2, , CuO1+x Ti–O–Cu .
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15.
The state of Al3+, Ga3+ and Si4+ in erionites obtained by hydrothermal crystallization from Ga–Al–Si gels has been examined. The results suggest that gallium cations can isomorphously substitute a part of silicon cations in the zeolite framework, to a notable extent in the sites having no aluminium cations in the second coordination sphere of silicon.
Al3+, Ga3+ Si4+ , . , , .
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16.
V2O5/Al2O3 catalysts prepared by impregnation and by ammonia treatment of impregnated samples were tested for activity in the NO–NH3 reaction. The ammonia treated samples, with higher proportions of strongly bound vanadia, were found to be comparable in activity to the impregnated catalysts and equally sensitive to the presence of oxygen.
V2O5/Al2O3, , NO–NH3. .
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17.
Methane oxidation on Pt/SiO2 is a structure sensitive reaction at 260–335°C. The higher the percentage exposed, the lower the turnover frequency with decreasing reaction order in PCH 4 from 1.0 to 0.5 and slightly decreasing the activation energies of reaction from 90 to 80 kJ/mol, caused by the shift of rate-determining step.
Pt/SiO2 260–335°C . , PCH 4 1,0 0,5 90 80 /. , .
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18.
H2 and O2 uptakes at 296 K on a Pt/Al2O3 catalyst remained constant during repeated H2–O2 titration cycles conducted in a high vacuum adsorption system. Previously reported variations in these uptakes are attributed to adsorption of contaminants during desorption conditions. Also, it was found that nearly 40% of the H2 adsorbed could be removed by degassing at 296 K for 1 hr.
H2 O2 296 Pt/Al/2O3 H2–O2, . . , 40% H2 1 296 .
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19.
An increase of the temperature of reduction of Ni/SiO2 from 900 to 1120 K results in a decrease of catalytic activity per unit area in benzene hydrogenation and ethane hydrogenolysis. O2–H2 treatments restore the activities. This behavior is similar to that observed on Pt-based catalysts. In contrast, the CO+H2 reaction on nickel is not affected by such treatments.
Ni/SiO2 900 1120 . O2–H2 . , , CO+H2 .
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20.
The effect of the activation conditions of Pt/Al2O3 catalysts has been investigated in the hydrogenation of benzene and in the hydrogenolysis of ethane. Whatever the conditions of calcination or reduction, specific activities of all catalysts for benzene hydrogenation remain constant. On the other hand, for identical dispersities, the cacination in a wet argon flow increases the specific activity of platinum for hydrogenolysis of ethane, pointing out the role of wet pretreatment on defect building or on the faceting of supported metallic catalysts.
Pt/Al2O3 . , . , , . .
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