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1.
T. P. Maniecki K. Bawolak P. Mierczyński P. Kaczorowski W. K. Jóźwiak 《Kinetics and Catalysis》2011,52(5):711-715
The effect of the carrier on catalytic properties of ruthenium supported catalysts in partial oxidation of methane (POM) was
investigated. A variety of supports differed in texture and reducibility (Al2O3, SiO2, TiO2, Cr2O3, CeO2 and Fe2O3) were used. The catalyst activity is governed by ruthenium phase formation (RuO2 → Ru0), and it depends on redox properties of the support as well as support-ruthenium phase interaction. The activity of Ru supported
catalysts decreases in the order Al2O3 ≈ SiO2 > Cr2O3 > TiO2 > CeO2 > Fe2O3. No significant effects of the specific surface area and porosity of catalysts on the methane conversion and selectivity
of CO formation were found. The selectivity of CO2 formation (total oxidation of CH4) under conditions of POM (a ratio of CH4/O2 = 2) is associated with the contribution of reducible support oxides into the catalytic performance. 相似文献
2.
M. G. Kotur 《Theoretical and Experimental Chemistry》1998,34(5):297-300
We have studied the correlation between the crystal structure and the catalytic activity of manganese oxides MnO, MnO2, Mn3O4, and Mn2O3 in liquid-phase oxidation of 1-octene by molecular oxygen. The catalytic activity decreases in the series of oxides with
octahedral coordination environment for the manganese atoms MnO−Mn2O3−MnO2. The oxide Mn3O4 (with mixed tetrahedral and octahedral environment for the Mn atoms) catalyzes the process according to a different mechanism.
L'vov Polytechnic State University, 12 S. Bandery ul., L'vov-13 290646, Ukraine. Translated from Teoreticheskaya i éksperimental'naya
Khimiya, Vol. 34, No. 5, pp. 324–327, September–October, 1998. 相似文献
3.
A. M. Gololobov I. E. Bekk G. O. Bragina V. I. Zaikovskii A. B. Ayupov N. S. Telegina V. I. Bukhtiyarov A. Yu. Stakheev 《Kinetics and Catalysis》2009,50(6):830-836
The specific activity of 0.8% Pt/Al2O3 catalysts in the deep oxidation of C1–C6
n-alkanes increases with an increase in the Pt particle size from 1 to 3–4 nm. Further coarsening of the particles insignificantly
changes the specific activity. The size effect was studied for a series of catalysts containing platinum nanoparticles 1 to
11 nm in diameter. The specific catalytic activity variation range depends on the size of the reacting hydrocarbon molecules.
As the platinum particle size increases, the specific catalytic activity increases 3–4 times for the oxidation of CH4 and C2H6 and by a factor of 20–30 for the oxidation of n-C4H10 and n-C6H14. 相似文献
4.
T. N. Rostovshchikova M. S. Korobov D. A. Pankratov G. Yu. Yurkov S. P. Gubin 《Russian Chemical Bulletin》2005,54(6):1425-1432
Nanosized iron oxides stabilized on the surface of ultradispersed poly(tetrafluoroethylene) (UPTFE) granules were synthesized
by the thermal destruction of iron formate in boiling bed of UPTFE on the surface of heated mineral oil. The particle size
of nanoparticles (∼6 nm) containing 5, 10, and 16 wt.% Fe depends weakly on the temperature of synthesis and iron to polymer
ratio. The metal state is determined by the synthesis conditions. The nanoparticles synthesized at 280 °C consist mainly of
the Fe3O4 and Fe2O3 phases. The samples obtained at 320 °C also contain iron(II) oxide. The catalytic properties of the obtained samples were tested in dichlorobutene isomerization. Unlike isomerization
on the iron oxide nanoparticles supported on silica gel, reaction over the UPTFE supports proceeds without an induction period.
The sample with 10 wt.% Fe containing magnetically ordered γ-Fe2O3 nanoparticles possesses the highest catalytic activity. Fast electron exchange between the iron ions in different oxidation
states and high defectiveness of the nanoparticles contribute, most likely, to the catalytic activity.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1383–1390, June, 2005. 相似文献
5.
The activity of samples containing indium in the selective catalytic reduction (SCR) of NO with C1-C4 hydrocarbons depends on nature of the carrier, Al2O3, ZrO2, the quantity of indium oxide, and the method of its introduction. The most active catalysts (2.5–5.0% In2O3/Al2O3) are stable to water and are characterized by a large overall concentration of oxide centers.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 107–111, March–April, 2007. 相似文献
6.
Gold catalysts with loadings ranging from 0.5 to 7.0 wt% on a ZnO/Al2O3 support were prepared by the deposition–precipitation method (Au/ZnO/Al2O3) with ammonium bicarbonate as the precipitation agent and were evaluated for performance in CO oxidation. These catalysts
were characterized by inductively coupled plasma-atom emission spectrometry, temperature programmed reduction, and scanning
transmission electron microscopy. The catalytic activity for CO oxidation was measured using a flow reactor under atmospheric
pressure. Catalytic activity was found to be strongly dependent on the reduction property of oxygen adsorbed on the gold surface,
which related to gold particle size. Higher catalytic activity was found when the gold particles had an average diameter of
3–5 nm; in this range, gold catalysts were more active than the Pt/ZnO/Al2O3 catalyst in CO oxidation. Au/ZnO/Al2O3 catalyst with small amount of ZnO is more active than Au/Al2O3 catalyst due to higher dispersion of gold particles. 相似文献
7.
Małecki A. Prochowska-Klisch B. Gajerski R. 《Journal of Thermal Analysis and Calorimetry》1998,54(1):25-34
It has been found that the modified Zhuravlev equation, [(1−α)−1/3−1]2=ktn, which describes the kinetics of oxidation of V2O4 and V6O13 in the temperature range 820–900 K and in the oxygen pressure range 1.0–20 kPa, can be derived via the assumption that the
changes in the observed activation energy result from the changing contributions of the two diffusion processes controlling
the reaction rate. The values of the observed activation energy are in the range 160–175 kJ mol−1 for V2O4 and 188–201 kJ mol−1 for V6O13 in the scope of the experimental oxygen pressures and temperatures and conversion degrees of 0.1–0.9.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
Ibrahim M. EI-Mehasseb Abd El-Motaleb M. Ramadan Raafat M. Issa 《Transition Metal Chemistry》2006,31(6):730-739
The oxidation of catechol by molecular oxygen in the presence of a catalytic amount of copper(II) complex with 2-methyl-3-amino-(3H)quinazoline-4-one (MAQ) and various anions (Cl−, Br−, ClO
4
−
, SCN−, NO
3
−
and SO
4
–
) was studied. The catecholase biomimetic catalytic activity of the copper(II) complexes has been determined spectrophotometrically
by monitoring the oxidative transformation of catechol to the corresponding light absorbing o-quinone (Q). The rate of the catalytic oxidation reaction was investigated and correlated with the catalyst structure, time,
concentration of catalyst and substrate and finally solvent effects. Addition of pyridine or Et3N showed a dramatic effect on the rate of oxidation reaction. Kinetic investigations demonstrate that the rate of oxidation
reaction has a first order dependence with respect to the catalyst and catechol concentration and obeying Michaelis–Menten
Kinetics. It was shown that the catalytic activity depends on the coordination environment of the catalyst created by the
nature of counter anions bound to copper(II) ion in the complex molecule and follows the order: Cl− > NO
3
−
> Br− > SO
4
–
> SCN− > ClO
4
−
. To further elucidate the catalytic activity of the complexes, their electrochemical properties were investigated and the
catecholase mimetic activity has been correlated with the redox potential of the Cu2+/Cu+ couple in the complexes. 相似文献
9.
Guillermo González-Alatorre Andres García-Godínez Vicente Rico-Ramírez Eleazar Escamilla-Silva Enrique A. Botello 《Reaction Kinetics and Catalysis Letters》2008,94(2):337-344
The oxygenation constants and thermodynamic parameters (ΔHo, ΔSo) of a series of novel Co(II) dihydroxamic acids containing a central functional group (-OCH3) CoL1∼CoL6 were measured, their catalytic performance in the oxidation of p-xylene to p-toluic acid (PTA) were examined. The influence of` ligand structure, the substituents (X = Cl, OCH3 and Y = H, CH3, Cl) of the aromatic rings and added alkaline cations on the O2-binding capabilities and catalytic oxidation activities were investigated. 相似文献
10.
V. M. Pinchuk E. S. Kotlyarova N. V. Parkhomenko P. N. Tsybulev 《Journal of Structural Chemistry》1996,37(4):544-556
The studies concerned with the oxidation of carbon monoxide on the nickel surface are reviewed. The Eley-Rideal (ER) collision
and Langmuir-Hinshelwood (LH) adsorption mechanisms of the oxidation are analyzed. Calculations of the activation barriers
of the oxidation of carbon monoxide on the Ni (111), (100), and (110) faces were performed for the first time and involved
optimization of the reaction paths by the collision and adsorption mechanisms. It is shown that on the Ni (111) and (110)
faces the ER collision mechanism of the reaction is preferable with the activation barriers ΔE
dis
O
2=62 kJ/mole and ΔE
trans
O
A21F50012x=25 kJ/mole for Ni (111) and ΔE
dis
O
2=72 kJ/mole and ΔE
trans
O
2=20 kJ/mole for Ni (110); on the Ni (100) face, the LH adsorption mechanism with the activation barriers ΔE
dis
O
2=75 kJ/mole and ΔE
trans
O
2=42 kJ/mole is favored. Analysis of the potential barriers for the catalytic oxidation of carbon monoxide on the Ni surfaces
suggests the LH mechanism to be preferential, although insignificant differences in the activation barries can lead to the
oscillatory reaction mechanism, which is confirmed experimentally. The calculations were performed by the LCAO MO SCF method
in the MINDO/3 approximation.
Kiev Polytechnical Institute. Translated fromZhurnal Struktumoi Khimii, Vol. 37, No. 4, pp. 628–645, July–August, 1996.
Translated by I. Izvekova 相似文献
11.
Ashraf A. Mohamed 《Monatshefte für Chemie / Chemical Monthly》2001,132(8):919-928
Summary. A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of iodide. The
method is based on the catalytic effect of iodide on the reaction of triflupromazine (TFP) with H2O2. The reaction is followed spectrophotometrically by tracing the oxidation product at 498 nm within 1 min after addition of
H2O2. The optimum reaction conditions are TFP (0.4 × 10−3
M), H2SO4 (1.0M), H3PO4 (2.0M), and H2O2 (1.6M) at 30°C. Following this procedure, iodide can be determined with a linear calibration graph up to 4.5 ng ċ cm−3 and a detection limit of 0.04 ng ċ cm−3, based on the 3 Sb criterion. The method can also be applied to the determination of iodate and periodate ions. Determination of as little as
0.2, 1.0, 2.0, and 4.0 ng ċ cm−3 of I−, IO3
-, or IO4
- in aqueous solutions gave an average recovery of 98% with relative standard deviations below 1.6% (n = 5). The method was applied to the determination of iodide in Nile river water and ground waters as well as in various food
samples after alkaline ashing treatment. The method is compared with other catalytic spectrophotometric procedures for iodide
determination.
Received January 19, 2001. Accepted (revised) March 12, 2001 相似文献
12.
H2S oxidation by oxygen on catalysts V2O5/Al2O3, V2O5/TiO2, V2O5/Al2O3/TiO2 was studied at temperatures below the sulfur dew point. High activity and the oscillation character of the oxidation were
demonstrated by catalysts with low contents of V2O5 (3–5 wt.%). The increase in the V2O5 concentration to 10–20 wt.% results in the reduction of the catalytic activity and oscillation ability. On a pure V2O5 catalyst, the oscillations were not detected. The difference between the catalysts with the high and low concentrations of
V2O5 is explained in terms of the structures of the V5+ species formed in the catalysts.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
V. K. Yatsimirskii N. A. Boldyreva E. V. Ishchenko A. I. Senkevich G. G. Tsapyuk 《Theoretical and Experimental Chemistry》1998,34(2):108-110
We have studied the catalytic activity of TiN0.65, TiO2, Al2O3, and palladium catalysts supported on them in the oxidation of carbon monoxide. The order in which the activities of the
supported catalysts vary, Pd/Al2O3>Pd/TiO2>Pd/TiN0.65, is the reverse of the activity series for the supports. This is explained by the effect of transfer of electron density
from the palladium to the substrate.
Taras Shevchenko Kiev University, 64 Vladimirskaya ul., Kiev 252033, Ukraine, G. V. Kurdyumov Institute of the Physics of
Metals, National Academy of Sciences of Ukraine, 36 Akademika Vernadskogo bul’var, Kiev-142 252642, Ukraine. Translated from
Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 118–121, March–April, 1998. 相似文献
14.
Ashraf A. Mohamed 《Monatshefte für Chemie / Chemical Monthly》2001,56(2):919-928
A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of iodide. The method is based on the catalytic effect of iodide on the reaction of triflupromazine (TFP) with H2O2. The reaction is followed spectrophotometrically by tracing the oxidation product at 498 nm within 1 min after addition of H2O2. The optimum reaction conditions are TFP (0.4 × 10−3 M), H2SO4 (1.0M), H3PO4 (2.0M), and H2O2 (1.6M) at 30°C. Following this procedure, iodide can be determined with a linear calibration graph up to 4.5 ng ċ cm−3 and a detection limit of 0.04 ng ċ cm−3, based on the 3 Sb criterion. The method can also be applied to the determination of iodate and periodate ions. Determination of as little as 0.2, 1.0, 2.0, and 4.0 ng ċ cm−3 of I−, IO3 -, or IO4 - in aqueous solutions gave an average recovery of 98% with relative standard deviations below 1.6% (n = 5). The method was applied to the determination of iodide in Nile river water and ground waters as well as in various food samples after alkaline ashing treatment. The method is compared with other catalytic spectrophotometric procedures for iodide determination. 相似文献
15.
V. V. Lesnyak V. K. Yatsimirskii T. D. Kinder O. Yu. Boldyreva 《Theoretical and Experimental Chemistry》2009,45(5):331-337
Catalysts prepared by the hydrogen reduction of Nb2O5 in the presence of Pt or Pd have specific surface much greater than for the starting oxide and their catalytic activity in
the oxidation of hydrogen is much greater than the activity of Pt/Al2O3 or Pd/Al2O3. X-ray phase analysis and X-ray photoelectron spectroscopy were used to establish the existence of Nb2O5–x
nonstoichiometric oxides in the catalyst, which enhances the catalytic activity of the surface. The kinetic behavior of the
oxidation of hydrogen on these catalysts is explained in the framework of the Eley–Riedel mechanism. 相似文献
16.
V. V. Lesnyak V. K. Yatsimirskii O. Yu. Boldyreva T. D. Kinder 《Theoretical and Experimental Chemistry》2008,44(3):189-194
The catalytic activity in the oxidation of hydrogen (in the gaseous state in the presence of excess oxygen) has been studied
for samples of Pt(Pd)/Ta2O5−x, formed by reduction with hydrogen. The samples obtained had greater activity than the traditional catalysts Pt(Pd)/Al2O3. According to X-ray diffraction analysis and electron microscopic studies, Ta2O5−x becomes amorphous with the formation of more reduced non-stoichiometric oxygen-deficient tantalum oxides with a surface layer
of catalyst.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 3, pp. 180–185, May–June, 2008. 相似文献
17.
The catalytic properties of supported mono- and bimetallic catalysts of the Tc/support, M/support, and M-Tc/support types
(M=Pt, Pd, Rh, Ru, Ni, Re, Co; supports are γ-Al2O3, MgO, SiO2) were investigated in the acetone hydrogenation. The main products of this reaction are isopropyl alcohol and propane. The
catalytic activity in the acetone hydrogenation of the metals studied decreases in the consequence Pt>Tc≈Rh>Pd>Ru >Ni≈Re>Co
(with γ-Al2O3 as the support). The influence of support nature on the catalytic activity was investigated for the Rh−Tc system as an example.
A nonadditive increase in the catalytic activity of Rh−Tc/γ-Al2O3 in comparison with monometallic catalysts was found. The state of the surface of the catalysts was characterized by the UV-VIS
diffuse reflectance spectra.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 414–417, March, 1998. 相似文献
18.
A. A. Firsova T. I. Khomenko A. N. Il’ichev V. N. Korchak 《Kinetics and Catalysis》2011,52(3):434-445
The catalytic properties of systems prepared by the supporting of CuO onto CeO2, ZrO2, and Zr0.5Ce0.5O2 with particle sizes of 15–25 nm (nitrate pyrolysis (p)) and 5–6 nm (microemulsion method (me)) in the reaction of CO oxidation
in an excess of H2 were studied. In the latter case, the supports had an almost homogeneous surface and a small number of defects. The catalytic
activity of (me) and (p) supports was low and almost the same, whereas the catalytic activity of CuO/(CeO2, ZrO2, and Zr0.5Ce0.5O2)(me) samples was lower than that of CuO/(CeO2 and ZrO2)(p). The maximum CO conversion (∼100% at 125°C) was observed on 5% CuO/CeO2 (p). The CO and CO2 adsorption species on (p) and (me) catalysts were studied by TPD. Differences in the compositions of copper-containing centers
on the surfaces of (p) and (me) systems were found using TPR. The nature of the active centers of CO oxidation and the effect
of support crystallite size on the catalytic activity were considered. 相似文献
19.
K Kiruthiga P Aravindan S Anandan P Maruthamuthu 《Research on Chemical Intermediates》2006,32(2):115-135
N,N,N′,N′-Tetramethylbenzidine (TMB) is an aromatic amine that undergoes oxidation by various oxidizing agents such as Ce4+, MnO−4, Cr2O2−7; HSO−5, S2O−8, H2O2, Cl2, Br2 and I2, thereby serving as a reducing substrate. One-electron oxidation of TMB results in a radical cation (TMB˙+), and on further oxidation leads to the product dication (TMB++) were monitored by stopped-flow spectrophotometer at the absorption wavelength of TMB˙+(λmax; 460 nm). ESR data was also provided to confirm the formation of radical cation. The rates of both the formation and decay
of TMB˙+ have been followed by a total second-order kinetics, a first-order dependence each on [TMB] (or) [TMB˙+] and [oxidant]. The kinetic and transition state parameters have been evaluated for the effects of pH and temperature on
the formation and decay of TMB˙+ and discussed with suitable reaction mechanisms. Also, the rate constants for the reactions of the radical cation with various
reducing agents such as sulfite (SO2−3), thiosulfate (S2O2−3), dithionite (S2O2−4) and disulfite (S2O2−5) and ascorbic acid (vitamin C, AH2 were determined. Besides these, this article also explains how TMB acts as a better electron relay than unsubstituted benzidine,
even though both of them undergo one-electron oxidation and are used in the chemical routes to solar energy conversions. The
observed rate constants for electron transfer were correlated theoretically using Marcus theory. The observed and calculated
rate constants have good correlation. 相似文献
20.
Jian-zhang Li Shen-xin Li Feng Xie Bo Zhou Wei Zeng Sheng-ying Qin 《Transition Metal Chemistry》2006,31(8):1066-1070
Mono-Schiff base CoII complexes, CoL
2
1
–CoL
2
6
with aza-crown or morpholino pendants were synthesized. The O2 uptake of these complexes in MeOCH2CH2OMe solution was determined at different temperatures, and the equilibrium constants (KO2) and thermodynamic parameters (ΔH
0, ΔS
0) for oxygenation were calculated. The corresponding MnIII complexes, MnL
2
1
Cl–MnL
2
6
Cl, were employed to catalyze epoxidation of styrene at ambient temperature and pressures. Crown ether effects on the modulation
of O2-binding capability and the catalytic oxidation of styrene are discussed. The results indicate that the dioxygen affinities
of the CoII complexes are much more enhanced by aza-crown pendants than that by morpholino pendants, and the O2-binding capabilities of CoL
2
1
–CoL
2
3
with aza-crown pendants can also be enhanced by adding alkali metal (Li+, Na+ and K+) cations; similarly, the catalytic activities of the MnIII complexes with aza-crown pendants, MnL
2
1
Cl–MnL
2
3
Cl, are higher than those of the MnIII complexes with morpholino pendants, MnL
2
4
Cl–MnL
2
6
Cl. 相似文献