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1.
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.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 107–111, March–April, 2007. 相似文献
2.
Liquid-phase reduction NO
3
−
using monometallic and bimetallic catalysts (5% Rh/Al2O3, 5% Rh-0.5% Cu/Al2O3, 5% Rh-1.5% Cu/Al2O3, 5% Rh-5% Cu/Al2O3 and a physical mixture of 5% Rh/Al2O3 and 1.5% Cu/Al2O3) was studied in a slurry reactor operating at atmospheric pressure. Kinetic measurements were performed for a low concentration
of nitrate (0.4 × 10−3−3.2 × 10−3 mol dm−3) and the temperature range 293–313 K. From the experimental data, it was found that the reduction of nitrate is first order
with respect to nitrate. On the basis of the rate constants, the apparent activation energy was established using a graphic
method.
Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 6, pp. 881–886.
This article was submitted by the authors in English. 相似文献
3.
A series of Pd/Al2O3–ZrO2 catalysts were prepared to be used in methane oxidation. The effect of the addition order of metal alkoxides on the texture,
structure and catalytic properties of the solids is studied. The control of the preparation parameters is achieved via sol
gel way as an attractive route of the preparation of these catalysts. N2 physisorption, XRD, Scanning Electronic Microscopy (SEM) and H2 chemisorption are the main techniques used to characterize the prepared Pd/Al2O3–ZrO2 catalysts. Textural analysis reveals the mesoporosity of all the catalysts independently of the addition order of alkoxides
while surface area is more pronounced when the aluminium alkoxide is added before or with the zirconium precursor. XRD patterns
show the development of the zirconia tetragonal phase for all the catalysts. Better metallic dispersion is obtained when aluminium
alkoxide is added first which can be justified by the high homogeneity observed on the corresponding catalyst as revealed
by SEM technique. 相似文献
4.
Chemisorption of SO2 and O2 on the In2O3 surface containing a zinc additive (0.4–2.7 at.%) was studied in a temperature range of 22–200 °C. At least three forms of
sorbed SO2 exist on the modified In2O3 surface. The temperature affects the contribution of single forms of SO2 sorption and, hence, the change in the electric conductivity. The preliminary sorption of O2 favors the formation of a donor form of chemisorbed SO2.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2228–2232, October, 2005. 相似文献
5.
L. A. Dunyushkina A. I. Vshivkova A. A. Pankratov B. D. Antonov V. P. Gorelov 《Russian Journal of Electrochemistry》2010,46(7):767-773
The surface of ceramic electrolyte ZrO2 + 9 mol % Y2O3, hereinafter referred to as YSZ (abbreviated yttria stabilized zirconia), was modified with 0.1 to 0.2 μm oxide films of
ZrO2, Y2O3, and YSZ (same composition as substrate) by dip coating in alcohol solutions of the relevant salts and further annealing.
The results of scanning electronic microscopy and X-ray diffraction evidence epitaxial film growth. By means of impedance
spectroscopy at the temperatures of 500 to 600°C, the effect of YZS electrolyte surface modification with ZrO2, Y2O3, and YSZ films to the polarization resistance of silver electrode was studied. 相似文献
6.
A. O. Turakulova E. V. Golubina E. S. Lokteva A. V. Korotkov V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(3):402-407
Deposited palladium catalysts of the hydrodechlorination of 1,3,5-trichlorobenzene were studied. Pure zirconium and aluminum
oxides and ZrO2-Al2O3 mixtures with 1, 5, and 10 mol % Al2O3 prepared by coprecipitation were used as supports. Palladium was deposited by the precipitation of its hydroxide on supports.
Catalysts on binary supports (ZrO2 + 1% Al2O3 and ZrO2 + 5% Al2O3) exhibited higher activity and stability in hydrodechlorination compared with catalysts on pure supports. The suggestion
was made that the high activity and stability of these systems in hydrodechlorination was related to the formation of binary
oxide in the interaction of ZrO2 with palladium oxide at the stage of annealing of the catalyst precursor. Binary oxide, which was a center of the activation
of the C-Cl bond, was simultaneously a source of active hydrogen. The presence of various palladium states in catalysts was
substantiated by the temperature programmed reduction method. 相似文献
7.
S. A. Solov’ev E. V. Gubareni Ya. P. Kurilets 《Theoretical and Experimental Chemistry》2008,44(6):368-373
It has been established that oxides of the rare-earth elements with moderate redox potentials (La2O3, CeO2) increased the activity and working stability of Ni-Al2O3/cordierite catalysts in the reactions of deep and partial oxidation of methane. In the presence of the (NiO + La2O3 + Al2O3)/cordierite catalyst the process of carbon dioxide conversion of methane can be intensified by introduction of oxygen into
the reaction gas mixture which decreases the temperature to achieve high conversion to 75–100 °C and has practically no effect
on selectivity with respect to H2.
Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 44, No. 6, pp. 359–364, November–December, 2008. 相似文献
8.
A study was carried out on the properties of Ni/Al2O3 and Cu-ZnO/Al2O3 composites supported on ceramic honeycomb monoliths made from synthetic cordierite in the carbon dioxide conversion of methane
and the partial oxidation of methanol. The structured nickel-alumina catalysts are significantly more efficient than the conventional
granulated catalysts. The improved working stability of these catalysts was achieved by adjusting the acid-base properties
of the surface by introducing sodium and potassium oxides, which leads to inhibition of surface carbonization. The hydrogen
yield was close to 90% in the partial oxidation of methanol with a stoichiometric reagent ratio in the presence of the Cu-ZnO/Al2O3/cordierite catalyst. A synergistic effect was found, reducing the selectivity of CO formation in the presence of the Cu-ZnO
catalyst relative to samples derived from the individual components Cu and ZnO.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 5, pp. 299–306, September–October, 2007. 相似文献
9.
A. Yu. Kapran L. M. Alekseenko S. N. Orlik 《Theoretical and Experimental Chemistry》2009,45(5):338-342
Cerium dioxide as a component of CuO-ZnO-CeO2/Al2O3/cordierite catalysts stabilizes their action in the decomposition of methanol by preventing carbon deposition on the surface
and facilitating hydrogen formation with selectivity and yield in the range 85–96%. The optimal indices for this reaction
are obtained for a CeO2-CuO/Al2O3/cordierite sample prepared using an ammonium precursor for cerium, (NH4)2Ce(NO3)6. This catalyst displays enhanced reductive capacity relative to the analogous CeO2-CuO composition prepared using Ce(NO3)3·6H2O. 相似文献
10.
Carbon dioxide reforming (CDR) of methane to synthesis gas over supported nickel catalysts has been reviewed. The present
review mainly focuses on the advantage of ceria based nickel catalysts for the CDR of methane. Nickel catalysts supported
on ceria–zirconia showed the highest activity for CDR than nickel supported on other oxides such as zirconia, ceria and alumina.
The addition of zirconia to ceria enhances the catalytic activity as well as the catalyst stability. The catalytic performance
also depends on the crystal structure of Ni–Ce–ZrO2. For example, nickel catalysts co-precipitated with Ce0.8Zr0.2O2 having cubic phase gave synthesis gas with CH4 conversion more than 97% at 800 °C and the activity was maintained for 100 h during the reaction. On the contrary, Ni–Ce–ZrO2 having tetragonal phase (Ce0.8Zr0.2O2) or mixed oxide phase (Ce0.5Zr0.5O2) deactivated during the reaction due to carbon formation. The enhanced catalytic performance of co-precipitated catalyst
is attributed to a combination effect of nano-crystalline nature of cubic Ce0.8Zr0.2O2 support and the finely dispersed nano size NiO
x
crystallites, resulting in the intimate contact between Ni and Ce0.8Zr0.2O2 particles. The Ni/Ce–ZrO2/θ–Al2O3 also exhibited high catalytic activity during CDR with a synthesis gas conversion more than 97% at 800 °C without significant
deactivation for more than 40 h. The high stability of the catalyst is mainly ascribed to the beneficial pre-coating of Ce–ZrO2 resulting in the existence of stable NiO
x
species, a strong interaction between Ni and the support, and an abundance of mobile oxygen species in itself. TPR results
further confirmed that NiO
x
formation was more favorable than NiO or NiAl2O4 formation and further results suggested the existence of strong metal-support interaction (SMSI) between Ni and the support.
Some of the important factors to optimize the CDR of methane such as reaction temperature, space velocity, feed CO2/CH4 ratio and H2O and/or O2 addition were also examined. 相似文献
11.
A. L. Zharnyl’skaya V. V. Vol’khin H. Reuther 《Russian Journal of Applied Chemistry》2009,82(8):1364-1369
Samples of a precursor for an aluminum oxide ceramics reinforced with zirconium oxide were synthesized by hydrolysis of various
aluminum salts in the presence of a ZrO2 sol under conditions of urea decomposition at 90°C and pH < 4 maintained, with hydrolysis products deposited onto the surface
of ZrO2 sol particles. It was found that the nature of a salt anion affects the interaction of hydrolysis products of the aluminum
cation with the surface of ZrO2 sol particles. The structure of products formed in thermal treatment of samples of a precursor for Al2O3-ZrO2 (T = 1250°C) was characterized by X-ray phase analysis and scanning electron microscopy. The phase transition temperatures of
the oxides Al2O3 and ZrO2 contained in the precursor were estimated using the results of thermal analysis of the samples in the temperature range 20–1300°C. 相似文献
12.
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.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 3, pp. 180–185, May–June, 2008. 相似文献
13.
Chun-guang Gao Yong-xiang Zhao Yin Zhang Dian-sheng Liu 《Journal of Sol-Gel Science and Technology》2007,44(2):145-151
The Ni/ZrO2/SiO2 aerogels catalysts were synthesized via three different routes: (i) impregnation ZrO2–SiO2 composite aerogels with a aqueous solution of Ni(NO3)2, (ii) impregnation SiO2 aerogels with a mixed aqueous solution of Ni(NO3)2 and ZrO(NO3)2 · 2H2O, (iii) one-pot sol–gel procedure from precursors Ni(NO3)2/ZrO(NO3)2 · 2H2O/Si(OC2H5)4. These catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), ammonia temperature-programmed
desorption (NH3-TPD), N2 adsorption–desorption isotherms and Fourier transform infrared (FT-IR). The Liquid-phase hydrogenation of maleic anhydride
(MA) was performed over these catalysts. The results revealed that the different preparation routes result in a difference
between the obtained samples, concerning the crystal structure and composition, surface acidity, mixed level of each component,
texture, and catalytic selectivity. 相似文献
14.
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
15.
T. P. Maniecki P. Mierczyński W. Maniukiewicz D. Gebauer W. K. Jozwiak 《Kinetics and Catalysis》2009,50(2):228-234
The comparative study of the role of binary oxide support on catalyst physico-chemical properties and performance in methanol
synthesis were undertaken and the spinel like type structures (ZnAl2O4, FeAlO3, CrAl3O6) were prepared and used as the supports for 5% metal (Cu, Ag, Au, Ru) dispersed catalysts. The monometallic 5% Cu/support
and bimetallic 1% Au (or 1% Ru)-5% Cu/support (Al2O3, ZnAl2O4, FeAlO3, CrAl3O6) catalysts were investigated by BET, XRD and TPR methods. Activity tests in methanol synthesis of CO and CO2 mixture hydrogenation were carried out. The order of Cu/support catalysts activity in methanol synthesis: CrAl3O{ia6} > FeAlO3 > ZnAl2O4 is conditioned by their reducibility in hydrogen at low temperature. Gold appeared more efficient than ruthenium in promotion
of Cu/support catalysts.
Published in Russian in Kinetika i Kataliz, 2009, Vol. 50, No. 2, pp. 242–248.
The article is published in the original. 相似文献
16.
V. V. Brei D. V. Shistka S. I. Levitskaya 《Theoretical and Experimental Chemistry》2009,45(2):122-124
Based on electronic diffuse reflectance spectra of indicators adsorbed on La2O3–ZrO2, obtained at 25-200 °C, we have shown that the strength of its basic sites sharply increases from H–S ≤ +17.2 to H–S ≤ +33.0 in the range 25-140 °C.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 2, pp. 112-114, March-April, 2009. 相似文献
17.
Kh. B. Amosova M. A. Borik A. V. Kulebyakin E. E. Lomonova N. I. Medvedovskaya 《Russian Journal of Electrochemistry》2011,47(4):442-447
This paper presents the results of our experimental studies of quantitative redistribution and isotope fractionation of oxygen
during the crystal growth of cubic solid solutions based on ZrO2. The single crystals were grown by directional crystallization of a melt in a cold container. As stabilizing oxides, we used
Y2O3, Gd2O3, and Yb2O3 in concentrations of 8–40 mol %. The results showed that the oxygen isotopic growth effects changed depending on the type
and content of the stabilizer in the crystals of ZrO2-R2O3 solid solutions. 相似文献
18.
A. D. Chervonnyi 《Russian Journal of Inorganic Chemistry》2010,55(4):556-559
The A1, O, AlO, A12O, Al2O2, WO2, and WO3, partial pressures in the vapor over Al2O3 in a tungsten Knudsen effusion cell between 2300 and 2600 K were derived from A1+, O+, AlO+, A12O+, Al2O2+, WO2+, and WO3+, ion intensities. The mass spectrometer was calibrated against the equilibrium constant of the WO3(g) = WO2(g) + O(g) reaction. Refined values of the ionization cross sections of AlO and A12O2 were used in the partial pressure calculations. The enthalpies of atomization of aluminum suboxides were determined to be
Δat
H
o(AlO, g, 0) = 510.7 ± 3.3 kJ mol−1, Δat
H
o(Al2O, g, 0) = 1067.2 ± 6.9 kJ mol−1, and Δat
H
o(Al2O2, g, 0) = 1556.7 ± 9.9 kJ mol−1. 相似文献
19.
V. V. Brei S. V. Prudius I. I. Lozhechnik E. I. Oranskaya D. V. Shistka 《Theoretical and Experimental Chemistry》2011,47(3):188-191
The TPR spectra of the conversion of 2-methyl-3-butyn-2-ol (MBOH) on mixed ZrO2-Al2O3 oxides with different ZrO2 contents were obtained by desorption mass spectrometry. It was shown that MBOH is dehydrated to 3-methyl-3-buten-1-yne on
the acid centers (H0 ≥ –3.3) and is decomposed to acetylene and acetone at the basic centers (H– ≤ +6.8) of this oxide. The formation of acid centers in the amorphous structure of ZrO2-Al2O3 at 1.5 < Al/Zr < 3is explained by the Tanabe rule. 相似文献
20.
L. Yu. Dolgikh Yu. I. Pyatnitskii S. I. Reshetnikov I. V. Deinega L. A. Staraya É. M. Moroz P. E. Strizhak 《Theoretical and Experimental Chemistry》2011,47(5):324-330
A study was carried out on the steam reforming of bioethanol (15 vol.% ethanol in water) at 250–500 °C on copper catalysts
supported on ZrO2 of the monoclinic (Z) and yttrium-stabilized tetragonal crystalline modifications (YSZ). Copper nanoparticles in such catalysts
have similar reactivity regardless of the copper content and crystalline modification of the support. Cu/YSZ is highly selective
relative to CO2, which may be related to enhanced mobility of oxygen in the support in the presence of Y2O3 stabilizing additive. 相似文献