共查询到20条相似文献,搜索用时 78 毫秒
1.
Liming He Xiaochun Chen Jingsheng Ma Hailong He Wei Wang 《Journal of Sol-Gel Science and Technology》2010,55(3):285-292
A series of Cu/SiO2 catalysts with copper loadings ranging from 17.8 to 42.2 wt% were prepared by the sol–gel method and evaluated for the hydrogenolysis
of diethyl oxalate to ethylene glycol. The physicochemical properties of these catalysts were systematically characterized
by means of different techniques. It is found that copper loadings have great influence on the catalytic performance; the
catalyst with a copper loading of 37.8 wt% exhibited the best activity and ethyl glycol selectivity. The sol–gel derived catalyst
was superior in catalytic performance to the catalyst prepared by the deposition precipitation method, a result due to the
presence of finely dispersed copper phyllosilicate. 相似文献
2.
Žaneta Dohnalová Petra Šulcová Miroslav Trojan 《Journal of Thermal Analysis and Calorimetry》2010,101(3):973-978
The main aim of this work was to synthesize the magnesium orthostannate doped by terbium cations and tested whether these
materials can be used for colouring of the different materials, e.g. organic binder and ceramic glazes. Initial composition
of pigments was counted according the general formula 2MgO(1 − x)SnO2–xTbO2, where values of x varied from 0.1 to 0.5 in 0.1 steps. The simultaneous TG/DTA measurements of mixture containing tin oxide, magnesium carbonate
hydroxide and terbium oxide showed that the formation of a new compound started at temperature 1,029 °C, but single-phase
system was not prepared. Granulometric compositions of samples that were prepared by calcining at temperatures 1,300–1,400 °C
are characterized by values of median (d
50) in range 4–8 μm. The calcining temperature 1,500 °C caused the increase of the particle sizes at around 12 μm. The composition
of sample 2MgO–1.5SnO2–0.5TbO2 and heating temperature 1,500 °C are the most suitable conditions for preparation of colourfully interesting pigment that
can be recommended also for colouring of ceramic glazes. Especially, for colouring of decorative lead containing glaze G 07091
containing 5 wt% of PbO and 8 wt% of Al2O3. 相似文献
3.
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
4.
P. I. Kirienko T. M. Boichuk S. N. Orlik S. A. Solov’ev 《Theoretical and Experimental Chemistry》2012,47(6):384-389
It is shown that palladium–cobalt oxide–cerium catalyst deposited on cordierite catalyzes the reduction of nitrogen(II) oxide
with carbon monoxide, and cobalt–iron catalysts in simultaneous reduction of NO + N2O with C3-C4 alkanes retained high activity in the presence of water vapor and sulfur dioxide. The Pd-Co3O4/cordierite catalyst exceeds the Pt-Co3O4/codierite catalyst in the conversion of NO and CO in the reaction mixture CO + NO + O2 + H2O + SO2. Modification of the Pd-Co3O4/cordierite with cerium oxide considerably increases its sulfur resistance. 相似文献
5.
Baogeng Xie Guanzhong Lu Qiguang Dai Yanqin Wang Yun Guo Yanglong Guo 《Journal of Cluster Science》2011,22(4):555-561
Tetragonal CeVO4 was prepared through hydrothermal treatment and sonication method with the same precursor in the absence of any catalysts
or templates, and the products were characterized by XRD, TEM and Raman. It is found that microrods, nanoparticles, nanorods
and nanoplates have been obtained. The bigger nanorods produced through hydrothermal treatment have average diameters of 15–25 nm
and lengths of 20–60 nm. The smaller nanorods prepared through ultrasound treatment have average diameters of 6–12 nm and
lengths of 10–18 nm. Uniform nanoplates have been produced. The nanoplates produced through hydrothermal method are composed
of CeVO4 and CeO2. The mechanism of shape changing has been discussed. And the existing vanadium which is sensitive to the pH value of synthesis
solution may be a key factor for the resulted sizes and shapes of the obtained nanocrystals. The samples prepared through
hydrothermal treatment and sonication method were used as the catalysts for the combustion of trichloroethylene to test their
catalytic activity. 相似文献
6.
Jan A. Claußen Gonzalo Ochoa Maritza Páez Juan Costamagna Miguel Gulppi Tebello Nyokong Fethi Bedioui José H. Zagal 《Journal of Solid State Electrochemistry》2008,12(5):473-481
We have investigated the electrocatalytic activity of several substituted and unsubstituted cobalt–phthalocyanines of substituted
tetraphenyl porphyrins and of vitamin B12, for the electro-oxidation of 2-mercaptoacetate, with the complexes pre-adsorbed on a pyrolytic graphite electrode. Several
N4-macrocyclic were used to have a wide variety of Co(II)/(I) formal potentials. The electrocatalytic activity, measured as
current at constant potential, increases with the Co(II)/(I) redox potential for porphyrins as Co–pentafluorotetraphenylporphyrin < Co–tetrasulfonatotetraphenylporphyrin < Co-2,2′,2″,2‴tetra-aminotetraphenylporphyrin
and decreases for cobalt phthalocyanines as Co-3,4-octaethylhexyloxyphthalocyanine > Co–octamethoxyphthalocyanine > Co–tetranitrophthalocyanine
Co–tetraaminophthalocyanine > Co–unsubstituted phthalocyanine > Co–tetrasulfonatophthalocyanine > Co–perfluorinated phthalocyanine.
Vitamin B12 exhibits the maximum activity. A correlation of log I (at constant potential) versus the Co(II)/(I) formal potential of the catalysts gives a volcano curve. This clearly shows
that the search for better catalysts for this reaction point to those N4-macrocyclic complexes with Co(II)/(I) formal potentials close to −0.84 V versus SCE, which correspond to an optimum situation
for the interaction of the thiol with the active site.
Dedicated to Prof. Dr. Teresa Iwasita on the occasion of her 65th birthday in recognition of her numerous contributions to
interfacial electrochemistry. 相似文献
7.
T. M. Boichuk V. L. Struzhko S. N. Orlik 《Russian Journal of Applied Chemistry》2010,83(10):1742-1749
The combined conversion conditions were examined for the reactions of decomposition and reduction of N2O and NO with C1,C3–C4 hydrocarbons, in particular, in gas mixtures containing oxygen and sulfur dioxide, over Fe- and Co-containing catalysts supported
on zeolites and zirconia, as well as on structured honeycomb monoliths. 相似文献
8.
M. R. Kantserova S. N. Orlik V. P. Kazimirov 《Theoretical and Experimental Chemistry》2007,43(6):399-404
Alumina-and zirconia-manganese catalysts for the deep oxidation of methane were studied by X-ray phase analysis, temperature-programmed
hydrogen reduction, and IR spectroscopy. The most active catalyst has the optimal combination of dimensional, redox, and acid
characteristics. The zirconia-manganese catalysts formed on the surface of a kaolin-aerosil honeycomb matrix provides for
80–100% conversion of methane to CO2 at 690–750 °C.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 6, pp. 367–372, November–December, 2007. 相似文献
9.
T. V. Mironyuk V. L. Struzhko S. N. Orlik 《Theoretical and Experimental Chemistry》2007,43(4):255-260
A series of cobalt-containing granulated and structured catalysts based on zirconium and aluminum oxides has been studied.
The optimum composition of binary oxide samples (80% ZrO2 − 20% Al2O3) for the selective reduction of nitrogen monoxide with methane (84% conversion of NO achieved at 320 °C) has been determined.
The activity of the structured catalysts depends on both the composition of the secondary carrier (ZrO2, Al2O3, and their mixture) and on the nature of the skeleton of the cellular structure (cordierite, kaolin-aerosil).
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 4, pp. 237–241, July–August, 2007. 相似文献
10.
Xiangzhong Ren Yingkai Jiang Peixin Zhang Jianhong Liu Qianling Zhang 《Journal of Sol-Gel Science and Technology》2009,51(2):133-138
One-dimensional (1D) submicron-belts of V2O5 have been prepared by a sol–gel route using V2O5, H2O2 and aniline as starting materials. Thermogravimetric and differential thermal analysis, X-ray diffraction, Fourier transform
infrared spectroscopy and scanning electron microscopy were employed to characterize the samples. Electrochemical behaviors
as cathode material in rechargeable lithium-ion batteries were investigated by galvanostatic charge–discharge measurement
and cyclic voltammeter. The results showed that the synthesized V2O5 appeared to be submicron-belts and orthorhombic structure. The V2O5 submicron-belts exhibited a high initial discharge capacity of 346 mAh/g and stayed 240 mAh/g after 20 cycles at 0.1 C discharge
rate in the potential region 1.8–4.0 V. 相似文献
11.
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
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.
Seung-Chan Baek Ki-Won Jun Yun-Jo Lee Jae Dong Kim Dal Young Park Kwan-Young Lee 《Research on Chemical Intermediates》2012,38(6):1225-1236
The effects of Ru on the self-reducibility of Ru-doped Ni/MgAl2O4 catalysts, which do not need pre-reduction treatment with H2, were investigated in the steam reforming of methane (SRM). The Ru-promoted Ni/MgAl2O4 catalysts with various amounts of Ru (0–0.5 wt%) were prepared by stepwise impregnation and co-impregnation methods using
hydrotalcite-like MgAl2O4 support. For comparison, Ru/MgAl2O4 catalysts with the same amount of Ru were also prepared by the impregnation method. The catalysts were characterized by the
N2-sorption, XRD, H2-TPR, H2-chemisorption, and XPS methods. Ni/MgAl2O4 catalyst in the presence of even the trace amount of Ru (Ru content ≥0.05 wt%) showed higher conversion without pre-reduction
as compared to Ru/MgAl2O4 catalysts in SRM under the same conditions. The self-activation of Ru–Ni/MgAl2O4 catalysts is mainly attributed to the spillover of hydrogen, which is produced on Ru at first and then reduces NiO species
under reaction conditions. Besides, Ru doping makes the reduction of NiO easier. The stepwise impregnated Ru/Ni/MgAl2O4 catalyst produced superior performance as compared to co-impregnated Ru–Ni/MgAl2O4 catalyst for SRM. 相似文献
15.
Danniely S. de Melo M. R. C. Santos Iêda M. G. Santos L. E. B. Soledade M. I. B. Bernardi E. Longo A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2007,87(3):697-701
SnO2-based
materials are used as sensors, catalysts and in electro–optical devices.
This work aims to synthesize and characterize the SnO2/Sb2O3-based
inorganic pigments, obtained by the polymeric precursor method, also known
as Pechini method (based on the metallic citrate polymerization by means of
ethylene glycol). The precursors were characterized by thermogravimetry (TG)
and differential thermal analysis (DTA). After characterization, the precursors
were heat-treated at different temperatures and characterized by X-ray diffraction.
According to the TG/DTA curves basically two-step mass loss process was observed:
the first one is related to the dehydration of the system; and the second
one is representative to the combustion of the organic matter. Increase of
the heat treatment temperature from 500 to 600°C and 700°C resulted
higher crystallinity of the formed product. 相似文献
16.
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
17.
Carlos J. Lucio-Ortiz Javier Rivera De la Rosa Aracely Hernandez Ramirez Jose A. De los Reyes Heredia Paz del Angel Severino Muñoz-Aguirre Lina M. De León-Covián 《Journal of Sol-Gel Science and Technology》2011,58(2):374-384
Two mesoporous alumina samples were synthesized using the sol–gel method, and these samples were tested as catalysts in trichloroethylene
combustion reaction. One alumina sample was doped with Fe to study the influence of a small amount of this agent on the characteristics
and properties of alumina as a catalyst. Both catalysts (pure alumina and alumina doped with Fe) were thoroughly characterized
by different techniques, such as DTA/TGA, FT-IR, XRD, SEM and TEM, and the porous characterization was conducted using a N2 physisorption technique. The doping agent presented a particular influence on the morphology and textural porosity in the
alumina catalyst and therefore, it exhibited different catalytic behavior than the pure alumina catalyst. For both catalysts,
the crystalline phase of γ-alumina was reported using XRD technique, and the crystallite size ranged from 7.8 to 12.8 nm.
Using TEM images, the alumina catalyst doped with Fe revealed to contain a mixture of three types of iron oxide (maghemite,
magnetite and hematite), mainly as roughly spherical nanoparticles. For both alumina catalysts, trichloroethylene catalytic
combustion was conducted on a packed bed reactor in air at a temperature range of 50 to 600 °C. The alumina catalyst doped
with Fe showed a higher catalytic activity than pure alumina, mainly due to the presence of micropores and grain morphology
of flat faces. 相似文献
18.
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
19.
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
20.
V. K. Yatsimirskii V. V. Lesnyak I. N. Gut O. Yu. Boldyreva 《Theoretical and Experimental Chemistry》2005,41(5):329-333
We have shown that WO3 and MoO3 with Pt or Pd additives exhibit high catalytic activity in the reaction of H2 oxidation. In the temperature range 313 K to 353 K, we have studied the kinetic behavior of the reaction on 0.1 mass % Pt(Pd)/WO3 and Pt(Pd)/MoO3 samples. We have established that the kinetics of H2 oxidation on these catalysts correspond to an Eley - Rideal mechanism.
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Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 313–316, September–October, 2005. 相似文献