共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
Hydrotalcite-like compounds (HTlcs) can be used as the catalysts as it is since they contain various transition metal cations
as the catalytically active species well dispersed on the basic support materials. Moreover, increasing numbers of the applications
of HTlcs after the heat treatment have been found since the oxides with very small crystal size, stable to thermal treatments,
are obtained after the calcination. The oxides possess interesting properties such as high surface area, basic properties
and further form small and thermally stable metal crystallites by reduction. Moreover, the calcined oxides show a unique property,
i.e., “memory effect,” which allows the reconstitution of the original hydrotalcite structure. We have developed the catalytic
applications of hydrotalcites as it is and moreover the mixed oxides derived from hydrotalcites for various catalytic reactions,
i.e., oxidation, dehydrogenation and reforming of hydrocarbons, and even for the reforming of methanol and the CO shift reaction.
Aerobic oxidation of alcohols, Baeyer−Villiger oxidation of ketones and O3 oxidation of oxalic acid have been successfully carried out with the Mg−Al hydrotalcites containing Ni, Fe and Cu, respectively,
as the catalysts in liquid phase. In the O3 oxidation of oxalic acid, the catalytic activity was enhanced by the “memory effect,” i.e., Mg(Cu)–Al hydrotaclite was reconstituted
on the surface of Mg(Cu,Al)O periclase particles and oxalic acid was incorporated as anions in the hydrotalcite layer, resulting
in an enhanced oxidation of oxalic acid. As the catalysts in the vapor phase reactions, Mg/Fe/Al mixed oxides prepared from
Mg–Al(Fe) hydrotalcites and effectively catalyzed the dehydrogenation of ethylbenzene. Supported Ni metal catalysts have been
prepared from Mg(Ni)–Al hydrotalcites and successfully used in the steam reforming and the oxidative reforming of methane
and propane. Moreover, the Ni catalysts have been improved by combining a trace amount of noble metals by adopting the “memory
effect” and used in the production of hydrogen for the PEFC under the daily startup and shutdown operation. Also starting
from aurichalcite or hydrotalcite precursor as the precursor, Cu/Zn/Al catalysts with high Cu metal surface area have been
prepared and successfully applied in the steam reforming of methanol and dimethyl ether, and moreover in the CO shift reaction. 相似文献
3.
A. V. Gural’skii G. R. Kosmambetova É. M. Moroz V. I. Gritsenko P. E. Strizhak 《Theoretical and Experimental Chemistry》2011,47(4):251-256
We have studied the catalytic properties in oxidation of hydrogen for copper–cerium oxide systems deposited on supports obtained
by calcination of yttrium-stabilized zirconium dioxide at 300–1000 °C. We have shown that the catalytic activity of the samples
obtained depends on the specific surface area of the original supports and the amount of reduced copper within the composition
of the catalyst. In samples whose support has high specific surface area, the content of reduced metallic copper is greater
and the catalytic activity is higher. 相似文献
4.
Following gradual shift of primary resources from fossil towards renewable ones in chemical industry, biomass based ethanol
has been attracting growing interests as a fuel to replace gasoline and as a chemical feed stock to replace ethylene. This
paper reviews major work reported in the last 10 years for the production of acetaldehyde, acetic acid, and other related
compounds from ethanol. At present acetic acid can be industrially produced more economically from methanol than from ethylene,
the production of acetic acid from ethanol is not profitable. Acetaldehyde, which is more expensive than ethanol, can be selectively
produced in gas phase by dehydrogenation over supported Cu catalysts and by oxidation with O2 over V and Mo based oxides. It is noteworthy that gold nanoparticles deposited on basic and acidic metal oxides are highly
selective to acetaldehyde by oxidation with O2. Acetic acid can be produced in water solvent over Au catalysts supported on MgAl2O4 or on Cu doped NiO, while in gas phase over Mo–V–Nb mixed oxides combined with TiO2 colloids. 相似文献
5.
A. V. Gural’skii V. P. Pakharukova G. R. Kosmambetova P. E. Strizhak É. M. Moroz V. I. Gritsenko 《Theoretical and Experimental Chemistry》2009,45(2):125-130
We studied the catalytic properties of copper–cerium oxide systems, deposited on supports obtained by calcination of yttrium-stabilized
zirconium dioxide at 300-1000 °C, in the reaction of selective oxidation of CO in a stream of hydrogen. We have shown that
the catalytic activity of the samples obtained correlates with the activity of the original supports in the reaction of CO
oxidation: the highest CO conversion is observed on catalysts with the highest and the lowest specific surface area.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 2, pp. 115-120, March-April, 2009. 相似文献
6.
铜锆复合氧化物的结构对其催化选 择还原-氧化氮性 能的影响 总被引:2,自引:0,他引:2
用浸渍法和共沉淀法分别制得CuO---ZrO~2复合氧化具物有不同的选择还原NO~x的催化性能,采用XRD,BET,EXAFS和H~2---TPR等手段对样品进行了表征,发现浸渍法制备的样品具有的比表面较大,氧化锆被稳定在四方相。EXAFS实验表明,浸渍法制得样品的铜离子填入氧化锆表面空穴中,并以Cu^2+形式存在;500℃焙条件下用共沉淀法引入的铜离子可部分取代锆离子,在氧化锆体相高度分散形成均匀的无定形固溶体,铜离子在氧化锆体相的高度分散是形成表面弧立铜物种的关键。溶入氧化锆体相的铜离子在取代部位由于局部负电荷而使氧化性降低,是共沉淀法制备样品具有较高催化活性的主要原因。 相似文献
7.
Kuz'mina R. I. Ivanova Yu. V. Sevost'yanov V. P. 《Theoretical and Experimental Chemistry》2003,39(4):259-262
We have studied the reaction of NO and CO on aluminum/nickel/copper catalysts obtained under short high-voltage discharge conditions. We have established that electrohydraulic shock affects formation of heterogeneous catalytic systems and increases the activity of catalysts during simultaneous removal of nitrogen and carbon oxides from gaseous exhausts. 相似文献
8.
The effects of preparation conditions, component ratio, and pretreatment temperature (1000–1550‡C) of silica-alumina samples
on their phase composition, texture characteristics, and catalytic properties are studied in the reaction of the oxidative
dehydrogenation of propane by sulfur dioxide. It is shown that the samples contain individual silicon and aluminum oxides.
The product of their interaction (mullite) is formed only at 1550°C. Mesoporous and macroporous catalysts with monoand polydispersed
pore distributions over sizes are obtained. It is found that the porous structure of the catalyst plays a key role in the
process of the oxidative dehydrogenation of propane in the presence of sulfur dioxide at 600–700°C. The apparent rate of propylene
formation increases with an increase in the pore volume with radii between 10 and 100 nm. Propane is transformed into propylene
more selectively on the catalyst where the pores with radii of 10–100 nm dominate; narrower pores (< 10 nm) are favorable
for the formation of coke and complete oxidation products. 相似文献
9.
《中国化学快报》2020,31(5):1201-1206
The effective valuation of catalyst supports in the catalytic oxidation makes the contribution to understand the support effect of great interest. Here, the role of active substrate in the performance and stability of Cu-Fe-Co ternary oxides was studied towards the complete catalytic oxidation of CO. The Cu-Fe-Co oxide thin films were deposited on copper grid mesh (CUGM) using one-step pulsed-spray evaporation chemical vapor deposition method. Crystalline structure and morphology analyses revealed nano-crystallite sizes and dome-top-like morphology. Synergistic effects between Cu, Fe and Co, which affect the surface Cu2+, Fe3+, Co3+ and chemisorbed oxygen species (O2− and OH−) of thin films over the active support and thus result in better reducibility. The thin film catalysts supported on CUGM exhibited attractive catalytic activity compared to the ternary oxides supported on inert grid mesh at a high gas hourly space velocity. Moreover, the stability in time-on-stream of the ternary oxides on CUGM was evaluated in the CO oxidation for 30 h. The adopted deposition strategy of ternary oxides on CUGM presents an excessive amount of adsorbed active oxygen species that play an important role in the complete CO oxidation. The catalysts supported on CUGM showed better catalytic conversion than that on inert grid mesh and some literature-reported noble metal oxides as well as transition metal oxides counterparts, revealing the beneficial effect of the CUGM support in the improvement of the catalytic performance. 相似文献
10.
A series of Pd/Al2O3–ZrO2 materials have been prepared via sol gel method as an attractive route to obtain more homogeneous binary oxides Al2O3–ZrO2. A Zr loading between 2 and 15 wt% was used to investigate the Zr promotion of Pd/Al2O3 materials. The prepared catalysts were calcined at two different temperatures. Very interesting results have been obtained
at low zirconium content. A small amount of Zr is seen to be sufficient to stabilize the activity and to obtain good catalytic
performances with developed textural properties compared to conventional catalysts used to oxidize methane. The increase of
the zirconium loading is seen to decrease the catalytic activity may be due to the development of tetragonal zirconia phase
detected by XRD. Similar effect has been observed after heating catalysts at high temperatures. A loss in BET surface area
and in metal dispersion has been also observed for zirconium rich catalysts. A contradictory effect on textural and structural
properties is seen after their calcination at 700 °C. 相似文献
11.
V. V. Lesnyak V. K. Yatsimirskii I. N. Gut O. Yu. Bondyreva 《Theoretical and Experimental Chemistry》2008,44(2):134-138
It has been shown that the phases HxMO3 and MO3−x (M = Mo, W), obtained by reduction of the oxides WO3 and MoO3 with hydrogen with supported Pt(Pd) (0.5 mass %), have higher catalytic activity in the deep oxidation of methane than the
catalysts Pt/Al2O3 and Pd/Al2O3 with the same amount of supported metal. At temperatures above 700 K the activity of these catalysts decreases in consequence
of the thermal decomposition of the phases HxMO3 and MO3−x and they become similar in activity with Pt(Pd)/Al2O3.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 2, pp. 126–129, March–April, 2008. 相似文献
12.
The surface characteristics of mixed zirconium and titanium oxides prepared from different starting materials are investigated.
One mode of preparation entailed the use of zirconium sulfate and titanium oxysulfate as starting materials and ammonium hydroxide
as precipitating agent. The produced oxides were washed to different extents to obtain samples with different sulfate content.
A second preparative mode used zirconium oxychloride and titanous chloride as starting materials also with ammonium hydroxide
as precipitating agent. The oxidation of the titanous to the titanic form for these oxides was carried out by means of oxygen
gas. Resulting samples were heat treated at 400 °C and 600 °C, and textural characteristics determined from the adsorption
of N2 at 77 K, complemented by infrared and thermal studies.
The samples precipitated from the oxychloride and chloride salts of zirconium and titanium, as well as those precipitated
from the sulfate and oxysulfate salts and washed free of the sulfate ions displayed quite similar textural characteristics.
The unheated samples and those heat-treated at 400 °C were mesoporous, with some microporosity, and relatively large surface
areas in the order of 200–300 m2/g. Heat treatment to 600 °C led to a relative decrease in surface area, in the order of 100 m2/g, and to the disappearance of microporosity.
The mixed zirconium and titanium oxides with a sulfate content of ≈17% displayed significantly lower surface areas, smaller
than 10 m2/g, with a prevalence of micro and mesoporosity. Infrared and thermal studies indicated the presence of differently bounded
sulfato groups, which seem to have a blocking effect on the pores, resulting in the observed smaller surface areas. 相似文献
13.
Lucjan Chmielarz Małgorzata Rutkowska Piotr Kuśtrowski Marek Drozdek Zofia Piwowarska Barbara Dudek Roman Dziembaj Marek Michalik 《Journal of Thermal Analysis and Calorimetry》2011,105(1):161-170
Hydrotalcite-like materials containing apart from magnesium and aluminum also copper, cobalt, nickel, and iron were prepared
by a co-precipitation method. Thermal transformations of hydrotalcite-like materials were studied by thermal analysis methods
as well as XRD, UV–vis–DRS, and XPS measurements of the samples calcined at various temperatures (600, 700, and 800 °C). Calcined
hydrotalcites, especially those containing cobalt and copper, were found to be active and selective catalysts of N2O decomposition. It was shown that an increase in the calcination temperature significantly activated the Co-containing catalysts.
Promotion of the samples with potassium resulted in activation of the hydrotalcite-based catalysts. 相似文献
14.
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
15.
The carbon nanotubes supported palladium(Pd/CNT)nanocatalysts were modified by cerium oxides/ hydroxides and their catalytic performances for methanol oxidation were evaluated.Electrochemical measurements indicate that the introduction of cerium remarkably improves the catalytic activity of Pd/CNT catalysts towards methanol oxidation.X-Ray photoelectron spectra results reveal an interaction between palladium and cerium oxides.It is also observed that cerium-modified catalysts have excellent poison resistances,which is attributed to the poison-removal ability of cerium oxides/hydroxides.The highly oxidized cerium oxides/hydroxides have a strong ability to inhibit the accumulation of carbonaceous intermediates on the active sites of Pd catalysts. 相似文献
16.
O. V. Mokhnachuk S. A. Solov’ev A. I. Senkevich 《Theoretical and Experimental Chemistry》2006,42(1):48-52
We have established that the thermal stability of supported Pd/Al2O3 catalysts is increased after they are modified by rare earth oxides (La2O3, Ce2O3). We have observed the effect of thermal activation of an aluminopalladium catalyst modified by lanthanum oxide. This effect
is apparent in the increase of the specific catalytic activity in the reaction of high-temperature reduction of nitrogen oxides
by methane after heat treatment of the catalyst at 850 °C. We have used X-ray photoelectron spectroscopy (XPS) to show that
the reason for the thermal activation effect is stabilization of palladium in the Pd1+ state.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 44–48, January–February, 2006. 相似文献
17.
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
18.
This study presented results on reduction of alumina
supported chromium and platinum–chromium catalysts using temperature
programmed reduction method (TPR). It has been shown that catalysts after
earlier oxidation step but without calcinations one undergo reduction in lower
temperature in comparison to calcined only catalysts. Moreover, addition platinum
to Cr/Al2O3 catalysts also caused
decrease of reduction temperature. It has been observed that over the examined
catalysts oxidation CO to CO2 and reduction CO to CH4
occurs. However, on Pt–Cr catalysts both reactions proceed at lower
temperature compare to Cr catalysts. 相似文献
19.
G. N. Pirogova N. M. Panich R. I. Korosteleva Yu. V. Voronin N. N. Popova 《Russian Chemical Bulletin》2000,49(9):1536-1539
The catalytic properties of supported cobaltites MCo2O4 (M=Cu, Mn, Zn, Mg) in the oxidation of CO, C3H6, and ethylbenzene and reduction of nitrogen oxides were investigated. The catalytic activity depends on the calcination temperature
and the nature of the cation. The regularities of formation and the state of the surface of the catalysts were studied by
IR spectra and diffuse reflectance spectra in the UV and visible regions.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1547–1550, September, 2000. 相似文献
20.
A. V. Lavrenov I. A. Basova M. O. Kazakov V. P. Finevich O. B. Belskaya E. A. Buluchevskii V. K. Duplyakin 《Russian Journal of General Chemistry》2007,77(12):2272-2283
Experimental evidence on the production, structure, and physiochemical properties of aluminum, zirconium, and titanium oxides modified with halides, sulfates, and boron and tungsten oxides. Information on the application of anion-modified metal oxides as catalysts in the production of ecologically pure components of motor fuels, with decreased contents of aromatic hydrocarbons and sulfur compounds. Therewith, along with traditional hydrocarbon oligomerization, isomerization, alkylation reactions, actual arene hydroisomerization processes and production of diesel fuels from vegetable materials are considered. 相似文献