Showing papers on "Mixed oxide published in 1997"
TL;DR: In this paper, Bismuth sodium titanate (Bi 0.5Na0.5TiO3, BNT) with 0.6 at.% lanthanum was prepared by the conventional mixed oxide method.
Abstract: Bismuth sodium titanate (Bi0.5Na0.5TiO3, BNT) with 0–6 at.% lanthanum was prepared by the conventional mixed oxide method. Each composition was calcined at 800–900°C for 2–5 h to form a pure perovskite phase. Green pellets were sintered at 1050–1150°C for 1–4 h to obtain dense ceramics with at least 95% of theoretical density. X–ray diffraction (XRD) showed phase distortion as lanthanum was added to this system. Meanwhile, a small amount of La was found to affect the grain size and had an influence on the poling conditions and electrical properties. The BNT–based composition with 1 at.% La doping provided a dielectric constant (K) of 560, a piezoelectric charge constant (d33) of 92 pC/N, and a hydrostatic piezoelectric coefficient (dh) of 72 pC/N.
405 citations
TL;DR: In this article, a steady state, CO-oxidation kinetics at 515 K have been measured on model, Pd catalysts, prepared by vapor deposition of Pd onto either zirconia, praseodymia, ceria, or a ceria-zirconica mixed oxide.
Abstract: Steady-state, CO-oxidation kinetics at 515 K have been measured on model, Pd catalysts, prepared by vapor deposition of Pd onto either zirconia, praseodymia, ceria, or a ceria-zirconia mixed oxide. A second rate process (RE2), associated with both the metal and the oxide support and observed previously on ceria-supported catalysts in excess CO [7], was also found for Pd supported on ceria-zirconia, but neither zirconia nor praseodymia had any effect on CO oxidation under the conditions of our study. For ceria and ceria-zirconia, deactivation, through the loss of RE2, caused by high-temperature calcination, was examined, with the Pd added after calcination so that the metal particle size was not a factor in deactivation. For ceria, there was a strong dependence on calcination temperature, with almost complete loss of RE2 above 1170 K. XRD showed that the loss was accompanied by a large increase in the crystallite size. Results for ceria-zirconia showed that the loss in this case was more gradual, with CO oxidation activity due to RE2 maintained to much higher calcination temperatures. Taking the importance of RE2 as a measure of the ability of the catalyst to use oxygen from the oxide, the implications of these results with respect to oxide structure and the effect of aging on oxygen-storage properties of reducible oxides are discussed.
144 citations
TL;DR: Mo-V-Nb-Te mixed metal oxides are highly active and selective for the ammoxidation of propane to acrylonitrile as discussed by the authors, and the efficiency of the catalyst is higher than that of V-Sb and Bi-Mo mixed metal oxide catalysts.
Abstract: Mo-V-Nb-Te mixed metal oxides are highly active and selective for the ammoxidation of propane to acrylonitrile. Acrylonitrile yield reaches nearly 50% by the optimizing reactor temperature and NH3/propane feed ratio. The efficiency of the catalyst is higher than that of V-Sb and Bi-Mo mixed metal oxide catalysts. In addition to a higher acrylonitrile yield, the required reaction temperature is also lower. X-ray diffraction pattern and Raman spectrum of Mo-V-Nb-Te catalysts are unique. There are at least two crystal phases (Phase-M1 and Phase-M2), participating the elementary steps of the ammoxidation of propane, in Mo-V-Nb-Tc mixed metal oxide catalysts. Propane, seems to be activated on Phase-M1 to form dehydrogenated species, which transfer to Phase-M2. And the dehydrogenated species seem to react with activated NH species to form acryronitrilc via ρ-arryl species on Phase-M2.
144 citations
TL;DR: In this paper, the depth concentration profile of the oxidized layers was measured by Rutherford Backscattering Spectrometry (RBS) and showed that at temperatures between 750 and 900°C, a two-layer structure was formed, consisting generally in a protective superficial layer of Al 2 O 3 with traces of Ti, followed by a titanium-rich zone.
Abstract: (Ti,Al)N coatings prepared by combined DC and RF magnetron sputtering were annealed in air at temperatures between 500 and 900°C, in order to obtain information regarding the oxidation behaviour. The depth concentration profile of the oxidized layers was measured by Rutherford Backscattering Spectrometry (RBS). During the heat treatment at 500°C, the Ti 0.35 Al 0.65 N coating forms a Ti and Al mixed oxide with about 10 at% of nitrogen. After the annealing at 600°C of Ti 0.62 Al 0.38 N and Ti 0.35 Al 0.65 N coatings, the nitrogen amount disappears and the oxide layer is still homogeneous. At temperatures between 750 and 900°C, a two-layer structure is formed, consisting generally in a protective superficial layer of Al 2 O 3 with traces of Ti, followed by a titanium-rich zone. The Ti 0.35 Al 0.65 N system showed a slightly higher oxidation resistance than the Ti 0.62 Al 0.38 N one. On the other hand, the Al-rich coating, Ti 0.19 Al 0.81 N, revealed the worst oxidation resistance, similar to the AlN coating, and the oxide layer is always homogeneous.
118 citations
TL;DR: In this paper, the structural and electrical properties of these aerogels are characterized after annealing using X-ray diffraction, Xray photoelectron spectroscopy, surface-area measurements, and impedance spectrographs.
Abstract: High-surface area RuO2−TiO2 is an important material for catalytic and power source technologies. To create this mixed oxide as a nanoscale, high-surface-area material, we have synthesized electrically conductive aerogels of RunTi1-nOx via sol−gel chemistry and supercritical drying of the resulting gel. The structural and electrical properties of these aerogels are characterized after annealing using X-ray diffraction, X-ray photoelectron spectroscopy, surface-area measurements, and impedance spectroscopy. Their properties are affected by the nature of the RuCl3 precursor and the initial sol-gel chemistry. Whereas bulk 32 mol % RuO2·TiO2 is an electronic conductor, a dominant ionic response is measured in the impedance of Ru0.32Ti0.68Ox aerogels. This impedance is ascribed to a proton conduction mechanism associated primarily with the hydrous surface of the RuOx component. The electrical conductivity of these Ru0.32Ti0.68Ox aerogels at 25 °C increases from 10-4 S cm-1 in ambient air to 10-2 S cm-1 under a...
104 citations
TL;DR: In this article, it was shown that the oxide layer can be activated through cathodic polarization, leading to an increase of the electrocatalytic activity for hydrogen evolution, and the ratio between the current density at a given electrode potential before and after completion of the activation process was used to quantify this activation phenomenon.
Abstract: Ruthenium, iridium, and mixed ruthenium/iridium oxide layers on titanium substrates have been obtained by thermal decomposition of chloride solutions. The decomposition temperature of RuO 2 and IrO 2 was varied from 300 to 500°C and from 400 to 500°C, respectively. That on the mixed Ru x Ir 1-x 0 2 layer was kept constant at 400°C. For the mixed oxide electrode, the Ru content was varied over the whole compositional range. Current-potential curves and cyclic voltammetry measurements were performed in 1 M H 2 SO 4 . It is shown that such oxide layers can be activated through cathodic polarization, leading to an increase of the electrocatalytic activity for hydrogen evolution. The ratio between the current density at a given electrode potential before and after completion of the activation process or the ratio between the exchange current density before and after the completion of the activation process was used to quantify this activation phenomenon. Values as high as 100 have been observed in some cases, but typical values are around ten. Through a series of specific measurements and comparison with data taken from the literature, it is shown that this activation phenomenon is not related to an increase of the electrochemically active surface area as determined through cyclic voltammetry measurements. An explanation is proposed whereby H-chemisorption within the oxide layer is ultimately responsible for the increase of the electrocatalytic activity of the oxide layer.
89 citations
TL;DR: In this article, it is found that the oxidation of polycrystalline SixGe1−x films with different compositions (i.e., different values of x) is carried out in pyrogenic steam at 800 °C for various lengths of time.
Abstract: The oxidation of polycrystalline SixGe1−x films with different compositions (i.e., different values of x) is carried out in pyrogenic steam at 800 °C for various lengths of time. It is found that the oxidation is enhanced by the presence of germanium and that the enhancement effect is more pronounced for the films richer in germanium. A mixed oxide in the form of either (Si,Ge)O2 or SiO2–GeO2 is found at the sample surface if the initial SixGe1−x contains more than 50% of germanium. However, a surface silicon cap layer of about 14 nm is found to have a significant impact on the oxidation of the Si0.5Ge0.5 films; it leads to the growth of about 115-nm-thick SiO2 which is about four times that of the SiO2 resulting from the oxidation of the cap layer itself. On the SixGe1−x films with only 30% of germanium, the SiO2 continues to grow after oxidation for 180 min resulting in 233-nm-thick SiO2 which is about 2.4 times greater than the SiO2 grown on 〈100〉 silicon substrates. Rejection of germanium results in p...
70 citations
TL;DR: In this paper, the thermal decomposition of a synthetic hydrotalcite-type (HT) sample [Mg0.71Al0.29(OH)2(CO3)0.145·mH2O] has been investigated by neutron diffraction using a programmed temperature control facility.
Abstract: The thermal decomposition of a synthetic hydrotalcite-type (HT) sample [Mg0.71Al0.29(OH)2(CO3)0.145·mH2O] has been investigated by neutron diffraction using a programmed temperature control facility. The evolution from HT phase to mixed oxide leading ultimately to the partial segregation of a spinel phase is reported. Structural modification ascribed to the interlayer water loss from the HT phase is accompanied by a reduction of the c-axis parameter and changes in the neutron powder pattern. The neutron diffraction patterns of five Mg/Ni/Al mixed oxides obtained from HT samples by calcination at 923 K were subjected to structural refinement by the Rietveld method. The model that best describes the refined data consists of a supercell with an a-axis twice that of the stoichiometric rock-salt type oxide, a certain degree of ordered cation vacancies in the octahedral sites, and partially occupied tetrahedral sites. Although the samples essentially show the typical patterns of a rock-salt type structure, the ...
65 citations
TL;DR: In this article, the authors developed a kinetic model to describe the oxidation behavior of Si1−xGex alloys during Ge segregation, which compares the Deal-Grove flux of oxidant diffusing through the oxide to the maximum flux of Si diffusing in the Ge-rich layer.
Abstract: We have developed a kinetic model to describe the oxidation behavior of Si1−xGex alloys during Ge segregation, which compares the Deal–Grove flux of oxidant diffusing through the oxide to the maximum flux of Si diffusing through the Ge-rich layer. This is motivated by thermal oxidation experiments on Si1−xGex alloys (x<0.17) using a fluorine-containing ambient (O2 and 200 ppm of NF3). The fluorine is known to modify point defect generation during oxidation of pure Si toward vacancy production, which is also the case for Ge in Si. We demonstrate that fluorinated oxidation of Si1−xGex enhances the oxidation rate by 25%–40% in the temperature range of 700–800 °C. Oxides formed at these temperatures were SiO2, while those formed at 600 °C exhibited a transition from SiO2 to mixed oxide growth at some point during the very early phase of oxidation, depending on the alloy composition. Consideration of these data suggests that other factors in addition to oxidation temperature must be considered in predicting wh...
58 citations
TL;DR: In this article, a new method to compare the oxygen buffering capacity (OBC) of catalysts showed that Ce−Tb mixed oxide presents an exceptional ability for attenuating fast oscillations of oxygen partial pressure.
52 citations
TL;DR: In this article, a solid electrolyte-based coulometric technique was used to obtain information concerning the extent of oxygen stoichiometry, thep-T-x diagram of any mixed oxide phase, the kinetics of the oxygen exchange and the phase transitions.
Abstract: The oxidation-reduction behaviour of transition metal and rare earth oxide systems in oxygen potential controlled atmospheres was investigated by means of a solid electrolyte-based coulometric technique (SEC) in carrier gas mode to obtain information concerning the extent of oxygen stoichiometry, thep-T-x diagram of any mixed oxide phase, the kinetics of the oxygen exchange and the phase transitions.
TL;DR: In this paper, the performance of hydrotalcite-type (HT) anionic clays was investigated in the selective catalytic reduction (SCR) of NO by NH3, either in the absence or presence of oxygen.
Abstract: Cu/Mg/Al mixed oxides (CuO = 4.0–12.5 wt%), obtained by calcination of hydrotalcite-type (HT) anionic clays, were investigated in the selective catalytic reduction (SCR) of NO by NH3, either in the absence or presence of oxygen, and their behaviours were compared with that of a CuO-supported catalyst (CuO = 10.0 wt%), prepared by incipient wetness impregnation of a Mg/Al mixed oxide also obtained by calcination of an HT precursor. XRD analysis, UV-visible-NIR diffuse reflectance spectra and temperature-programmed reduction analyses showed the formation, in the mixed oxide catalysts obtained from HT precursors, mainly of octahedrally coordinated Cu2+ ions, more strongly stabilized than Cu-containing species in the supported catalyst, although the latter showed a lower percentage of reduction. The presence of well dispersed Cu2+ ions improved the catalytic performances, although similar behaviours were observed for all catalysts in the absence of oxygen. On the contrary, when the mixture with excess oxygen was fed, very interesting catalytic performances were obtained for the catalyst richest in copper (CuO = 12.5 wt%). This catalyst exhibited a behaviour comparable to that of a commercial V2O5–WO3TiO2 catalyst, without any deactivation phenomena after four consecutive cycles and following 8 h of time-on-stream at 653 K. Decreasing the copper content or increasing the calcination time and temperature led to considerably poorer performances and catalytic behaviours similar to that of the CuO-supported catalyst, due to the side-reaction of NH3 combustion on the free Mg/Al mixed oxide surface.
TL;DR: In this article, the ammonia adsorption and oxidation on CuxMg0.710-xAl0.290 catalysts (x = 0.022, 0.046, and 0.072, as atomic ratio), obtained by calcination for 14 h at 923 K of hydrotalcite-type anionic clays precipitates, have been investigated and compared with those of the corresponding Mg 0.710Al 0.290 sample.
Abstract: Cu/Mg/Al catalysts obtained by controlled calcination of hydrotalcite-type (HT) anionic clays may be new interesting and cheap catalysts for the selective catalytic reduction (SCR) of NO by NH3. In this paper the ammonia adsorption and oxidation on CuxMg0.710-xAl0.290 catalysts (x = 0.022, 0.046, and 0.072, as atomic ratio), obtained by calcination for 14 h at 923 K of HT precipitates, have been investigated and compared with those of the corresponding Mg0.710Al0.290 sample. The presence of copper strongly increases the SCR activity and the selectivity to nitrogen in ammonia oxidation, while the Mg/Al catalyst did not show SCR activity in these conditions and formed significant amounts of nitrogen oxides by ammonia oxidation. All samples adsorbed coordinatively ammonia on medium-week Lewis acid sites, while no Bronsted acidity was found, showing that protonic acidity is not necessary for both SCR and ammonia oxidation. With an increase in the copper content, the ammonia gave rise by oxidation to adsorbed ...
TL;DR: In this paper, a new microporous sol-pillared clay was prepared by ion exchange of the interlayer Na+ ions of montmorillonite with SiO2−Fe2O3 mixed oxide sol particles.
Abstract: A new microporous sol-pillared clay was prepared by the ion-exchange of the interlayer Na+ ions of montmorillonite with SiO2−Fe2O3 mixed oxide sol particles. The mixed oxide sol solution was prepar...
TL;DR: In this article, a sheet-like hydrotalcite was synthesized with a width to thickness ratio in excess of 100 by using pseudoboehmite and a monocarboxylic acid.
TL;DR: In this article, Zirconium hydroxide, tin hyroxide and mixed hydroxides of tin and zirconsium (1:9) have been prepared, sulfated with a 0.1% sulfate concentration, at 873 K. The chemical composition of these solids has been characterized by chemical analysis, differential thermal analysis, X-ray photoelectron spectroscopy (XPS) and energy dispersive capabilities.
Abstract: Zirconium hydroxide, tin hydroxide and the mixed hydroxide of tin
and zirconium (1:9) have been prepared, sulfated with a 0.1
Maqueous H
2
SO
4
solution and
calcinated at 873 K. The chemical composition of these solids has been
characterized by chemical analysis, differential thermal analysis
(DTA), X-ray photoelectron spectroscopy (XPS) and energy dispersive
X-ray (EDX–) scanning transmission electron microscopy (STEM),
and their structural and textural properties have been studied by BET
surface area and XRD techniques. The nature of the acid sites
(Bronsted or Lewis) was characterized by in
situ IR study of pyridine adsorption and desorption and their
amount was found to depend on the sulfate content.
Catalytic properties have been studied for the isomerization
reaction of n-butane to isobutane, in the 423 to 523 K range
and for propan-2-ol conversion, in the 373 to 473 K range. Addition of
Sn to ZrO
2
(SnO
2
:ZrO
2
=1:9) led to a
solid solution and enhanced slightly (ca. 30%) the weak acid
features of ZrO
2
and removed the basic properties of pure
SnO
2
which was shown to convert propan-2-ol to acetone.
Upon sulfation of ZrO
2
,
SnO
2
–ZrO
2
[1:9] and SnO
2
, the
acidity of the oxides was sharply enhanced.
SO
4
2-
/SnO
2
, which was inactive for
the isomerization reaction, was only 60% less active than
SO
4
2-
/ZrO
2
for propan-2-ol
dehydration. This shows that sulfation of SnO
2
generates
acid sites of moderate strength. The presence of only 10% of
SnO
2
in ZrO
2
decreased the reaction rates per
SO
4
2-
by a factor of six for the initial
n-butane isomerization reaction and by a factor of seven for
the propan-2-ol dehydration to propene and diisopropyl ether. It is
suggested that the presence of Sn decreases the electron acceptor
properties of Zr and thus its acidity strength. Since the rate per
sulfated species of both reactions decreased in the same proportion,
one may consider that on SO
4
2-
/ZrO
2
and SO
4
2-
/SnO
2
–ZrO
2
samples there is no site of moderate strength able to dehydrate
propan-2-ol without isomerising n-butane.
TL;DR: In this article, it was shown that the encapsulated Pd exists in the form of metallic particles on the order of 10 nm in diameter held under a large (as much as 3.6 GPa) compressive stress by the mixed oxide.
Abstract: Redox aging above 1000°C of initially high-surface-area (of order 100 m2/g) cerium-rich ceria-zirconia mixed oxides containing a few wt% Pd results in the loss of most of the surface area and concomitant encapsulation of a substantial fraction of the Pd. The encapsulated Pd exists in the form of metallic particles on the order of 10 nm in diameter held under a large (as much as 3.6 GPa) compressive stress by the mixed oxide. This stress, evidently arising from changes in lattice parameter of the mixed oxide, induced by aging, produces a volume contraction of Pd, which appears as a shift of Pd-peak positions in XRD measurements. Subsequent reduction and reoxidation of the mixed oxide in turn relieves and restores the stress on the Pd particles, which remain metallic throughout, demonstrating that this portion of the Pd is effectively lost for catalytic purposes.
TL;DR: A series of ternary oxides of nominal composition Ru0.3Ti(0.7 − x)CexO2 was prepared by thermal decomposition on Ti supports and used as electrodes to study the effect of substituting Ce for Ti on the kinetics and electrocatalysis of the Cl2 evolution reaction as mentioned in this paper.
TL;DR: In this paper, a microemulsion mediated synthesis was developed to prepare fine powders of TiO2, ZrO2 and BaTiO3 in the size range between 10-40nm.
TL;DR: In this paper, the electrochemical properties of a new mixed oxide Fe0.11V2O5.16 as a Li intercalation compound are investigated in relation with structural characteristics.
TL;DR: In this article, the bulk and surface properties of a series of titanium-rich Al 2 O 3 -TiO 2 mixed oxides catalytic supports have been determined by different techniques (S BET, pore size distribution, XRD, DTA, FTIR, FT-Raman, UV-vis diffuse reflectance and FTIR of adsorbed pivalonitrile and pyridine).
TL;DR: In this article, it was shown that the chemical diffusion coefficient of the hydroxide ion through the mixed oxide has a marked temperature dependence; and Eyring-type graphs have two linear regions.
TL;DR: In this article, the reaction kinetics of the ODH of n-butane over vanadia supported on a heat-treated Mg/Al hydrotalcite (37.3 wt % of V2O5) was investigated by both linear and nonlinear regression techniques.
Abstract: The reaction kinetics of the oxidative dehydrogenation (ODH) of n-butane over vanadia supported on a heat-treated Mg/Al hydrotalcite (37.3 wt % of V2O5) was investigated by both linear and nonlinear regression techniques. A reaction network including the formation of butenes (1-, 2-cis-, and 2-trans-butene), butadiene, and carbon oxides by parallel and consecutive reactions, at low and high n-butane conversions, has been proposed. Langmuir−Hinshelwood (LH) models can be used as suitable models which allows reproduction of the global kinetic behavior, although differences between oxydehydrogenation and deep oxidation reactions have been observed. Thus, the formation of oxydehydrogenation products can be described by a LH equation considering a dissociative adsorption of oxygen while the formation of carbon oxides is described by a LH equation with a nondissociative adsorption of oxygen. Two different mechanisms operate on the catalyst: (i) a redox mechanism responsible of the formation of olefins and diol...
Patent•
20 Nov 1997
TL;DR: In this paper, a catalyst for oxidation reactions, particularly the oxidation of ammonia comprises oxides of (a) at least one element A selected from rare earths and yttrium, and (b) cobalt, said cobalt and element A being in such proportions that the element A to cobalt atomic ratio is in the range 0.8 to 1.2, with less than 25 % of the cobalt (by atoms) being present as free cobalt oxides.
Abstract: A catalyst for oxidation reactions, particularly the oxidation of ammonia comprises oxides of (a) at least one element A selected from rare earths and yttrium, and (b) cobalt, said cobalt and element A being in such proportions that the element A to cobalt atomic ratio is in the range 0.8 to 1.2, at least some of said cobalt and element A oxides being present as a mixed oxide phase with less than 25 % of the cobalt (by atoms) being present as free cobalt oxides. The catalyst may be supported on a secondary support in the form of an alkali-free alumina or lanthana wash coat on a primary support in the form of a mesh, gauze, pad, or monolith formed from a high temperature iron/aluminium alloy or a mesh, gauze, pad, monolith, or foam of a ceramic material.
TL;DR: In this paper, a mathematical model of oxidation of SixGe1−x alloys is presented, where the growth of SiO2 is simulated in conjunction with the determination of silicon distribution in SixGe 1−x using numerical methods.
Abstract: A mathematical model of oxidation of SixGe1−x alloys is presented. The growth of SiO2 is simulated in conjunction with the determination of silicon distribution in SixGe1−x using numerical methods. The main feature of the model is the assumption of simultaneous oxidation of germanium and silicon when exposing the SixGe1−x to an oxidizing atmosphere. In accordance with thermodynamics, the GeO2 formed is subsequently reduced by the (free) silicon available at the interface between the growing SiO2 and the remaining SixGe1−x through a reduction reaction. Thus, the enhanced oxidation of silicon in the presence of germanium is modeled as a result of the rapid oxidation of germanium followed by the quick reduction of GeO2 by silicon. The growth of a mixed oxide in the form of either (Si,Ge)O2 or SiO2–GeO2 only occurs when the supply of silicon to the SiO2/SixGe1−x interface is insufficient. A comparison is made between simulation and experiment for wet oxidation (in pyrogenic steam) of polycrystalline SixGe1−x ...
TL;DR: In this paper, the mixed oxide catalyst (Mn2O3 + SnO2) prepared by the coprecipitation method has been impregnated with Pd metal and it's catalytic behaviour for CO oxidation reaction has been investigated.
Abstract: The mixed oxide catalyst (Mn2O3 + SnO2) prepared by the coprecipitation method has been impregnated with Pd metal and it's catalytic behaviour for CO oxidation reaction has been investigated. In the coprecipitated material, Mn2O3 and SnO2 were found to crystallise at 875 K and 1175 K, respectively, which are significantly higher than the crystallisation temperatures of individual oxides prepared under similar conditions. Results of catalytic oxidation of CO, carried out using the pulse method for the mixed oxide system and the individual oxides, suggest significant synergistic effects between these two oxides. The impregnation of palladium metal facilitated CO oxidation and the catalyst Pd/(Mn2O3 + SnO2) was found to be quite effective for CO oxidation even at room temperature. Further, the CO disproportionation has been observed on palladium sites in the temperature range 350 to 400 K for the individual oxide systems.
Patent•
19 Jun 1997
TL;DR: In this article, a pyrogenic mixed oxide is used as the silicon and metal source to synthesize microporous and mesoporous metal silicates, which are then used as oxidation catalysts.
Abstract: Microporous and mesoporous metal silicates are prepared by the hydrothermal reaction of a silicon and metal source in the presence of a template. The choice of raw materials influences the purity and hence the catalytic activity of the products. A pyrogenic mixed oxide is used as the silicon and metal source. Prepared products have the composition (SiO2)1-x (Am On)x, where A is Ti, Al, B, V or Zr and x is 0.005 to 0.1. Shaped objects of the microporous and mesoporous metal silicates are obtained directly by using a shaped object of the pyrogenic mixed oxide. The products obtained are used as oxidation catalysts.
TL;DR: In this article, the electrochemical insertion of Mg into the mixture of mixed oxide was studied in regard to its possible use as a positive electrode in magnesium ion-transfer batteries.
Abstract: The electrochemical insertion of Mg
2+
into the
cation-deficient mixed oxide
Mn
2.15
Co
0.37
O
4
is studied in regard to
its possible use as a positive electrode in magnesium ion-transfer
batteries. The cation vacancies of the mixed oxide offer a pathway for
Mg
2+
insertion with a maximum uptake of 0.23 Mg per mole of
oxide. Voltammetric and chronopotentiometric measurements indicate a
single insertion step located near 2.9 V vs Li/Li
+
.
The strong polarizing effect of Mg
2+
ions induces a more
pronounced disordering process than for Li accommodation. This results in
a limited stable specific capacity of 30 A h kg
-1
when
discharge–charge cycles are performed at a C/6 rate within the
cycling limits 4.05–1.85 V vs. Li/Li
+
.
Patent•
08 Apr 1997TL;DR: A catalytic material effective for the reduction of NOx and the oxidation of at least carbon monoxide includes an oxygen storage component that provides superior oxygen storage function as mentioned in this paper, including an intimately combined mixed oxides including cerium, neodymium, and zirconium.
Abstract: A catalytic material effective for the reduction of NOx and the oxidation of at least carbon monoxide includes an oxygen storage component that provides superior oxygen storage function The oxygen storage component includes an intimately combined mixed oxides including cerium, neodymium and zirconium Typically, the ceria constitutes more than about 30 percent by weight of the ceria plus zirconia in the intimately combined mixed oxide, eg, from about 32 to 44 weight percent Preferably, the intimately combined mixed oxide also includes up to about 26 percent neodymia by weight of the ceria, eg, from 186 to 235 percent The intimately combined mixed oxide may be a co-formed material that may be prepared by, eg, co-precipitating compounds of zirconium and the rare earth metal and calcining the co-precipitate
TL;DR: In this article, the thermal decomposition of Ag2Ni(C2O4)2 · 2H20 in dynamic air and N2 flow has been studied and it is established that the atmosphere plays a significant role upon the nature of decomposition as well as the type of thermoproducts and their thermal stability.