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1.
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
2.
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
3.
A. I. Gubanov E. M. Churakova S. D. Badmaev P. V. Sytnikov E. Yu. Filatov P. E. Plyusnin N. V. Kurat’eva V. A. Sobyanin S. V. Korneev 《Russian Journal of Applied Chemistry》2011,84(10):1677-1683
Precursor compounds [Co(NH3)6][Rh(NO2)6] and [Co(NH3)6][Co(NO2)6], solid solutions [Co(NH3)6] [Rh(NO2)6]1−x
[Co(NO2)6]
x
, and solid solutions Na3[Rh1−x
Co
x
(NO2)6] were synthesized and studied by IR spectroscopy and elemental, X-ray phase, X-ray diffraction, and thermogravimetric analyses.
X-ray phase analysis was employed to examine products of thermal decomposition of precursors in the atmospheres of hydrogen
and helium. Catalysts with a Co-Rh active system, supported by ZrO2, were prepared and tested in the reaction of steam conversion of ethanol. 相似文献
4.
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
5.
Li XiaoHong Dong JinLing Xiao HanShuang Lu PeiDong Hu YongAn Zhang YunHong 《中国科学B辑(英文版)》2008,51(2):128-137
The efflorescence and deliquescence processes of Mg(NO3)2 aerosol particles deposited on ZnSe substrate have been investigated through in situ Fourier transform infrared-attenuated total reflection (FTIR-ATR) technique at the molecular level. At relative humidity
(RH) of ∼3%, Mg(NO3)2 particles existed as amorphous states. The amorphous Mg(NO3)2 particles were transformed into crystalline Mg(NO3)2 · nH2O (n ≤ 5) with slight increasing of RH. Thermodynamically stable Mg(NO3)2·6H2O crystals were gradually formed on the particle surface and started to be dissolved at the saturation point (∼53% RH). At
the same time, a continuous phase transition from Mg(NO3)2 · nH2O (n≤5) to Mg(NO3)2·6H2O occurred on the particle surface. This led the solid particles to completely deliquesce at 76% RH, which was much higher
than the saturation point of 53% RH. In the efflorescence process, Mg(NO3)2 droplets entered into the supersaturated region due to the gradual evaporation of water. Finally, amorphous particles were
formed when RH decreased below 5%. In the FTIR-ATR spectra of the supersaturated Mg(NO3)2 droplets, the absorbance of the symmetric stretching vibration of NO
3
−
(v
1- NO
3
−
) clearly became stronger. It resulted from the continuous formation of solvent share ion pairs (SIPs), and even the contact
ion pairs (CIPs) between Mg2+ and NO
3
−
.
Supported by the Trans-Century Program Foundation for the Talents by the Ministry of Education of China, the National Natural
Science Foundation of China (Grant Nos. 20073004, 20473012, and 20673010), the 111 Project (B07012), and the State Key Laboratory
of Physical Chemistry for Solid Surface of Xiamen University 相似文献
6.
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
7.
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
8.
This work is focused on the role of gold and Al3CrO6 support for physicochemical properties, and catalytic activity of supported nickel catalysts in partial oxidation of methane
(POM). Catalysts, containing 5% Ni and 5% Ni-2% Au active phases dispersed on mono- (Al2O3, Cr2O3) and bi-oxide Al3CrO6 support, were investigated by TPR, BET and XRD methods, and the activity tests in POM reaction were carried out. Bimetallic
Ni-Au catalysts dispersed on Al3CrO6 support remained highly stable and active. The amorphous binary oxide Al3CrO6 can stabilize considerable amount of Cr4+, Cr5+, and Cr6+ species in Ni-Au/Al3CrO6 catalyst network during its calcination in the air. Nickel supported on binary oxide Ni/Al3CrO6 can form Ni(III)CrO3 bi-oxide phase in reductive conditions. During TPR H2 reduction of Ni-Au/Al3CrO6 catalyst chromium(II) oxide Cr(II)O phase is observed. After POM reaction the existence of bimetallic Au-Ni alloy was experimentally
confirmed on mono-oxide Al2O3 support surface, but its formation was not identified on bioxide Al3CrO6 support.
Published in Russian in Kinetika i Kataliz, 2009, Vol. 50, No. 1, pp. 149–156.
The article is published in the original.
Based on a report at the VII Russ. Conf. on Mechanisms of Catalytic Reactions (with international participation), St. Petersburg,
July 2–8, 2006. 相似文献
9.
S. -X. Wang Z. -C. Tan Y. -S. Li L. -X. Sun Y. Li 《Journal of Thermal Analysis and Calorimetry》2008,92(2):483-487
Synthesis, characterization and thermal analysis of polyaniline (PANI)/ZrO2 composite and PANI was reported in our early work. In this present, the kinetic analysis of decomposition process for these
two materials was performed under non-isothermal conditions. The activation energies were calculated through Friedman and
Ozawa-Flynn-Wall methods, and the possible kinetic model functions have been estimated through the multiple linear regression
method. The results show that the kinetic models for the decomposition process of PANI/ZrO2 composite and PANI are all D3, and the corresponding function is ƒ(α)=1.5(1−α)2/3[1−(1-α)1/3]−1. The correlated kinetic parameters are E
a=112.7±9.2 kJ mol−1, lnA=13.9 and E
a=81.8±5.6 kJ mol−1, lnA=8.8 for PANI/ZrO2 composite and PANI, respectively. 相似文献
10.
The adsorption of NO, NO/O2 mixtures and NO2 on pure ZrO2 and on two series of catalysts supported on ZrO2, one containing vanadia and the other molybdena (ZV and ZMo, respectively), has been investigated. The V and Mo surface contents
of the latter were ≤3 atoms nm−2 and ≤5 atoms nm−2, respectively. All samples had been previously submitted to a standard oxidation treatment.
On all samples, only extremely minor amounts of NOx surface species are formed by NO interaction at room temperature (RT). NOx surface species are formed in greater amounts on pure ZrO2 when NO and O2 are coadsorbed at RT; they are mainly nitrites, small amounts of nitrates, and small amounts of (O2NO−H)δ− species; when ZrO2 is warmed to 623 K in the NO/O2 mixture, nitrites decrease, nitrates and (O2NO−H)δ− species increase. The same NOx species as on the ZrO2 surface free from V (or Mo) are formed on ZV (or ZMo) samples with surface V (or Mo) density <1.5 atoms nm−2; however, they occur in decreased amount with increasing V (or Mo) coverage. On ZV samples with a surface V density of 1.5–3
atoms nm−2 (or ZMo samples with a surface Mo density of 1.5–5 atoms nm−2) when NO and O2 are coadsorbed at RT, there is formation of small amounts of nitrites, nitrates (both on ZrO2 surface free from V (or Mo) and at the edges of V- or Mo-polyoxoanions) and NO2
δ+ species, associated with V5+ (or Mo6+) of very strong Lewis acidity; when samples are warmed up 623 K in the NO/O2 mixture, nitrites disappear, nitrates increase, NO2
δ+ species remain constant or slightly decrease. When NO2 is allowed into contact at RT with oxidized samples, surface situations almost identical to those obtained for each sample
warmed to 623 K in NO/O2 mixture is reached. The NOx surface species stable at 623 K, the temperature at which catalysts show the best performance in the selective catalytic
reduction (SCR) of NO by NH3, are nitrates, both on ZrO2 and on polyvanadates or polymolybdates at high nuclearity. On the contrary, nitrites and NO2
δ+ species are unstable at 623 K. 相似文献
11.
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
12.
R. Amadelli A. De Battisti L. Doubova A. B. Velichenko 《Russian Journal of Electrochemistry》2008,44(1):131-137
An electrochemical kinetic investigation of nitrite oxidation to nitrate on RuO2 is discussed. The process is studied by cyclic voltammetry, steady-state measurements and potential step measurements. The
overall oxidation reaction is a two-electron process where the first step involves a reversible charge transfer: NO2− ⇔ NO2 + e− The one-electron oxidation of nitrite yields adsorbed NO2 which is further oxidized to adsorbed (NO2)+ and subsequently desorbed via a chemical reaction. In the general case, fit of experimental data is obtained with adsorption
described by a Temkin isotherm unless the electrode is pre-treated at a cathodic potential where the (NO2)ads is removed. This treatment lowers the degree of coverage by intermediates but not the nature of the slow step.
Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 1, pp. 142–149.
The text was submitted by the authors in English. 相似文献
13.
Xiaohuin Liu Yong Guo Wenjie Xu Yanqin Wang Xueqing Gong Yanglong Guo Yun Guo Guanzhong Lu 《Kinetics and Catalysis》2011,52(6):817-822
The influence of the alumina support on the catalytic activity of Pt/Al2O3 catalysts in aqueous phase reforming of ethylene glycol to hydrogen was studied. The catalysts were prepared by impregnation
of γ-, δ-, and α-alumina with H2PtCl6. The highest rate of hydrogen production (452 μmol min−1 g−1) obtained with the Pt/α-Al2O3 catalyst can be related to the highest extent of dispersion of Pt on α-Al2O3. XPS, TEM-EDX and TPR-H2 measurements showed the absence of chloride-containing surface complexes in the Pt/α-Al2O3 catalyst. However, chloride-containing entities were found on the surface of Pt/γ-Al2O3 and Pr/δ-Al2O3 catalysts. When chloride ions are removed chlorinated Pt species facilitate the sintering of Pt crystallites and in this
way affect the extent of Pt dispersion. Moreover, depending upon the particular crystalline form, alumina atoms have different
coordination and alumina surfaces contain varying amounts of OH groups of different nature which affect the interaction between
Pt and the support. 相似文献
14.
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).
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 4, pp. 237–241, July–August, 2007. 相似文献
15.
The reaction of 3,6-di-(3-methyl-pyridin-2-yI)-s-tetrazine (DMPTZ, II) with CeIII salt [Ce(NO3)3 · 6H2O] generates a new ligand, N-(3-methyl-pyridin-2-yl)-formimidoyl-(3-methyl-pyridin-2-yl) hydrazone (L), and forms a new complex:
a mononuclear complex [Ce(L)(NO3)2 (H2O)3] · NO3 (III). Crystal data for III: space group P-1, with a = 0.7133(4) nm, b = 1.1139(2) nm, c = 1.4572(3) nm, α= 102.13(2)°, β=
99.81(3)°, γ= 91.10(3)°, Z = 2, V = 1113.6(7) nm3, μ = 2.123 mm−1 and F(000) = 630. L acts as a tri-dentate chelating ligand in III. There are 10 coordination sites around Ce3+ of III, which are respectively occupied by seven oxygen atoms (four from two nitrate anions and three from three H2O molecules) and three nitrogen atoms (all from L). The cerium atom and three chelating nitrogen atoms are coplanar. The mechanism
of the metal assisted decomposition is discussed briefly. 相似文献
16.
M. M. Godneva D. L. Motov M. P. Rys’kina 《Russian Journal of Inorganic Chemistry》2011,56(9):1363-1369
The ZrO(NO3)2-H3PO4-CsF-H2O system was studied at 20°C along the section at a molar ratio of PO43−/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO2 concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated
for the first time: crystalline fluorophosphates CsZrF2PO4 · H2O, amorphous oxofluorophosphate Cs2Zr3O2F4(PO4)2 · 3H2O, and amorphous oxofluorophosphate nitrate CsZr3O1.25F4(PO4)2(NO3)0.5 · 4.5H2O. The compound Cs3Zr3O1.5F6(PO4)2 · 3H2O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following
new compounds was established: Cs2Zr3O1.5F5(PO4)2 · 2H2O, Cs2Zr3F2(PO4)4 · 4.5H2O, and Zr3O4(PO4)1.33 · 6H2O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical,
thermal, and IR spectroscopic analyses. 相似文献
17.
研究了不同载体负载的Pt-Ni双金属和单金属催化剂上乙醇重整和1,3-丁二烯加氢反应性能, 以考察氧化物载体对双金属结构和催化活性的影响. 所用的氧化物载体包括γ-Al2O3, SiO2, TiO2, CeO2以及高比表面积(HSA)和低比表面积(LSA)ZrO2. 采用共浸渍法制备催化剂, 用CO化学吸附、透射电镜和扩展X射线吸收精细结构光谱进行催化剂表征, 采用傅里叶变换红外间歇反应器进行化学反应评价. 对于乙醇重整反应, Pt-Ni双金属催化剂优于单金属催化剂, Pt-Ni双金属催化剂活性顺序为TiO2 > SiO2 > γ-Al2O3 ≈ LSA-ZrO2 > CeO2 > HSA-ZrO2. 对于1,3-丁二烯加氢反应, 在SiO2, TiO2和HSA-ZrO2载体上双金属催化剂优于单金属催化剂, Pt-Ni双金属催化剂活性顺序为SiO2 > CeO2 > γ-Al2O3 > LSA-ZrO2 > HSA-ZrO2 ≈ TiO2. 相似文献
18.
The present work presents an alternative approach to ethanol production from sweet sorghum: without detoxification, acid-impregnated
fresh sweet sorghum stem which contains soluble (glucose and sucrose) and insoluble carbohydrates (cellulose and hemicellulose)
was steam pretreated under mild temperature of 100 °C. Simultaneous saccharification and fermentation experiments were performed
on the pretreated slurries using Saccharomyces cerevisiae. Experimentally, ground fresh sweet sorghum stem was combined with H2SO3 at dosages of 0.25, 0.50, and 0.75 g/g dry matter (DM) and steam pretreated by varying the residence time (60, 120, or 240 min).
According to enzymatic hydrolysis results and ethanol yields, H2SO3 was a powerful and mild acid for improving enzymatic digestibility of sorghum stem. At a solid loading of 10% (w/v) and acid dosage of 0.25 g/g DM H2SO3 at 100 °C for 120 min, 44.5 g/L ethanol was obtained after 48 ± 4 h of simultaneous saccharification and fermentation. This
corresponded to an overall ethanol yield of 110% of the theoretical one, based on the soluble carbohydrates in the fresh sweet
sorghum stem. The concentrations of hydroxymethylfurfural and furfural of the sulfurous acid pretreated samples were below
0.4 g/L. Ethanol would not inhibit the cellulase activity, at least under the concentration of 34 g/L. 相似文献
19.
K. Opoku-Gyamfi Zahra M. Tafreshi A. A. Adesina 《Reaction Kinetics and Catalysis Letters》1998,64(2):229-238
The methane oxidation activities of Pt−NiO and Co−NiO bimetallic catalysts have been investigated as part of a larger research
program on the autothermal reforming of methane (combined methane oxidation and steam reforming) in a fluidized bed reactor.
Experiments at atmospheric pressure and 783–1023 K for both catalysts showed that the reaction was more selective towards
H2 production at CH4∶O2 ratios greater than unity. Light-off temperature increased with decreasing CH4∶O2 ratios, but increase in gas velocity (beyond minimum fluidization) increased the light-off temperature. Co−NiO was as promising
as the more expensive Pt−NiO catalyst for the oxidation. 相似文献
20.
Polymorphism and thermal decomposition of [Mg(DMSO)6](NO3)2, where DMSO =(CH3)2SO, were studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). The gaseous products of the decomposition
were on-line identified by a quadruple mass spectrometer (QMS). Three phase transitions have been detected for this compound
in the temperature range of 95–370 K between the following solid phases: stable KIb↔stable KIa at T
C3=195 K, metastable KII↔supercooled K0 at T
C2=230 K and stable KIa→stable K0 at T
C1=337 K.
Thermal decomposition of the title compound proceeds in three main stages. In the first stage, which starts just above ca.
380 K, and is continued up to ca. 540 K, the compound loses in two steps four DMSO molecules per one formula unit and undergoes
into [Mg(DMSO)2](NO3)2. The second stage starts just immediately after liberating four DMSO ligands and is connected with the decomposition of [Mg(DMSO)2](NO3)2 and the formation of a mixture of solid anhydrous magnesium sulfate, magnesium nitrate and magnesium oxide and also a mixture
of gaseous products of the DMSO and Mg(NO3)2 decomposition. The third and the last stage corresponds to the decomposition of not decomposed yet magnesium nitrate and
formation of magnesium oxide, nitrogen oxides and oxygen. 相似文献