共查询到20条相似文献,搜索用时 31 毫秒
1.
N. N. Sazonova L. T. Tsykoza A. V. Simakov G. B. Barannik Z. R. Ismagilov 《Reaction Kinetics and Catalysis Letters》1994,52(1):101-106
The performance of V2O5–TiO2 catalysts doped by WO3 and Nb2O5 in sulfur dioxide oxidation, and in selective catalytic reduction (SCR) of NO by ammonia has been studied. Addition of tungsten and niobium oxides was found to suppresses sulfur dioxide oxidation thus increasing the catalysts resistance to SO2 poisoning and their activity in SCR. 相似文献
2.
G. N. Pirogova N. M. Panich R. I. Korosteleva Yu. V. Tyurkin Yu. V. Voronin 《Russian Chemical Bulletin》1994,43(10):1634-1636
The catalytic activity of MIMII
2O3 spinel-type complex oxides (MI = Cu, Ni, Mn, Zn, Mg, Co, MII = Co, Cr, Al) in the oxidation of CO and ethylbenzene has been investigated. The Co-containing catalysts were more active than the Cr- and Al-containing catalysts. The nature of the cation influenced the catalytic activity. Higher activities were observed for the catalysts containing two transition elements. A correlation between the catalytic and adsorption properties was established.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1730–1732, October, 1994. 相似文献
3.
The Effect of Nb Loading on Catalytic Properties of Ni/Ce0.75Zr0.25O2 Catalyst for Methane Partial Oxidation
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Sitthiphong Pengpanich Vissanu Meeyoo Thirasak Rirksomboon Johannes Schwank 《天然气化学杂志》2007,16(3):227-234
In this study,the effect of Nb loading on the catalytic activity of Ce_(0.75)Zr_(0.25)O_2-supported Ni catalysts was studied for methane partial oxidation.The catalysts were characterized by BET,H_2 chemisorption,XRD,TPR,TEM and tested for methane partial oxidation to syngas in the temperature range of 400-800℃at atmospheric pressure.The results showed that the activity of methane partial oxidation on the catalysts was apparently dependent on Nb loading.It seemed that the addition of Nb lowered the catalytic activity for methane partial oxidation and increased the extent of carbon deposition. This might be due to the strong interaction between NiO and Nb-modified support and reduction of surface oxygen reducibility. 相似文献
4.
Aleksandra S. Ivanova Galina S. Litvak Vladimir V. Mokrinskii Lyudmila M. Plyasova Vladimir I. Zaikovskii Vasilii V. Kaichev Aleksandr S. Noskov 《Journal of molecular catalysis. A, Chemical》2009,310(1-2):101-112
Physicochemical and catalytic properties of compositions Fe(Ce)–Mn–O/support (gamma-, theta-, alpha-Al2O3, SiO2 as the support) and Pt/CeO2/theta-Al2O3 for oxidation of soot were characterized. It was established that the phase composition of the initial catalysts depended mainly on the nature of the active component and preparation conditions. Non-isothermal treatment of the soot–catalyst compositions at the temperature up to 1000 °C resulted in a change in the phase composition depending mainly on the final treatment temperature. The catalyst surface area was determined by the support nature. It was established that catalyst activities for oxidation of soot are determined by both catalyst nature and composition of gas mixture. The process of the soot oxidation is thought to involve oxygen from the catalyst surface. The higher proportion of weakly bound surface oxygen, the higher was the catalyst activity. An increase in the oxygen concentration from 5% O2/N2 to 15% O2/N2 is shown to lead to a decrease of the temperature of the soot oxidation. The influence of the oxygen concentration on the process of soot oxidation becomes weaker in the presence of water vapor. Results showed that the presence of NO in the gas mixture favors a decrease in the oxidation temperature of the soot, the higher being the nitrogen oxide concentration, the more pronounced effect. Introduction of SO2 in amount of 50 ppm in the gas mixture has no noticeable effect on the process of the soot oxidation. Among the catalysts under study, Fe–Mn–K–O/gamma-Al2O3 is most effective to oxidation of the soot at otherwise identical conditions. 相似文献
5.
Summary The adsorption of aromatic and aliphatic hydrocarbons was investigated using gas chromatography on Bi2O3, MoO3 and mixed Bi–Mo oxidation catalysts. As a measure of polarity of a catalyst, the difference between the chemical potential of aromatic and aliphatic hydrocarbons at the same surface concentration was used. The chemical potentials were estimated from elution chromatographic data. The data for C6–C9 methylbenzenes and C6–C12 n-alkanes were obtained in the temperature range 60–300°C in nitrogen as a carrier gas. Using air as carrier gas, introduction of water pulses on a catalyst does not change the elution characteristics. The elution of alkenes, alkynes, dienes and carbonyl compounds was disturbed by reaction of these compounds on the surface. The polarity of catalysts decreased in the order mixed Bi–Mo catalysts, MoO3, Bi2O3. The polarities observed are compared with polarities of some other solids and liquids and the role of polarity of the surface in catalytic oxidation reactions is briefly discussed. 相似文献
6.
Jong Rack Sohn Young Il Pae Man Young Park Sung Guk Jo 《Reaction Kinetics and Catalysis Letters》1995,55(2):325-332
For V2O5–ZrO2 catalysts, up to 10 mol% the crystalline structure of V2O5 was not observed, indicating a good dispersity the surface of ZrO2. V2O5–ZrO2 catalyst modified with H2SO4 exhibited much on higher catalytic activity for propene partial oxidation than unmodified catalysts due to the increased acidity and acid strength of modified catalyst. 相似文献
7.
V. V. Lesnyak V. K. Yatsimirskii T. D. Kinder O. Yu. Boldyreva 《Theoretical and Experimental Chemistry》2009,45(5):331-337
Catalysts prepared by the hydrogen reduction of Nb2O5 in the presence of Pt or Pd have specific surface much greater than for the starting oxide and their catalytic activity in
the oxidation of hydrogen is much greater than the activity of Pt/Al2O3 or Pd/Al2O3. X-ray phase analysis and X-ray photoelectron spectroscopy were used to establish the existence of Nb2O5–x
nonstoichiometric oxides in the catalyst, which enhances the catalytic activity of the surface. The kinetic behavior of the
oxidation of hydrogen on these catalysts is explained in the framework of the Eley–Riedel mechanism. 相似文献
8.
I. Atribak A. Bueno-Lpez A. García-García 《Journal of molecular catalysis. A, Chemical》2009,300(1-2):103-110
Ce1−xYxO2 and Ce0.85−xZr0.15YxO2 mixed oxides have been prepared by 1000 °C-nitrates calcination to ensure thermally stable catalysts. The physico-chemical properties of the mixed oxides have been studied by N2 adsorption at −196 °C, XPS, XRD, Raman spectroscopy and H2-TPR, and the catalytic activity for soot oxidation in air has been studied by TG in the loose and tight contact modes. Yttrium is accumulated at the surface of Ce1−xYxO2 and Ce0.85−xZr0.15YxO2, and this accumulation is more pronounced for the former formulation than for the latter, because the deformation of the lattice due to zirconium doping favours yttrium incorporation. Yttrium and zirconium exhibit opposite effects on the surface concentration of cerium; while zirconium promotes the formation of cerium-rich surfaces, yttrium hinders the accumulation of cerium on the surface. For experiments in tight contact between soot and catalyst, all the Ce1−xYxO2 catalysts are more active than bare CeO2, and Ce0.99Y0.01O2 is the most active catalyst. The benefit of yttrium doping in catalytic activity of ceria can be related to two facts: (i) the Y3+ surface enrichment hinders crystallite growth; (ii) the surface segregation of Y3+ promotes oxygen vacancies creation. High yttrium loading (x = 0.12) is less effective than low dosage (x = 0.01) because yttrium is mainly accumulated at the surface of the particles and hinders the participation of cerium in the soot oxidation reaction, which is the active component. For the mixed oxides with formulation Ce0.85−xZr0.15YxO2 (operating in tight contact) the effect of zirconium on the catalytic activity prevails with respect to that of yttrium. For experiments in loose contact between soot and catalyst, the catalytic activity depends on their BET surface area, and the catalysts Ce0.85−xZr0.15YxO2 (BET = 10–13 m2/g) are more active than the catalysts Ce1−xYxO2 (BET = 2–3 m2/g). In the loose contact mode, the yttrium doping and loading have a minor or null affect on the activity, and the stabilising effect of the BET area due to zirconium doping prevails. 相似文献
9.
G. N. Pirogova R. I. Korosteleva N. M. Panich T. A. Lagutina Yu. V. Voronin 《Russian Chemical Bulletin》1994,43(4):551-554
The catalytic activity of MIMIIO3] perovskite-type complex oxides (MI = La, Y, Nd, Yb; MII = Co, Mn, Ni) in the oxidation of CO, propylene, benzene, ethylbenzene,o-xylene, and ethyl acetate was investigated. The Co-containing catalysts were shown to be more active in the oxidation than the Mn-containing catalysts. A relationship between the catalytic and adsorption properties was established.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 602–605, April, 1994. 相似文献
10.
The preparation and catalytic activity of ferric oxide and its composite oxides supported gold catalysts for low-temperature CO oxidation were investigated detailedly, and characterized extensively by XRD, XPS, TPR, EC and XAFS techniques. It was found that containing highly dispersed Au of partially oxidized state, these nano-structured oxides supported Au/Fe2O3 and Au/NiFe2O4 catalysts had higher low-temperature activities. The possible catalytic active center is the gold of partially oxidized state (Auζ+). 相似文献
11.
Abbas Khaleel 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,346(1-3):130-137
Nanostructured iron–titanium mixed oxides with different Fe/Ti ratios were prepared by sol–gel methods under different preparative conditions. When equal molar amounts of Fe and Ti ions were employed, the product calcined at 500 °C showed an X-ray diffraction pattern that resembles Fe2Ti3O9. On the other hand, lower Fe/Ti ratios favored the formation of Fe2TiO5 while higher ratios resulted in free α-Fe2O3 and TiO2. Besides the effect of the Fe/Ti ratio, the composition of the final product was dependent on the preparative conditions and the calcination temperature. Enhancing the gelation process by heating or by employing an acid catalyst favored the formation of Fe2TiO5 at relatively low temperatures. Compared with the corresponding pure oxides, the prepared iron–titanium mixed oxides showed modified textural characteristics which were also dependent on the composition and the calcination temperature. The mixed oxides showed higher catalytic activity in the oxidation of methanol than their corresponding pure oxides with a noticeable enhanced oxidation potential forming methyl formate and carbon dioxide. 相似文献
12.
T. P. Maniecki K. Bawolak P. Mierczyński P. Kaczorowski W. K. Jóźwiak 《Kinetics and Catalysis》2011,52(5):711-715
The effect of the carrier on catalytic properties of ruthenium supported catalysts in partial oxidation of methane (POM) was
investigated. A variety of supports differed in texture and reducibility (Al2O3, SiO2, TiO2, Cr2O3, CeO2 and Fe2O3) were used. The catalyst activity is governed by ruthenium phase formation (RuO2 → Ru0), and it depends on redox properties of the support as well as support-ruthenium phase interaction. The activity of Ru supported
catalysts decreases in the order Al2O3 ≈ SiO2 > Cr2O3 > TiO2 > CeO2 > Fe2O3. No significant effects of the specific surface area and porosity of catalysts on the methane conversion and selectivity
of CO formation were found. The selectivity of CO2 formation (total oxidation of CH4) under conditions of POM (a ratio of CH4/O2 = 2) is associated with the contribution of reducible support oxides into the catalytic performance. 相似文献
13.
Ki Baek Kim Min Kyu Kim Yun Ha Kim Kwang Sup Song Eun Duck Park 《Research on Chemical Intermediates》2010,36(6-7):603-611
We prepared Pd catalysts supported on various metal oxides, viz. γ-Al2O3, α-Al2O3, SiO2–Al2O3, SiO2, CeO2 and TiO2 by an incipient wetness method and applied them to propane combustion. Several techniques: N2 physisorption, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), CO chemisorption, temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPO) were employed to characterize the catalysts. Pd/SiO2–Al2O3 showed the least catalytic activity at high temperatures among Pd catalysts supported on irreducible metal oxides, viz. SiO2, Al2O3 and SiO2–Al2O3. Pd/γ-Al2O3 was much superior for this reaction to Pd/α-Al2O3. The Pd catalyst supported on reducible metal oxides (CeO2 and TiO2) with a less specific surface area showed the higher catalytic activity compared with that supported on reducible metal oxides with a higher specific surface area, even though the former had a less Pd dispersion than the latter. In the case of Pd/SiO2–Al2O3, the initially reduced Pd catalyst was superior to the fully oxidized one. The oxidation of metallic Pd occurred in the presence of O2 with increasing reaction temperature, which resulted in the change in the catalytic activity. 相似文献
14.
V. K. Yatsimirskii E. V. Ishchenko N. A. Boldyreva N. N. Khomenko G. G. Tsapyuk 《Theoretical and Experimental Chemistry》2001,37(5):315-318
We have used thermal desorption to study the catalytic activity in CO oxidation and the state of the surface of an iron–cobalt oxide system. In the region of co-existence of the spinels CoFe2O4 and CoCo2O4, the activity and specific surface area are practically constant. We observe substantial deviation from additivity for the catalytic activity in the region of co-existence of the oxide Fe2O3 and the spinel CoFe2O4. We have established that chemisorption of CO on the surface of the oxides leads to formation of a number of stable forms of chemisorbed CO2, among which the least strongly bound 2 form is characteristic of the most active catalysts. 相似文献
15.
The catalytic properties of supported mono- and bimetallic catalysts of the Tc/support, M/support, and M-Tc/support types
(M=Pt, Pd, Rh, Ru, Ni, Re, Co; supports are γ-Al2O3, MgO, SiO2) were investigated in the acetone hydrogenation. The main products of this reaction are isopropyl alcohol and propane. The
catalytic activity in the acetone hydrogenation of the metals studied decreases in the consequence Pt>Tc≈Rh>Pd>Ru >Ni≈Re>Co
(with γ-Al2O3 as the support). The influence of support nature on the catalytic activity was investigated for the Rh−Tc system as an example.
A nonadditive increase in the catalytic activity of Rh−Tc/γ-Al2O3 in comparison with monometallic catalysts was found. The state of the surface of the catalysts was characterized by the UV-VIS
diffuse reflectance spectra.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 414–417, March, 1998. 相似文献
16.
ShaoBin Du Jin Wang HongYuan Zheng FuTai Ma 《Reaction Kinetics and Catalysis Letters》1993,51(2):415-421
A series of LaMn1–xNixO3 (x=0–1.0) catalysts with perovskite structure has been prepared. The relationship among composition, crystal structure, reducilibity and the catalytic activities for CO oxidation has been investigated. XRD showed that samples for x=0.0–0.4 and x=0.8–1.0 had rhombohedral symmetry, and then pseudo-cubic symmetry for x=0.5–0.8. Research by IR and TPR indicated there were interactions between Mn and Ni coexisting in the B site of LaMn1–xNixO3. The oxidation activities of the catalysts were also measured. 相似文献
17.
P.G.N. Mertens S.L.F. Corthals X. Ye H. Poelman P.A. Jacobs B.F. Sels I.F.J. Vankelecom D.E. De Vos 《Journal of molecular catalysis. A, Chemical》2009,313(1-2):14-21
Bimetallic gold–palladium clusters, with an average size of 1.9 nm and composed of 80 mol% gold, proved to be highly active and selective metal catalysts for the organic phase oxidation with O2 of aliphatic, allylic and benzylic alcohols to the corresponding carbonyl products. Polyvinylpyrrolidone stabilized gold–palladium clusters dispersed in N,N-dimethylformamide emerged as promising quasihomogeneous metal catalysts for the oxidation of benzyl alcohol to benzaldehyde with full selectivity; they could be efficiently recycled with unaffected catalytic performance by solvent-resistant nanofiltration. Highly active and durable heterogeneous catalysts for the amide phase or solvent-free alcohol oxidation were prepared by the quantitative immobilization of the optimized gold–palladium clusters on the high surface area basic BaAl2O4 spinel support with preservation of the bimetallic clusters’ nanodispersion. 相似文献
18.
不同RuO2含量对RuO2-Fe2O3催化剂氨选择性催化氧化性能的影响 总被引:1,自引:0,他引:1
不同RuO含量对RuO-FeO催化剂氨选择性催化氧化性能的影响 《燃料化学学报》2019,47(2):215-223
采用溶胶-凝胶法(sol-gel)制备了一系列具有不同RuO2含量的RuO2-Fe2O3催化剂,并将其应用于氨选择性催化氧化(NH3-SCO)研究中。结果表明,所有RuO2-Fe2O3催化剂都表现出较好的低温活性,且RuO2含量对催化剂的NH3催化氧化活性影响显著。此外,利用BET、XRD、H2-TPR和DRIFTS等表征手段研究了催化剂的物理化学性质和催化活性之间的关系。结果表明,RuO2的加入增大了催化剂的比表面积。RuO2与Fe2O3之间存在的协同效应提高了催化剂的氧化还原能力,从而提高了催化剂的氨氧化活性。同时,RuO2含量对催化剂表面酸性影响很大,且催化剂表面主要存在Lewis酸性位点。 相似文献
19.
N. Ya. Usachev I. A. Gorevaya E. P. Belanova A. V. Kazakov O. K. Atal"yan V. V. Kharlamov 《Russian Chemical Bulletin》2004,53(3):538-546
Selective oxidation of CO that is in mixtures enriched in H2 was studied to investigate catalytic properties of the 0.5—80% CuO/Ce0.7Zr0.3O2 system. The catalysts were prepared by the combined decomposition of copper, cerium, and zirconyl nitrates at 300 °C. The systems studied are active and stable under mild conditions of the process (80—160 °C) and at high space velocities (to 100000 h–1) of the reaction mixture (2% CO, 1% O2, 40—50% H2). With an increase in the CuO content in the catalysts up to 20%, the degree of CO removal achieves 60% (120 °C and V = 35000 h–1) and further does not change appreciably. The contribution of oxygen participation into CO oxidation is virtually independent of the copper concentration in the sample and ranges from 65 to 75%. The dependences of the Arrhenius equation parameters for CO and H2 oxidation on the catalyst composition were determined, which makes it possible to calculate the conversion of reactants and selectivity of CO conversion under the specified conditions of the process. The addition of CO2 and H2O (12—15%) to the reaction mixture decreases the catalyst activity and simultaneously increases the selectivity of CO oxidation to 100%. It is shown by the TPR and X-ray diffraction methods that the combined decomposition of the starting Cu2+, Ce3+, and ZrO2+ nitrates produces solid solutions of oxides with a high content of CuO. The reductive pre-treatment of fresh samples of the studied catalysts results in the destruction of the solid solution and formation of highly dispersed Cu particles on the surface of Ce—Zr—O. These particles are active in CO oxidation. 相似文献
20.
O. V. Udalova D. P. Shashkin M. D. Shibanova O. V. Krylov 《Kinetics and Catalysis》2005,46(4):535-544
The role of various components of a multiphase oxide catalytic system in the partial oxidation of propylene to acrolein is investigated. Catalytic activity is studied for the Co6–8Mo12Fe2–3Bi0.5–0.75Sb0.1K0.1Ox catalyst, which is taken to be the reference, and for catalysts in which the amount of some component is progressively reduced down to zero. The results obtained provide insights into the role of the components of the catalyst.CoMoO4 forms the structural framework of the catalyst. Iron molybdate can be stabilized on CoMoO4 as β-phase. As its content is increased, the catalyst gains activity but its selectivity declines. Bismuth molybdate is responsible for the selectivity of the process. When present in small amounts, MoO3 raises the selectivity, binds free oxides, and converts reduced molybdates into their oxidized forms. Excess molybdenum trioxide causes a dramatic fall in the catalytic activity. Potassium and antimony decrease the catalytic activity, but even small amounts of these elements raise the selectivity of the catalyst. Chromium can substitute for iron atoms in the multicomponent catalyst. Ni, Mn, and Mg substitute for Fe in iron molybdate to decrease the catalytic activity.__________Translated from Kinetika i Kataliz, Vol. 46, No. 4, 2005, pp. 569–579.Original Russian Text Copyright © 2005 by Udalova, Shashkin, Shibanova, Krylov. 相似文献