共查询到20条相似文献,搜索用时 210 毫秒
1.
E. M. Churakova S. D. Badmaev P. V. Snytnikov A. I. Gubanov E. Yu. Filatov P. E. Plyusnin V. D. Belyaev S. V. Korenev V. A. Sobyanin 《Kinetics and Catalysis》2010,51(6):893-897
The properties of supported bimetallic Rh-Co/ZrO2 catalysts in ethanol steam reforming into hydrogen-containing gas were studied. The particles of Rh-Co solid solutions on
the catalyst surface were prepared by the thermal decomposition of the double complex salt [Co(NH3)6][Rh(NO2)6] and the solid solution Na3[RhCo(NO2)6]. It was found that the bimetallic Rh-Co/ZrO2 catalysts exhibited high activity in the reaction of ethanol steam reforming. The equilibrium composition of reaction products
was attained at 500–700°C and a reaction mixture space velocity of 10000 h−1. 相似文献
2.
P. V. Snytnikov A. I. Stadnichenko G. L. Semin V. D. Belyaev A. I. Boronin V. A. Sobyanin 《Kinetics and Catalysis》2007,48(3):439-447
A series of copper-cerium oxide catalysts were prepared, and their properties toward the reaction of CO oxidation in hydrogen-containing gas mixtures were studied. It was found that the copper-cerium oxide catalysts are stable, active, and selective in this reaction. The conditions under which these catalysts decreased the concentration of CO from 1 to <10?3 vol % in hydrogen containing water vapor and carbon dioxide were determined. 相似文献
3.
Rengui Li Yixuan Yang Dr. Na Sun Dr. Long Kuai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15586-15593
Development of Pt group metal-free catalysts for low-temperature CO oxidation remains critical. In this work, active and stable mesoporous Cu-Ce-Ox solid solutions are prepared by using spray pyrolysis. The specific surface areas and pore volumes reach as high as 170 m2 g−1 and 0.24 cm3 g−1, respectively. The results of CO oxidation study suggest that (1) the catalyst obtained by spray pyrolysis possesses much higher activity than those made by co-precipitation, sol-gel, and hydrothermal methods; (2) the optimal Cu0.2-Ce0.8-Ox solid solution presents a reactivity over 28 times that of both single-component CuO and CeO2 at 70 °C. Based on the study of pure-phase Cu-Ce-Ox solid solutions by selective leaching of segregated CuOx species, the active center for CO oxidation is confirmed as the bimetallic Cu-Ce-O site, whereas the individual CuOx particles not only act as spectators but also block the active Cu-Ce-O sites. A low apparent activation energy of approximately 48 kJ mol−1 is detected for CO oxidation at the Cu-Ce-O site, making Cu-Ce-Ox solid solutions able to present high activity at low temperature. Furthermore, the Cu-Ce-Ox catalysts exhibit excellent stability and thermal tolerance toward CO oxidation. 相似文献
4.
《Journal of Molecular Catalysis #》1992,71(2):215-232
Magnesia-supported catalysts were prepared from [Os3(CO)12], [H3Re3(CO)12], a combination of the two, and [H3ReOs3(CO)13]. The catalysts were tested for hydrogenation of CO in a flow reactor, the surface structures were characterized by infrared spectroscopy and wet chemical extraction (cation metathesis), and the used catalysts were investigated with transmission electron microscopy and energy dispersive X-ray spectroscopy. The catalysts all lost activity during operation; the catalyst made from the triosmium cluster lost activity as a result of being converted into the inactive [OS10C(CO)24]2−, as observed previously. The catalyst made from the bimetallic cluster lost activity less rapidly than the others, and the IR spectra indicate that formation of the decaosmium cluster had been prevented by Re, which was present near the Os particles in the used catalyst. In contrast, when [Os3(CO)12] and [H3Re3(CO)12] were used in combination, the formation Of [Os10C(CO)24]2− took place, the deactivation was relatively rapid, and there was negligible Re in the immediate neighborhood of the Os particles. Evidently, Re remote from the Os exerted no stabilizing effect. These results indicate an advantage of having the two metals initially bonded to each other in the catalyst precursor. 相似文献
5.
M. M. Zyryanova P. V. Snytnikov Yu. I. Amosov S. A. Ven’yaminov E. Z. Golosman V. A. Sobyanin 《Kinetics and Catalysis》2010,51(6):907-913
The screening of commercial nickel catalysts for methanation and a series of nickel catalysts supported on CeO2, γ-Al2O3, and ZrO2 in the reaction of selective CO methanation in the presence of CO2 in hydrogen-containing mixtures (1.5 vol % CO, 20 vol % CO2, 10 vol % H2O, and the balance H2) was performed at the flow rate WHSV = 26000 cm3 (g Cat)−1 h−1. It was found that commercial catalytic systems like NKM-2A and NKM-4A (NIAP-07-02) were insufficiently effective for the
selective removal of CO to a level of <100 ppm. The most promising catalyst is 2 wt % Ni/CeO2. This catalyst decreased the concentration of CO from 1.5 vol % to 100 ppm in the presence of 20 vol % CO2 in the temperature range of 280–360°C at a selectivity of >40%, and it retained its activity even after contact with air.
The minimum outlet CO concentration of 10 ppm at 80% selectivity on a 2 wt % Ni/CeO2 catalyst was reached at a temperature of 300°C. 相似文献
6.
János Raskó ákos Koós Kornélia Baán János Kiss 《Reaction Kinetics and Catalysis Letters》2007,90(1):187-195
On X-ray photoelectron spectra of the Au-Rh/TiO2 catalysts the position of Au4f peak was practically unaffected by the presence of rhodium, the peak position of Rh3d, however,
shifted to lower binding energy with the increase of gold content of the catalysts. Rh enrichment in the outer layers of the
bimetallic crystallites was experienced. The bands due to Au0-CO, Rh0-CO and (Rh0)2-CO were observed on the IR spectra of bimetallic samples, no signs for Rh+-(CO)2 were detected on these catalysts. The results were interpreted by electron donation from titania through gold to rhodium
and by the higher particle size of bimetallic crystallites. 相似文献
7.
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
8.
Odysseas Paschos Alexander N. Simonov Alesya N. Bobrovskaya Moritz Hantel Matthias Rzepka Petra Dotzauer Anton N. Popov Pavel A. Simonov Valentin N. Parmon Ulrich Stimming 《Electrochemistry communications》2010,12(11):1490-1492
The electrocatalytic activity of bimetallic BiPd catalysts supported on Sibunit carbon towards hydrogen oxidation/evolution reactions (HOR/HER) was studied in a gas diffusion electrode (GDE) setup. Catalysts were synthesized by deposition of Pd on the carbon support, followed by impregnation of Pd/C precursor with Bi(NO3)3 solution and reduction in hydrogen. Transmission electron microscopy and local EDX elemental analysis revealed that BiPd/C catalysts contain bimetallic particles with narrow size distribution with maxima at 3.2–4.1 nm. X-ray diffraction evidenced that bimetallic particles are constituted by Pd–Bi solid solution. It was shown that modification of Pd/C by bismuth increases the specific activity of palladium towards HOR/HER by a factor of 3. 相似文献
9.
Investigations on Metal Catalysts. XXXII. On Alloying and Dispersion of Nickel-Rhenium Catalysts Unsupported Ni? Re catalysts were prepared by reduction of mixtures from NiO and NH4ReO4 at 400°C with hydrogen (1st series), followed by a heat treatment at 650°C in flowing hydrogen (2nd series). The bimetallic powders were characterized by DTA investigations, X-ray measurements, N2 adsorption, and CO chemisorption. The degree of alloying and the changes in dispersion as a result of adding a second metal to a basic one is discussed. 相似文献
10.
Metal-organic frameworks(MOFs) as a type of crystalline heterogeneous catalysts have shown potential application in photocatalytic CO2 reduction.However,MOF catalysts with high efficiency and selectivity are still in pursuit.Herein,by a bimetallic strategy,the catalytic performance of a Co-MOF for photocatalytic CO2 reduction was enhanced.Specifically,the Co-MOF based on 4,5-dicarboxylic acid(H3 IDC) and4,4’-bipydine(4,4’-bpy) can catalyze CO2 reductio... 相似文献
11.
E. Yu. Filatov S. A. Novopashin S. V. Korenev 《Russian Journal of Inorganic Chemistry》2013,58(1):78-83
Nanoparticle ensembles in Co-Pt and Fe-Pt systems embedded in a carbon matrix are prepared by a plasma-arc method. Two-phase samples based on disordered FCC solid solutions are prepared in both systems. In the Co-Pt system, the solid solujtions are mixed within one ensemble; in the Fe-Pt system, they are spatially separated. A magnetization hysteresis curve from Co-Pt nanoparticles (3–12 nm) fully coincides with a magnetization curve from a single-phase disordered solid solution Co0.50Pt0.50 (7–9 nm) prepared at 325°C by thermolysis of the precursor double complex salt (DCS). Metal ratios, solid solution structures, and particle sizes being the same, the magnetic response is dictated exclusively by the amount of a magnetic phase of mixed and interacting particles and is independent of the distribution of the magnetic phase over the solid solution phases. 相似文献
12.
P. V. Markov G. O. Bragina G. N. Baeva O. P. Tkachenko I. S. Mashkovskii I. A. Yakushev M. N. Vargaftik A. Yu. Stakheev 《Kinetics and Catalysis》2016,57(5):617-624
The formation of Pd–In catalysts synthesized from the heteronuclear acetate complex PdIn(CH3COO)5 was studied by temperature-programmed reduction, electron microscopy, IR spectroscopy of adsorbed CO and hydrogen temperature-programmed desorption (H2-TPD). IR spectroscopy of adsorbed CO and H2-TPD confirmed the formation of bimetallic Pd–In nanoparticles. It was found that the Pd–In nanoparticle surface contains predominantly Pd atoms separated from one another by indium atoms, which is evidenced by the disappearance of the CO band shift resulting from the lateral dipole–dipole interaction between adsorbed CO molecules and by a significant decrease in the band intensity of CO adsorbed in bridged form. Almost complete inhibition of palladium hydride (PdHx) provides additional evidence of the formation of Pd–In bimetallic particles. 相似文献
13.
Brenda L. García Burjor Captain Richard D. Adams Ana B. Hungria Paul A. Midgley Sir John Meurig Thomas John W. Weidner 《Journal of Cluster Science》2007,18(1):121-130
The cluster complex Pt2Ru4(CO)18 was used as a precursor to prepare a 60 wt% 1:2 Pt:Ru nanoparticles on carbon (PtRu/C) for use as an electrocatalyst for
methanol oxidation. This bimetallic carbonyl cluster complex was found to provide smaller, more uniform bimetallic nanoparticle
that exhibited higher electrocatalytic activity than a 60 wt% 1:1 Pt:Ru commercial catalyst from E-Tek. Using bimetallic cluster
precursors simplifies the synthetic procedures by reducing the need for high temperature reduction and assures a more intimate
mixing of the two different metals. Transmission electron microscopy (TEM) images of the catalyst obtained from the cluster
precursor showed bimetallic nanoparticles having a narrow size range of 2–3 nm that were dispersed uniformly over the surface
of the support. Images of the commercial catalyst showed particles 3–4 nm in diameter that tended to agglomerate near the
edges of the carbon support particles. Cyclic voltammograms of methanol oxidation from the two catalysts showed significantly
higher activity for the cluster-derived catalyst. The onset potential for methanol oxidation for the cluster-derived catalyst
was approximately 170 mV lower than that of the commercial catalyst at 100 A/g Pt, and approximately 250 mV lower at 400 A/g
Pt.
* This report is dedicated to Prof. Günter Schmid on the occasion of his 70th birthday. 相似文献
14.
V. Yu. Borovkov S. P. Kolesnikov V. I. Koval’chuk J. L. d’Itri 《Russian Chemical Bulletin》2007,56(5):863-869
Adsorption of 13C18O+12C16O mixtures on the Pt(2.9%)/γ-Al2O3, (Pt(2.6%)+Cu(2.7%))/γ-Al2O3, and (Pt(2.6%)+Cu(5.1%))/γ-Al2O3 catalysts was studied by FTIR spectroscopy. On the metallic Pt surface at coverages close to saturation, CO is adsorbed both
strongly and weakly to form linear species for which the vibrational frequencies of the isolated 13C18O molecules adsorbed on Pt are ∼1940 and ∼1970 cm−1, respectively. The redistribution of intensities of the high-and low-frequency absorption bands in the spectra of adsorbed
13C18O indicates that these linear forms are present on the adjacent metal sites. The weak adsorption is responsible for the fast
isotope exchange between the gaseous CO and CO molecules adsorbed on metal. The Pt-Cu alloys, in which the electronic state
of the surface Pt atoms characteristic of monometallic Pt remains unchanged, are formed on the surface of the reduced Pt-Cu
bimetallic catalysts. The decrease in the vibrational frequencies of the isolated C=O bonds in the isolated Pt-CO complexes
suggests that the CO molecules adsorbed on the Cu atoms affect the electronic properties of Pt.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 831–836, May, 2007. 相似文献
15.
Ahmed K. Aboul‐Gheit Sohair M. Abdel‐Hamid Sameh M. Aboul‐Fotouh Noha A. K. Aboul‐Gheit 《中国化学会会志》2006,53(4):793-802
The hydroconversion of cyclohexene (CHE) using monometallic catalysts containing 0.35wt% of Pt, Pd, Ir or Re on a γ‐alumina support, as well as bimetallic catalysts containing combinations of 0.35wt% Pt with 0.35wt% of either Pd, Ir or Re on γ‐alumina, were investigated in a plug flow‐type fixed‐bed reactor. The Cyclohexene (CHE) feed was injected continuously with a rate of 8.33 × 10?3mole h?1 on 0.2 g of catalyst using a simultaneous hydrogen gas flow of 20 cm3 min?1 throughout a broad reaction temperature range of 50–400 °C. The dispersion of the metals in the catalysts was determined via H2 or CO chemisorption. The activities of the monometallic catalysts were found to be in the order: Pd > Pt > Ir > Re, whereas those of the bimetallic catalysts were in the order: PtPd > PtIr > PtRe. Cyclohexene hydrogenation and dehydrogenation reactions using the current mono‐ and bimetallic catalysts were kinetically investigated applying the absolute reaction rate theory, whereby reaction rate constant, activation energy, enthalpy and entropy of activation were computed to explain surface variations on these catalysts. 相似文献
16.
T. F. Sheshko Yu. M. Serov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(1):51-54
The reaction of the hydrogenation of a mixture of carbon oxides on ultradisperse powder (UDP) catalysts containing Fe and
Ni nanoparticles and their bimetallic mechanical mixtures was investigated. It was established that the main reaction product
on UDP Ni is methane, while the main products on the bimetallic systems are methane and ethylene. A synergetic effect was
observed on the bimetallic catalyst under investigation. It was revealed that the hydrogenation of a mixture of carbon oxides
proceeds through the stage of dissociative adsorption of both components, CO and CO2. The olefin selectivity of the process was explained by the participation of different forms of adsorbed hydrogen (HI: HII) at the catalyst surface. It is assumed that the hydrogenation of carbon oxides on iron-nickel catalysts proceeds either
through the jumpover effect or via hydrogen spillover. 相似文献
17.
In this paper we present theoretical study of the reverse water gas shift (RWGS) reaction catalyzed by ruthenium halogen carbonyl complexes. Three mechanisms, including hydrogen chloride, formic acid and oxidation–reduction mechanism, have been explored by density functional theory. The calculations indicate that the oxidation–reduction mechanism contributes to the TDI and TDTS in the ESM TOF calculations. Bimetallic catalysts would be likely to be more highly active than monometallic catalyst for the RWGS reaction. Among bimetallic catalysts studied, both bimetallic catalysts [Ru(μ-Cl)Cl(CO)3]2 and [Ru(μ-CO)Cl(CO)3]2 shows higher activity than [Ru(μ-Cl)(CO)4]2 catalyst with [Ru(μ-CO)Cl(CO)3]2 considering as the most efficient catalyst for RWGS reaction. 相似文献
18.
Efforts have been made to develop Ru/Mo bimetallic catalyst systems for hydrodenitrogenation (HDN) of tetrahydroquinoline (THQ). In the course of these studies, it was discovered that in ethanol, under hydrogen and in the presence of carbon disulfide (CS2), precatalyst solutions containing ruthenium [as Ru3(CO)12 or RuCl3] and molybdenum [as the H3PMo12O40 heteropolyanion (HPA)] decompose to form bimetallic, sulfided particles. Particle diameters run from 0.1 to 5μm depending on the rate of stirring. Catalyst particles with sizes ranging from 0.1 to 1μm can be prepared reproducibly. BET-measured surface areas for these size particles ranged from 2 to 20m2 g?1. These sulfided particles were found to catalyze, at temperatures of 200–250°C and hydrogen pressures of 200–1000 psig (1.4–6.9 MPa) hydrogen, the N-ethylation of THQ to form N-ethyltetrahydroquinoline (N-Et-THQ), rather than the formation of propylcyclohexane or propylbenzene, reaction products expected for HDN of THQ. Monometallic heterogeneous catalysts prepared from the individual precatalyst complexes, under identical conditions, show minimal activity for N-ethylation by comparison with the bimetallic catalyst. In the absence of hydrogen, the reaction proceeds so that THQ is converted to quinoline, N-Et-THQ, N-C4H9-THQ and N-C6H13-THQ. The latter products appear to arise via acetaldehyde, formed as an intermediate by dehydrogenation of ethanol. Acetaldehyde either condenses with THQ to form N-Et-THQ, or self-condenses (aldol condensation) prior to reaction with THQ, thereby giving higher-homolog alkylation products. 相似文献
19.
Li‐Na Wang Dr. Xiao‐Na Li Li‐Xue Jiang Bin Yang Dr. Qing‐Yu Liu Dr. Hong‐Guang Xu Prof. Wei‐Jun Zheng Prof. Sheng‐Gui He 《Angewandte Chemie (International ed. in English)》2018,57(13):3349-3353
Catalytic CO oxidation by molecular O2 is an important model reaction in both the condensed phase and gas‐phase studies. Available gas‐phase studies indicate that noble metal is indispensable in catalytic CO oxidation by O2 under thermal collision conditions. Herein, we identified the first example of noble‐metal‐free heteronuclear oxide cluster catalysts, the copper–vanadium bimetallic oxide clusters Cu2VO3–5? for CO oxidation by O2. The reactions were characterized by mass spectrometry, photoelectron spectroscopy, and density functional calculations. The dynamic nature of the Cu?Cu unit in terms of the electron storage and release is the driving force to promote CO oxidation and O2 activation during the catalysis. 相似文献
20.
掺杂Zr4+对纳米Au/TiO2催化剂结构和性能的影响 总被引:1,自引:0,他引:1
采用氨水反滴加沉淀法合成了Zr4+掺杂的系列TiO2载体,以尿素溶液为沉淀剂,用沉积-沉淀法制备负载金催化剂。运用N2吸附-脱附(BET)、X射线衍射(XRD)、X射线荧光(XRF)、高分辨电镜(HR-TEM)和氨吸附红外光谱(NH3-IR)等技术对催化剂的结构与形貌进行了表征,并在色谱-微反应装置上考察了催化剂对CO氧化反应的活性。结果表明:(1)少量的Zr4+掺杂可形成锐钛矿型固溶体,且载体的比表面积增大;随着Zr4+掺杂量增加至10%以上,载体逐渐向无定形转变,同时比表面积急剧增大。(2)保持规整锐钛矿晶相的Zr4+掺杂载体,其表面Lewis酸位占有率较高,且具备结构缺陷,而无定形载体表面的Lewis酸位占有率大幅度降低。(3)载体表面的Lewis酸位以及结构缺陷有利于增强载体对Au颗粒的锚定作用,从而减弱焙烧过程中的颗粒聚集。(4)少量Zr4+掺杂入TiO2载体中,可以提高Au颗粒的抗烧结能力,焙烧所得的Au颗粒尺寸较小(3.63 nm),且表现出优异的催化活性,在常温下就可以将CO完全氧化。 相似文献