The promoting effect of noble metal addition on niobia-supported cobalt catalysts

Noronha, Fábio B.; Frydman, A.; Aranda, Donato Alexandre Gomes; Perez, Carlos A.; Soares, Ricardo R.; Morawek, B.; Castner, David G.; Campbell, C. T.; Fréty, R.; Schmal, Martín

doi:10.1016/0920-5861(95)00218-9

Cited by 39 publications

(40 citation statements)

References 18 publications

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“…29,30 Similar noble metalinduced effects were observed for alumina-supported cobalt Fischer-Tropsch catalysts, 40,41 and on other bimetallic cobaltbased systems. 36,[42][43][44] It is frequently observed that the presence of a second metal can greatly influence the intrinsic surface properties of a specific metal. It is emphasized that in contrast to bulk alloys, nanosized bimetallic systems are extremely sensitive to the structure, morphology, and valence state of the oxide support, on which the nanoparticles were prepared.…”

Section: +mentioning

confidence: 99%

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation

Varga

Pusztai

Óvári³

et al. 2015

Phys. Chem. Chem. Phys.

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The interaction of CeO 2 -supported Rh, Co and bimetallic Rh-Co nanoparticles, which are active catalysts in hydrogen production via steam reforming of ethanol, a process related to renewable energy generation, was studied by X-ray diffraction (XRD), high resolution electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). Furthermore, diffuse reflectance infrared spectroscopy (DRIFTS) of adsorbed CO as a probe molecule was used to characterize the morphology of metal particles. At small loadings (0.1%), Rh is in a much dispersed state on ceria, while at higher contents (1-5%), Rh forms 2-8 nm particles. Between 473-673 K pronounced oxygen transfer from ceria to Rh is observed and at 773 K significant agglomeration of Rh occurs. On reduced ceria, XPS indicates a possible electron transfer from Rh to ceria. The formation of smaller ceria crystallites upon loading with Co was concluded from XRD and HRTEM; for 10% Co, the CeO 2 particle size decreased from 27.6 to 10.7 nm. A strong dissolution of Co into ceria and a certain extent of encapsulation by ceria were deduced by XRD, XPS and LEIS. In the bimetallic system, the presence of Rh enhances the reduction of cobalt and ceria.During thermal treatments, reoxidation of Co occurs, and Rh agglomeration as well as oxygen migration from ceria to Rh are hindered in the presence of cobalt.

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Section: +mentioning

confidence: 99%

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation

Varga

Pusztai

Óvári³

et al. 2015

Phys. Chem. Chem. Phys.

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“…Catalisadores mono e bimetálicos de Co/Nb 2 O 5 e Pd-Co/ Nb 2 O 5 apresentaram resultados interessantes de seletividade na síntese de Fischer-Tropsch (Noronha et al 1996, Rosenir et al 1993. A presença de metal nobre aumentou a seletividade de C + 5 e diminuiu a formação de metano dependendo da temperatura de redução.…”

Section: Introductionunclassified

“…The addition of a noble metal to Co/Nb 2 O 5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al 1996, Rosenir et al 1993. The presence of a noble metal increased the C + 5 selectivity and decreased the methane formation independent of the reduction temperature.…”

Section: Introductionmentioning

confidence: 99%

“…One might argue: is there anything fundamental to be discovered through the interplay between catalysis and surface science?Real catalysts of monometallic and bimetallic Co/Nb 2 O 5 and Pd-Co/Nb 2 O 5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al 1996, Rosenir et al 1993. The presence of a noble metal increased the C + 5 selectivity and decreased the methane formation depending of the reduction temperature.…”

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Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

Schmal¹,

Freund

2009

An. Acad. Bras. Ciênc.

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The science of catalysis and surface science have developed, independently, key information for understanding catalytic processes. One might argue: is there anything fundamental to be discovered through the interplay between catalysis and surface science?Real catalysts of monometallic and bimetallic Co/Nb 2 O 5 and Pd-Co/Nb 2 O 5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al. 1996, Rosenir et al. 1993. The presence of a noble metal increased the C + 5 selectivity and decreased the methane formation depending of the reduction temperature. Model catalyst of Co-Pd supported on niobia and alumina were prepared and characterized at the atomic level, thus forming the basis for a comparison with "real" support materials. Growth, morphology and structure of both pure metal and alloy particles were studied. It is possible to support the strong metal support interaction suggested by studies on real catalysts via the investigation of model systems for niobia in comparison to alumina support in which this effect does not occur. Formation of Co 2+ penetration into the niobia lattice was suggested on the basis of powder studies and can be fully supported on the basis of model studies. It is shown for both real catalysts and model systems that oxidation state of Co plays a key role in controlling the reactivity in Fischer-Tropsch reactions systems and that the addition of Pd is a determining factor for the stability of the catalyst. It is demonstrated that the interaction with unsaturated hydrocarbons depends strongly on the state of oxidation.

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“…As a consequence, this weakens the OH bond and generates the Brønsted acid sites. Furthermore, based on the XPS data by Noronha et al [35] and Bosman et al [36] found the increased in the covalency of Si-O bonds in binary SiO 2 -TiO 2 and SiO 2 -ZrO 2 systems, respectively, that leads to the creation of Brønsted acid sites.…”

Section: CMmentioning

confidence: 99%

Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite

Prasetyoko

Ramli

Endud

et al. 2008

Advances in Materials Science and Engineering

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Niobic acid, Nb 2 O 5 ·nH 2 O, has been supported on the titanium silicalite by impregnation method. The obtained materials were characterized by X-ray diffraction, infrared, and ultra-violet-visible diffuse reflectance spectroscopy, temperature programmed reduction, pyridine adsorption, and field emission scanning electron microscopy techniques. It was demonstrated that the tetrahedral titanium species still retained after impregnation of niobic acid. The results revealed that niobium species interacted with hydroxyl groups on the surface of TS-1. The niobium species in the catalysts are predominantly polymerized niobium oxides species or bulk niobium oxide with the octahedral structure. All catalysts showed both Brønsted and Lewis acid sites. The catalysts have been tested for epoxidation of 1-octene with aqueous hydrogen peroxide. It was found that the presence of niobic acid in the catalysts enhanced the rate of the formation of epoxide at the initial reaction time. Diol as a side product was also observed due to the acidic properties of the catalysts.

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The promoting effect of noble metal addition on niobia-supported cobalt catalysts

Cited by 39 publications

References 18 publications

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation

Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite

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The promoting effect of noble metal addition on niobia-supported cobalt catalysts

Cited by 39 publications

References 18 publications

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO2 support: catalytic materials for alternative energy generation

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO2 support: catalytic materials for alternative energy generation

Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite

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Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation