Fischer–Tropsch synthesis: Temperature programmed EXAFS/XANES investigation of the influence of support type, cobalt loading, and noble metal promoter addition to the reduction behavior of cobalt oxide particles

Jacobs, Gary; Ji, Yaying; Davis, Burtron H.; Cronauer, Donald C.; Kropf, A. Jeremy; Marshall, Christopher L.

doi:10.1016/j.apcata.2007.07.027

Cited by 311 publications

(161 citation statements)

References 40 publications

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“…This earlier onset suggests slightly easier reduction, potentially related to the improved site accessibility in the LDH/GO hybrids, discussed above. The pure and hybrid CoAl-LDH catalysts showed broad reduction profiles at considerably higher temperatures (400-600°C), consistent with literature reports on the H2-TPR characteristics of cobalt-containing materials [57]. For the CoAl-LDH/GO sample, a clear additional reduction peak at a lower temperature of around 325°C was observed, indicating again easier reduction of the GO-containing hybrid catalyst.…”

Section: Resultssupporting

confidence: 77%

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

Ahmed

Menzel

Wang

et al. 2017

Journal of Solid State Chemistry

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Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterization by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl-and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. As a result, the recyclability of the heterogeneous catalyst systems is greatly enhanced. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

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Section: Resultssupporting

confidence: 77%

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

Ahmed

Menzel

Wang

et al. 2017

Journal of Solid State Chemistry

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“…These effects can be explained by a hydrogen spill over phenomenon. 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.…”

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confidence: 48%

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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“…First, between 100ºC and 200ºC carbon dioxide, water and methane evolved due to decomposition of the surfactant. Between 300 and 450ºC a broad water peak appears that corresponds to the reduction of CoO to metallic cobalt [29]. At 550-650ºC methane evolution was observed, which we assign to the hydrogenation of carbonaceous species on the surface of the catalyst.…”

Section: Catalytic Activity Of Sio 2 Supported Catalystsmentioning

confidence: 81%

Influence of the Cobalt Particle Size in the CO Hydrogenation Reaction Studied by In Situ X-Ray Absorption Spectroscopy

et al. 2009

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TitleInfluence of the cobalt particle size in the CO hydrogenation reaction studied by in situ X-ray absorption spectroscopy To whom correspondence should be addressed. E-mail: MBSalmeron@lbl.govThe influence of particle size in the carbon monoxide hydrogenation reaction has been studied using cobalt nanoparticles (NP) with narrow size distribution prepared by colloidal chemistry. The surfactant covering the NP after synthesis could be removed by heating to 200-270ºC in H 2 . Soft X ray absorption spectroscopy was performed in a gas flow cell under reaction conditions of H 2 and CO at atmospheric pressure. Flow of pure hydrogen at 350ºC removed the protecting surfactant layer and reduced the NP from oxidized to metallic. The NP remained metallic during the methanation reaction with their surface covered by CO. The methanation turnover frequency of silica supported NP was found to decrease with diameter below 10 nm, while the reaction activation energy was found to be independent of NP size. H-D exchange experiments indicated that it is the dissociation of H 2 that is responsible for the observed decrease in activity with size.2 KEYWORDS. Cobalt, nanoparticles, Fischer-Tropsch, X-ray absorption (XAS), in situ studies, soft xray spectroscopy, particle size dependence.

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Fischer–Tropsch synthesis: Temperature programmed EXAFS/XANES investigation of the influence of support type, cobalt loading, and noble metal promoter addition to the reduction behavior of cobalt oxide particles

Cited by 311 publications

References 40 publications

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

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

Influence of the Cobalt Particle Size in the CO Hydrogenation Reaction Studied by In Situ X-Ray Absorption Spectroscopy

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Fischer–Tropsch synthesis: Temperature programmed EXAFS/XANES investigation of the influence of support type, cobalt loading, and noble metal promoter addition to the reduction behavior of cobalt oxide particles

Cited by 311 publications

References 40 publications

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

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

Influence of the Cobalt Particle Size in the CO Hydrogenation Reaction Studied by In Situ X-Ray Absorption Spectroscopy

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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