Metal–support interactions in cobalt-aluminum co-precipitated catalysts: XPS and CO adsorption studies

Khassin, A. A.; Yurieva, T. M.; Каичев, В. В.; Bukhtiyarov, Valerii I.; Budneva, A. A.; Паукштис, Е. А.; Parmon, Valentin N.

doi:10.1016/s1381-1169(01)00216-3

Cited by 260 publications

(154 citation statements)

References 35 publications

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“…The spectra obtained after calcination contain an intense Co 2p 3/2 peak at 780.9 eV, attributed to the presence of Co 2+ and Co 3+ species, and two Co2p 1/2 peaks at 789.8 and 787 eV attributable to Co 3+ and Co 2+ , respectively. [34][35][36] Following reduction under H 2 , the spectra for both samples show a main Co 2p 3/2 peak at 778.3 eV, which is characteristic of Co 0 . After this procedure, the samples were treated under H 2 O.…”

Section: Temperature-programmed Reduction Measurementsmentioning

confidence: 96%

The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO₂ Catalysts

et al. 2011

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The effect of zinc promotion on the oxidation state of cobalt in Co/ZrO(2) catalysts was investigated and correlated with the activity and selectivity for ethanol steam reforming (ESR). Catalysts were synthesized by applying incipient wetness impregnation and characterized by using Brunauer-Emmett-Teller (BET), temperature-programmed reduction (TPR) measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Higher ethanol conversion and lower CH(4) selectivity are observed for the Co/ZrO(2) catalyst promoted with Zn as compared to the Co/ZrO(2) catalyst alone. Addition of Zn inhibits the oxidation of metallic cobalt (Co(0) ) particles and results in a higher ratio of Co(0) /Co(2+) in the Zn-promoted Co/ZrO(2) catalyst. These results suggest that metallic cobalt (Co(0) ) is more active than Co(2+) in the ethanol conversion through dehydrogenation and that Co(2+) may play a role in the CH(4) formation. TPR measurements, on the other hand, reveal that Zn addition inhibits the reduction of Co(2+) and Co(3+) , which would lead to the false conclusion that oxidized Co is required to reduce the CH(4) formation. Therefore, TPR measurements may not be appropriate to correlate the degree of metal reducibility (in this case Co(0)) with the catalyst activity for reactions, such as ESR, where oxidizing conditions exist.

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Section: Temperature-programmed Reduction Measurementsmentioning

confidence: 96%

The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO₂ Catalysts

et al. 2011

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“…As a result, Co catalysts, typically, deactivate faster when bioethanol is fed. 164 However, these authors have shown that the stability of this catalytic system was exactly the same when using either ethanol or bioethanol in the feed-stream, achieving a stable gas phase composition up to 300 h time-on-stream (H 2 selectivity stabilized around 62%, CO 2 around 21%, CO and CH 4 around 5-8%). Recently, Liu et al 165 investigated a series of cobalt-cerium materials prepared by two methods.…”

Section: Green Chemistry Critical Reviewmentioning

confidence: 97%

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

et al. 2017

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Layered double hydroxides (LDHs) and derived materials have been widely used as heterogeneous catalysts for different types of reactions either in gas or in liquid phase. Among these processes, the valorization/upgrading of lignocellulosic biomass and derived molecules have attracted enormous attention because it constitutes a pivotal axis in the transition from an economic model based on fossil resources to one based on renewable biomass resources with preference for biomass waste streams. Proof of this is the increasing amount of literature reports regarding the rational design and implementation of LDHs and related materials in catalytic processes such as: depolymerization, hydrogenation, selective oxidations, and C-C coupling reactions, among others, where biomass-derived compounds are used. The major aim of this contribution is to situate the most recent advances on the implementation of these types of catalysts into a lignocellulosic-feedstock biorefinery scheme, highlighting the versatility of LDHs and derived materials as multifunctional, tunable, cheap and easy to produce heterogeneous catalysts.

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“…Cobalt reducibility is known to depend on particle size [16]. The interaction of cobalt species with aluminium should also be considered [17]. Alternatively, gas phase methods for cobalt-based catalyst production have been explored.…”

Section: Introductionmentioning

confidence: 99%

Co-Al spinel-based nanoparticles synthesized by flame spray pyrolysis for glycerol conversion

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Karhunen

et al. 2017

Advanced Powder Technology

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The catalytic properties of Co-Al spinel nanoparticles prepared by flame spray pyrolysis (FSP) were investigated in the glycerol conversion in gas phase in an atmosphere of hydrogen. Reduction under hydrogen atmosphere at 1123 K of the as-synthesized spinel nanoparticles induced the formation a new phase containing metallic cobalt species. Although, the reducibility of cobalt oxides is greatly decreased due to interaction with aluminium species, this strong interaction may prevent the aggregation of Co particles under the harsh reduction conditions. X-ray photoelectron spectroscopy (XPS) of the reduced spinel nanoparticles at 1123 K revealed that the Co/Al atomic ratio has decreased from 0.27 to 0.11, which represents a significant reduction in the exposed cobalt. This is in accordance with the reduction of CoAl 2 O 4 into metallic Co and partial agglomeration (sintering) of Co. X-ray diffraction (XRD) and high resolution electron microscopy (HRTEM) also reinforced the formation of metallic cobalt species after reduction of cobalt from the spinel nanoparticles at 1123 K. The main products obtained from the conversion of glycerol in the gas phase were hydroxyacetone, pyruvaldehyde, lactic acid and lactide. FSP successfully gave insights to ensure uniform dispersion of the active metal on a support material.

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Metal–support interactions in cobalt-aluminum co-precipitated catalysts: XPS and CO adsorption studies

Cited by 260 publications

References 35 publications

The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO₂ Catalysts

The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO₂ Catalysts

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

Co-Al spinel-based nanoparticles synthesized by flame spray pyrolysis for glycerol conversion

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Metal–support interactions in cobalt-aluminum co-precipitated catalysts: XPS and CO adsorption studies

Cited by 260 publications

References 35 publications

The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO2 Catalysts

The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO2 Catalysts

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

Co-Al spinel-based nanoparticles synthesized by flame spray pyrolysis for glycerol conversion

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The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO₂ Catalysts

The Effect of Zinc Addition on the Oxidation State of Cobalt in Co/ZrO₂ Catalysts