Metal–support interaction in Co/SiO2 and Co/TiO2

Riva, Roberto; Mießner, H.; Vitali, Roberta; Piero, G. Del

doi:10.1016/s0926-860x(99)00460-3

Cited by 198 publications

(111 citation statements)

References 27 publications

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“…In situ SR PXRD measurements can be acquired with a time resolution ranging from milliseconds to minutes, thereby allowing for the acquisition of a series of PXRD patterns as time progresses throughout activation or a FTS reaction. [6] This allows for the tracking of crystalline phase changes with time, and importantly, variation in crystallite size -yielding valuable information on the system and its evolution with time under a controlled atmosphere.…”

Section: Ii1 Powder X-ray Diffraction (Pxrd)mentioning

confidence: 99%

“…Co 0 particles are believed to be the primary active sites as the metallic Co is present throughout FTS [4]. Other cobalt species found in FTS catalysts include; cobalt oxide (both CoO and Co 3 O 4 ), cobalt carbide (Co 2 C) and cobalt-supported compounds (such as cobalt aluminate (CoAl 2 O 4 ) or cobalt titanate (CoTiO 3 )) [6]. The oxidation of cobalt catalysts by water to form cobalt oxides, first raised as an issue in work by A. Holmen [7], has been extensively discussed in the literature as research groups strive to determine whether oxidation is in fact a catalytic deactivation mechanism [7,8].…”

Section: Introductionmentioning

confidence: 99%

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X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based Fischer–Tropsch synthesis catalysts

Herbert

Sénécal

Martin

et al. 2016

Catal. Sci. Technol.

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(2016) 'X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based FischerTropsch synthesis catalysts.', Catalysis science and technology., 6 (15). pp. 5773-5791. Further information on publisher's website:http://dx.doi.org/10.1039/C6CY00581KPublisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract: This review aims to critically assess the use of X-ray techniques, both of a scattering (e.g. X-ray diffraction (XRD), Pair Distribution Function (PDF)) and spectroscopic nature (X-ray Absorption spectroscopy (XAFS)), in the study of cobalt-based Fisher-Tropsch Synthesis (FTS) catalysts. In particular, the review will focus on how these techniques have been successfully used to describe the salient characteristics of these catalysts that govern subsequent activity and selectivity, as well as to afford insight into deactivation phenomena that have seemingly stifled their application. We discuss how these X-ray-based techniques have been used to yield insight into the bulk structure, the catalyst surface, oxidation states, local (cobalt) geometry, and elemental composition of particles, primarily from a 1D perspective but we also highlight how, with recent developments in advanced X-ray characterisation methods, crucial information can now be obtained in 2D and 3D. The examples chosen focus on data acquired in situ/operando, under realistic operating conditions and during activation which often allow for obtaining a more relevant perspective on the changes in catalyst structure that accompany a change in catalyst performance. We conclude with a perspective on some of the challenges that beset the Co-based FTS technology and discuss how X-ray based techniques could be used to solve them.2

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Section: Ii1 Powder X-ray Diffraction (Pxrd)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based Fischer–Tropsch synthesis catalysts

Herbert

Sénécal

Martin

et al. 2016

Catal. Sci. Technol.

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“…To enhance the activity of cobalt catalysts the active compound precursors were dispersed on porous carriers with SiO 2 , Al 2 O 3 and TiO 2 being the most frequently used. The interaction between cobalt and the supports leads to the formation of Co-support compounds including Co 2 SiO 4 , COAl 2 O 4 and CoTiO 3 compounds, which can be only reduced or decomposed at elevated temperatures (>1000 K), and declines the activity of catalysts in FTS [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

The formation of Co2C species in activated carbon supported cobalt-based catalysts and its impact on Fischer–Tropsch reaction

et al. 2005

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The cobalt carbide (Co 2 C) species was formed in some activated carbon supported cobalt-based (Co/AC) catalysts during the activation of catalysts. It was found that the activity of Fischer-Tropsch reaction over Co-based catalysts decreased due to the formation of cobalt carbide species. Some promoters and pretreatment of activated carbon with steam could restrain the formation of cobalt carbide.

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“…This makes them the catalysts of choice for FTS. 2,3 Reducibility of supported-cobalt particles strongly depends on the support used [4][5][6] and on the preparation method. 7,8 For supports without a strong interaction with cobalt, such as silica, highly reducible cobalt oxide clusters are normally formed.…”

Section: Introductionmentioning

confidence: 99%

In situ X‐Ray Absorption of Co/Mn/TiO₂ Catalysts for Fischer—Tropsch Synthesis.

Morales¹,

Groot²,

Glatzel³

et al. 2004

ChemInform

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The reduction behavior of Co/TiO 2 and Co/Mn/TiO 2 catalysts for Fischer-Tropsch synthesis has been investigated by soft X-ray absorption spectroscopy (XAS). In situ XAS measurements of the L 2,3 edges of Co and Mn have been carried out during reduction treatments of the samples in H 2 at a pressure of 2 mbar and at temperatures up to 425°C. The changes of Co and Mn 3d valences and the symmetries throughout the reduction have been determined by comparison with theoretical calculations based on the charge transfer multiplet code. Furthermore, bulk Co 3 O 4 has been reduced under the same conditions to evaluate the effect of TiO 2 as a support on the reducibility of Co oxides. The average Co valence at the various temperatures has been determined from a linear combination of the reference spectra. It was found that the unsupported Co 3 O 4 was easily reduced to Co 0 at 425°C, whereas the Co 3 O 4 supported on TiO 2 catalysts was only reduced to a mixture of CoO and Co 0 , even after 12 h reduction at 425°C. The presence of Mn further retards the reduction of the supported Co 3 O 4 particles. The Mn III ions were easily reduced to MnO at temperatures lower than 300°C , and they remained in this oxidation state even after further temperature increase. In addition, catalytic tests in the Fischer-Tropsch synthesis reaction at a pressure of 1 bar indicate that the selectivity of these catalysts might be related to the extent of Co reduced after the activation treatment (i.e., the reduction with H 2 ).

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Metal–support interaction in Co/SiO2 and Co/TiO2

Cited by 198 publications

References 27 publications

X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based Fischer–Tropsch synthesis catalysts

X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based Fischer–Tropsch synthesis catalysts

The formation of Co2C species in activated carbon supported cobalt-based catalysts and its impact on Fischer–Tropsch reaction

In situ X‐Ray Absorption of Co/Mn/TiO₂ Catalysts for Fischer—Tropsch Synthesis.

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Metal–support interaction in Co/SiO2 and Co/TiO2

Cited by 198 publications

References 27 publications

X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based Fischer–Tropsch synthesis catalysts

X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based Fischer–Tropsch synthesis catalysts

The formation of Co2C species in activated carbon supported cobalt-based catalysts and its impact on Fischer–Tropsch reaction

In situ X‐Ray Absorption of Co/Mn/TiO2 Catalysts for Fischer—Tropsch Synthesis.

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In situ X‐Ray Absorption of Co/Mn/TiO₂ Catalysts for Fischer—Tropsch Synthesis.