X-ray nanoscopy of cobalt Fischer–Tropsch catalysts at work

Cats, Korneel H.; Gonzalez-Jimenez, Ines D.; Liu, Yijin; Nelson, Johanna; Campen, Douglas Van; Meirer, Florian; Eerden, Ad M. J. van der; Groot, Frank M. F. de; Andrews, Joy C.; Weckhuysen, Bert M.

doi:10.1039/c3cc00160a

Cited by 75 publications

(79 citation statements)

References 19 publications

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“…Whilst conventional packed-bed studies have observed that Co reoxidation does occur under FTS conditions, more recent high-resolution X-ray nanospectroscopy suggested otherwise. [99] Whilst the comment can be made that the latter only examines a single and rather large particle, the results from both studies could be affected by for example gas diffusion as well as the position of sample illumination along the length of the reactor bed which, if operated in plug-flow mode, leads to a change in gas composition along the reactor length. Future in situ/operando studies should therefore consider the impact of spatial variation on the results obtained when measuring under process conditions so as to be able to put the results obtained into a better context of catalytic activity in a reactor.…”

Section: Discussionmentioning

confidence: 99%

“…The 3D tomographic image of a catalyst particle of the unreduced 15 wt% Co/TiO 2 at the Co K-edge is seen in figure 12, as well as 2D slices of the image [99]. It can be seen that the cobalt in the sample is concentrated at the centre of the catalyst particle, and under …”

Section: Iii4 Transmission X-ray Microscopymentioning

confidence: 99%

“…The use of nanospectroscopy and TXM has proved effective in observing the spatial elemental composition under reaction conditions including the behaviour of the surface. [99] With the continued improvement of spatial and time resolution of nano/μ-sized beams future experiments will be capable of investigating catalyst particles of more realistic sizes in operando, such experiments will be able to provide insight into the special evolution of the catalyst particles specific to any surface reconstruction.…”

Section: Discussionmentioning

confidence: 99%

“…Transmission X-ray Microscopy (TXM) using synchrotron radiation was originally performed on Co catalysts by Cats et al [99]. The catalysts studied were Co/TiO 2 of 10 wt% and 15 wt% cobalt, examined during reduction in a flow of H 2 and FTS under conditions of T = 523K, P = 10 bar and H 2 /CO = 2.…”

Section: Iii4 Transmission X-ray Microscopymentioning

confidence: 99%

“…The catalysts studied were Co/TiO 2 of 10 wt% and 15 wt% cobalt, examined during reduction in a flow of H 2 and FTS under conditions of T = 523K, P = 10 bar and H 2 /CO = 2. TXM was used to obtain 2D chemical maps, XANES spectra were collected for each pixel by varying the beam energy, and the 3D elemental distribution of an individual particle was collected using acquisition tomography above and below an absorption edge [99].TXM and XANES were used to examine the change in [99].…”

Section: Iii4 Transmission X-ray Microscopymentioning

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: Discussionmentioning

confidence: 99%

Section: Iii4 Transmission X-ray Microscopymentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Iii4 Transmission X-ray Microscopymentioning

confidence: 99%

Section: Iii4 Transmission X-ray Microscopymentioning

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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Advances in F ischer– T ropsch Synthesis for the Production of Fuels and Chemicals

Zhong¹

2022

Heterogeneous Catalysis for Sustainable Energy

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Capturing the Genesis of an Active Fischer–Tropsch Synthesis Catalyst with Operando X‐ray Nanospectroscopy

et al. 2018

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Astate-of-the-art operando spectroscopic technique is applied to Co/TiO 2 catalysts,which account for nearly half of the worldst ransportation fuels produced by Fischer-Tropsch catalysis.This allows determination of,ataspatial resolution of approximately 50 nm, the interdependence of formed hydrocarbon species in the inorganic catalyst. Observed trends show intra-and interparticular heterogeneities previously believed not to occur in particles under 200 mm. These heterogeneities are strongly dependent on changes in H 2 /CO ratio,but also on changes therebyi nduced on the Co and Ti valence states.W e have captured the genesis of an active FTS particle over its propagation to steady-state operation, in which microgradients lead to the gradual saturation of the Co/TiO 2 catalyst surface with long chain hydrocarbons (i.e., organic film formation).Heterogeneous catalytic reactions such as the Fischer-Tr opsch synthesis (FTS) of long-chain hydrocarbons are dynamic and complex, often comprised of inorganic (catalyst) and organic parts (reactants and products). Conventional and widely applied spectroscopic techniques often focus on either the organic part (e.g., vibrational spectroscopy) or on the inorganic part (e.g., X-ray spectroscopic techniques). The combination of both inorganic and organic information shows great promise to answer long-standing questions about complex catalytic reactions.T he FTS propagates through ac omplex surface polymerization process of adsorbed C 1 reaction intermediates derived from synthesis gas (a mixture of CO and H 2 ). [1][2][3][4][5][6][7] Cobalt-based FTS catalysts are an integral part of this gas-to-liquid (GTL) process because of their high wax selectivity and relatively high stability. [8,9] Theactivation and deactivation of these cobalt nanoparticles supported on an inorganic oxide,such as Al 2 O 3 or TiO 2 ,isbelieved to occur through am ultitude of mechanisms,h owever consensus in literature is often still lacking. While the literature is imbued with proposed deactivation mechanisms, [5,10,11] the equally interesting catalyst activation period is often overlooked. [12,13] During the day(s)-long activation or induction period (which is highly dependent on reaction conditions and the catalyst), FTS catalyst particles are believed to be gradually saturated by afilm of long-chain hydrocarbons,followed by pore filling through which further reactants must diffuse. [12,14,15] The complexity of the FTS process is also captured in the myriad of proposed deactivation mechanisms,w hich are generally related to the conversion of the active phase, considered as metallic cobalt, into an inert phase.F or example,cobalt reoxidation or carburization, [16,17] the formation of support oxide-cobalt species occurring through strong metal-support interactions (SMSI), [8,18,19] the loss of active cobalt surface area arising from crystalline growth (i.e., metal sintering), [11,[20][21][22] and finally fouling for example by hydrocarbon deposition in the form of various carbon species formed at the cob...

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X-ray nanoscopy of cobalt Fischer–Tropsch catalysts at work

Cited by 75 publications

References 19 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

Advances in F ischer– T ropsch Synthesis for the Production of Fuels and Chemicals

Capturing the Genesis of an Active Fischer–Tropsch Synthesis Catalyst with Operando X‐ray Nanospectroscopy

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