Fischer–Tropsch synthesis over un-promoted and Re-promoted γ-Al2O3 supported cobalt catalysts with different pore sizes

Borg, Øyvind; Hammer, Nina; Eri, Sigrid; Lindvåg, O.A.; Myrstad, Rune; Blekkan, Edd A.; Rønning, Magnus; Rytter, Erling; Holmén, Anders

doi:10.1016/j.cattod.2009.01.012

Cited by 90 publications

(57 citation statements)

References 24 publications

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“…Therefore, it is not surprising that lower methane and higher C 5 + were achieved with a 0.26%Ru-25%Co/Al 2 O 3 catalyst relative to an unpromoted one. Re promoter was also found to give slightly better selectivities, in agreement with the work of Borg et al [17] (Table 6). However, an atomically equivalent amount of Pt slightly (though not prohibitively) worsened the selectivities, and an attempt to use Pd to replace Pt resulted in a significantly poorer product distribution.…”

Section: Example #1-coppersupporting

confidence: 82%

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

Jacobs¹,

Ma²,

Davis³

2014

Catalysts

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This focused review article underscores how metal reduction promoters can impact deactivation phenomena associated with cobalt Fischer-Tropsch synthesis catalysts. Promoters can exacerbate sintering if the additional cobalt metal clusters, formed as a result of the promoting effect, are in close proximity at the nanoscale to other cobalt particles on the surface. Recent efforts have shown that when promoters are used to facilitate the reduction of small crystallites with the aim of increasing surface Co 0 site densities (e.g., in research catalysts), ultra-small crystallites (e.g., <2-4.4 nm) formed are more susceptible to oxidation at high conversion relative to larger ones. The choice of promoter is important, as certain metals (e.g., Au) that promote cobalt oxide reduction can separate from cobalt during oxidation-reduction (regeneration) cycles. Finally, some elements have been identified to promote reduction but either poison the surface of Co 0 (e.g., Cu), or produce excessive light gas selectivity (e.g., Cu and Pd, or Au at high loading). Computational studies indicate that certain promoters may inhibit polymeric C formation by hindering C-C coupling.

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Section: Example #1-coppersupporting

confidence: 82%

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

Jacobs¹,

Ma²,

Davis³

2014

Catalysts

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“…This is in contrast to the use of pelletised wafers which are easier to interrogate with analytical methods, but which are susceptible to problems with gas-diffusion [15] Sample loadings applied are typically of the order of a few mg thereby enabling the gas delivery system to deliver flows of the order of ml/min which is very much in the order of the weight hourly space velocities (WHSV) and gas hourly space velocities (GHSV) reported for FTS experiments [30]. [34].…”

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

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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(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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“…When Co was co-precipitated with a second metal such as Re or Pt the enhanced F-T synthesis activity obtained for the resulting catalyst, usually ill-characterized yet generally assumed to be some alloy form, is attributed to high reducibility of Co [96][97][98]. In this work, a two-dimensional film of bimetallic CoPt alloy NPs, monodisperse 4 nm in size and 50:50 compositions, were investigated in redox atmospheres (H 2 or O 2 ) at temperatures in the 125-250°C range.…”

Section: The Role Of Nobler Metal In Co-based Bimetallicmentioning

confidence: 99%

Nanocatalysis II: In Situ Surface Probes of Nano-Catalysts and Correlative Structure–Reactivity Studies

Alayoǧlu

Somorjai

2014

Catal Lett

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Model nano-catalysts with monodisperse particle sizes and architectures are essential for a fundamental understanding of surface property dynamics during catalytic reactions. Surface tools and techniques, when conducted under catalytically relevant temperature and pressure conditions, render possible measurements of dynamic surface properties such as oxidation state, composition, coordination, and bonding. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy with purposely built in situ reaction cells and ambient pressure X-ray photoelectron spectroscopy (APXPS) provide (near) surface sensitive and chemical specific information on the oxidation states of metal and oxide (co-)catalysts as well as adsorbent functional elements such C, O and N under reactive gas atmospheres and even liquid environments. Likewise, sum frequency generation (SFG) vibrational spectroscopy with in situ reaction cells helps uncover the bonding geometry and configuration of the topmost surface again under conditions pertinent to catalysis. Furthermore, the local dynamics in the nanoscale and on the single particle level are revealed by environmental transmission electron microscopy (ETEM) and the spectro-microscopy techniques equipped within. A correlative approach, where an array of these in situ tools and techniques were conducted in parallel with catalytic measurements, was employed to gain molecular insight into some of the modern scientific challenges in heterogeneous catalysis.Several case examples of this correlative approach are presented here. The CO oxidation reaction over hybrid nano-catalysts of Pt nanoparticles (NPs) with various mesoporous metal oxides such as Co 3 O 4 , MnO 2 and CeO 2 was explored in relation to bifunctional catalysis and interfacial charge transfer chemistry by using in situ NEXAFS spectroscopy. Likewise, bimetallic CoPt and PtSn nanoparticle catalysts supported on silica were investigated by using a combination of in situ NEXAFS spectroscopy and APXPS. Next, CO 2 hydrogenation was carried out over bimetallic CoPt/SiO 2 and Co/TiO 2 hybrid nano-catalysts. In this case, in situ NEXAFS spectroscopy, APXPS, and ETEM indicated severe, yet reversible, surface restructuring that involved hydrogen atom spillover. Finally, *2 nm Pt NPs were investigated using in situ SFG to study hydrogenation and hydrogenative isomerization reactions. Specifically, SFG indicated that the hydrogenation of furfural and crotonaldehyde proceed by interfacial hydrogen atom spillover from TiO 2 , while the hydrogenative isomerization of methylcyclopentane (MCP) proceeds by spillover and surface diffusion of cyclohexene over mesoporous zeolites. These studies unequivocally indicated the presence of a particular reaction channel that involved one way flow of charged (i.e. electrons or protons) or neutral species (i.e. reactants) at a broadly defined interface between metals and oxides. In addition to these case studies, experimental approaches employing capillary flow micro-reactors are discussed in relation toward t...

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Fischer–Tropsch synthesis over un-promoted and Re-promoted γ-Al2O3 supported cobalt catalysts with different pore sizes

Cited by 90 publications

References 24 publications

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

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

Nanocatalysis II: In Situ Surface Probes of Nano-Catalysts and Correlative Structure–Reactivity Studies

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