Decoupling the deactivation mechanisms of a cobalt Fischer–Tropsch catalyst operated at high conversion and ‘simulated’ high conversion

2020 ◽  
Vol 10 (20) ◽  
pp. 7056-7066 ◽  
Author(s):  
Chelsea Lyn Tucker ◽  
Michael Claeys ◽  
Eric van Steen
Keyword(s):  
High Conversion ◽  
Fischer Tropsch

In situ magnetometer study shows that high conversions facilitate sintering, reversible Co(ii)O and irreversible CoAl2O4 formation within cobalt-based Fischer–Tropsch systems.

scholarly journals Ultrafine metal-polymer catalysts based on polyconjugated systems for Fisher–Tropsch synthesis

2020 ◽  
Vol 92 (6) ◽  
pp. 977-984
Author(s):  
Mayya V. Kulikova ◽  
Albert B. Kulikov ◽  
Alexey E. Kuz’min ◽  
Anton L. Maximov
Keyword(s):  
Tropsch Synthesis ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
Force Microscopy ◽  
Composite Catalysts ◽  
Fe Catalyst ◽  
Atomic Force ◽  
And Function ◽  
Metal Polymer

AbstractFor previously studied Fischer–Tropsch nanosized Fe catalyst slurries, polymer compounds with or without polyconjugating structures are used as precursors to form the catalyst nanomatrix in situ, and several catalytic experiments and X-ray diffraction and atomic force microscopy measurements are performed. The important and different roles of the paraffin molecules in the slurry medium in the formation and function of composite catalysts with the two types of aforementioned polymer matrices are revealed. In the case of the polyconjugated polymers, the alkanes in the medium are “weakly” coordinated with the metal-polymer composites, which does not affect the effectiveness of the polyconjugated polymers. Otherwise, alkane molecules form a “tight” surface layer around the composite particles, which create transport complications for the reagents and products of Fischer-Tropsch synthesis and, in some cases, can change the course of the in situ catalyst formation.

scholarly journals Unraveling the Structure of Mn-Promoted Co/TiO2 Fischer-Tropsch Catalysts by In Situ X-Ray Absorption Spectroscopy

2007 ◽  
Author(s):  
Didier Grandjean ◽  
Fernando Morales ◽  
Ad Mens ◽  
Frank M. F. de Groot ◽  
Bert M. Weckhuysen
Keyword(s):  
Absorption Spectroscopy ◽  
Fischer Tropsch ◽  
X Ray ◽  
X Ray Absorption

57Fe Mössbauer Spectroscopic Study of the Geometrical Effects In the Catalytic Reactions with Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
P.P. Vaishnava ◽  
P.A. Montano
Keyword(s):  
Ferric Chloride ◽  
Catalytic Reactions ◽  
Fischer Tropsch ◽  
Reaction Conditions ◽  
Intercalated Graphite ◽  
The Third ◽  
Intercalated Compounds ◽  
Catalytic Sites ◽  
Geometrical Effects

ABSTRACTIn situ 57Fe Mössbauer spectra are reported for the first-, higher-stage ferric chloride, and a mixed ferric chloride-potassium chloride intercalated graphite catalysts under reduction and Fischer-Tropsch reaction conditions. The mass spectroscopic measurements reveal a different catalytic selectivity for the three catalysts. The first two catalysts predominantly possess a higher selectivity for methane, whereas the third catalyst has higher selectivity for the formation of propane. The differences are attributed to geometrical effects in the catalytic sites of the intercalated compounds.

scholarly journals In situ observation of phase changes of a silica-supported cobalt catalyst for the Fischer–Tropsch process by the development of a synchrotron-compatible in situ/operando powder X-ray diffraction cell

2018 ◽  
Vol 25 (6) ◽  
pp. 1673-1682 ◽  
Author(s):  
Adam S. Hoffman ◽  
Joseph A. Singh ◽  
Stacey F. Bent ◽  
Simon R. Bare
Keyword(s):  
High Pressure ◽  
Elevated Pressure ◽  
Phase Changes ◽  
In Situ Observation ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
X Ray ◽  
And Performance ◽  
Co Nanoparticles

In situ characterization of catalysts gives direct insight into the working state of the material. Here, the design and performance characteristics of a universal in situ synchrotron-compatible X-ray diffraction cell capable of operation at high temperature and high pressure, 1373 K, and 35 bar, respectively, are reported. Its performance is demonstrated by characterizing a cobalt-based catalyst used in a prototypical high-pressure catalytic reaction, the Fischer–Tropsch synthesis, using X-ray diffraction. Cobalt nanoparticles supported on silica were studied in situ during Fischer–Tropsch catalysis using syngas, H2 and CO, at 723 K and 20 bar. Post reaction, the Co nanoparticles were carburized at elevated pressure, demonstrating an increased rate of carburization compared with atmospheric studies.

In situ X-ray diffraction of Fischer-Tropsch catalysts—Effect of water on the reduction of cobalt oxides

2017 ◽  
Vol 546 ◽  
pp. 103-110 ◽  
Author(s):  
James Paterson ◽  
Mark Peacock ◽  
Ewen Ferguson ◽  
Manuel Ojeda ◽  
Jay Clarkson
Keyword(s):  
Cobalt Oxides ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
X Ray ◽  
Effect Of Water

Size dependent stability of cobalt nanoparticles on silica under high conversion Fischer–Tropsch environment

2017 ◽  
Vol 197 ◽  
pp. 243-268 ◽  
Author(s):  
Moritz Wolf ◽  
Hendrik Kotzé ◽  
Nico Fischer ◽  
Michael Claeys
Keyword(s):  
Type Species ◽  
Tropsch Synthesis ◽  
High Conversion ◽  
Metallic Surface ◽  
Metallic State ◽  
Direct Oxidation ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Metal Support ◽  
Presence And Absence

Highly monodisperse cobalt crystallites, supported on Stöber silica spheres, as model catalysts for the Fischer–Tropsch synthesis were exposed to simulated high conversion environments in the presence and absence of CO utilising an in house developedin situmagnetometer. The catalyst comprising the smallest crystallites in the metallic state (average diameter of 3.2 nm) experienced pronounced oxidation whilst the ratio of H2O to H2was increased stepwise to simulate CO conversions from 26% up to complete conversion. Direct exposure of this freshly reduced catalyst to a high conversion Fischer–Tropsch environment resulted in almost spontaneous oxidation of 40% of the metallic cobalt. In contrast, a model catalyst with cobalt crystallites of 5.3 nm only oxidised to a small extent even when exposed to a simulated conversion of over 99%. The largest cobalt crystallites were rather stable and only experienced measurable oxidation when subjected to H2O in the absence of H2. This size dependency of the stability is in qualitative accordance with reported thermodynamic calculations. However, the cobalt crystallites showed an unexpected low susceptibility to oxidation,i.e.only relatively high ratios of H2O to H2partial pressure caused oxidation. Similar experiments in the presence of CO revealed the significance of the actual Fischer–Tropsch synthesis on the metallic surface as the dissociation of CO, an elementary step in the Fischer–Tropsch mechanism, was shown to be a prerequisite for oxidation. Direct oxidation of cobalt to CoO by H2O seems to be kinetically hindered. Thus, H2O may only be capable of indirect oxidation,i.e.high concentrations prevent the removal of adsorbed oxygen species on the cobalt surface leading to oxidation. However, a spontaneous direct oxidation of cobalt at the interface between the support and the crystallites by H2O forming presumably cobalt silicate type species was observed in the presence and absence of CO. The formation of these metal–support compounds is in accordance with conducted thermodynamic predictions. None of the extreme Fischer–Tropsch conditions initiated hydrothermal sintering. Seemingly, the formation of metal–support compounds stabilised the metallic crystallites and/or higher partial pressures of CO are required to increase the concentration of mobile, cobalt oxide-type species on the metallic surface.

In situ magnetometer study on the formation and stability of cobalt carbide in Fischer–Tropsch synthesis

2014 ◽  
Vol 318 ◽  
pp. 193-202 ◽  
Author(s):  
M. Claeys ◽  
M.E. Dry ◽  
E. van Steen ◽  
E. du Plessis ◽  
P.J. van Berge ◽  
...  
Keyword(s):  
Tropsch Synthesis ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Cobalt Carbide
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