Development of an Innovative XRD-DRIFTS Prototype Allowing<i>Operando</i>Characterizations during Fischer-Tropsch Synthesis over Cobalt-Based Catalysts under Representative Conditions

The Fischer‐Tropsch reaction transforms syngas into high added value products, among which liquid fuels. Numerous parameters determine catalytic activity and selectivity towards the most desired hydrocarbons. The performances of cobalt‐based catalysts used in the reaction are known to depend critically on Co particle size and crystallographic phase. Here, we present a comparative study of Co‐based catalysts supported on three carbon supports: multi‐wall carbon nanotubes, carbon nanofibers and a fibrous material. Our results show that, while the selectivity towards C5+ follows the expected tendency with respect to Co particle size, this is not the case for the TOF. These results can be rationalized considering that the amount of H2 uptake on each catalyst increases with oxygen and defect concentration on the support. The catalyst on the support presenting many edges and oxygen surface groups, necessary for H2 spillover, presents the highest activity. Furthermore, the hydrogen spillover contributes to the enhancement of olefin hydrogenation and methane production.

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“…Where

S_{i}

is the selectivity in a j product containing i carbon atoms, and

{\dot{F}}_{j}

is the molar flow rate of the product out of the reactor…”

Section: Methodsmentioning

confidence: 99%

Hydrogen Spillover in the Fischer‐Tropsch Synthesis on Carbon‐supported Cobalt Catalysts

et al. 2019

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“…However, the presence of infraredtransparent species such as atomic carbon, amorphous polymeric carbon or graphene could not be ruled out, as already suggested in a similar study. 21 Operando DRIFT spectra also indicate the formation of cobalt carbonyl species at the surface of the catalyst (Fig. 6).…”

Section: Drifts Operando Characterizationmentioning

confidence: 93%

Simultaneous investigation of the structure and surface of a Co/alumina catalyst during Fischer–Tropsch synthesis: discrimination of various phenomena with beneficial or disadvantageous impact on activity

Scalbert

Clémençon

Lecour

et al. 2015

Catal. Sci. Technol.

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A system combining XRD and DRIFTS characterization techniques was developed to monitor the structure and the surface of a cobalt catalyst during the Fischer-Tropsch synthesis. In the present study, several phenomena could be observed and discriminated. Firstly, residual cobalt oxide was found to further reduce during the reaction, but this enhancement in reduction degree did not clearly lead to a gain of activity. Secondly, the formation of linear and bridged carbonyls took place rapidly at the surface of the catalyst. A surprising increase in activity was observed while the concentration of carbonyls decreased, supporting the idea that CO dissociation was a crucial step in the Fischer-Tropsch mechanism. Arising from that, the increase in activity was attributed to surface reconstruction which transforms sites favoring strong CO adsorption into sites active for CO dissociation. Finally, most of the catalyst deactivation was assigned to the formation of surface oxygenate species, which were suspected to result from the reduction of CoO with hydrocarbons.Catal. Sci. Technol. This journal is † Electronic supplementary information (ESI) available: TEM and magnetism measurements; conversion, selectivity, yield and TOF calculations; estimation of reduction degree. See

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“…Continuous reaction and analysis is a relevant approach for sustainable chemical process [1] [2]. Ideally, techniques should provide scalable data and should be suitable for adaptation to industrial equipment (for ultimate application to process and quality control).…”

Section: Introductionmentioning

confidence: 99%

Forward Looking Analysis Approach to Assess Copper Acetate Thermal Decomposition Reaction Mechanism

Youssef¹,

Sall²,

Dintzer³

et al. 2019

AJAC

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Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with µ gas chromatography-mass spectrometry (µGC-MS) with other analytical techniques (thermogravimetry analysis and in situ X-ray diffraction). Non-isothermal kinetic was examined in air and Ar.A complete analysis of the evolution of infrared spectra matched with crystalline phase transition data during the course of reaction allows access to significant and accurate information about molecular dynamics. While thermogravimetry gives broad conclusion about two steps reaction (dehydration and decarboxylation), in line approach (in situ X-ray and in situ DRIFT coupled to µGC-MS) is proposed as an example of a new robust and forward-looking analysis. While decomposition mechanism of copper acetate monohydrate is still not well elucidated yet previously, the present in-line characterization results lead to accurate data making the corresponding mechanism explicit. techniques able to analyze data about different reaction media: powder, solid, liquid and gases. Two strategies could be proposed: continuous sampling coupled with fast analytical technique on one hand and in situ spectroscopic analysis on the other hand. Both approaches are complementary.Metal carboxylates are useful reagents particularly for organic synthesis [3] and applied in several fields of research as solid-state, surface chemistry and catalysis [3] [4] [5] [6]. The thermal decomposition of metal carboxylates is a feasible route to synthesize metal nanoparticles suitable for catalytic purposes [7] [8]

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Development of an Innovative XRD-DRIFTS Prototype AllowingOperandoCharacterizations during Fischer-Tropsch Synthesis over Cobalt-Based Catalysts under Representative Conditions

Cited by 7 publications

References 21 publications

Hydrogen Spillover in the Fischer‐Tropsch Synthesis on Carbon‐supported Cobalt Catalysts

Hydrogen Spillover in the Fischer‐Tropsch Synthesis on Carbon‐supported Cobalt Catalysts

Simultaneous investigation of the structure and surface of a Co/alumina catalyst during Fischer–Tropsch synthesis: discrimination of various phenomena with beneficial or disadvantageous impact on activity

Forward Looking Analysis Approach to Assess Copper Acetate Thermal Decomposition Reaction Mechanism

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