Attachment of Iron Oxide Nanoparticles to Carbon Nanotubes and the Consequences for Catalysis

Krans, Nynke A.; Feltz, Ewout C. van der; Xie, Jingxiu; Dugulan, Iulian; Zečević, Jovana; Jong, K.P. de

doi:10.1002/cctc.201800487

Cited by 12 publications

(14 citation statements)

References 44 publications

(100 reference statements)

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“…After 187 h of TOS particle sizes slightly increased for both promoted and unpromoted catalysts (Figure 7) while the latter show the lower growing rate (Table 1). In agreement with previous studies, oxygen-treatment of the CNTs leads to undesired delay of catalyst activation and lower catalytic activity independent of the presence or absence of promoters [28,29,43] .…”

Section: Properties Of the Fe/cnt Catalysts In The Fto Reactionsupporting

confidence: 92%

Tandem promotion of iron catalysts by sodium-sulfur and nitrogen-doped carbon layers on carbon nanotube supports for the Fischer-Tropsch to olefins synthesis

Lama

Weber

Heil

et al. 2018

Applied Catalysis A: General

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Section: Properties Of the Fe/cnt Catalysts In The Fto Reactionsupporting

confidence: 92%

Tandem promotion of iron catalysts by sodium-sulfur and nitrogen-doped carbon layers on carbon nanotube supports for the Fischer-Tropsch to olefins synthesis

Lama

Weber

Heil

et al. 2018

Applied Catalysis A: General

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“…Applications involving iron oxide nanoparticles (IONPs) receive considerable attention in fields requiring large quantities such as biomass recovery and agriculture [1][2][3], and waste water treatment [4]. IONPs with higher quality requirements find applications in catalysis [5,6], batteries [7] and especially biomedicine [8][9][10][11], including drug delivery [12,13], magnetic hyperthermia therapy of cancer [10,14,15], and contrast agent for magnetic resonance imaging [16,17]. Their performance depends strongly on the oxide phase, the particle morphology, the size and size distribution, the internal composition (e.g., impurities, and grain boundaries) and the surface chemistry.…”

Section: Introductionmentioning

confidence: 99%

Co-precipitation synthesis of stable iron oxide nanoparticles with NaOH: New insights and continuous production via flow chemistry

Besenhard

LaGrow

Hodžić

et al. 2020

Chemical Engineering Journal

100

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Co-precipitation is by far the most common synthesis for magnetic iron oxide nanoparticles (IONPs), as cheap and environmentally friendly precursors and simple experimental procedures facilitate IONP production in many labs. Optimising co-precipitation syntheses remains challenging however, as particle formation mechanisms are not well understood. This is partly due to the rapid particle formation (within seconds) providing insufficient time to characterise initial precipitates. To overcome this limitation, a flow chemistry approach has been developed using steady-state operation to "freeze" transient reaction states locally. This allowed for the first time a comprehensive analysis of the early stages of co-precipitation syntheses via in-situ Small Angle X-ray Scattering and in-situ synchrotron X-Ray Diffraction. These studies revealed that after mixing the ferrous/ferric chloride precursor with the NaOH base solution, the most magnetic iron oxide phase forms within 5 s, the particle size changes only marginally afterwards, and co-precipitation and agglomeration occur simultaneously. As these agglomerates were too large to achieve colloidal stability via subsequent stabiliser addition, co-precipitated IONPs had to be de-agglomerated. This was achieved by adding the appropriate quantity of a citric acid solution which yielded within minutes colloidally stable IONP solutions around a neutral pH value. The new insights into the particle formation and the novel stabilisation procedure (not requiring any ultra-sonication or washing step) allowed to design a multistage flow reactor to synthesise and stabilise IONPs continuously with a residence time of less than 5 min. This reactor was robust against fouling and produced stable IONP solutions (of ~ 1.5 mg particles per ml) reproducibly via fast mixing (< 50 ms) and accurate temperature control at large scale (> 500 ml/h) for low materials cost.

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“…Iron oxide nanoparticles (Fe-NP) of 6 nm were synthesized according to a previously published method. , Figure A shows a transmission electron micrograph of the colloidal particles synthesized with organic oleic acid and oleylamine ligands. The organic ligands separated the iron oxide particles by 2 nm when dried on the transmission electron microscopy (TEM) grid, which is associated with the length of one oleic acid or oleylamine ligand. , These Fe-NP were used in an inorganic ligand exchange step to add Na + S promoters, following a procedure mentioned in previous research , (FeP-NP).…”

Section: Resultsmentioning

confidence: 99%

“…Here, an iron precursor is decomposed at higher temperatures in a solvent in the presence of organic ligands, resulting in ligand stabilized Fe-NP in suspension. Colloidal particles are subsequently attached to different support materials, obtaining relatively sinter-resistant catalysts. − …”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, model catalysts composed of colloidal iron nanoparticles supported on carbon nanotubes (CNT) were used to study the FTO reaction. , These colloidal particles were promoted with sodium and sulfur using an inorganic ligand exchange method. − Here, the organic ligands stabilizing the Fe-NP are (partially) replaced with inorganic ligands that can also act as promoters, such as Na 2 S. , When applied in the FTO process, this exchange was performed after the Fe-NP were attached to the support material . However, so far it has been challenging to direct the promoters so that they specifically attach to the iron particles and not to the support material.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Promotion on the Growth of Anchored Colloidal Iron Oxide Nanoparticles during Synthesis Gas Conversion

et al. 2020

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Using colloidal iron oxide nanoparticles with organic ligands, anchored in a separate step from the supports, has been shown to be beneficial to obtain homogeneously distributed metal particles with a narrow size distribution. Literature indicates that promoting these particles with sodium and sulfur creates an active Fischer−Tropsch catalyst to produce olefins, while further adding an H-ZSM-5 zeolite is an effective way to obtain aromatics. This research focused on the promotion of iron oxide colloids with sodium and sulfur using an inorganic ligand exchange followed by the attachment to H-ZSM-5 zeolite crystals. The catalyst referred to as FeP/Z, which consists of iron particles with inorganic ligands attached to a H-ZSM-5 catalyst, was compared to an unpromoted Fe/Z catalyst and an Fe/Z-P catalyst, containing the colloidal nanoparticles with organic ligands, promoted after attachment. A low CO conversion was observed on both FeP/Z and Fe/Z-P, originating from an overpromotion effect for both catalysts. However, when both promoted catalysts were washed (FeP/Z-W and Fe/Z−P-W) to remove the excess of promoters, the activity was much higher. Fe/Z-P-W simultaneously achieved low selectivity toward methane as part of the promoters were still present after washing, whereas for FeP/Z-W the majority of promoters was removed upon washing, which increased the methane selectivity. Moreover, due to the addition of Na+S promoters, the iron nanoparticles in the FeP/Z(-W) catalysts had grown considerably during catalysis, while those in Fe/Z-P(-W) and Fe/Z(-W) remained relatively stable. Lastly, as a large broadening of particle sizes for the used FeP/Z-W was found, where particle sizes had both increased and decreased, Ostwald ripening is suggested for particle growth accelerated by the presence of the promoters.

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Attachment of Iron Oxide Nanoparticles to Carbon Nanotubes and the Consequences for Catalysis

Cited by 12 publications

References 44 publications

Tandem promotion of iron catalysts by sodium-sulfur and nitrogen-doped carbon layers on carbon nanotube supports for the Fischer-Tropsch to olefins synthesis

Tandem promotion of iron catalysts by sodium-sulfur and nitrogen-doped carbon layers on carbon nanotube supports for the Fischer-Tropsch to olefins synthesis

Co-precipitation synthesis of stable iron oxide nanoparticles with NaOH: New insights and continuous production via flow chemistry

Influence of Promotion on the Growth of Anchored Colloidal Iron Oxide Nanoparticles during Synthesis Gas Conversion

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