Synthesis of CNT-supported cobalt nanoparticle catalysts using a microemulsion technique: Role of nanoparticle size on reducibility, activity and selectivity in Fischer–Tropsch reactions

Trépanier, Mariane; Dalai, Ajay K.; Abatzoglou, Nicolas

doi:10.1016/j.apcata.2009.11.029

Cited by 146 publications

(105 citation statements)

References 26 publications

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“…This facilitated reduction of metal oxide induced by confinement in CNTs appears to be a general phenomenon because a similar trend was observed for ruthenium 20 and cobalt. 28 Raman spectroscopy showed that the FeÀO band redshifted for the outside Fe 2 O 3 particles with respect to bulk Fe 2 O 3 . 22 However, it blue-shifted for the CNT-confined Fe 2 O 3 particles compared with the outside oxide.…”

Section: Gas-phase Reactionsmentioning

confidence: 98%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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T he unique tubular morphology of carbon nanotubes (CNTs) has triggered wide research interest. These structures can be used as nanoreactors and to create novel composites through the encapsulation of guest materials in their well-defined channels. The rigid nanotubes restrict the size of the encapsulated materials down to the nanometer and even the subnanometer scale. In addition, interactions may develop between the encapsulated molecules and nanomaterials and the CNT surfaces. The curvature of CNT walls causes the π electron density of the graphene layers to shift from the concave inner to the convex outer surface, which results in an electric potential difference. As a result, the molecules and nanomaterials on the exterior walls of CNTs likely display different properties and chemical reactivities from those confined within CNTs. Catalysis that utilizes the interior surface of CNTs was only explored recently. An increasing number of studies have demonstrated that confining metal or metal oxide nanoparticles inside CNTs often leads to a different catalytic activity with respect to the same metals deposited on the CNT exterior surface. Furthermore, this inside and outside activity difference varies based on the metals used and the reactions catalyzed.In this Account, we describe the efforts toward understanding the fundamental effects of confining metal nanoparticles inside the CNT channels. This research may provide a novel approach to modulate their catalytic performance and promote rational design of catalysts. To achieve this, we have developed strategies for homogeneous dispersion of nanoparticles inside nanotubes. Because researchers have previously demonstrated the insertion of nanoparticles within larger nanotubes, we focused specifically on multiwalled carbon nanotubes (MWCNTs) with an inner diameter (i.d.) smaller than 10 nm and double-walled carbon nanotubes (DWCNTs) with 1.0À1.5 nm i.d. The results show that CNTs with well-defined morphology and unique electronic structure of CNTs provide an intriguing confinement environment for catalysis.

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Section: Gas-phase Reactionsmentioning

confidence: 98%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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“…Interestingly, the temperature of the first reduction peak decreased with decreasing cobalt oxide nanoparticle size from 9.12 to 7.32 nm. Terapnier et al [11]. Observed that the reduction temperature of the first peak decreases with decreasing cobalt particle size from 10 to 3 nm.The second reduction peak for IW catalyst shifts to higher temperatures (473 °C) compared to CR catalyst (455 °C).…”

Section: Characterization Of Catalystsmentioning

confidence: 99%

“…According to Fig. 4, the deposition of cobalt nanoparticles synthesized by chemical reduction on the alumina support shift the reduction temperature of the Co 3 O 4 to CoO species (first peak in 358°C) to a lower temperature compared to the catalyst prepared by the incipient wetness impregnation method (380°C), which indicated higher reducibility for uniform particles of CR catalyst [11]. Interestingly, the temperature of the first reduction peak decreased with decreasing cobalt oxide nanoparticle size from 9.12 to 7.32 nm.…”

Section: Characterization Of Catalystsmentioning

confidence: 99%

“…For each two catalyst, the low temperature peak (300-400 °C) was assigned to reduction of Co 3 O 4 to CoO [11].The second broad peak (400-500 °C) was related to reduction of small CoO to Co0 species [11].The high temperature reduction peaks a (545°C for CR catalyst and 560°C for IW catalyst) would be assigned to reduction of cobalt aluminate formation due to a strong interaction between cobalt and the alumina support, which is in agreement with results of XRD analysis [7]. According to Fig.…”

Section: Characterization Of Catalystsmentioning

confidence: 99%

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Role of Nanoparticle Size on Performance of Partial Oxidation of Butane Process to Syngas

Fakoori¹,

Honarvar

2017

J. Chil. Chem. Soc.

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In this study, performance of nano structure Co/γ-Al 2 O 3 catalysts in partial oxidation of butane was investigated. The catalysts were produced through chemical reduction and incipient wetness impregnation methods. Prepared catalysts were characterized with X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM),N 2 adsorption/desorption (BET), temperature programmed reduction (TPR) and thermal gravity analysis (TGA).The characterization results confirmed the uniform dispersion of Co nanoparticles over γ-Al 2 O 3 by using chemical reduction. Butane conversion, H 2 and CO selectivities increased by decreasing of Co particle size due to higher dispersion and reducibility. The optimum value of H 2 /CO ratio of 2 obtained from chemical reduction technique. The results showed that the stability of catalyst produced by chemical reduction method was higher than incipient wetness impregnation ones.

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“…Carbon nanotubes (CNT), when used as a catalyst carrier-support for Co nanoparticles, provides a higher reproducibility and higher degree of dispersion of catalyst [79]. Moreover, the catalytic activity of Co in FTS depends on its size distribution [80]:…”

Section: Fischer-tropsch Synthesismentioning

confidence: 99%

Microemulsion Route for the Synthesis of Nano-Structured Catalytic Materials

Hussain¹,

Batool²

2017

Properties and Uses of Microemulsions

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Owing to their unique properties, use of microemulsion-based synthetic techniques for the generation of shape-controlled nanocatalyst is an area of great current interest. Nanocatalysts of any specific shape, morphology, surface area, size, geometry, homogeneity and composition are widely being prepared using the soft techniques of microemulsion. Easy handling, inexpensive equipment and mild reaction conditions make microemulsion an attractive reaction medium. Herein, a nanosized precursor reactant can be incorporated, leading to the formulation of a highly monodispersed metal nanoagglomerate with controlled size, shape and composition. Several factors such as presence of electrolyte, molar ratio of water to surfactant, nature and concentration of surfactant and solvent, size of water droplets and concentration of reducing agents influence the size of the nanoparticles. The reverse micelle method can be used for the fabrication of several nanosized catalysts with a diverse variety of suitable materials including silica, alumina, metals (e.g. Au, Pd, Rh, Pt), metal oxides, etc. The morphology, size distribution and shape of the nanocatalysts make them useable for a wide range of applications, for example, fuel cells, electrocatalysis, photocatalysis, environmental protection, etc. The recovery of nanoparticles from the reaction mixture is a challenge for the researchers. This chapter discusses the preparation of nanoparticles using microemulsion techniques, widely being used for the synthesis of nanocatalysts from a wide range of materials.

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Synthesis of CNT-supported cobalt nanoparticle catalysts using a microemulsion technique: Role of nanoparticle size on reducibility, activity and selectivity in Fischer–Tropsch reactions

Cited by 146 publications

References 26 publications

The Effects of Confinement inside Carbon Nanotubes on Catalysis

The Effects of Confinement inside Carbon Nanotubes on Catalysis

Role of Nanoparticle Size on Performance of Partial Oxidation of Butane Process to Syngas

Microemulsion Route for the Synthesis of Nano-Structured Catalytic Materials

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