Decomposition of metal carbides as an elementary step of carbon nanotube synthesis

Ni, Lei; Kuroda, Keiji; Zhou, Lei; Ohta, Keishin; Matsuishi, Kiyoto; Nakamura, Junji

doi:10.1016/j.carbon.2009.07.009

Cited by 55 publications

(40 citation statements)

References 37 publications

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“…. These five peaks attributed to MgO were also detected in the XRD pattern of the reduced Fe-Mo/MgO catalyst in a study conducted by Ni et al (2009) and in the XRD pattern for the calcined as well as reduced CoMo/MgO catalyst, also reported earlier by Ni et al (2006). The patterns also demonstrated that the intensity of the MgO peaks decreased as the metal loading increased.…”

Section: Xrd Analysissupporting

confidence: 74%

The Effect of Metal Loading on the Performance of Tri-metallic Supported Catalyst for Carbon Nanotubes Synthesis from Liquefied Petroleum Gas

Setyopratomo

Wulan²,

Sudibandriyo³

2018

IJTech

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Carbon nanotubes (CNT) were synthesized from liquefied petroleum gas by a chemical vapor deposition method using a Fe-Co-Mo/MgO supported catalyst. Metal loading was varied from 2.5 to 20 wt%. The catalyst with metal loading of 10 wt% produced the highest CNT yield, at 4.55 g CNT/g catalyst. This high CNT yield was attributed to the high pore volume of the catalyst. The diameter of the CNT was quite variable: the outer diameter ranged from about 4 to 12 nm, while the inner diameter ranged from about 2 to 5 nm. The catalyst with 10 wt% metal loading produced CNT with the highest surface area and the largest total pore volume. XRD analysis detected the existence of highly oriented pyrolytic graphite, C(002), at 2 theta ≈ 26 o , which was attributed to the CNT.

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Section: Xrd Analysissupporting

confidence: 74%

The Effect of Metal Loading on the Performance of Tri-metallic Supported Catalyst for Carbon Nanotubes Synthesis from Liquefied Petroleum Gas

Setyopratomo

Wulan²,

Sudibandriyo³

2018

IJTech

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“…The presence of cementite (Fe 3 C) in the XRD pattern suggests that (metastable) iron carbides are active in the catalytic graphitization process. The decomposition temperature of Fe 3 C is T = 700°C, 13 which is similar to the temperature of reduction of the iron oxide (FeO) The Journal of Physical Chemistry C Article to metallic iron (Fe(0)) and is in line with the temperature at which graphite formation is observed. Figure 10A shows a TEM image of the graphitic material obtained during pyrolysis of iron-loaded MCC beads at T = 800°C.…”

Section: Resultsmentioning

confidence: 86%

Base Metal Catalyzed Graphitization of Cellulose: A Combined Raman Spectroscopy, Temperature-Dependent X-ray Diffraction and High-Resolution Transmission Electron Microscopy Study

et al. 2015

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Microcrystalline cellulose (MCC) spheres homogeneously loaded with the nitrate salts of copper, nickel, cobalt, or iron are excellent model systems to establish the temperature at which highly dispersed base metal nanoparticles are formed as well as to establish the temperature at which catalytic graphitization occurs during pyrolysis in the temperature regime T = 500−800°C. Temperature-dependent X-ray diffraction (TD-XRD) and high-resolution transmission electron microscopy (HRTEM) showed that the base metal nanoparticles are smoothly formed from related base metal oxides via carbothermal reduction (fcc copper, T < 500°C; fcc nickel, T < 500°C; fcc cobalt, T = 570°C; bcc iron, T = 700°C). Moreover, it is shown that at distinct temperatures nickel (T ≥ 800°C), cobalt (T ≥ 800°C), and iron (T ≥ 715°C) nanoparticles catalyze the conversion of the amorphous carbon support into ribbons of turbostratic graphitic carbon according to Raman spectroscopy and TD-XRD. Copper, however, was found to be inactive. Furthermore, HRTEM revealed that nickel (500°C ≤ T < 800°C) and cobalt nanoparticles (700°C ≤ T < 800°C) after their initial formation become encapsulated by graphite-like shells prior to the onset of catalytic graphitization. This does not occur in the presence of iron nanoparticles. This distinction is attributed to the temperature required to access iron nanoparticles by carbothermal reduction and their concomitant mobility. Evidence (HRTEM) is provided that for the onset of catalytic graphitization nickel and cobalt nanoparticles first have to escape from their graphite-like shells. Therefore, iron nanoparticles are the most active catalyst. Our results further show that (metastable) metal carbides play a pivotal role in catalytic graphitization. This is demonstrated by the inactivity of copper nanoparticles, the distinct onset temperatures of catalytic graphitization, and the identification of cementite in the case of iron nanoparticles.

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“…In Table 3, a decrease with time on stream is observed in the Ni crystallite size of the used catalysts, from 10.0 to 5.1 nm. According to the literature, this decrease in Ni crystallite size can be explained by the formation of NiC due to the diffusion of C reactive species (from the carbonaceous intermediates and products in the process) through Ni particles [33,59,60]. This NiC is considered an intermediate in the formation of filamentous coke, according to a mechanism in which dissolved C (from NiC or low-reactive C species) diffuses through Ni and nucleates and precipitates on the base of a Ni crystallite.…”

Section: Evolution Of Ni Particles and Cokementioning

confidence: 95%

Monitoring Ni 0 and coke evolution during the deactivation of a Ni/La 2 O 3 –αAl 2 O 3 catalyst in ethanol steam reforming in a fluidized bed

Montero

Ochoa

Castaño

et al. 2015

Journal of Catalysis

228

110

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Decomposition of metal carbides as an elementary step of carbon nanotube synthesis

Cited by 55 publications

References 37 publications

The Effect of Metal Loading on the Performance of Tri-metallic Supported Catalyst for Carbon Nanotubes Synthesis from Liquefied Petroleum Gas

The Effect of Metal Loading on the Performance of Tri-metallic Supported Catalyst for Carbon Nanotubes Synthesis from Liquefied Petroleum Gas

Base Metal Catalyzed Graphitization of Cellulose: A Combined Raman Spectroscopy, Temperature-Dependent X-ray Diffraction and High-Resolution Transmission Electron Microscopy Study

Monitoring Ni 0 and coke evolution during the deactivation of a Ni/La 2 O 3 –αAl 2 O 3 catalyst in ethanol steam reforming in a fluidized bed

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