Formation of Nickel, Cobalt, Copper, and Iron Aluminates fromα- andγ-Alumina-Supported Oxides: A Comparative Study

Nickel, iron, cobalt and copper catalysts were prepared by impregnation and used to produce carbon nanotubes and hydrogen gas from a LDPE feedstock. A two stage catalytic pyrolysis process was used to enable large yields of both products. Plastics samples were pyrolysed in nitrogen at 600°C, before the evolved gases were passed to a second stage and allowed to deposit carbon onto the catalyst at a temperature of 800°C. Carbon nanotubes were successfully generated on nickel, iron and cobalt but were barely observed on the copper catalyst. Iron and nickel catalysts gave the largest yield of both hydrogen and carbon nanotubes as a result of metal-support interactions which were neither too strong, like cobalts, nor too weak like copper. These metal support interactions proved a key factor in CNT production. A nickel catalyst with a weaker interaction was prepared using a lower calcination temperature. Yields of both carbon nanotubes and hydrogen gas were lower on the Ni-catalyst prepared at the lower calcination temperature, as a result of sintering of the nickel particles. In addition, the catalyst prepared at a lower calcination temperature produced metal particles which were too large for CNT growth, producing amorphous carbons which deactivate the catalyst instead. Overall the iron catalyst gave the largest yield of CNTs, which is attributed to both its good metal-support interactions and irons large carbon solubility.

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“…This is in accordance with literature which reports that iron forms aluminates less readily than nickel [53].…”

Section: Iron Aluminasupporting

confidence: 94%

“…The lack of cobalt oxide agrees well with literature since Co is reported to form aluminates more readily than both nickel and iron [53]. TPR results ( Figure 4) for cobalt show no significant peak associated with reduction in the temperature range tested.…”

Section: Cobalt Aluminasupporting

confidence: 89%

The use of different metal catalysts for the simultaneous production of carbon nanotubes and hydrogen from pyrolysis of plastic feedstocks

Acomb

Williams

2016

Applied Catalysis B: Environmental

221

120

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“…01-1153) produced by the chemical reactions between copper oxide and -, -alumina were also found, which is consistent with some early results [37][38][39].The main reaction paths in the temperature range of 600 ~ 1100 o C can therefore be proposed as…”

Section: Thermal Analysis and Reaction Kineticssupporting

confidence: 89%

Thermal-Chemical Characteristics of Al–Cu Alloy Nanoparticles

et al. 2015

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This work investigated the oxidation, ignition and thermal reactivity of alloy nanoparticles of aluminum and copper (nAlCu) using simultaneous thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) method. The microstructure of the particles was characterized with scanning electron microscope (SEM) and transmission electron microscope (TEM), and the elemental composition of the particles before and after the oxidation was investigated with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD).The particles were heated from room temperature to 1200 o C under different heating rates from 2 to 30 K/min in the presence of air. The complete oxidation process of the nAlCu was characterized by two exothermic and two endothermic reactions, and the reaction paths up to 1200 o C were proposed. An early ignition of nAlCu, in the temperature around 565 o C, was found at heating rates ≥ 8 K/min. The eutectic melting temperature of nAlCu was identified at ~ 546 o C, which played a critical role in the early ignition. The comparison of the reactivity with that of pure Al nanoparticles showed that the nAlCu was more reactive through alloying.

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“…25 Fe catalysts since a slight addition of Ni to the binary system is optimal to attain a remarkable effect on the product distribution. 22 we can assume that copper segregates towards the bulk via CuFe 2 O 4 spinel formation at the expense of a surface enrichment of Fe 2 O 3 . Nonetheless, the surface iron concentration was practically identical to its bulk composition, which is in strong contrast to the case of Cu 3 Al, 6 where aluminium strongly segregated to the surface (Fig.…”

Section: 14mentioning

confidence: 99%

Surface state during activation and reaction of high-performing multi-metallic alkyne hydrogenation catalysts

et al. 2011

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In partial hydrogenation of highly unsaturated compounds, high-performance heterogeneous catalysts usually consist of multi-metallic systems providing enhanced selectivity. These materials often undergo complex segregation phenomena and to understand their function, a surface-sensitive in situ methodology is crucial. Recently, we reported a novel family of ternary Cu-Ni-Fe catalysts for propyne hydrogenation with exceptional selectivity to propene. Herein, we detail our study on the surface composition and electronic state of two representative samples (Cu 2.75 Ni 0.25 Fe and Cu 3 Fe) using in situ X-ray photoelectron (XPS) and X-ray absorption (XAS) spectroscopies. Surface segregation phenomena during activation of the catalyst precursors (calcination and reduction) and hydrogenation reaction were evaluated. The multiple functions of nickel in the catalyst, which account for the extraordinary alkene selectivity, are unravelled.

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Formation of Nickel, Cobalt, Copper, and Iron Aluminates fromα- andγ-Alumina-Supported Oxides: A Comparative Study

Cited by 157 publications

References 24 publications

The use of different metal catalysts for the simultaneous production of carbon nanotubes and hydrogen from pyrolysis of plastic feedstocks

The use of different metal catalysts for the simultaneous production of carbon nanotubes and hydrogen from pyrolysis of plastic feedstocks

Thermal-Chemical Characteristics of Al–Cu Alloy Nanoparticles

Surface state during activation and reaction of high-performing multi-metallic alkyne hydrogenation catalysts

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