Structural changes in a nickel–copper catalyst during growth of nitrogen-containing carbon nanofibers by ethylene/ammonia decomposition
✍ Scribed by O.Yu. Podyacheva; Z.R. Ismagilov; A.E. Shalagina; V.A. Ushakov; A.N. Shmakov; S.V. Tsybulya; V.V. Kriventsov; A.V. Ischenko
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 685 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0008-6223
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✦ Synopsis
Structural changes in a 65Ni-25Cu-Al 2 O 3 catalyst during the decomposition of a C 2 H 4 /NH 3 mixture at different stages of nitrogen-containing carbon nanofiber (N-CNF) synthesis were studied by X-ray diffraction (XRD) analysis, X-ray diffraction using anomalous scattering effect and extended X-ray absorption fine structure (EXAFS) spectroscopy. The N-CNF growth over a catalyst particle was supposed to proceed via the formation of an oversaturated solid solution of carbon and nitrogen in a nickel-enriched alloy ''NiCu x C y N z ''. The latter resulted in an increase of the alloy lattice parameter to abnormally large values a = 3.616-3.706 A ˚without destruction of its cubic structure. The formation of the ''NiCu x- C y N z '' phase and its presence in the system coincide with the optimum time for the synthesis of N-CNFs with the highest nitrogen concentration and maximum values of specific surface area and total pore volume.