期刊
APPLIED CATALYSIS A-GENERAL
卷 301, 期 1, 页码 16-24出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apcata.2005.11.013
关键词
nickel catalysts; alumina; reducibility; co-precipitation; impregnation; catalyst preparation; stability; sol-gel synthesis
Three Ni-Al2O3 catalysts, with nickel loadings of 10-13 wt.%, were prepared by co-precipitation (Ni-Al co-precip), impregnation on an in-house sol-gel derived alumina (Ni/sol-gel Al2O3), and impregnation on a commercial gamma-Al-2-O-3 (Ni/-gamma-Al2O3). The catalysts were characterized by N-2 physisorption, H-2 chemisorption, TPR, XRD, SEM and TEM. The Ni species, Ni particle size, and Ni reducibility depended on the preparation method. The Ni-Al co-precip and Ni/sol-gel Al2O3 catalysts contained NiAl2O4 species after calcination, while the Ni/-gamma-Al2O3 catalyst contained NiO and NiAl2O4 species after calcination. Although the Ni/gamma-Al2O3 catalyst was the easiest to reduce, according to TPR, this catalyst had the lowest hydrogen uptake over a 100 h temperature-staged reduction experiment. The Ni-Al co-precip and Ni/sol-gel Al2O3 catalysts had Ni dispersions of over 7% with reduction at 550 degrees C for 31 h, and maximum dispersions of similar to 10%, after reduction at 650 degrees C for 7 h. After reduction at 550 degrees C, the Ni particles were not evident by TEM examination. The results suggest that the formation of a surface NiAl2O4 spinet phase during preparation is beneficial for a high Ni dispersion in the reduced catalyst. (c) 2005 Elsevier B.V. All rights reserved.
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