Comparison of reducibility and stability of alumina-supported Ni catalysts prepared by impregnation and co-precipitation
Comparison of reducibility and stability of alumina-supported Ni catalysts prepared by impregnation and co-precipitation
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DOI：
10.1016/j.apcata.2005.11.013
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发表时间：
2006-02-10
影响因子：
5.5
通讯作者：
Hill, JM
中科院分区：
文献类型：
--
作者：
Li, GH;Hu, LJ;Hill, JM
通过共沉淀（Ni-Al 共沉淀）、内部溶胶-凝胶衍生的氧化铝（Ni/溶胶-凝胶 Al2O3）浸渍和商业 γ-Al-2-O-3（Ni/-γ-Al2O3）浸渍，制备了三种镍负载量为 10-13 wt.% 的 Ni-Al2O3 催化剂。通过N-2物理吸附、H-2化学吸附、TPR、XRD、SEM和TEM对催化剂进行了表征。 Ni种类、Ni颗粒尺寸和Ni还原性取决于制备方法。 Ni-Al共沉淀物和Ni/sol-gel Al2O3催化剂在煅烧后含有NiAl2O4物质，而Ni/-γ-Al2O3催化剂在煅烧后含有NiO和NiAl2O4物质。尽管 Ni/gamma-Al2O3 催化剂最容易还原，但根据 TPR，该催化剂在 100 小时的温度分级还原实验中具有最低的氢吸收量。 Ni-Al共沉淀和Ni/溶胶-凝胶Al2O3催化剂在550℃还原31小时后镍分散度超过7%，在650℃还原7小时后最大分散度接近10%。在 550 摄氏度还原后，通过 TEM 检查，Ni 颗粒不明显。结果表明，制备过程中表面NiAl2O4尖晶石相的形成有利于还原催化剂中Ni的高分散。 (c) 2005 Elsevier B.V. 保留所有权利。
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.