Promotional effect of Au on reduction of Ni(II) to form Au-Ni alloy catalysts for hydrogenolysis of benzylic alcohols
Promotional effect of Au on reduction of Ni(II) to form Au-Ni alloy catalysts for hydrogenolysis of benzylic alcohols
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DOI：
10.1016/j.jcat.2013.07.027
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发表时间：
2013-11-01
影响因子：
7.3
通讯作者：
Tokunaga, Makoto
中科院分区：
文献类型：
--
作者：
Nishikawa, Hiroaki;Kawamoto, Daisuke;Tokunaga, Makoto
以Au/NiO和Au(OH)(3)-Ni(OH)(2)-NiCO3共沉淀物为原料，经氢处理制备金-镍双金属催化剂。通过H-2-TPR和原位XAFS测试证实，在100-150℃的较低温度下，金促进了Ni（II）还原为Ni(0)，而不含Au的NiO即使在300℃下也不能完全还原。通过XRD、HAADF-STEM、XAFS和Au-197 Mossbauer对催化剂进行了表征，这些分析揭示了催化剂中Au-Ni合金成分的形成。在Au/NiO经H-2处理制备的Au- ni -1中，Au以Au纳米粒子的形式与Au- ni合金组分一起存在。当Au(OH)(3)-Ni(OH)(2)-NiCO3在H-2流中处理生成Au-Ni-2时，没有明显观察到Au NPs的形成，这意味着Au原子在得到的催化剂中以单原子和/或小簇的形式高度分散。此外，大部分Au原子与Ni原子形成Au-Ni-2合金。所得的Au-Ni-1和Au-Ni-2对苯基醇选择性氢解生成烷基苯衍生物具有优异的催化活性，反应速率由催化剂表面积归一化。因此，Au-Ni-1和Au-Ni-2的反应速率分别为4.79和9.79 mmol L-1 h(-1) m（-2）。这些值大于Raney Ni (0.14 mmol L-1 h（-1) m(-2)）。此外，Au-Ni-2的反应速率比Au-Ni-1快，因为Au-Ni合金含量较高。由于Au/TiO2对氢解的催化活性较差，Au-Ni合金增强了Ni(0)的催化活性。(C) 2013爱思唯尔公司版权所有。
Gold-nickel bimetallic catalysts were prepared from Au/NiO and Au(OH)(3)-Ni(OH)(2)-NiCO3 coprecipitates by treatment with hydrogen. Gold promoted the reduction of Ni(II) to Ni(0) at relatively low temperatures in the range of 100-150 degrees C, which was confirmed by H-2-TPR and in situ XAFS measurements, whereas NiO without Au was not fully reduced even at 300 degrees C. The obtained catalysts were characterized by XRD, HAADF-STEM, XAFS, and Au-197 Mossbauer, and these analyses revealed the formation of Au-Ni alloy components in the obtained catalysts. Au existed as Au nanoparticles together with Au-Ni alloy components in Au-Ni-1 prepared from Au/NiO by H-2 treatment. When Au(OH)(3)-Ni(OH)(2)-NiCO3 was treated in a flow of H-2 to produce Au-Ni-2, the formation of Au NPs was not clearly observed, thereby meaning that Au atoms were highly dispersed as a single atom and/or small clusters in the obtained catalysts. Moreover, most of the Au atoms were alloyed with Ni atoms for Au-Ni-2. The obtained Au-Ni-1 and Au-Ni-2 exhibited superior catalytic activities for the selective hydrogenolysis of benzylic alcohols into alkylbenzene derivatives in terms of reaction rates normalized by catalyst surface area. Accordingly, Au-Ni-1 and Au-Ni-2 recorded the reaction rates of 4.79 and 9.79 mmol L-1 h(-1) m(-2), respectively. These values were greater than that obtained for Raney Ni (0.14 mmol L-1 h(-1) m(-2)). In addition, Au-Ni-2, which contains higher Au-Ni alloy content, showed greater reaction rates when compared to Au-Ni-1. Since Au/TiO2 showed poor catalytic activity for the hydrogenolysis, Au-Ni alloy enhanced the catalytic activities of Ni(0). (C) 2013 Elsevier Inc. All rights reserved.