The liquid-phase hydrogenation of 1-heptyne over Pd-Au/TiO₂ catalysts prepared by the combination of incipient wetness impregnation and deposition-precipitation

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• 作者：Prathan Kittisakmontree^a ; Boontida Pongthawornsakun^a ; Hiroshi Yoshida^b ; Shin-ichiro Fujita^b ; Masahiko Arai^b ; Joongjai Panpranot^a ; ^{joongjai.p@chula.ac.th}
• 关键词：1-Heptyne ; Selective hydrogenation ; Liquid-phase hydrogenation ; Pd&ndash ; Au bimetallic catalysts
• 刊名：Journal of Catalysis
• 出版年：2013
• 出版时间：January, 2013
• 年：2013
• 卷：297
• 期：Complete
• 页码：155-164
• 全文大小：1446 K

文摘

TiO₂-supported Pd-Au catalysts were prepared with Pd (0.5 wt % ) by impregnation and then Au (1.0 wt % ) by deposition-precipitation (Au/Pd/TiO₂) and vice versa (Pd/Au/TiO₂). For the former sample, the state of dispersion of Pd on TiO₂ changed during the loading of Au, resulting in the formation of small Au-Pd alloy particles and thus changing the electronic properties of Pd species. The alloy formation was not clearly detected on the Pd/Au/TiO₂, and the electronic properties of Pd were not so different from those of monometallic Pd/TiO₂. All the catalysts were selective to 1-heptene (>95 % ) until close to the complete conversion of 1-heptyne. However, the selectivity of 1-heptene drastically decreased to 0 % (which was further hydrogenated to heptane) in 120 min for the Au/Pd/TiO₂ while it still remained >60 % for the Pd/Au/TiO₂ similar to the monometallic Pd/TiO₂ catalyst. The rate of 1-heptene hydrogenation (in the second step) did not depend on the Pd dispersion but was found to be greatly enhanced as the Pd species became electron-rich in the Au-Pd alloy particles. The modification of Pd species by Au was less significant for the first step of hydrogenation of 1-heptyne to 1-heptene.