Surface dynamics of the intermetallic catalyst Pd₂Ga, Part II - Reactivity and stability in liquid-phase hydrogenation of phenylacetylene

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• 作者：Gregor Wowsnick ; Detre Teschner ; Marc Armbr眉ster ; Igor Kasatkin ; Frank Girgsdies ; Yuri Grin ; Robert Schl枚gl ; Malte Behrens
• 关键词：Selective hydrogenation ; Phenylacetylene ; Pd2Ga ; Intermetallic compound ; d-Band shift ; Stability ; Lindlar&rsquo ; s catalyst
• 刊名：Journal of Catalysis
• 出版年：January, 2014
• 年：2014
• 卷：309
• 期：Complete
• 页码：221-230
• 全文大小：1584 K

文摘

The catalytic properties of unsupported Pd₂Ga for the liquid-phase hydrogenation of phenylacetylene are investigated after different pre-treatments with focus on the stability of the catalyst during reaction. The surface of as-prepared Pd₂Ga consists mainly on Pd and oxidized Ga species. Under the conditions of the liquid-phase hydrogenation of phenylacetylene, the intermetallic surface cannot be reformed in situ by reduction of Ga oxide. After a reductive pre-treatment in 5% H₂/Ar at 400 掳C, an almost clean Pd₂Ga surface can be obtained. Its hydrogenation activity is significantly lowered compared to elemental Pd, which is due to the intrinsic adsorption properties of the intermetallic surface. However, residues of H₂O or O₂ lead to oxidation of this surface. Excluding these impurities, the decomposition can be suppressed. In this case, the bulk material of Pd₂Ga gets cracked during phenylacetylene hydrogenation. The controlled modification of the crystal and the electronic structure of Pd by formation of the intermetallic compound Pd₂Ga are accompanied with a decreased stability.