Relationships between the Hydrogenation and Dehydrogenation Properties of Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Studied by In Situ MAS NMR Spectroscopy and Conventional Heterogeneous Catalysis
Relationships between the Hydrogenation and Dehydrogenation Properties of Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Studied by In Situ MAS NMR Spectroscopy and Conventional Heterogeneous Catalysis
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DOI：
10.1021/acs.jpcc.5b11367
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发表时间：
2016-02-01
影响因子：
3.7
通讯作者：
Hunger, Michael
中科院分区：
文献类型：
--
作者：
Obenaus, Utz;Neher, Felix;Hunger, Michael
在半间歇条件下，用原位固体核磁共振波谱研究了同系含贵金属分子筛Y的本征加氢活性。测定了丙烯腈加氢反应的反应速率顺序为：Pd/H，Na-Y&Gt；Rh/H，Na-Y&Gt；Pt/H，NaY&Gt；Ir/H，Na-Y。丙烷在这些沸石上的脱氢反应表现出Ir/H、Na-Y&Gt、Rh/H、Na-Y&Gt、Pd/H、Na-Y沸石的顺序，而铂/H、Na-Y沸石表现出较高的活性。利用程序升温脱氢(H-2-TPD)技术研究了H-2与金属的相互作用强度。高温峰的位置依次为2.8Pd/H，Na-Y(723K)和Gt；2.3Rh/H，Na-Y(713K)和Gt；4.7Ir/H，Na-Y(663K)。与Rh/H，Na-Y和Ir/H，Na-Y沸石相比，Pd/H，Na-Y沸石具有较高的加氢活性。在丙烷脱氢反应中，Pd/H、Na-Y分子筛中较强的H-2/Pd相互作用阻碍了反应产物H-2的脱附，这解释了这些分子筛的脱氢活性低于Rh/H、Na-Y和Ir/H、Na-Y分子筛。为了使铂/氢、钠-Y沸石具有较高的催化活性，讨论了强化学吸附的氢原子在铂团簇中的作用。
The intrinsic hydrogenation activities of homologous series of noble-metal-containing zeolites Y were studied by in situ solid-state NMR spectroscopy under semibatch conditions. For the hydrogenation of acrylonitrile, reaction rates in the sequence Pd/H,Na-Y > Rh/H,Na-Y > Pt/H,Na Y > Ir/H,Na-Y were determined. The dehydrogenation of propane at these zeolites gave a sequence of the turnover frequencies of Ir/H,Na-Y > Rh/H,Na-Y > Pd/H,Na-Y, while Pt/H,Na-Y zeolites showed significantly higher activities. The temperature-programmed desorption of hydrogen (H-2-TPD) was utilized for studying the strength of H-2/metal interactions. The positions of the high temperature peaks were arranged according to 2.8Pd/H,Na-Y (723 K) > 2.3Rh/H,Na-Y (713 K) > 4.7Ir/H,Na-Y (663 K). Comparison of these data indicates that strong H-2/metal interactions are accompanied by a preferred formation of surface hydrogen atoms, which are the reason for the high hydrogenation activity of Pd/H,Na-Y zeolites compared with Rh/H,Na-Y and Ir/H,Na-Y zeolites. In the case of the propane dehydrogenation, the strong H-2/Pd interactions in Pd/H,Na-Y zeolites hinder the desorption of the reaction product H-2, explaining the lower dehydrogenation activity of these zeolites compared with Rh/H,Na-Y and Ir/H,Na-Y zeolites. For the high catalytic activities of the Pt/H,Na-Y zeolites, an effect of strongly chemisorbed hydrogen atoms inside the Pt clusters is discussed.