Pairwise Stereoselective Hydrogenation of Propyne on Supported Pd–Ag Catalysts Investigated by Parahydrogen-Induced Polarization
Pairwise Stereoselective Hydrogenation of Propyne on Supported Pd–Ag Catalysts Investigated by Parahydrogen-Induced Polarization
复制标题
通过仲氢诱导极化研究负载型 Pd-Ag 催化剂上丙炔的成对立体选择性氢化
DOI：
10.1021/acs.jpcc.1c02560
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发表时间：
2021-08
期刊：
影响因子：
--
通讯作者：
Feng Deng
中科院分区：
文献类型：
--
作者：
Weiyu Wang;Qiang Wang;Yueying Chu;Guodong Qi;Shenhui Li;Jun Xu;Feng Deng
炔烃半氢化提供了合成立体分子的关键方法。采用仲氢诱导极化（PHIP）核磁共振技术研究了 Al2O3 负载的 Pd-Ag 双金属催化剂上丙炔立体选择性加氢制丙烯的过程。负载型催化剂通过初湿浸渍法制备，并通过改变 Pd 和 Ag 组分来系统调节其性能。 X 射线衍射、红外光谱和透射电子显微镜的结构表征表明，在 Al2O3 载体上形成了具有随机合金结构的高度分散的双金属 Pd-Ag 纳米颗粒。对于较高Ag浓度的Pd-Ag催化剂上的丙炔加氢，吸附的质子主要限制在活性Pd系综上，这有利于丙炔上更高的成对氢加成，从而产生更强的PHIP效应。产物立体选择性测量表明，丙炔的成对顺式加成随着 Pd-Ag 合金中 Ag 含量的增加而增加。反应条件影响成对氢化立体选择性。较低的反应物流量的 H2/丙炔比率或较高的总反应物流量增强了表观成对顺式加成立体选择性，这可以通过抑制顺反异构化过程和/或更高的内在成对顺式加成选择性来解释。
Alkyne semihydrogenation offers a key approach for the synthesis of stereodefined molecules. The stereoselective hydrogenation of propyne to propene over Al2O3-supported Pd–Ag bimetallic catalysts is studied by using parahydrogen-induced polarization (PHIP) NMR technique. The supported catalysts were prepared by an incipient-wetness impregnation method, and their properties were systemically tuned by altering Pd and Ag components. Structural characterization by X-ray diffraction, infrared spectra, and transmission electron microscope shows the formation of highly dispersed bimetallic Pd–Ag nanoparticles with random alloy structures on Al2O3support. For the hydrogenation of propyne over Pd–Ag catalysts with higher Ag concentration, the adsorbed protons are mostly restricted on the active Pd ensembles, which favors a higher pairwise hydrogen addition to propyne, leading to a stronger PHIP effect. The product stereoselectivity measurements show that the pairwise syn-addition to propyne increases with Ag content in the Pd–Ag alloy. The reaction conditions impact the pairwise hydrogenation stereoselectivity. A lower H2/propyne ratio of reactant flow or a higher total reactant flow rate enhances the apparent pairwise syn-addition stereoselectivity, which can be accounted for by the suppressed cis–trans isomerization process and/or a higher intrinsic pairwise syn-addition selectivity.
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影响因子：
1.9
作者：
HANSEN, W;BERTOLO, M;JACOBI, K
通讯作者：
JACOBI, K
影响因子：
8.4
作者：
Salnikov OG;Liu HJ;Fedorov A;Burueva DB;Kovtunov KV;Copéret C;Koptyug IV
通讯作者：
Koptyug IV
影响因子：
--
作者：
Jeffrey McCormick;S. Korchak;S. Mamone;Y. N. Ertas;Zhiyu Liu;Luke Verlinsky;S. Wagner;S. Glöggler-S.-Gl
通讯作者：
Jeffrey McCormick;S. Korchak;S. Mamone;Y. N. Ertas;Zhiyu Liu;Luke Verlinsky;S. Wagner;S. Glöggler-S.-Gl
影响因子：
3.3
作者：
Kovtunov, Kirill V.;Beck, Irene E.;Koptyug, Igor V.
通讯作者：
Koptyug, Igor V.
影响因子：
5.5
作者：
A. Sárkány;Z. Révay
通讯作者：
A. Sárkány;Z. Révay