含Pt，Rh，Ir和Pd的固体催化剂的介孔和微孔内的对氢诱导超极化,The Journal of Physical Chemistry C

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含Pt，Rh，Ir和Pd的固体催化剂的介孔和微孔内的对氢诱导超极化
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-04-26 00:00:00 , DOI: 10.1021/acs.jpcc.7b01899
Utz Obenaus ₁ , Swen Lang ₁ , Robin Himmelmann ₁ , Michael Hunger ₁

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气相使用了一系列相同的固体催化剂（二氧化硅，SBA-15，脱铝的DeA-Y沸石，H，Na-Y沸石），并载有不同的贵金属（Pt，Rh，Ir，Pd）用对位富氢（pH ₂）进行丙烯加氢，以产生对氢诱导的极化（PHIP）。通过在连续流动条件下通过原位¹ H MAS NMR光谱研究了将pH ₂成对引入丙烯中形成的超极化现象。通过评估特征¹研究了超极化反应产物的1 H NMR反相信号，含贵金属的多孔催化剂的实验参数和性能，它们影响了PHIP的形成和弛豫。对于所研究的催化剂，发现小孔径和超极化产物分子与孔内核的相互作用，例如骨架铝原子和骨架外钠阳离子，可增强通过成对引入pH形成的超极化的弛豫。_2个转化为烯烃反应物。此外，含贵金属的催化剂（Pd / H，Na–Y）的很高的氢化活性会减少PHIP的形成，这可能是由于反应性溢出的H物质数量过多而没有自旋相关性，从而阻碍了成对反应。将pH ₂引入烯烃反应物中。

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Parahydrogen-Induced Hyperpolarization inside Meso- and Micropores of Pt-, Rh-, Ir-, and Pd-Containing Solid Catalysts

Homologous series of solid catalysts (silica, SBA-15, dealuminated zeolite DeA–Y, zeolite H,Na–Y) with different pore sizes and loaded with different noble metals (Pt, Rh, Ir, Pd) were applied for the gas phase hydrogenation of propene with para-enriched hydrogen (p-H₂) with the aim to produce parahydrogen-induced polarization (PHIP). This hyperpolarization formed by the pairwise incorporation of p-H₂ into propene was studied via in situ ¹H MAS NMR spectroscopy under continuous-flow conditions. By evaluating the characteristic ¹H NMR antiphase signals of the hyperpolarized reaction products, the experimental parameters and properties of noble-metal-containing porous catalysts were investigated, which affect the formation and relaxation of PHIP. For the catalysts under study, small pore diameters and interactions of the hyperpolarized product molecules with nuclei inside the pores, such as framework aluminum atoms and extra-framework sodium cations, were found to enhance the relaxation of the hyperpolarization formed by the pairwise incorporation of p-H₂ into olefinic reactants. Furthermore, a very high hydrogenation activity of the noble-metal-containing catalyst (Pd/H,Na–Y) decreases the formation of PHIP, possibly caused by a too large number of reactive spillover H species without spin correlation, which hinders the pairwise incorporation of p-H₂ into the olefinic reactants.

更新日期：2017-04-26

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