Acetylene Oligomerization over Pd Nanoparticles with Controlled Shape: A Parahydrogen-Induced Polarization Study

Живонитко, Владимир В.; Skovpin, Ivan V.; Crespo‐Quesada, Micaela; Kiwi‐Minsker, Lioubov; Koptyug, Igor V.

doi:10.1021/acs.jpcc.5b12391

Cited by 32 publications

(32 citation statements)

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“…In principle, sequential dehydrogenation–hydrogenation can also lead to the spin hyperpolarization if para-H 2 addition proceeds in a pairwise manner, as was reported previously. 8 , 11 , 19 , 20 This route of production of hyperpolarized substances is referred to in the literature as “pairwise replacement”. 19 , 20 Thus, propane dehydrogenation over VCAT may produce hyperpolarized propane.…”

Section: Introductionmentioning

confidence: 99%

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

et al. 2018

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Parahydrogen can be used in catalytic hydrogenations to achieve substantial enhancement of NMR signals of the reaction products and in some cases of the reaction reagents as well. The corresponding nuclear spin hyperpolarization technique, known as parahydrogen-induced polarization (PHIP), has been applied to boost the sensitivity of NMR spectroscopy and magnetic resonance imaging by several orders of magnitude. The catalyst properties are of paramount importance for PHIP because the addition of parahydrogen to a substrate must be pairwise. This requirement significantly narrows down the range of the applicable catalysts. Herein, we study an efficient silica-supported vanadium oxo organometallic complex (VCAT) in hydrogenation and dehydrogenation reactions in terms of efficient PHIP production. This is the first example of group 5 catalyst used to produce PHIP. Hydrogenations of propene and propyne with parahydrogen over VCAT demonstrated production of hyperpolarized propane and propene, respectively. The achieved NMR signal enhancements were 200–300-fold in the case of propane and 1300-fold in the case of propene. Propane dehydrogenation in the presence of parahydrogen produced no hyperpolarized propane, but instead the hyperpolarized side-product 1-butene was detected. Test experiments of other group 5 (Ta) and group 4 (Zr) catalysts showed a much lower efficiency in PHIP as compared to that of VCAT. The results prove the general conclusion that vanadium-based catalysts and other group 4 and group 5 catalysts can be used to produce PHIP. The hydrogenation/dehydrogenation processes, however, are accompanied by side reactions leading, for example, to C4, C2, and C1 side products. Some of the side products like 1-butene and 2-butene were shown to appear hyperpolarized, demonstrating that the reaction mechanism includes pairwise parahydrogen addition in these cases as well.

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Section: Introductionmentioning

confidence: 99%

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

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“…Keywords Size-dependent · Nanoparticle · Melting · Enthalpy 1 Introduction Palladium nanoparticles have received growing interest due to their novel properties such as size (Chen et al, 2016) and shape (facet) (Wang et al, 2017) dependent catalytic activity, controlled oligomerization (Zhivonitko et al, 2016) and enhanced hydrogen storage (Rangel et al, 2016). However, due to the higher surface to volume ratio (Schmidt et al, 1998;Safaei et al, 2008), the nanoparticles are known as the most unstable structures among different nanosolids.…”

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confidence: 99%

Size and shape-dependent melting mechanism of Pd nanoparticles

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Molecular dynamics simulation is employed to understand the thermodynamic behavior of cuboctahedron (cub) and icosahedron (ico) nanoparticles with 2 − 20 number of full shells. The original embedded atom method (EAM) was compared to the more recent highly optimized version as interatomic potential. The thermal stability of clusters were probed using potential energy and specific heat capacity as well as structure analysis by radial distribution function (G(r)) and common neighbor analysis (CNA), simultaneously, to make a comprehensive picture of the solid state and melting transitions. The result shows ico is the only stable shape of small clusters (Pd 55 -Pd 309 using original EAM and Pd 55 using optimized version) those are melting uniformly due to their small diameter. An exception is cub Pd 309 modeled via optimized EAM that transforms to ico at elevated temperatures. A similar cub to ico transition was predicted by original EAM for Pd 923 -Pd 2075 clusters while for the larger clusters both cub and ico are stable up to the melting point. As detected by G(r) and CNA, moderate and large cub clusters were showing surface melting by nucleation of the liquid phase at (100) planes and growth of liquid phase at the surface before inward growth. While diagonal (one corner to another) melting was dominating over ico clusters owing to their partitioned

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“…The same group also found that the hydrogenation of acetylene over palladium nanoparticles of different morphologies (cubes, octahedra, and cuboctahedra) could also afford C 4 ‐oligomeric products (1,3‐butadiene, 1‐butene, and 2‐butene). Such oligomers exhibited high levels of polarization (up to 1.7 %) …”

Section: Heterogeneous Phipmentioning

confidence: 99%

“…Such oligomers exhibited high levels of polarization (up to 1.7 %). [153] The range of substrates that can produce PHIP effects is not limitedt ou nsaturated hydrocarbons. The hydrogenation reactions of a,b-unsaturated carbonyl compounds over various supported catalysts, [154] C 6 -cyclic compounds, [155] and furan derivatives over Rh/TiO 2 ,P d/TiO 2 ,P t/TiO 2 catalysts, [156] as well as the hydrodesulfurization of thiophene over MoS 2 /g-Al 2 O 3 and Pt/TiO 2 catalysts, [157] with parahydrogen have been performed.…”

Section: Heterogeneous Phipmentioning

confidence: 99%

Hyperpolarized NMR Spectroscopy: d‐DNP, PHIP, and SABRE Techniques

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Salnikov

et al. 2018

Chemistry An Asian Journal

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The intensity of NMR signals can be enhanced by several orders of magnitude by using various techniques for the hyperpolarization of different molecules. Such approaches can overcome the main sensitivity challenges facing modern NMR/magnetic resonance imaging (MRI) techniques, whilst hyperpolarized fluids can also be used in a variety of applications in material science and biomedicine. This Focus Review considers the fundamentals of the preparation of hyperpolarized liquids and gases by using dissolution dynamic nuclear polarization (d-DNP) and parahydrogen-based techniques, such as signal amplification by reversible exchange (SABRE) and parahydrogen-induced polarization (PHIP), in both heterogeneous and homogeneous processes. The various new aspects in the formation and utilization of hyperpolarized fluids, along with the possibility of observing NMR signal enhancement, are described.

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Acetylene Oligomerization over Pd Nanoparticles with Controlled Shape: A Parahydrogen-Induced Polarization Study

Cited by 32 publications

References 53 publications

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

Parahydrogen-Induced Polarization Study of the Silica-Supported Vanadium Oxo Organometallic Catalyst

Size and shape-dependent melting mechanism of Pd nanoparticles

Hyperpolarized NMR Spectroscopy: d‐DNP, PHIP, and SABRE Techniques

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