Interaction of triethylaluminium with acetylacetonates of transition metals

Schmidt, Friedrich; Ratovskii, G. V.; Dimitrieva, T.V.; Ivleva, Natalia P.; Borod'ko, Yu. G.

doi:10.1016/s0022-328x(00)99208-8

Cited by 34 publications

(11 citation statements)

References 6 publications

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“…The goal of the present study is to repeat the analyses performed on the Ir model Ziegler-type hydrogenation catalyst system with Co- and Ni-based catalysts made from the authentic Co(neodecanoate) 2 or Ni(2-ethylhexanoate) 2 precursor materials used for industrial polymer hydrogenation. As such, this work expands not only on our own previous study using the Ir model system, but also on the results of othersnotably the valuable studies by Schmidt and co-workers, and Bönnemann and co-workersthat suggest transition metal nanoclusters are present in the Ziegler-type systems they studied.…”

Section: Introductionsupporting

confidence: 65%

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)₂ or Ni(2-ethylhexanoate)₂ and AlEt₃: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis

et al. 2011

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Ziegler-type hydrogenation catalysts are important for industrial processes, namely, the large-scale selective hydrogenation of styrenic block copolymers. Ziegler-type hydrogenation catalysts are composed of a group 8-10 transition metal precatalyst plus an alkylaluminum cocatalyst (and they are not the same as Ziegler-Natta polymerization catalysts). However, for ∼50 years two unsettled issues central to Ziegler-type hydrogenation catalysis are the nature of the metal species present after catalyst synthesis, and whether the species primarily responsible for catalytic hydrogenation activity are homogeneous (e.g., monometallic complexes) or heterogeneous (e.g., Ziegler nanoclusters defined as metal nanoclusters made from combination of Ziegler-type hydrogenation catalyst precursors). A critical review of the existing literature (Alley et al. J. Mol. Catal. A: Chem. 2010, 315, 1-27) and a recently published study using an Ir model system (Alley et al. Inorg. Chem. 2010, 49, 8131-8147) help to guide the present investigation of Ziegler-type hydrogenation catalysts made from the industrially favored precursors Co(neodecanoate)(2) or Ni(2-ethylhexanoate)(2), plus AlEt(3). The approach and methods used herein parallel those used in the study of the Ir model system. Specifically, a combination of Z-contrast scanning transmission electron microscopy (STEM), matrix assisted laser desorption ionization mass spectrometry (MALDI MS), and X-ray absorption fine structure (XAFS) spectroscopy are used to characterize the transition metal species both before and after hydrogenation. Kinetic studies including Hg(0) poisoning experiments are utilized to test which species are the most active catalysts. The main findings are that, both before and after catalytic cyclohexene hydrogenation, the species present comprise a broad distribution of metal cluster sizes from subnanometer to nanometer scale particles, with estimated mean cluster diameters of about 1 nm for both Co and Ni. The XAFS results also imply that the catalyst solutions are a mixture of the metal clusters described above, plus unreduced metal ions. The kinetics-based Hg(0) poisoning evidence suggests that Co and Ni Ziegler nanoclusters (i.e., M(≥4)) are the most active Ziegler-type hydrogenation catalysts in these industrial systems. Overall, the novelty and primary conclusions of this study are as follows: (i) this study examines Co- and Ni-based catalysts made from the actual industrial precursor materials, catalysts that are notoriously problematic regarding their characterization; (ii) the Z-contrast STEM results reported herein represent, to our knowledge, the best microscopic analysis of the industrial Co and Ni Ziegler-type hydrogenation catalysts; (iii) this study is the first explicit application of an established method, using multiple analytical methods and kinetics-based studies, for distinguishing homogeneous from heterogeneous catalysis in these Ziegler-type systems; and (iv) this study parallels the successful study of an Ir model Ziegler catalyst system...

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Section: Introductionsupporting

confidence: 65%

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)₂ or Ni(2-ethylhexanoate)₂ and AlEt₃: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis

et al. 2011

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“…Unlike the systems based on acetylacetonate of Ni [1,2,4] and Co [1,2], which give mainly ethane, the content of ethane and ethylene in the case of Pd(Acac) 2 at different ratios of the initial components is close to the equimolar (Table 1). This fact suggests that the destruction of the Pd ethyl complexes formed as a result of the exchange of the Acac ligands, follows the mechanism of the β-hydrate shift.…”

Section: Resultsmentioning

confidence: 94%

“…The formation of hydrogen in the reaction system Pd(Acac) 2 At Al : Pd = 5, the quantitative transformation of Pd(Acac) 2 is observed. In addition to AlEt 2 (Acac), the reaction system also contains triethylaluminium in a free state.…”

Section: Resultsmentioning

confidence: 96%

“…The quantity of the surface atoms in the metal nanoparticles 2.5-3 nm in diameter reaches 45-39% [15]. Taking into account steric factor and capability of AlEt 2 (Acac) to form dimers [2], one can suggest that the ligand shell consists of several layers of diethylaluminium acetylacetonate.…”

Section: Resultsmentioning

confidence: 99%

“…The reactions of components of the systems based on β -diketonate or carboxylate complexes of metals of the first transition series with organoaluminium compounds are well studied [1][2][3][4][5][6]. However, the products of reactions of Pd or Pt bis(acetylacetonates) with trialkylaluminium, which show a high catalytic activity, are studied to a lesser extent [7,8].…”

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confidence: 99%

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Reactions of Pd β-Diketonate Complexes with Triethylaluminium

et al. 2005

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Reactions of Pd ( Acac ) 2 and Pd ( Acac ) 2 PPh 3 complexes with triethylaluminium in an inert atmosphere are studied by the NMR and IR, electronic microscopy, and X-ray powder diffraction methods. The final products of conversion of the initial Pd(II) complexes are the Pd(0) nanoparticles with the predominant diameter 2-4 nm. The main factors determining the size of Pd(0) particles and the nature of the ligand shell are considered.

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Nickel(II) Acetylacetonate

Doyon

2001

Encyclopedia of Reagents for Organic Synthesis

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Interaction of triethylaluminium with acetylacetonates of transition metals

Cited by 34 publications

References 6 publications

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)₂ or Ni(2-ethylhexanoate)₂ and AlEt₃: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)₂ or Ni(2-ethylhexanoate)₂ and AlEt₃: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis

Reactions of Pd β-Diketonate Complexes with Triethylaluminium

Nickel(II) Acetylacetonate

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Interaction of triethylaluminium with acetylacetonates of transition metals

Cited by 34 publications

References 6 publications

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)2 or Ni(2-ethylhexanoate)2 and AlEt3: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)2 or Ni(2-ethylhexanoate)2 and AlEt3: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis

Reactions of Pd β-Diketonate Complexes with Triethylaluminium

Nickel(II) Acetylacetonate

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Product

Resources

About

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)₂ or Ni(2-ethylhexanoate)₂ and AlEt₃: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis

Industrial Ziegler-Type Hydrogenation Catalysts Made from Co(neodecanoate)₂ or Ni(2-ethylhexanoate)₂ and AlEt₃: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis