scholarly journals Catalytic activation of ethylene C–H bonds on uniform d8 Ir(i) and Ni(ii) cations in zeolites: toward molecular level understanding of ethylene polymerization on heterogeneous catalysts

2019 ◽  
Vol 9 (23) ◽  
pp. 6570-6576 ◽  
Author(s):  
Nicholas R. Jaegers ◽  
Konstantin Khivantsev ◽  
Libor Kovarik ◽  
Daniel W. Klas ◽  
Jian Zhi Hu ◽  
...  
Keyword(s):  
Metal Ions ◽  
Ethylene Polymerization ◽  
Heterogeneous Catalysts ◽  
Molecular Level ◽  
Catalytic Activation

The long-debated intermediates of ethylene polymerization are revealed using uniform d8 metal ions in zeolites.

scholarly journals Catalytic activation of ethylene C-H bonds on uniform d8 Ir(I) and Ni(II) cations in zeolites: toward molecular level understanding of ethylene polymerization on heterogeneous catalysts

2019 ◽  
Author(s):  
Nicholas R. Jaegers ◽  
Konstantin Khivantsev ◽  
Libor Kovarik ◽  
Dan Klaus ◽  
Jian Zhi Hu ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Molecular Level ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Catalytic Activation ◽  
Dehydrogenative Coupling ◽  
Ethylene Conversion ◽  
Active Metal ◽  
First Time

<div> <p>The homolytic activation of the strong C-H bonds in ethylene is demonstrated, for the first time, on d<sup>8</sup> Ir(I) and Ni(II) single atoms in the cationic positions of zeolites H-FAU and H-BEA under ambient conditions. The oxidative addition of C<sub>2</sub>H<sub>4</sub> to the metal center occurs with the formation of a d<sup>6</sup> metal vinyl hydride, explaining the initiation of the Cossee-Arlman cycle on d<sup>8</sup> M(I/II) sites in the absence of pre-existing M-H bonds. Under mild reaction conditions (80-220ᵒC, 1 bar), the catalytic dimerization to butenes and dehydrogenative coupling of ethylene to butadiene occurs over these catalysts. Butene-1 is not converted to butadiene under the reaction conditions applied. Post-reaction characterization of the two materials reveals that the active metal cations remain site-isolated whereas deactivation occurs due to the formation of carbonaceous deposits on the zeolites. Our findings have significant implications for the molecular level understanding of ethylene conversion and the development of new ways to functionalize C-H bonds under mild conditions.</p> </div>

scholarly journals Catalytic activation of ethylene C-H bonds on uniform d8 Ir(I) and Ni(II) cations in zeolites: toward molecular level understanding of ethylene polymerization on heterogeneous catalysts

2019 ◽  
Author(s):  
Nicholas R. Jaegers ◽  
Konstantin Khivantsev ◽  
Libor Kovarik ◽  
Dan Klaus ◽  
Jian Zhi Hu ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Molecular Level ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Catalytic Activation ◽  
Dehydrogenative Coupling ◽  
Ethylene Conversion ◽  
Active Metal ◽  
First Time

<div> <p>The homolytic activation of the strong C-H bonds in ethylene is demonstrated, for the first time, on d<sup>8</sup> Ir(I) and Ni(II) single atoms in the cationic positions of zeolites H-FAU and H-BEA under ambient conditions. The oxidative addition of C<sub>2</sub>H<sub>4</sub> to the metal center occurs with the formation of a d<sup>6</sup> metal vinyl hydride, explaining the initiation of the Cossee-Arlman cycle on d<sup>8</sup> M(I/II) sites in the absence of pre-existing M-H bonds. Under mild reaction conditions (80-220ᵒC, 1 bar), the catalytic dimerization to butenes and dehydrogenative coupling of ethylene to butadiene occurs over these catalysts. Butene-1 is not converted to butadiene under the reaction conditions applied. Post-reaction characterization of the two materials reveals that the active metal cations remain site-isolated whereas deactivation occurs due to the formation of carbonaceous deposits on the zeolites. Our findings have significant implications for the molecular level understanding of ethylene conversion and the development of new ways to functionalize C-H bonds under mild conditions.</p> </div>

Bifunctional heterogeneous catalysts derived from the coordination of adenosine monophosphate to Sn(IV) for effective conversion of sucrose to 5-hydroxymethylfurfural

2021 ◽  
Author(s):  
Chenyu Wang ◽  
Lutong Jiao ◽  
Han Meng ◽  
Peijun Ji
Keyword(s):  
Metal Ions ◽  
Functional Groups ◽  
Heterogeneous Catalysts ◽  
Adenosine Monophosphate

Adenosine 5’-monophosphate (AMP) with multiple functional groups can bind to various metal ions. In this work, AMP has been used as the ligand to coordinate Sn(IV) for the synthesis of...

ChemInform Abstract: Solid-State NMR: A Key Tool for the Understanding at a Molecular Level of Well-defined Heterogeneous Catalysts

ChemInform ◽  
2013 ◽  
Vol 44 (19) ◽  
pp. no-no
Author(s):  
David Gajan ◽  
Giuseppe Lapadula ◽  
Martin Schwarzwalder ◽  
Christophe Coperet
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Heterogeneous Catalysts ◽  
Molecular Level

scholarly journals THE SYNTHESIS OF TRIAZOLE CONTAINING ANALOGUES OF SALEN AND VANEN

2017 ◽  
pp. 37-39
Author(s):  
Y. Bibik ◽  
D. Khomenko ◽  
R. Doroschuk ◽  
R. Lampeka
Keyword(s):  
Ir Spectroscopy ◽  
Transition Metal ◽  
Metal Ions ◽  
Electronic Properties ◽  
Coordination Compounds ◽  
Binuclear Complex ◽  
Heterogeneous Catalysts ◽  
Complex Compounds ◽  
Coordination Behavior ◽  
Antiviral Activities

Facile methods of the preparation of heterocyclic analogues of Salen and Vanen are reported. The azamethine fragments of Schiff bases were replaced by 1,2,4-triazoles. The method of synthesis described may afford to prepare the series of ligand systems with different substituents with high overall yields relatively to the hydrazide. Unlike Schiff's bases, all synthesized compounds are chemically stable and resistant to oxidizing and reducing agents. The molecules are entirely conjugate to the π-systems, which is likely to be reflected in the electronic properties of coordination compounds. Obtained ligand systems could maintain great interest in the synthesis of various transition metal coordination compounds. These could be concluded from the fact that coordination behavior of synthesized ligands is expected to be similar to that is observed for Salen an Vanen type ligands respectively. The resulting compounds have the same donor centers from Salen and Vanen, having a similar planar structure and coordination behavior. All ligands are tetradentate, may leave vacant positions in the coordination sphere of transition metals and form five- and six-membered cycles. The Vanen analogues are capable of forming binuclear complex compounds, since they have internal N2O2 (for coordination with 3d metal ions) and external O2O2 (for exo-coordination of ions of lantanides) donor centers. The compounds obtained are capable of forming coordination compounds with antibacterial, antifungal, anticancer, antioxidant, anti-inflammatory, antimalarial, antiviral activities and also as homogeneous and heterogeneous catalysts in polymerization, epoxidation, hydrosilylation reactions, sensors etc. The analogues were analyzed by NMR and IR spectroscopy.

scholarly journals Predicting the DNP-SENS efficiency in reactive heterogeneous catalysts from hydrophilicity

2018 ◽  
Vol 9 (21) ◽  
pp. 4866-4872 ◽  
Author(s):  
Eva Pump ◽  
Anissa Bendjeriou-Sedjerari ◽  
Jasmine Viger-Gravel ◽  
David Gajan ◽  
Baptiste Scotto ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dynamic Nuclear Polarization ◽  
Heterogeneous Catalysts ◽  
Nuclear Polarization ◽  
Molecular Level ◽  
Surface Enhanced

Identification of surfaces at the molecular level has benefited from progress in dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS).

In-situ X-ray Studies of Clean Catalytic Technologies

2011 ◽  
Vol 1351 ◽  
Author(s):  
Adam F. Lee ◽  
Christine V. Ellis ◽  
Mark A. Newton ◽  
Christopher M. Parlett ◽  
Karen Wilson
Keyword(s):  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Molecular Level ◽  
Aerobic Oxidation ◽  
Allylic Alcohols ◽  
Time Resolved ◽  
X Ray ◽  
Adsorbed Layers ◽  
Insight Into

ABSTRACTThe rational design of new heterogeneous catalysts for clean chemical technologies can be accelerated by molecular level insight into surface chemical processes. In-situ methodologies, able to provide time-resolved and/or pressure dependent information on the evolution of reacting adsorbed layers over catalytically relevant surfaces, are therefore of especial interest. Here we discuss the application of in-situ XPS and in-situ, synchronous DRIFTS/MS/XAS methodologies to elucidate the active site in Pd-catalyzed, selective aerobic oxidation of allylic alcohols.

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