A Formulation Protocol with Pyridine to Enable Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy on Reactive Surface Sites: Case Study with Olefin Polymerization and Metathesis Catalysts

2020 ◽  
Vol 11 (9) ◽  
pp. 3401-3407
Author(s):  
Alexander V. Yakimov ◽  
Deni Mance ◽  
Keith Searles ◽  
Christophe Copéret
Keyword(s):  
Nmr Spectroscopy ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Olefin Polymerization ◽  
Surface Sites ◽  
Reactive Surface ◽  
Surface Enhanced ◽  
Metathesis Catalysts

scholarly journals A Formulation Protocol with Pyridine to Enable DNP-SENS on Reactive Surface Sites: Case Study with Olefin Polymerization and Metathesis Catalysts

2020 ◽  
Author(s):  
Alexander Yakimov ◽  
Deni Mance ◽  
Keith Searles ◽  
Christophe Copéret
Keyword(s):  
Nuclear Polarization ◽  
Propylene Polymerization ◽  
Surface Sites ◽  
Reactive Surface ◽  
Material Chemistry ◽  
Polymerization Catalyst ◽  
Surface Enhanced ◽  
Metathesis Catalysts ◽  
Nmr Signals

<div>Dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP-SENS) has emerged as a powerful characterization tool in material chemistry and heterogeneous catalysis by dramatically increasing, by up to two orders of magnitude, the NMR signals associated with surface sites. DNP-SENS mostly relies on using exogenous polarizing agents (PAs) – typically di-nitroxyl radicals, to boost the NMR signals, that may interact with the surface or even react with highly reactive surface sites, thus leading to loss/quenching of DNP enhancements. Herein, we describe the development of a DNP-SENS formulation that allows us to broaden the application of DNP-SENS to samples containing highly reactive surface sites, namely a Ziegler-Natta propylene polymerization catalyst, a sulfated zirconia-supported metallocene and a silica-supported cationic Mo alkylidene. The protocol consists of adsorbing pyridine prior to the impregnation of the DNP formulation (TEKPol/TCE). The addition of pyridine does not only preserve the PAs and thereby restore the DNP enhancement, but it also allows probing the presence of Lewis acid and Brønsted acid surface sites that are often present on these catalysts.</div>

scholarly journals A Formulation Protocol with Pyridine to Enable DNP-SENS on Reactive Surface Sites: Case Study with Olefin Polymerization and Metathesis Catalysts

2020 ◽  
Author(s):  
Alexander Yakimov ◽  
Deni Mance ◽  
Keith Searles ◽  
Christophe Copéret
Keyword(s):  
Nuclear Polarization ◽  
Propylene Polymerization ◽  
Surface Sites ◽  
Reactive Surface ◽  
Material Chemistry ◽  
Polymerization Catalyst ◽  
Surface Enhanced ◽  
Metathesis Catalysts ◽  
Nmr Signals

<div>Dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP-SENS) has emerged as a powerful characterization tool in material chemistry and heterogeneous catalysis by dramatically increasing, by up to two orders of magnitude, the NMR signals associated with surface sites. DNP-SENS mostly relies on using exogenous polarizing agents (PAs) – typically di-nitroxyl radicals, to boost the NMR signals, that may interact with the surface or even react with highly reactive surface sites, thus leading to loss/quenching of DNP enhancements. Herein, we describe the development of a DNP-SENS formulation that allows us to broaden the application of DNP-SENS to samples containing highly reactive surface sites, namely a Ziegler-Natta propylene polymerization catalyst, a sulfated zirconia-supported metallocene and a silica-supported cationic Mo alkylidene. The protocol consists of adsorbing pyridine prior to the impregnation of the DNP formulation (TEKPol/TCE). The addition of pyridine does not only preserve the PAs and thereby restore the DNP enhancement, but it also allows probing the presence of Lewis acid and Brønsted acid surface sites that are often present on these catalysts.</div>

scholarly journals Uncovering selective and active Ga surface sites in gallia–alumina mixed-oxide propane dehydrogenation catalysts by dynamic nuclear polarization surface enhanced NMR spectroscopy

2021 ◽  
Author(s):  
Pedro Castro-Fernández ◽  
Monu Kaushik ◽  
Zhuoran Wang ◽  
Deni Mance ◽  
Evgenia Kountoupi ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dynamic Nuclear Polarization ◽  
Mixed Oxide ◽  
Nuclear Polarization ◽  
Propane Dehydrogenation ◽  
Alumina Nanoparticles ◽  
Lewis Acidity ◽  
Coordination Geometry ◽  
Surface Sites ◽  
Surface Enhanced

Coordination geometry and Lewis acidity of Ga and Al (bulk and surface) sites in mixed oxide gallia–alumina nanoparticles is correlated with the performance in propane dehydrogenation.

scholarly journals Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

2017 ◽  
Vol 8 (1) ◽  
pp. 284-290 ◽  
Author(s):  
Eva Pump ◽  
Jasmine Viger-Gravel ◽  
Edy Abou-Hamad ◽  
Manoja K. Samantaray ◽  
Bilel Hamzaoui ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Porous Materials ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Organometallic Complexes ◽  
Surface Species ◽  
Reactive Surface ◽  
Surface Enhanced

Reactive surface species immobilized inside porous materials with suitably small windows can be studied by DNP SENS.

scholarly journals Structure of Colloidal Quantum Dots from Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy

2015 ◽  
Vol 137 (43) ◽  
pp. 13964-13971 ◽  
Author(s):  
Laura Piveteau ◽  
Ta-Chung Ong ◽  
Aaron J. Rossini ◽  
Lyndon Emsley ◽  
Christophe Copéret ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Nmr Spectroscopy ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Colloidal Quantum Dots ◽  
Surface Enhanced

In Situ XRD and Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy Unravel the Deactivation Mechanism of CaO-Based, Ca3Al2O6-Stabilized CO2 Sorbents

2018 ◽  
Vol 30 (4) ◽  
pp. 1344-1352 ◽  
Author(s):  
Sung Min Kim ◽  
Wei-Chih Liao ◽  
Agnieszka M. Kierzkowska ◽  
Tigran Margossian ◽  
Davood Hosseini ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
In Situ Xrd ◽  
Surface Enhanced ◽  
Deactivation Mechanism

scholarly journals Surface enhanced dynamic nuclear polarization solid-state NMR spectroscopy sheds light on Brønsted–Lewis acid synergy during the zeolite catalyzed methanol-to-hydrocarbon process

2019 ◽  
Vol 10 (39) ◽  
pp. 8946-8954 ◽  
Author(s):  
Abhishek Dutta Chowdhury ◽  
Irina Yarulina ◽  
Edy Abou-Hamad ◽  
Andrei Gurinov ◽  
Jorge Gascon
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Lewis Acid ◽  
Dynamic Nuclear Polarization ◽  
Solid State Nmr ◽  
Nuclear Polarization ◽  
Solid State Nmr Spectroscopy ◽  
Surface Enhanced ◽  
Methanol To Hydrocarbon

Surface-enhanced dynamic nuclear polarization solid-state NMR spectroscopy has been applied to identify the role of surface-carbene species and elucidating Brønsted–Lewis acid synergy during the zeolite-catalyzed methanol-to-hydrocarbon process.

scholarly journals From single-site tantalum complexes to nanoparticles of TaxNy and TaOxNy supported on silica: elucidation of synthesis chemistry by dynamic nuclear polarization surface enhanced NMR spectroscopy and X-ray absorption spectroscopy

2017 ◽  
Vol 8 (8) ◽  
pp. 5650-5661 ◽  
Author(s):  
Janet C. Mohandas ◽  
Edy Abou-Hamad ◽  
Emmanuel Callens ◽  
Manoja K. Samantaray ◽  
David Gajan ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Absorption Spectroscopy ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Single Site ◽  
X Ray ◽  
Surface Enhanced ◽  
X Ray Absorption

SOMC is exploited for synthesizing very fine nanoparticles of TaxNy/TaOxNy on silica, elucidating the strategies with DNP SENS and EXAFS.

Improved Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy through Controlled Incorporation of Deuterated Functional Groups

2013 ◽  
Vol 125 (4) ◽  
pp. 1260-1263 ◽  
Author(s):  
Alexandre Zagdoun ◽  
Aaron J. Rossini ◽  
Matthew P. Conley ◽  
Wolfram R. Grüning ◽  
Martin Schwarzwälder ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Functional Groups ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Surface Enhanced
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