Category Archives: Catalysis

Room temperature CO oxidation catalysed by supported Pt nanoparticles revealed by solid-state NMR and DNP spectroscopy #DNPNMR

Klimavicius, Vytautas, Sarah Neumann, Sebastian Kunz, Torsten Gutmann, and Gerd Buntkowsky. “Room Temperature CO Oxidation Catalysed by Supported Pt Nanoparticles Revealed by Solid-State NMR and DNP Spectroscopy.” Catalysis Science & Technology 9, no. 14 (2019): 3743–52.

https://doi.org/10.1039/C9CY00684B.

A series of 1 and 2 nm sized platinum nanoparticles (Pt-NPs) deposited on different support materials, namely, γ-alumina (γ-Al2O3), titanium dioxide (TiO2), silicon dioxide (SiO2) and fumed silica are investigated by solid-state NMR and dynamic nuclear polarization enhanced NMR spectroscopy (DNP). DNP signal enhancement factors up to 170 enable gaining deeper insight into the surface chemistry of Pt-NPs. Carbon monoxide is used as a probe molecule to analyze the adsorption process and the surface chemistry on the supported Pt-NPs. The studied systems show significant catalytic activity in carbon monoxide oxidation on their surface at room temperature. The underlying catalytic mechanism is the water–gas shift reaction. In the case of alumina as the support the produced CO2 reacts with the surface to form carbonate, which is revealed by solid-state NMR. A similar carbonate formation is also observed when physical mixtures of neat alumina with silica, fumed silica and titania supported Pt-NPs are studied.

[NMR] Open NMR Position at MPI Kohlenforschung in Mülheim an der Ruhr

A new position in the area NMR applied to catalysis research is now open in Mülheim an der Ruhr, Germany. Please distribute. (Basic German knowledge required 😉

http://www.kofo.mpg.de/de/karriere/stellenangebote/wissenschaftliche-r-mitarbeiter-in-

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Christophe Farès, Ph.D.

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NMR Department/NMR Abteilung

Max-Planck Insitut für Kohlenforschung/ Max-Planck Insitute for Coal Research

Kaiser-Wilhelm Platz 1

45470 Mülheim an der Ruhr

Tel: +49 208 306 2130 

E-mail: fares [a] mpi-muelheim [.] mpg [.] de

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This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

[NMR] NMR Symposium at the 255th ACS meeting in New Orleans, March 18-22, 2018

Dear Colleagues,

Susannah Scott, Nancy Washton, and I are organizing a magnetic resonance symposium in the Division of Catalysis Science and Technology (CATL) at the 255th ACS meeting in New Orleans which will take place between March 18th and 22nd. The symposium is titled: “New Techniques and Applications of Magnetic Resonance Methods in Heterogeneous Catalysis” and will focus on the development and application of NMR/EPR methods for studying heterogeneous catalysts and catalytic processes. You can find the call for papers here:

https://images.magnetmail.net/images/clients/ACS1_D/attach/Web13_MagenticResonance(1).pdf

and you can submit your abstracts here. Submission deadline is this Friday, October 20, 2017.

https://callforpapers.acs.org/nola2018/CATL

We encourage all interested researchers and students to submit an abstract and help make this inaugural symposium a success!

Best regards,

— 

Frédéric Perras, PhD

Ames Laboratory

US Department of Energy

Ames, IA, 50011

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This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

A DNP-supported solid-state NMR study of carbon species in fluid catalytic cracking catalysts #DNPNMR

Mance, D., et al., A DNP-supported solid-state NMR study of carbon species in fluid catalytic cracking catalysts. Chem Commun (Camb), 2017. 53(28): p. 3933-3936.

https://www.ncbi.nlm.nih.gov/pubmed/28327736

A combination of solid-state NMR techniques supported by EPR and SEM-EDX experiments was used to localize different carbon species (coke) in commercial fluid catalytic cracking catalysts. Aliphatic coke species formed during the catalytic process and aromatic coke species deposited directly from the feedstock respond differently to dynamic nuclear polarization signal enhancement in integral and crushed FCC particles, indicating that aromatic species are mostly concentrated on the outside of the catalyst particles, whereas aliphatic species are also located on the inside of the FCC particles. The comparison of solid-state NMR data with and without the DNP radical at low and ambient temperature suggests the proximity between aromatic carbon deposits and metals (mostly iron) on the catalyst surface. These findings potentially indicate that coke and iron deposit together, or that iron has a role in the formation of aromatic coke.

Parahydrogen enhanced NMR reveals correlations in selective hydrogenation of triple bonds over supported Pt catalyst

Zhou, R., et al., Parahydrogen enhanced NMR reveals correlations in selective hydrogenation of triple bonds over supported Pt catalyst. Phys Chem Chem Phys, 2015. 17(39): p. 26121-9.

http://www.ncbi.nlm.nih.gov/pubmed/26376759

Parahydrogen induced polarization using heterogeneous catalysis can produce impurity-free hyperpolarized gases and liquids, but the comparatively low signal enhancements and limited scope of substrates that can be polarized pose significant challenges to this approach. This study explores the surface processes affecting the disposition of the bilinear spin order derived from parahydrogen in the hydrogenation of propyne over TiO2-supported Pt nanoparticles. The hyperpolarized adducts formed at low magnetic field are adiabatically transported to high field for analysis by proton NMR spectroscopy at 400 MHz. For the first time, the stereoselectivity of pairwise addition to propyne is measured as a function of reaction conditions. The correlation between partial reduction selectivity and stereoselectivity of pairwise addition is revealed. The systematic trends are rationalized in terms of a hybrid mechanism incorporating non-traditional concerted addition steps and well-established reversible step-wise addition involving the formation of a surface bound 2-propyl intermediate.

Dynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis Research

Kobayashi, T., et al., Dynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis Research. ACS Catalysis, 2015. 5(12): p. 7055-7062.

http://dx.doi.org/10.1021/acscatal.5b02039

This article does not seem to have an abstract, therefore I’m posting the first two paragraphs.

A revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2–3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound.

With their unique sensitivity to the local electronic environment, the nuclear spins can play the role of perfect reporters in the quest for a fundamental understanding of the catalytic processes at the atomic-scale. Indeed, during the last several decades, SSNMR spectroscopy has evolved to become one of the premier analytical methods for structural characterization of heterogeneous catalytic systems, providing in-depth knowledge about catalyst supports, active sites, reacting molecules, and their interactions.(1-3) Noteworthy is also NMR’s ability to investigate a wide range of dynamic processes at solid–liquid and solid–gas interfaces under catalytically relevant pressures and temperatures. The development of sophisticated SSNMR instrumentation, methodology, and advances in theory have endowed the researchers with an ever increasing ability not only to identify and quantify individual chemical sites but also to determine the three-dimensional (3D) catalytic structures, which are often non-periodic and disordered. Of importance are also the active site distribution and the interactions between these sites and the reacting molecules. This area of multidimensional correlation NMR spectroscopy can open new frontiers for the definite characterization of increasingly complex catalytic materials, provided that the issue of low sensitivity can be overcome.

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