Category Archives: Resarch Article

Electrochemical Overhauser dynamic nuclear polarization #DNPNMR #ODNP

Tamski, Mika, Jonas Milani, Christophe Roussel, and Jean-Philippe Ansermet. “Electrochemical Overhauser Dynamic Nuclear Polarization.” Physical Chemistry Chemical Physics 22, no. 32 (2020): 17769–76.

Nuclear Magnetic Resonance (NMR) spectroscopy suffers from low sensitivity due to the low nuclear spin polarization obtained within practically achievable external magnetic fields. Dynamic Nuclear Polarization (DNP) refers to the techniques that increases NMR signal intensity by transferring spin polarization from electrons to the nuclei.

Spatially resolved NMR spectroscopy of heterogeneous gas phase hydrogenation of 1,3-butadiene with para-hydrogen

Svyatova, Alexandra, Elizaveta S. Kononenko, Kirill V. Kovtunov, Dmitry Lebedev, Evgeniy Yu. Gerasimov, Andrey V. Bukhtiyarov, Igor P. Prosvirin, et al. “Spatially Resolved NMR Spectroscopy of Heterogeneous Gas Phase Hydrogenation of 1,3-Butadiene with Para Hydrogen.” Catalysis Science & Technology 10, no. 1 (2020): 99–104

Glass tube reactors with Pd, Pt, Rh or Ir nanoparticles dispersed on a thin layer of TiO2, CeO2, SiO2 or Al2O3 provided mechanistic insight into the hydrogenation of 1,3-butadiene using para hydrogen. Magnetic resonance-based methods such as nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are widely used to provide in situ/ operando information of chemical reactions. However, the low spin density and magnetic field inhomogeneities associated with heterogeneous catalytic systems containing gaseous reactants complicate such studies. Hyperpolarization techniques, in particular para-hydrogen-induced polarization (PHIP), increase significantly the NMR signal intensity. In this study, we test 16 glass tube reactors containing Pd, Pt, Rh or Ir nanoparticles dispersed on a thin layer of TiO2, CeO2, SiO2 or Al2O3 for the hydrogenation of 1,3-butadiene using para-hydrogen. The catalytic coatings of Ir and Rh gave hydrogenation products with the highest nuclear spin polarization while the coatings of Pd are the most selective ones for the semihydrogenation of 1,3-butadiene to 1- and 2-butenes. Spatially resolved NMR spectroscopy of the reagent and the product distribution along the reactor axis provided further mechanistic insight into the catalytic function of these reactive coatings under operando conditions.

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