In Situ NMR Spectroscopy of Combustion

Anala, Satyanarayana; Pavlovskaya, Galina E.; Pichumani, Prakash; Dieken, Todd J.; Olsen, Michael D.; Meersmann, Thomas

doi:10.1021/ja035838b

Cited by 31 publications

(27 citation statements)

References 32 publications

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“…[53][54][55] It has been shown that the laser-hyperpolarized 129 Xe NMR technique is powerful for studying the porosity of porous materials, [56][57][58][59][60][61] or even diffusion and combustion process. 62,63 As shown in Fig. 4, we reported a design of laserhyperpolarized xenon premixed with a reactant outside the probe head which then entered the high-field coil region with an MAS NMR rotor to investigate the catalytic kinetics in nanocages by in situ continuous-flow MAS NMR.…”

Section: Continuous-flow Conditionsmentioning

confidence: 99%

“…It has been shown that the laserhyperpolarized (HP) 129 Xe NMR technique is powerful for the studying of porous materials. [56][57][58][59][60][61][62][63] The resultant 129 Xe NMR spectrum is from xenon atoms adsorbed in pores with dimensions down to the nanoscale, which could make it possible for investigation of the reaction kinetics in a restricted geometry. The kinetic parameters obtained from the NMR spectra could serve as the basis for the verification of quantum chemical calculations for molecule activation and conversion pathways.…”

Section: Reaction Kinetics In Heterogeneous Catalysismentioning

confidence: 99%

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In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

et al. 2012

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In situ solid-state NMR is a well-established tool for investigations of the structures of the adsorbed reactants, intermediates and products on the surface of solid catalysts. The techniques allow identifications of both the active sites such as acidic sites and reaction processes after introduction of adsorbates and reactants inside an NMR rotor under magic angle spinning (MAS). The in situ solid-state NMR studies of the reactions can be achieved in two ways, i.e. under batch-like or continuous-flow conditions. The former technique is low cost and accessible to the commercial instrument while the latter one is close to the real catalytic reactions on the solids. This critical review describes the research progress on the in situ solid-state NMR techniques and the applications in heterogeneous catalysis under batch-like and continuous-flow conditions in recent years. Some typical probe molecules are summarized here to detect the Brønsted and Lewis acidic sites by MAS NMR. The catalytic reactions discussed in this review include methane aromatization, olefin selective oxidation and olefin metathesis on the metal oxide-containing zeolites. With combining the in situ MAS NMR spectroscopy and the density functional theoretical (DFT) calculations, the intermediates on the catalyst can be identified, and the reaction mechanism is revealed. Reaction kinetic analysis in the nanospace instead of in the bulk state can also be performed by employing laser-enhanced MAS NMR techniques in the in situ flow mode (163 references).

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Section: Continuous-flow Conditionsmentioning

confidence: 99%

Section: Reaction Kinetics In Heterogeneous Catalysismentioning

confidence: 99%

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

et al. 2012

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“…The use of optical pumping techniques for the production of hyperpolarized (HP) xenon can increase sensitivity of several orders of magnitude (Â10 4 ) [35,36] and laser-hyperpolarized (HP) 129 Xe NMR is proved to be powerful technique in studying the porosity of porous materials [31,37], or even reaction processes and kinetics [32,38]. The observed 129 Xe chemical shift could reflect mainly interactions between xenon atoms and the surface.…”

mentioning

confidence: 99%

Multimodal Zr-Silicalite-1 zeolite nanocrystal aggregates with interconnected hierarchically micro-meso-macroporous architecture and enhanced mass transport property

Chen

et al. 2012

Journal of Colloid and Interface Science

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“…Hyperpolarized (hp) 3 He and hp 129 Xe (both I ϭ 1͞2) have both been used in a wide range of NMR and magnetic resonance imaging (MRI) experiments that are otherwise impossible (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). In particular hp 3 He has been applied for medical MRI diagnosis of pulmonary diseases (16)(17)(18)(19).…”

mentioning

confidence: 99%

“…However, 129 Xe adds a further parameter not available by 3 He, namely, the chemical shift that allows for insights into the local environment of the xenon atoms (22)(23)(24)(25)(26)(27). The 129 Xe chemical shift has been used extensively for research in materials science, engineering, and xenon dissolved in liquids including human blood (3,5,6,8,9,12,28). The chemical shift obtained from hp 129 Xe can be used to generate an in vivo MRI contrast that is a probe for gas perfusion in lungs (i.e., exchange of the gaseous xenon with the lung parenchyma) (29).…”

mentioning

confidence: 99%

Hyperpolarized krypton-83 as a contrast agent for magnetic resonance imaging

Pavlovskaya

Cleveland

Stupic

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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For the first time, magnetic resonance imaging (MRI) with hyperpolarized (hp) krypton-83 ( 83 Kr) has become available. The relaxation of the nuclear spin of 83 Kr atoms (I ‫؍‬ 9͞2) is driven by quadrupolar interactions during brief adsorption periods on surrounding material interfaces. Experiments in model systems reveal that the longitudinal relaxation of hp 83 Kr gas strongly depends on the chemical composition of the materials. The relaxationweighted contrast in hp 83 Kr MRI allows for the distinction between hydrophobic and hydrophilic surfaces. The feasibility of hp 83 Kr MRI of airways is tested in canine lung tissue by using krypton gas with natural abundance isotopic distribution. Additionally, the influence of magnetic field strength and the presence of a breathable concentration of molecular oxygen on longitudinal relaxation are investigated.NMR ͉ optical pumping ͉ pulmonary ͉ MRI ͉ xenon H igh nuclear spin polarization in noble gasses can be generated through rubidium vapor spin exchange optical pumping (RbSEOP) (1) and allows for NMR signal enhancements of many orders of magnitude (2). Hyperpolarized (hp) 3 He and hp 129 Xe (both I ϭ 1͞2) have both been used in a wide range of NMR and magnetic resonance imaging (MRI) experiments that are otherwise impossible (3-15). In particular hp 3 He has been applied for medical MRI diagnosis of pulmonary diseases (16)(17)(18)(19). One of the fundamental parameters with high diagnostic value for hp 3 He MRI is the spin-density that is a result of the helium concentration in a particular volume. Spin-density mapping of hp 3 He can be applied to visualize ventilation in lungs. Other useful parameters are 3 He diffusion that provides information about alveolar size distributions in lung tissue and hp 3 He relaxation that depends on oxygen partial pressure in lungs. In vivo MRI of airways with hp 129 Xe as a contrast agent (19-21) suffers from a lower sensitivity compared with hp 3 He. However, 129 Xe adds a further parameter not available by 3 He, namely, the chemical shift that allows for insights into the local environment of the xenon atoms (22-27). The 129 Xe chemical shift has been used extensively for research in materials science, engineering, and xenon dissolved in liquids including human blood (3,5,6,8,9,12,28). The chemical shift obtained from hp 129 Xe can be used to generate an in vivo MRI contrast that is a probe for gas perfusion in lungs (i.e., exchange of the gaseous xenon with the lung parenchyma) (29).3 He and 129 Xe are the only spin I ϭ 1͞2 stable isotopes of the noble gas group, but there are three more NMR active isotopes in this group with higher spin that possess a nuclear electric quadrupole moment. The three quadrupolar isotopes are 21 Ne (I ϭ 3͞2, natural abundance 0.27%), 83 Kr (I ϭ 9͞2, natural abundance 11.5%), and 131 Xe (I ϭ 3͞2, natural abundance 21%). Quadrupolar interactions in these noble gas atoms cause spin relaxation and coherent spin evolution that are probes for the shape, size, and symmetry of void spaces as well as the ...

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In Situ NMR Spectroscopy of Combustion

Cited by 31 publications

References 32 publications

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

Multimodal Zr-Silicalite-1 zeolite nanocrystal aggregates with interconnected hierarchically micro-meso-macroporous architecture and enhanced mass transport property

Hyperpolarized krypton-83 as a contrast agent for magnetic resonance imaging

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