Monitoring transition metal ions (TMI) in oxide catalysts during (re)action: the power of operando EPR

Brückner, Angelika

doi:10.1039/b305884k

Cited by 43 publications

(20 citation statements)

References 56 publications

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“…[27] The combination of the Operando ESR and the quasi in situ XPS was found to be very practical to study, for instance, the transformations between Cr 6C and Cr 3C states in the propane oxidation catalyst. [28] The quasi in situ XPS, however, does not allow real-time or in situ measurements. The other approach is to furnish the XPS apparatus with an in situ reagent dosage and employ the differentially pumped system ('high-pressure XPS').…”

Section: Introductionmentioning

confidence: 99%

An in situ temperature‐programmed XPS study of the surface chemical reactions of thiophene with Ag/titania

Samokhvalov

Duin

Nair

et al. 2010

Surface & Interface Analysis

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aThe Ag/titania sorbent for the ultradeep desulfurization of liquid fuels was characterized by electron spin resonance and was found to contain nearly the stoichiometric titania, without significant concentration of Ti 3+ or the reactive oxygen species. The surface chemical reactions of thiophene adsorbed on the Ag/titania were studied by temperature-programmed XPS from 25 to 525• C upon in situ thermal annealing in high vacuum and in situ oxidation by oxygen gas. The titania support is not chemically reactive under those conditions. Silver oxide in the Ag/titania sorbent is converted to Ag 2 S without formation of the transient surface sulfates or sulfites and is further oxidized by molecular oxygen.

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Section: Introductionmentioning

confidence: 99%

An in situ temperature‐programmed XPS study of the surface chemical reactions of thiophene with Ag/titania

Samokhvalov

Duin

Nair

et al. 2010

Surface & Interface Analysis

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“…Examples are XRD/ XAFS, [6][7][8][9] XAFS/UV-vis, 10,11 UV-vis/Raman, [12][13][14][15] and UVvis/EPR. [16][17][18] Thus, complementary information about the catalytic system can be obtained at the same time and measured under identical process conditions guaranteeing the validity of the measured species for building up the reaction scheme. 19 The goal of this paper is to show that there is an additional advantage of performing combined in-situ spectroscopy on catalytic systems.…”

Section: Introductionmentioning

confidence: 99%

Synchrotron Radiation Effects on Catalytic Systems As Probed with a Combined In-Situ UV−Vis/XAFS Spectroscopic Setup

et al. 2005

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UV-vis spectroscopy was used in a combined in-situ UV-vis/XAFS spectroscopic setup to study the synchrotron radiation effect on aqueous homogeneous copper solutions. Two different systems were studied. In the first study, the focus was on a copper bipyridine-catalyzed oxidation of benzyl alcohol to benzaldehyde with 2,2,6,6-tetramethylpiperidinyl-1-oxy and base as cocatalysts. It was found that when the reaction mixture is exposed to the X-ray beam, the features present in the in-situ UV-vis spectrum develop differently compared to the situation when the reaction mixture is not exposed to the X-ray beam. Besides a temperature effect of the X-ray beam, both the UV-vis analysis and the XAFS analysis showed a reducing influence of the X-ray beam on the sample. To investigate this in more detail, we studied a series of dilute aqueous copper solutions from different precursor salts, viz., Cu(NO 3 ) 2 ‚3H 2 O, CuSO 4 ‚5H 2 O, CuCl 2 , and CuBr 2 . It was found that the different aqueous copper solutions have different stabilities under the influence of the X-ray beam. Especially the solution from the CuCl 2 precursor salt was found to be unstable and to be subjected to reduction. These examples illustrate the need for a second technique, such as in-situ UV-vis spectroscopy, to evaluate the effect of synchrotron radiation used to measure in-situ XAFS on catalytic systems.

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“…Nonetheless, different designs have been shown to provide good results both for in-operando nuclear magnetic resonance (NMR) [6][7][8][9] and for electron paramagnetic resonance (EPR) [4]. For example, in-operando EPR of electrochemical cells has been performed for Nafion Ò based fuel cells [5], for lithium batteries [4,10] or for catalytic systems [11]. A set of specifications can be summarized for this purpose: The cell has to fit into the EPR resonator that offers limited space, the sample holder should not show an EPR signal that disturbs the measurement or complicates its analysis, and the sample holder must enable the functioning of the electrochemical system.…”

Section: Introductionmentioning

confidence: 98%

3D printed sample holder for in-operando EPR spectroscopy on high temperature polymer electrolyte fuel cells

Niemöller

Jakes

Kayser

et al. 2016

Journal of Magnetic Resonance

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Monitoring transition metal ions (TMI) in oxide catalysts during (re)action: the power of operando EPR

Cited by 43 publications

References 56 publications

An in situ temperature‐programmed XPS study of the surface chemical reactions of thiophene with Ag/titania

An in situ temperature‐programmed XPS study of the surface chemical reactions of thiophene with Ag/titania

Synchrotron Radiation Effects on Catalytic Systems As Probed with a Combined In-Situ UV−Vis/XAFS Spectroscopic Setup

3D printed sample holder for in-operando EPR spectroscopy on high temperature polymer electrolyte fuel cells

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