X-ray photoelectron spectroscopy (XPS) for catalysts characterization

Venezia, Anna Maria

doi:10.1016/s0920-5861(02)00380-2

Cited by 185 publications

(113 citation statements)

References 29 publications

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“…This indirect method allows for evaluation of the fraction of accessible active phase atoms, but results may be complicated by the uncertainty of the extent of reduction of the active phase. In contrast, XPS can provide direct information on the dispersion of supported metal oxide catalysts [10] such as vanadia supported on SiO 2 , Al 2 O 3 [11] and TiO 2 [12]. Interestingly, in previous XPS studies on silica supported vanadia catalysts and vanadia-silica mixed oxide systems V species with V 2p 3/2 binding energies of up to 2 eV higher compared to those of reference compounds such as V 2 O 5 were found, which were attributed to vanadium species strongly interacting with silica [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

The influence of water on the dispersion of vanadia supported on silica SBA-15

Heß

Schlögl

2006

Chemical Physics Letters

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The influence of water on the dispersion of silica SBA-15 supported vanadia model catalysts has been studied using X-ray photoelectron spectroscopy (XPS) as well as UV-VIS and Raman spectroscopy. XPS characterization of the V2p 3/2 state reveals the presence of two V 5+ states, which are assigned to vanadia with distinctly different cluster size. Upon dehydration a dramatic change in their intensity ratio is observed as a result of a substantial increase in the vanadia dispersion. It is shown that the observed changes in vanadia dispersion are directly associated with the changes in the molecular structure of the surface vanadia species.

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Section: Introductionmentioning

confidence: 99%

The influence of water on the dispersion of vanadia supported on silica SBA-15

Heß

Schlögl

2006

Chemical Physics Letters

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“…The evolution of the vanadium to total edge jump ratio (V/V + O), related to the V/V + Si abundance ratio, is shown in Figure 3(a) for the 6, 8, and 14V catalysts in O 2 after dehydration and in a mixture of C 3 H 8 and O 2 (2:1) below reaction temperature and at temperatures at which the catalyst produces propylene. An increase in the edge jump ratio that corresponds to an increase in the V to SiO 2 support ratio suggests an increase in dispersion as it is in the case of XPS methodology [25]. In this view, the increase of the intensity ratio of catalysts (6 and 8 V) with lower loading during dehydration (heating from 25 to 400 °C in O 2 ) suggests that the dispersion of vanadium oxide species is improved during this treatment.…”

Section: In Situ Nexafs and Xps Of Vxoy/sba-15mentioning

confidence: 86%

“…X-ray photoelectron spectroscopy is well established among the electron spectroscopy techniques to gather information about atom abundance and dispersion of supported metal particles, see Venezia et al and references therein [25] Unfortunately, low metal loading on insulating supports like SiO 2 often prevent the recording of high quality XP spectra due to differential charging. This effect is even more pronounced when using high brilliant monochromatic X-ray sources like a synchrotron beam for excitation.…”

Section: In Situ Nexafs and Xps Of Vxoy/sba-15mentioning

confidence: 99%

Restructuring of silica supported vanadia during propane oxidative dehydrogenation studied by combined synchrotron radiation based in situ soft X-ray absorption and photoemission

Hävecker

Düngen

Buller

et al. 2017

Catalysis, Structure & Reactivity

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A series of vanadia catalysts supported on mesoporous silica SBA-15 has been prepared with a loading in the range of 2-14 wt-% V and characterized under oxygen and propane oxidative dehydrogenation reaction conditions at elevated temperature up to 550 °C. In situ soft X-ray absorption spectra at the vanadium L-and oxygen K-edges and in situ synchrotron based X-ray photoemission spectra reveal a restructuring of vanadium species that results in an enhanced degree of dispersion of molecular vanadia species on the silica support. The impact of the X-ray beam on the XAS spectra of dispersed V x O y species has been studied and a brief perspective of X-ray based electron spectroscopy as a probe in catalyst characterization is given.

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“…Through their study, they found that Mn may migrate to the surface of TiO 2 to help reduce the production CH 4 and keep the activity of Co catalysts high. For those who are interested in using XPS to study catalysis, Venezia summarizes the studies of XPS on catalysis, which include both bulk and nanomaterials [141].…”

Section: Nanomaterials Made Ex Situmentioning

confidence: 99%

More power to X‐rays: New developments in X‐ray spectroscopy

Guo¹

2009

Laser & Photonics Reviews

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Recent developments in X-ray spectroscopy in the last decade are reviewed. A specific emphasis is placed on displaying the strong natural connection between X-ray spectroscopy and materials science. Brief explanations of several X-ray spectroscopic methods are given. X-ray spectroscopic instruments such as table-top X-ray sources are discussed in detail, whereas those employing synchrotron and other sources are briefly addressed. The spectroscopic methods and results from materials investigations are reviewed according to their positions in a 3D parameter space of time, length, and energy. New experimental measurements on atoms, molecules, nanomaterials, and bulk materials that include insulators, semiconductors, metals and magnetic materials using both static and time-resolved methods are reviewed.A typical table-top experimental setup to probe a sample using an optical pump (green color beam) -X-ray probe (purple color beam) technique. The X-ray pulses are produced by femtosecond optical pulses. Two exemplary data are displayed: One is direct imaging of plasmas generated from laser evaporation of a solid target (Imaging data) and the other is an X-ray absorption spectrum of a nickel sample (USEXAS data).

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X-ray photoelectron spectroscopy (XPS) for catalysts characterization

Cited by 185 publications

References 29 publications

The influence of water on the dispersion of vanadia supported on silica SBA-15

The influence of water on the dispersion of vanadia supported on silica SBA-15

Restructuring of silica supported vanadia during propane oxidative dehydrogenation studied by combined synchrotron radiation based in situ soft X-ray absorption and photoemission

More power to X‐rays: New developments in X‐ray spectroscopy

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