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Prosvirin, Igor P.; Tikhomirov, E. P.; Sorokin, A. A.; Каичев, В. В.; Bukhtiyarov, Valerii I.

doi:10.1023/a:1026198107334

Cited by 24 publications

(8 citation statements)

References 15 publications

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“…In an similar XPS study Buktiyarov et al attributed the state at 529.8 eV to chemisorbed oxygen and the peak at 531.2 eV to a Cu suboxide. 23,24 The term suboxide refers to the Cu/O stochiometry and thus comprises subsurface oxygen. Due to the smallness of the signal intensity of the O ad_b component found in our experiment, we did not attempt to analyze its intensity change with varying photon energy.…”

Section: Resultsmentioning

confidence: 99%

“…[7][8][9][10][11][12][13][14][15][16] Different in situ techniques were applied in order to identify the active surface phases on polycrystalline Cu at higher pressure (mbar range). [17][18][19][20][21][22][23][24][25][26] Cu(110) surfaces were investigated with temperatureprogrammed desorption (TPD), molecular beam techniques, low energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS) and scanning tunnelling microscopy (STM). 7,8,[10][11][12]15,[27][28][29][30] These techniques were typically applied under non-stationary conditions using sequential dosing and temperature-programmed experiments.…”

Section: Introductionmentioning

confidence: 99%

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Adsorbate coverages and surface reactivity in methanol oxidation over Cu(110): An in situ photoelectron spectroscopy study

Günther

Zhou

Hävecker

et al. 2006

The Journal of Chemical Physics

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The adsorbate species present during partial oxidation of methanol on a Cu(110) surface have been investigated in the 10 -5 mbar range with in situ x-ray photoelectron spectroscopy (XPS) and rate measurements. Two reaction intermediates were identified, methoxy with a C 1s binding energy (BE) of 285.4 eV and formate with a C 1s BE of 287.7 eV. The c(2x2) overlayer formed under reaction conditions is assigned to formate. Two states of adsorbed oxygen were found characterized by O 1s BE's of 529.6 and 528.9 eV, respectively. On the inactive surface present at low T around 300 -350 K formate dominates while methoxy is almost absent. Ignition of the reaction correlates with a decreasing formate coverage. A large hysteresis of ≈ 200 K width occurs in T-cycling experiments whose correlation with adsorbate species was studied with varying oxygen and methanol partial pressures. The two branches of the hysteresis differ mainly in the amount of adsorbed oxygen, the methoxy species and a carbonaceous species. Methoxy covers only a minor part of the catalytic surface reaching at most 20%. Above 650 K the surface is largely adsorbate free.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Adsorbate coverages and surface reactivity in methanol oxidation over Cu(110): An in situ photoelectron spectroscopy study

Günther

Zhou

Hävecker

et al. 2006

The Journal of Chemical Physics

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“…Each scheme shows also a profile of a sample and a sample holder. First drawing (figure 2, top) shows the original construction provided by VG [9,10], two other drawings (figure 2, middle and bottom) show constructions after the first modification finished in 1990 [11], and after the latest modification [20,21]. Motivations and details of the modifications will be presented below.…”

Section: Resultsmentioning

confidence: 99%

“…To avoid this disadvantage, a new modification of the gas cell was made [20,21]. The main characteristic of the new construction is a decreased distance between the sample and the outlet for photoelectrons (L < 5 mm), whereas the possibility to use a TPD sample holder and larger samples is preserved ( figure 2, bottom).…”

Section: Resultsmentioning

confidence: 99%

X-ray photoelectron spectroscopy as a tool for in-situ study of the mechanisms of heterogeneous catalytic reactions

2005

Self Cite

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An ESCALAB High Pressure photoelectron spectrometer specially designed by Vacuum Generators Co. (UK) for in-situ measurements at high pressures has been modified for adsorption and catalytic experiments. New construction of a gas cell, which serves to create a high-pressure zone, allows us to measure photoemission spectra in-situ at pressures up to 0.2-0.5 mbar and to use a sample holder with independent heating of a sample. This makes it possible to measure temperature programmed desorption and reaction spectra and, as a consequence, to characterize the catalytic properties simultaneously with the acquisition of X-ray photoelectron spectroscopy (XPS) data. Capabilities of the modified spectrometer are demonstrated by the examples of studies of CO and methanol adsorption on Pd(111) single crystal and methanol oxidation over Cu poly .The XPS study of high-pressure adsorption of CO on perfect and sputtered Pd (111) showed that raising the pressure has the same effect as decreasing the temperature. The CO coverage is increased due to adsorption of CO to weakly bound (on-top) state, which appears in addition to more strongly bound three-fold and bridged species. No indications of CO dissociation or carbonyl formation were found under the given experimental conditions (high pressure and sputtering-induced defects), provided that the CO gas was sufficiently clean.Two pathways of methanol decomposition to CH x,ads (x 3) and to CO ads was unambiguously identified, with their contribution being dependent on P and T. The decomposition to carbon-originated species had a small contribution in UHV conditions at room temperature, but became more significant at higher pressures and temperatures.Analysis of the distribution of the reaction products and surface species during methanol oxidation over copper in the submillibar pressure range showed that an increase in catalytic activity observed on heating the sample from 420 to 670 K is accompanied by transformation of the adlayer composition. At low temperatures, the surface is covered by methoxy-and, to a lesser extent, formate-groups. The active surface (T > 520 K) is metallic copper with two adsorbed oxygen species. The possible nature of these species is discussed.

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“…Now on some companies producing formaldehyde in "soft" conditions, the copper grids are placed in bottom of the reactor after a layer of crystalline silver and silver grids, forming thus multilayer Ag-Cu catalyst. For many years the interest of the researchers to copper catalysts for alcohol oxidation does not decay, and in the literature and our previous studies the different versions of copper and complex Ag-Cu contacts are permanently offered purposing to lower the consumption of the noble metal [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Formation of active surface of copper catalysts in methanol oxidation

Pestryakov

Лунин

Темкин

et al. 2012

2012 7th International Forum on Strategic Technology (IFOST)

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Features of the process of methanol partial and deep oxidation on supported copper catalysts as compared with silver samples have been studied. The influence of supports of different acid-base nature and modifying additives of Zr, Ce, La and Cs oxides on electronic states of supported copper was investigated by the methods of diffuse reflectance electron spectroscopy, XRD and electron microscopy. By comparison of catalytic and spectroscopic data a conclusion on the nature of active sites of copper catalysts in this process has been made.

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Untitled

Cited by 24 publications

References 15 publications

Adsorbate coverages and surface reactivity in methanol oxidation over Cu(110): An in situ photoelectron spectroscopy study

Adsorbate coverages and surface reactivity in methanol oxidation over Cu(110): An in situ photoelectron spectroscopy study

X-ray photoelectron spectroscopy as a tool for in-situ study of the mechanisms of heterogeneous catalytic reactions

Formation of active surface of copper catalysts in methanol oxidation

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