Electron paramagnetic resonance of SO2-on magnesium oxide

Schoonheydt, Robert A.; Lunsford, JH

doi:10.1021/j100647a008

Cited by 56 publications

(33 citation statements)

References 5 publications

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“…This leads to the formation of a SO 2 − species characterized by a +III oxidation state for sulfur. Similar species have been reported for SO 2 adsorption on MgO surfaces with trapped electrons 28 and on partially reduced TiO 2 . 29…”

Section: E So 2 − -Like Species and Activation Of So 2 For Dissociationsupporting

confidence: 84%

SOx on ceria from adsorbed SO2

Müller²,

Yang³

et al. 2011

The Journal of Chemical Physics

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Results from first-principles calculations present a rather clear picture of the interaction of SO(2) with unreduced and partially reduced (111) and (110) surfaces of ceria. The Ce(3+)∕Ce(4+) redox couple, together with many oxidation states of S, give rise to a multitude of SO(x) species, with oxidation states from +III to +VI. SO(2) adsorbs either as a molecule or attaches via its S-atom to one or two surface oxygens to form sulfite (SO(3)(2-)) and sulfate (SO(4)(2-)) species, forming new S-O bonds but never any S-Ce bonds. Molecular adsorption is found on the (111) surface. SO(3)(2-) structures are found on both the (111) and (110) surfaces of both stoichiometric and partially reduced ceria. SO(4)(2-) structures are observed on the (110) surface together with the formation of two reduced Ce(3+) surface cations. SO(2) can also partially heal the ceria oxygen vacancies by weakening a S-O bond, when significant electron transfer from the surface (Ce4f) into the lowest unoccupied molecular orbital of the SO(2) adsorbate takes place and oxidizes the surface Ce(3+) cations. Furthermore, we propose a mechanism that could lead to monodentate sulfate formation at the (111) surface.

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Section: E So 2 − -Like Species and Activation Of So 2 For Dissociationsupporting

confidence: 84%

SOx on ceria from adsorbed SO2

Müller²,

Yang³

et al. 2011

The Journal of Chemical Physics

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“…Waqif et a1. [7] have also examined the interaction of SO2 with MgO and find that sulfite, SOS, species are formed and Schoonheydt and Lunsford [8] reported that sulfate (Sod) species form upon heating. The interaction of SO2 with acid and basic sites of clean, fully dehydroxylated MgO have been investigated by Pacchioni, Clotet and Ricart [9]using ab initio cluster model calculations.…”

Section: Discussionmentioning

confidence: 99%

Experimental Investigations of the Interaction of SO₂ with MgO

1999

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High resolution adsorption isotherms, temperature programmed desorption (TPD), x-ray diffraction (XRD) and x-ray absorption near edge spectroscopy (XANES) methods were used to investigate the interaction of SO2 with high quality MgO powders. The results of these investigations indicate that when SO2 is deposited on MgO in monolayer quantities at temperatures near 100K both SOS and SO4 species form that are not removed by simply pumping on the pre-dosed samples at room temperature. TPD and XANES studies indicate that heating of pre-dosed MgO samples to temperatures above 350 "C is required for full removal of the SO3604 species. XANES measurements made as a function of film thickness indicate for coverages near monolayer completion that the SO4 species form first. IntroductionSulfur dioxide is one of the main pollutants released into the atmosphere as a result of volcanic activity, and the burning of sulfur bearing fossil fuels in automobile engines, industrial complexes, power plants and households. The subsequent interaction of the sulfur dioxide with air and atmospheric moisture results in the formation of "acid rain" leading to the corrosion of metals and degradation of stone buildings and statuary [ 11. To diminish the environmental effects of sulfur dioxide emissions one must either dissociate or remove the SO2 from the effluent. MgO and CaO are two materials that are widely used as commercial scrubbers in industry [2]. We describe our recent investigations using adsorption isotherms, TPD, XANES and XRD investigations of the interaction of SO2 with MgO.

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“…Thus the SO 4 2− group in this complex is concluded to be chelating bidentate or bridging bidentate ligands. The SO 4 2− group in S300 can be estimated as bridging bidentate ligand because the maximum absorption peak is less than 1200 cm −1 [34][35][36]. Compared with Fig.…”

Section: Characterization Of S300mentioning

confidence: 94%