SO2 adsorption and desorption kinetics on Pt(111)

Köhler, Ulrich; Wassmuth, H.-W.

doi:10.1016/0039-6028(83)90742-2

Cited by 63 publications

(20 citation statements)

References 12 publications

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“…It is therefore essential to understand the behaviour of SO 2 on the Pt surface in order to suggest less costly alternatives. Insights into the binding and reactivity of SO 2 on various transition metal surfaces, including Cu [18][19][20][21], Ni [22][23][24], Ag [25,26], Rh [27,28], Pd [20,[28][29][30][31][32], and Pt [20,27,[33][34][35][36], have accumulated through experimental and theoretical work over the past two decades. However, major difficulties have been experienced in experiments, in part due to the existence of various co-adsorbed surface sulphur species, even when pure sulphur oxides, such as SO 2 , are introduced from the gas phase onto the metal catalytic surfaces.…”

Section: Introductionmentioning

confidence: 99%

Interaction of SO2 with the Platinum (001), (011), and (111) Surfaces: A DFT Study

et al. 2020

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Given the importance of SO2 as a pollutant species in the environment and its role in the hybrid sulphur (HyS) cycle for hydrogen production, we carried out a density functional theory study of its interaction with the Pt (001), (011), and (111) surfaces. First, we investigated the adsorption of a single SO2 molecule on the three Pt surfaces. On both the (001) and (111) surfaces, the SO2 had a S,O-bonded geometry, while on the (011) surface, it had a co-pyramidal and bridge geometry. The largest adsorption energy was obtained on the (001) surface (Eads = −2.47 eV), followed by the (011) surface (Eads = −2.39 and −2.28 eV for co-pyramidal and bridge geometries, respectively) and the (111) surface (Eads = −1.85 eV). When the surface coverage was increased up to a monolayer, we noted an increase of Eads/SO2 for all the surfaces, but the (001) surface remained the most favourable overall for SO2 adsorption. On the (111) surface, we found that when the surface coverage was θ > 0.78, two neighbouring SO2 molecules reacted to form SO and SO3. Considering the experimental conditions, we observed that the highest coverage in terms of the number of SO2 molecules per metal surface area was (111) > (001) > (011). As expected, when the temperature increased, the surface coverage decreased on all the surfaces, and gradual desorption of SO2 would occur above 500 K. Total desorption occurred at temperatures higher than 700 K for the (011) and (111) surfaces. It was seen that at 0 and 800 K, only the (001) and (111) surfaces were expressed in the morphology, but at 298 and 400 K, the (011) surface was present as well. Taking into account these data and those from a previous paper on water adsorption on Pt, it was evident that at temperatures between 400 and 450 K, where the HyS cycle operates, most of the water would desorb from the surface, thereby increasing the SO2 concentration, which in turn may lead to sulphur poisoning of the catalyst.

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Section: Introductionmentioning

confidence: 99%

Interaction of SO2 with the Platinum (001), (011), and (111) Surfaces: A DFT Study

et al. 2020

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“…In this work, we examine the surface chemistry of SO 2 on polycrystalline Sn, Pt(111) and a ( × )R30°-Sn/Pt(111) surface alloy using synchrotron-based high-resolution photoemission an ab initio self-consistent field (SCF) calculations. The adsorption of SO 2 on Pt(111) has been the subject of several studies. ,, At 100 K, SO 2 adsorbs molecularly on Pt(111), whereas at 300 K the molecule dissociates and forms SO 3 /SO 4 species on the metal surface. We observe a different behavior for SO 2 on ( × )R30°-Sn/Pt(111).…”

Section: Introductionmentioning

confidence: 99%

Surface Chemistry of SO₂ on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

et al. 1998

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The surface chemistry of SO2 on polycrystalline Sn, Pt(111), and a ( x )R30°-Sn/Pt(111) surface alloy has been investigated using synchrotron-based high-resolution photoemission and ab initio self-consistent field calculations. Metallic tin has a large chemical affinity for SO2. At 100−150 K, SO2 disproportionates on polycrystalline tin forming multilayers of SO3 (2SO2,a → SOgas + SO3,a). At these low temperatures, the full dissociation of SO2 (SO2,a → Sa + 2Oa) is minimal. As the temperature is raised to 300 K, the SO3 decomposes, yielding SO4, S, and O on the surface. Pure tin exhibits a much higher reactivity toward SO2 than late transition metals (Ni, Pd, Pt, Cu, Ag, Au). In contrast, tin atoms in contact with Pt(111) interact weakly with SO2. A ( × )R30°-Sn/Pt(111) alloy is much less reactive toward SO2 than polycrystalline tin or clean Pt(111). At 100 K, SO2 adsorbs molecularly on ( × )R30°-Sn/Pt(111). Most of the adsorbed SO2 desorbs intact from the surface (250−300 K), whereas a small fraction dissociates into S and O. The drastic drop in reactivity when going from pure tin to the ( × )R30°-Sn/Pt(111) alloy can be attributed to a combination of ensemble and electronic effects. On the other hand, the low reactivity of the Pt sites in ( × )R30°-Sn/Pt(111) with respect to Pt(111) is a consequence of electronic effects. The Pt−Sn bond is complex, involving a Sn(5s,5p) → Pt(6s,6p) charge transfer and a Pt(5d) → Pt(6s,6p) rehybridization that localize electrons in the region between the metal centers. These phenomena reduce the electron donor ability of Pt and Sn, and both metals are not able to respond in an effective way to the presence of SO2. The Sn/Pt system illustrates how a redistribution of electrons that occurs in bimetallic bonding can be useful for the design of catalysts that have a remarkably low reactivity toward SO2 and for controlling sulfur poisoning.

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“…Wassmuth et al concluded that SO2 adsorbs dissociatively at 160 K forming SOa and Oa, which undergo recombinative desorption at 300 K [22,23,24]. In the light of their HREELS and XPS data, White et al [16] argue in favour of molecular adsorption at 130 K, followed at 300 K either by desorption as SO2, or dissociation to form adsorbed S, SO and SO4.…”

Section: Discussionmentioning

confidence: 99%

Short-Chain Alkane Activation

Wilson

Hardacre

Lambert

1996

ACS Symposium Series

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SO 2 chemisorption on oxygenated Pt(111) enormously enhances the dissociative chemisorption and subsequent combustion of propane. This activation of the metal surface is induced by an adsorbed sulfoxy species which is formed > 220 K. In the absence of adsorbed SO 2 the sticking probability of propane is immeasurably small. However in the presence of SO 2 , the precursor-mediated initial sticking probability rises from ~0.02 at 300 K to ~ 0.15 at 160 K. XPS and HREELS measurements identify the active species as SO4 2-, and also demonstrate the consumption of SO 4 during the oxidation reaction. Coincident CO 2 and SO 2 formation suggest decomposition of a complex reaction intermediate: this is supported by isotope experiments involving CO adsorption onto SO 2 / 18 O2 precovered Pt(111). Propane oxidation over sulphated AlO X films on Pt (111) is also reported, with increased activity for submonolayer oxidised Al films being observed compared to clean Pt(111).The activation of short chain alkanes is often the rate limiting step in catalytic oxidation of hydrocarbons [1]. In particular, the slow oxidation of alkanes, namely propane and methane, is a technological problem faced by the automotive exhaust catalyst industry [2]. Reactor studies of Pt/Al203 and Pt-Rh/Al203/Ce02 catalysts have shown that the inclusion of SO2 in the gas feed significantly promotes the oxidation of propane [3,4], whilst inhibiting reactions of CO, NO and propene. It has also been observed that in the presence of SO2, the activity of Pt/Al203 catalysts for propane oxidation becomes independent of Pt loading. In the absence of SO2, the activity usually increases with Pt loading, a result which suggests the formation of different active sites on inclusion of SO2 in the gas feed. Infra-red analysis of these catalysts following exposure to O2 and SO2, indicates the presence of S04^" on the support, which is thought to be involved in the activation process. Enhanced C-H bond dissociation is often attributed to catalyst acidity [5]; for example homogeneous Pt(III) solutions display increased oxidative capacity in the presence of sulphuric acid.

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SO2 adsorption and desorption kinetics on Pt(111)

Cited by 63 publications

References 12 publications

Interaction of SO2 with the Platinum (001), (011), and (111) Surfaces: A DFT Study

Interaction of SO2 with the Platinum (001), (011), and (111) Surfaces: A DFT Study

Surface Chemistry of SO₂ on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

Short-Chain Alkane Activation

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SO2 adsorption and desorption kinetics on Pt(111)

Cited by 63 publications

References 12 publications

Interaction of SO2 with the Platinum (001), (011), and (111) Surfaces: A DFT Study

Interaction of SO2 with the Platinum (001), (011), and (111) Surfaces: A DFT Study

Surface Chemistry of SO2 on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

Short-Chain Alkane Activation

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Surface Chemistry of SO₂ on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur