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

Marietjie J. Ungerer; David Santos‐carballal; Abdelaziz Cadi‐essadek; Cornelia G.C.E. van Sittert; Nora H. de Leeuw

doi:10.3390/catal10050558

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

Marietjie J. Ungerer, David Santos‐carballal, Abdelaziz Cadi‐essadek, Cornelia G.C.E. van Sittert, Nora H. de Leeuw

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

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 (E_ads = −2.47 eV), followed by the (011) surface (E_ads = −2.39 and −2.28 eV for co‐pyramidal and bridge geometries, respectively) and the (111) surface (E_ads = −1.85 eV). When the surface coverage was increased up to a monolayer, we noted an increase of E_ads/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.

Original language	English
Article number	558
Number of pages	18
Journal	Catalysts
Volume	10
Issue number	5
DOIs	https://doi.org/10.3390/catal10050558
Publication status	Published - 18 May 2020

Funding

Funding: This research was funded by the Engineering and Physical Sciences Research Council (EPSRC Grant Nos. EP/K016288/1 and EP/K009567/2) and the Economic and Social Research Council (ESRC Grant No. ES/N013867/1) Acknowledgments: We acknowledge the Engineering and Physical Sciences Research Council (EPSRC Grant Nos. EP/K016288/1 and EP/K009567/2), as well as the Economic and Social Research Council (ESRC Grant No. ES/N013867/1) and the National Research Foundation of South Africa for funding under the Newton Programme. This research was undertaken using resources of the Supercomputing Facilities at Cardiff University operated by Advanced Research Computing at Cardiff (ARCCA) on behalf of Supercomputing Wales (SCW) projects, which is partly funded by the European Regional Development Fund (ERDF) via the Welsh Government. We also acknowledge the use of facilities at the Centre for High Performance Computing (CHPC), South Africa. We wish to acknowledge the use of the EPSRC funded National Chemical Database Service hosted by the Royal Society of Chemistry. D.S.‐C. is grateful to the Department of Science and Technology (DST) and the National Research Foundation (NRF) of South Africa for the provision of a Visiting Postdoctoral Fellowship. M.J.U. would like to acknowledge the National Research Foundation of South Africa for funding under the Post‐ Doctoral Fellowship (NRF Grant No. 116728) and the North‐West University for their support and resources. All data created during this research are openly available from Cardiff University’s Research Portal at http://doi.org/10.17035/d.2020.0102392045.

Keywords

Adsorption
DFT
Platinum
SO
Sulphur Dioxide

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

abstract = "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.",

keywords = "Adsorption, DFT, Platinum, SO, Sulphur Dioxide",

author = "Ungerer, {Marietjie J.} and David Santos‐carballal and Abdelaziz Cadi‐essadek and {van Sittert}, {Cornelia G.C.E.} and {de Leeuw}, {Nora H.}",

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AU - Ungerer, Marietjie J.

AU - Santos‐carballal, David

AU - Cadi‐essadek, Abdelaziz

AU - van Sittert, Cornelia G.C.E.

AU - de Leeuw, Nora H.

PY - 2020/5/18

Y1 - 2020/5/18

N2 - 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.

AB - 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.

KW - Adsorption

KW - DFT

KW - Platinum

KW - SO

KW - Sulphur Dioxide

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

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