Identification of Intermediates in the Reaction Pathway of SO2 on the CaO Surface: From Physisorption to Sulfite to Sulfate. Issue 23 (16th March 2023)

• Record Type: Journal Article
• Authors: Schewe, Nils; Maleki, Farahnaz; Di Liberto, Giovanni; Gerdes, Andreas; Idriss, Hicham; Pacchioni, Gianfranco; Wöll, Christof
• Is Part Of: Chemistry. Volume 29:Issue 23(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-16
• Subjects: SO2 -- CaO(001) -- IRRAS -- Acid rain; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202203956
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The interaction of CaO and Ca(OH)2 with solvated or gaseous SO2 plays a crucial role in the corrosion of urban infrastructure by acid rain or in the removal of SO2 from flue gas. We carried out a combined spectroscopic and theoretical investigation on the interaction of SO2 with a CaO(001) single crystal. First, the surface chemistry of SO2 was investigated at different temperatures using polarization‐resolved IR reflection absorption spectroscopy. Three species were identified, and an in‐depth density functional theory study was carried out, which allowed deriving a consistent picture. Unexpectedly, low temperature exposure to SO2 solely yields a physisorbed species. Only above 100 K, the transformation of this weakly bound adsorbate first to a chemisorbed sulfite and then to a sulfate occurs, effectively passivatating the surface. Our results provide the basis for more efficient strategies in corrosion protection of urban infrastructure and in lime‐based desulfurization of flue gas. Abstract : Under ultra‐high vacuum conditions, three surface sulfur oxide species were IR‐spectroscopically detected on a CaO(001) single crystal surface. Polarisation dependent infrared reflection absorption spectroscopy and density functional theory were used to identify the chemical nature of the adsorbates as a physisorbate and two different chemisorbates.