DFT study of sulfur-oxygen substitution on Pr-doped CeO2(111)

BEATRIZ IRIGOYEN; AGUSTÍN SALCEDO

Santa Fe

Conferencia; VI San Luis Conference; 2018

UNL

Steam reforming of a methane stream obtained from biomass gasification is a potential route for sustainable syngas (CO+H2) and hydrogen production. The rate-limiting step for the methane steam reforming (MSR) reaction is thought to be CH4 activation. In this sense, a recent work by our group has shown that praseodymium-doped ceria-based catalysts promote methane activation. Besides, Pr-doped ceria has high oxygen storage capacity and has shown superior activity for CO-PROX and WGS reactions. Thus, we can anticipate great potential of these solids as supports for MSR. However, it is worth noting that the stream from biomass gasification employed for MSR also contains sulfur species. Therefore, it is important to understand how these species interact with Pr-doped ceria. At reaction conditions, these sulfur species are converted to hydrogen sulfide (H2S). Desorption of water upon ceria exposure to H2S suggest that sulfur replaces oxygen in the ceria lattice. Thus, in this work we performed density functional theory (DFT) calculations to examine the oxygen/sulfur substitution in both the pure and Pr-doped CeO2(111) surfaces.