We present a detailed study of the surface structure of sulfated zirconia and changes in the acid-base properties of this material upon sulfonation. By using periodic DFT approaches, we explored alternative configurations for sulfated zirconia after de dissociative adsorption of one and two H2SO4molecules, as well as of the putative dimeric species H2S2O7 over t-ZrO2 (101) surface. For the latter, special attention was given to alternative mechanisms and energy profile for its formation by condensation of neighboring sulfate groups. Alternatively, we discuss the possibility of hydrolysis of such species under ambient conditions. Finally, all distinct acid and basic surface sites present in the most stable structures identified for sulfated t-ZrO2 (101) surface were thoroughly mapped by using absorbed probe molecules (CO2, Pyridine, NH3, and H2O). These results provide new insights into the structure of sulfated zirconia-based systems, the effect of sulfate groups over its acid-base properties, and the feasibility of putative active species over its surface.
Maicon Delarmelina, (Cardiff), Haresh Manyar (QUB), Prof. Richard Catlow (UCL/Cardiff)
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Dr Maicon Delarmelina attained his PhD in 2018 from Fluminense Federal University, Rio de Janeiro, Brazil. Shortly after, he was granted a Post-Doctoral Fellowship in the same group by the Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ) to investigate new Frustrated Lewis Pairs containing N-heterocyclic carbenes for the activation of small molecules and hydrogenation of CO2. In February 2019 he joined the group of Prof Richard Catlow at Cardiff University as a Post-Doctoral Research Associate and is currently investigating by state-of-the art DFT calculations new zirconia-based catalyst for upgrading bio-oils obtained from hydrothermal treatment of wastewater solids. The main goal of this project is to develop more efficient catalytic systems for the production of biofuels and added-value chemicals from wastewater biomass. Different aspects of zirconia will be explored at atomic scale (ambient pressure phases, distinct facets, doped-ZrO2, and metal-supported ZrO2) to aid identifying and rationalizing distinct catalytic performances. For this purpose, computational approaches will be used to investigate effects of structure and chemical modifications of ZrO2 on the acidity and basicity of these materials, as well as their catalytic performance towards the transformation of bio-oil model molecules.