Construction of cross-linked δ-MnO2 with ultrathin structure for the oxidation of H2S: Structure-activity relationship and kinetics study

Cross-linked birnessite-type manganese oxides (δ-MnO2) with ultrathin structures (nanosheet and nanobelt) were successfully synthesized by a facile CTAB-intercalation exfoliation method. The unique ultrathin structure provides high percentage of exposed surface atoms, leading to an increase in the contact area with the reaction gases. Additionally, specific crystal facets were exposed on the different ultrathin structures and hence facilitate the control of oxygen vacancies (Vo), which strongly affects the physico-chemistry properties and therefore tunes the activity of reactive sites. As a result, ultrathin δ-MnO2 cross-linked nanosheets with major exposed (100) facet exhibits better activity for H2S oxidation in comparison with δ-MnO2 nanobelts with (002) facet and δ-MnO2 stacked nanosheets with (001) plane, giving complete H2S conversion and sulfur selectivity at 210 °C, which is superior to the most of reported manganese-based catalysts. In addition, kinetics study revealed that reaction between adsorbed O2 and H2S is the rate determining step.