Abstract
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•Pd/Mn3O4 catalysts were successfully prepared by different methods•The catalyst reducibility greatly improved after Pd nanoparticles deposition•The catalysts contain mixture of Pd° and Pd2+ species•The catalysts exhibited higher catalytic performance in CO oxidation•Oxygen vacancies, Pd° and Pd2+ may be responsible for the catalyst activity
Two methods were used to prepare Mn3O4 followed by deposition of Pd nanoparticles with 2 and 4 wt.%. The textural and structural properties were characterized by several methods. The XRD results showed the participation of MnO2 phase with small amount with tetragonal Mn3O4 due to hydrothermal treatment at 150 °C. Moreover, no changes in the textural properties of Mn3O4 due to the difference in preparation method or Pd nanoparticles deposition. TEM images showed different morphologies such as cubic, spheroid and plate-shaped structures. The XPS study confirmed the distribution of both Pd° and Pd2+ species on the Mn3O4 surface. The reducibility of pure Mn3O4 was greatly enhanced and shifted to lower temperatures after incorporation of Pd nanoparticles. The presence of Pd2+ may facilitate the providing of reactive lattice oxygen for CO oxidation by the support. The performance of the catalysts towards CO oxidation was much more enhanced as the Pd content increased to 4 wt. %. The results showed good stability and durability during the CO oxidation.