Preparation and characterization of highly active Pd nanoparticles supported Mn 3 O 4 catalyst for low-temperature CO oxidation

Abstract

Two methods were used to prepare Mn 3 O 4 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 MnO 2 phase with small amount with tetragonal Mn 3 O 4 due to hydrothermal treatment at 150 °C. Moreover, no changes in the textural properties of Mn 3 O 4 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 Pd 2+ species on the Mn 3 O 4 surface. The reducibility of pure Mn 3 O 4 was greatly enhanced and shifted to lower temperatures after incorporation of Pd nanoparticles. The presence of Pd 2+ 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.