Enhanced activity for CO oxidation over Pd/Al2O3 catalysts prepared by atmospheric-pressure cold plasma

• Pd/Al2O3 catalysts were fabricated by atmospheric-pressure dielectric barrier discharge cold plasma.
• The influences of the Pd precursors on the Pd/Al2O3 catalysts were investigated.
• Pd/Al2O3 catalysts fabricated by the fast and facile plasma method using Pd(NO3)2 as Pd precursor exhibited enhanced CO oxidation activity.
• The promoted activity may be attributed to the small size of the Pd nanoparticles and the chemisorbed oxygen species.

Atmospheric-pressure dielectric barrier discharge (DBD) cold plasma was employed to prepare Pd/Al2O3 catalysts by simple incipient wetness impregnation using Pd(NO3)2 and PdCl2 as precursors, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and N2 adsorption–desorption measurement were used to characterize the Pd/Al2O3 catalysts. CO catalytic oxidation reaction was adopted to investigate the activity of the catalysts. The activity for the Pd/Al2O3 samples prepared by cold plasma using the same Pd precursor was higher than that prepared by thermal reduction method, which indicated that cold plasma is an efficient method for preparing high-performance Pd/Al2O3 catalysts. The results also showed that the Pd/Al2O3 catalysts prepared using Pd(NO3)2 as precursor possess smaller size of Pd nanoparticles, and most of the Pd nanoparticles were distributed on the surface of the Al2O3 support. In addition, a certain amount of chemisorbed oxygen species were detected on the surface of Al2O3 support due to the oxygen-containing Pd precursor. Therefore, they exhibited significantly enhanced activity for CO oxidation than that prepared using PdCl2 as Pd precursor. Atmospheric-pressure DBD cold plasma is a fast and facile method (just 6-min reduction) for fabricating high-performance Pd/Al2O3 catalysts using Pd(NO3)2 as Pd precursor.

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