Insight into the Role of Pd State on Pd‐Based Catalysts in o‐Xylene Oxidation at Low Temperature

Abstract Pd‐based catalysts are long known to be efficient for catalytic oxidation of volatile organic compounds (VOCs), but the effect of the Pd state on the activity remains controversial. In this study, we prepared a series of Pd supported on Co 3 O 4 , MnO 2 , CeO 2 , TiO 2 , Al 2 O 3 , SiO 2 catalysts. The as‐prepared catalysts were pretreated by NaBH 4 and H 2 reduction, respectively, and then tested towards o ‐xylene oxidation. The samples were next characterized to investigate how the Pd state and the support type affect the catalytic activity. The test and characterization results clearly show that the metallic Pd species is much more active than the Pd oxide species for o ‐xylene oxidation at low temperatures, independent of the presence of reducible oxides as supports. Furthermore, NaBH 4 pretreatment could avoid undesired support reduction; thus, it is a more appropriate method than H 2 reduction for the preparation of supported metallic noble‐metal catalysts.