Facile Synthesis of (NH4)2[Pd(C2O4)2]·2H2O and Its Application as a New Precursor in the Preparation of Pd-Based Catalysts for VOC Oxidation

Developing a water-soluble and chlorine-free palladium compound to replace conventional PdCl2 or Pd(NO3)2 as the precursor for Pd-based catalysts remains both challenging and of considerable significance for highly efficient degradation of volatile organic compounds (VOCs). Herein, we report a facile synthetic route to such a Pd compound, (NH4)2[Pd(C2O4)2]·2H2O (denoted as Pd-X5), via a three-step reaction starting from PdCl2, under mild and readily controllable conditions, rendering the process amenable to industrial manufacture. The molecular structure of Pd-X5 was confirmed mainly by elemental analysis, FT-IR, and 13C NMR. The overall yield was greater than 95% and the content of residual chloride was reduced to below 100 ppm. Pd-X5 exhibited high water solubility of 350 g L−1. Subsequently, Pd-X5 was used as a catalytic precursor, and a Pd/Al2O3 catalyst was prepared by an impregnation technique and evaluated for its catalytic performance in the degradation of VOCs. Compared with Pd(NO3)2-derived Pd/Al2O3, the Pd-X5-based catalyst exhibited markedly enhanced activity for the oxidation of CH4 and C3H8 at different temperatures and under different contents of water vapor, indicating that Pd-X5 is superior to Pd(NO3)2 as a catalytic precursor and has potential application in the production of Pd-based catalysts.