PALLADIUM METAL AND PALLADIUM OXIDE PARTICLE-PRODUCTION BY SPRAY PYROLYSIS

Spray pyrolysis was used to produce dense, spherical palladium metal particles at and above 900-degrees-C in air and 800-degrees-C in nitrogen, well below the melting point of palladium (1554-degrees-C). Palladium oxide particles were produced at lower temperatures. At 500-degrees-C the PdO particles were composed of nanocrystalline grains 5 to 15 nm in diameter and had surface areas of 30.2 to 32.8 m2/g. The particles became less porous and less polycrystalline.as temperature increased. At 800-degrees-C the PdO particles were polycrystalline with grains of 20 to 50 nm and a surface area of 3.23 m2/g. The Pd particles produced at 900-degrees-C by decomposition of the oxide were single-crystalline and fully-dense. These observations are consistent with the formation of porous but not hollow aggregates of PdO at lower temperatures, which can be densified in the gas phase to form solid particles of Pd above 900-degrees-C.