Research on assembly of nano-Pd colloid and fabrication of supported Pd catalysts from the metal colloid

The ultrasonic-assisted membrane reduction (UAMR) method was used to prepare colloidal Pd nanoparticles. An orthogonal experiment was performed to investigate the effect of synthesis parameters in UAMR on Pd particle size. The average Pd particle size can be regulated in a wide range of 5–220 nm. The fabrication of supported Pd catalyst from a typical nano-sized Pd colloid with 1 wt% Pd loading was studied. The colloid and as-prepared catalyst were characterized by TEM, BET, ICP-OES, XRD, H2-TPR, and CO catalytic oxidation. Fabrication methods would have significant impacts on the actual Pd content, metal dispersion, PdO/Pd reducibility, textural property, etc., over different supports. The CO oxidation activity of the catalysts was consequently decided by these characters. The Pd/Ce0.5Zr0.5O2 catalyst prepared by adsorbing Pd nanoparticles on Ce0.5Zr0.5O2 showed the highest activity with CO complete oxidation at 150 °C among all of the catalysts investigated.