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

摘要

The ultrasonic-assisted membrane reduction (UAMR) method was used to prepare colloidal Pd nanopar-ticles. 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/Ce_(0.5)Zr_(0.5)O2 catalyst prepared by adsorbing Pd nanoparticles on Ce_(0.5)Zr_(0.5)O2 showed the highest activity with CO complete oxidation at 150 °C among all of the catalysts investigated.