Uses of Palladium in Automotive Emission Control Catalysts

Pd-containing perovskite-type oxides used for three-way catalysts

“…This indicates that (1) palladium was doped into the crystal lattice of ABO 3 prepared by means of precipitation, and (2) the surface structure of perovskite-type had been modified by reactant gases during reaction. 3 , Pd was in the lattice of perovskite-type oxide and strong interaction between Pd and O occurred and relative difficulty to be reduced. Combining with the activity results, we can conclude that the easier of the palladium to be reduced, the higher activity was obtained.…”

“…The Rh/Pt ratio in TWC with sufficient durability is considerably higher than mine ratio [1]. Palladium is well known to have a better resistance to thermal sintering, lower price than Pt and Rh, and also have a good activity for the oxidation of hydrocarbon and carbon monoxide [2][3][4][5]. Recent attention has been concentrated on the use of palladium-based catalyst for TWC formulations.…”

NO Heterogeneous Catalysis Viewed from the Angle of Nanoparticles

“…Fortunately, breakthroughs occurred in both, at the cost of increasingly complex catalytic materials and formulation strategies. Considering the light -off issue fi rst, research on Pd as an alternative to Pt/Rh for NOx control showed that excellent NOx reduction could be achieved with Pd formulations when suitably promoted (as noted above) and at loadings higher than those for Pt/Rh [58,59] . Simultaneously, segregating some of the Pd from ceria was recognized to yield a better low -temperature performance (including light -off) [60] .…”

Re-dispersion of Pd on Ce0.5Zr0.5O2 upon cooling in the presence of oxygen

“…Sintering has always been a longstanding problem affecting the lifetime of Pd based TWCs, as it results in severe decrease of Pd dispersion, especially in the case that the catalysts serve in continual oxygen oscillation as well as high temperature up to 1000 • C [11][12][13][14]. Many studies have reported that the decreasing dispersion of Pd species by sintering could strongly deteriorate the catalytic activity of supported Pd catalysts [15][16][17][18][19][20]. Hoffmann et al [21] compared reaction kinetics over two types of model catalysts with different Pd dispersion, and the sample with large Pd dispersion showed clear superiority.…”