Abstract:
The present invention relates to colloidal dispersions comprising a plurality of precious group nanoparticles, wherein about 90% or more of the precious group metal is in fully reduced form; a dispersion medium comprising a polar solvent; a water-soluble polymer suspension stabilizing agent; and a reducing agent, wherein the nanoparticle concentration is at least about 2 wt. % of the colloidal dispersion, wherein the nanoparticles have an average particle size of about 1 to about 6 nm and at least 95% of the nanoparticles have a particle size within this range; and further wherein the colloidal dispersion is substantially free of halides, alkali metals, alkaline earth metals and sulfur compounds. Methods of preparing, further processing, and using such colloidal dispersions are also provided herein.
Abstract:
Aspects of the invention pertain to catalytic articles and methods of making catalytic articles comprising a first catalytic coating comprising a platinum group metal, wherein the first catalytic coating is substantially free of Cu, Ni, Fe, Mn, V, Co, Ga, Mo, Mg, Cr and Zn; a second catalytic coating comprising a non-PGM metal, wherein the second catalytic coating is substantially free of any platinum group metal; and one or more substrates, wherein the first catalytic coating is separated from the second catalytic coating, optionally with a barrier layer.
Abstract:
Catalyst articles comprising palladium and related methods of preparation and use are disclosed. Disclosed is a catalyst article comprising a first catalytic layer formed on a substrate, wherein the first catalytic layer comprises palladium impregnated on a ceria-free oxygen storage component and platinum impregnated on a refractory metal oxide, and a second catalytic layer formed on the first catalytic layer comprising platinum impregnated on an oxygen storage component and rhodium impregnated on a zirconia-coated or yttria-coated alumina. The palladium component of the catalyst article is present in a higher proportion relative to the other platinum group metal components. The catalyst articles provide improved reductions in NOx in exhaust gases, particularly after lean-rich aging.