Disclosed herein are mixed oxide compositions comprising zirconium and cerium having a surprisingly small particle sizes. The compositions disclosed herein contain zirconium, cerium, optionally yttrium, and optionally one or more other rare earths other than cerium and yttrium. The compositions exhibit a particle size characterized by a D90 value of about 5 um to about 25 μm and a D99 value of about 5 μm to about 50 μm. Further disclosed are processes of producing these compositions using oxalic acid and an alcohol and heating in the process. The compositions can be used as a catalyst and/or part of an automobile exhaust system.

Redox catalysts having surface medication, methods of making redox catalysts with surface modification, and uses of the surface modified redox catalysts are provided. In some aspects, the redox catalysts include a core oxygen carrier region such as CaMnO.sub.3, BaMnO.sub.3−δ, SrMnO.sub.3−δ, Mn.sub.2SiO.sub.4, Mn.sub.2MgO.sub.4−δ, La.sub.0.8Sr.sub.0.2O.sub.3−δ, La.sub.0.8Sr.sub.0.2FeO.sub.3−δ, Ca.sub.9Ti.sub.0.1Mn.sub.0.9O.sub.3−δ, Pr.sub.6O.sub.11−δ, manganese ore, or a combination thereof; and an outer shell having an average thickness of about 1-100 monolayers surrounding the outer surface of the core region. The outer shell can include, for example a salt selected such as Li.sub.2WO.sub.4, Na.sub.2WO.sub.4, K.sub.2WO.sub.4, SrWO.sub.4, Li.sub.2MoO.sub.4, Na.sub.2MoO.sub.4, K.sub.2MoO.sub.4, CsMoO.sub.4, Li.sub.2CO.sub.3, Na.sub.2CO.sub.3, K.sub.2CO.sub.3, or a combination thereof.

Redox catalysts having surface medication, methods of making redox catalysts with surface modification, and uses of the surface modified redox catalysts are provided. In some aspects, the redox catalysts include a core oxygen carrier region such as CaMnO.sub.3, BaMnO.sub.3−δ, SrMnO.sub.3−δ, Mn.sub.2SiO.sub.4, Mn.sub.2MgO.sub.4−δ, La.sub.0.8Sr.sub.0.2O.sub.3−δ, La.sub.0.8Sr.sub.0.2FeO.sub.3−δ, Ca.sub.9Ti.sub.0.1Mn.sub.0.9O.sub.3−δ, Pr.sub.6O.sub.11−δ, manganese ore, or a combination thereof; and an outer shell having an average thickness of about 1-100 monolayers surrounding the outer surface of the core region. The outer shell can include, for example a salt selected such as Li.sub.2WO.sub.4, Na.sub.2WO.sub.4, K.sub.2WO.sub.4, SrWO.sub.4, Li.sub.2MoO.sub.4, Na.sub.2MoO.sub.4, K.sub.2MoO.sub.4, CsMoO.sub.4, Li.sub.2CO.sub.3, Na.sub.2CO.sub.3, K.sub.2CO.sub.3, or a combination thereof.

The present invention relates to a mixed oxide with enhanced resistance and NO.sub.x storage capacity. The mixed oxide may be used as a component of a NO.sub.x trap material in an exhaust system of an internal combustion engine. The invention also relates to a method for treating an exhaust gas from an internal combustion engine using the mixed oxide.

The present invention relates to a mixed oxide with enhanced resistance and NO.sub.x storage capacity. The mixed oxide may be used as a component of a NO.sub.x trap material in an exhaust system of an internal combustion engine. The invention also relates to a method for treating an exhaust gas from an internal combustion engine using the mixed oxide.

The presently claimed invention provides a catalytic article and an exhaust gas treatment system. The catalytic article comprises platinum supported on a first support comprising ceria containing metal oxide component; rhodium supported on a second support selected from a refractory alumina component, an oxygen storage component or a combination thereof; and a substrate, wherein said catalytic article is essentially free of palladium. The presently claimed invention also provides a process for preparing the catalytic article and use of the catalytic article and the exhaust gas treatment system for purifying a gaseous exhaust stream comprising hydrocarbons, carbon monoxide, and nitrogen oxide.

The presently claimed invention provides a catalytic article and an exhaust gas treatment system. The catalytic article comprises platinum supported on a first support comprising ceria containing metal oxide component; rhodium supported on a second support selected from a refractory alumina component, an oxygen storage component or a combination thereof; and a substrate, wherein said catalytic article is essentially free of palladium. The presently claimed invention also provides a process for preparing the catalytic article and use of the catalytic article and the exhaust gas treatment system for purifying a gaseous exhaust stream comprising hydrocarbons, carbon monoxide, and nitrogen oxide.

An improved SCRoF (selective catalytic reduction on filter) device for treating exhaust from an internal combustion engine. The filter has numerous entry and exit channels. Exhaust enters the entry channels and flows through side walls into the exit channels. Relative to the exhaust flow path, these side walls are coated on the downstream side with a ceria-based catalyst and on the upstream side with a Cu-zeolite catalyst. This allows the filter to optimally achieve both particulate matter oxidation and NOx reduction, respectively.

An improved SCRoF (selective catalytic reduction on filter) device for treating exhaust from an internal combustion engine. The filter has numerous entry and exit channels. Exhaust enters the entry channels and flows through side walls into the exit channels. Relative to the exhaust flow path, these side walls are coated on the downstream side with a ceria-based catalyst and on the upstream side with a Cu-zeolite catalyst. This allows the filter to optimally achieve both particulate matter oxidation and NOx reduction, respectively.

This invention relates to an aqueous dispersion of particles, the dispersion having a particle content of 10-70 wt %, and the particles comprising, on an oxide basis: (a) 10-98 wt % in total of ZrO.sub.2+HfO.sub.2, and (b) 2-90 wt % in total of AI.sub.2O.sub.3, CeO.sub.2, La.sub.2O.sub.3, Nd.sub.2O.sub.3, Pr.sub.6O.sub.11, Y.sub.2O.sub.3, or a transition metal oxide, wherein the dispersion has a Z-average particle size of 100-350 nm and the particles have a crystallite size of 1-9 nm. The invention also relates to a substrate coated with the aqueous dispersion of particles.