The present invention concerns a process for the production of metal doped cerium compositions comprising a cerium oxide and a metal oxide by precipitation. The invention also concerns metal doped cerium compositions providing high crystallites size and exhibiting high thermal stabilities, which may be used as a catalytic support or for polishing applications.

The present invention relates to a composition for use in a catalyst system in emission control systems comprising a transition alumina based material and rare earth phosphates and to a method for making same.

A diesel oxidation catalyst composition is provided, the composition including at least one platinum group metal impregnated onto a porous refractory oxide material in particulate form and at least one base metal oxide impregnated onto a porous refractory oxide material in particulate form, wherein the porous refractory oxide material impregnated with at least one platinum group metal and the porous refractory oxide material impregnated with at least one base metal oxide are in the form of a mixture or wherein the at least one platinum group metal and the at least one base metal oxide are impregnated on the same porous refractory oxide material. The diesel oxidation catalyst provides synergistic enhancement of carbon monoxide oxidation as well as relatively unimpaired hydrocarbon oxidation. Methods of making and using the catalyst composition are also provided, as well as emission treatment systems comprising a catalyst article coated with the catalyst composition.

An object of the present invention is to provide means for improving the hydrogen generation properties of a hydrogen-producing catalyst. A hydrogen-producing catalyst according to one aspect of the present invention comprises Rh and a composite containing Al, Ce, and Zr. When a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce) in the composite measured by X-ray fluorescence (XRF) analysis is R.sub.I and a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce,) in the composite measured by an Xray photoelectron spectroscopy (XPS) method is R.sub.2, a value of R.sub.2-R.sub.1 is greater than 2.25 and less than 5.92.

The present disclosure is directed to compositions comprising Ce-containing mixed oxides, especially those having a stoichiometry of Ln.sub.yCe.sub.xM.sub.wO.sub.z; where 0.15x0.5, y0.25, w=(1-x-y)0.5, and z=(2x+2w+1.5y); M is Zr, Hf, Ti, Sn or Ge or a combination thereof; Ln is Y and/or one or more rare earth metals, exclusive of Ce,
and the uses of these compositions. These compositions are characterized by the even distribution of the Ce in the lattice of the mixed oxide.

A lean NO.sub.x trap catalyst and its use in an emission treatment system for internal combustion engines is disclosed. The lean NO.sub.x trap catalyst comprises a first layer for storing nitrogen oxides (NOx) under lean exhaust gas conditions and releasing and/or reducing stored NOx during rich exhaust gas conditions, and a second layer, said second layer comprising a first zone for oxidizing carbon monoxide (CO) and/or hydrocarbons (HC), and a second zone for oxidizing nitric oxide (NO), and a substrate having an inlet end and an outlet end.

A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprises: a substrate; and a catalytic region on the substrate; wherein the catalytic region comprises a platinum group metal (PGM) component, an oxide, and a rare earth metal component; wherein the oxide is an inorganic oxide, an oxygen storage component (OSC) material, or a mixture thereof; wherein the rare earth metal component concentration by element on the surface of the oxide per unit specific surface area of the oxide is 1 mol/m.sup.2 to 20 mol/m.sup.2.

It is intended to provide a novel zeolite with a rare earth element-substituted framework which has a higher amount of NOx adsorbed and a method for producing the same, and a NOx adsorption member and a catalyst for automobile exhaust gas, etc. comprising the same. The present invention provides a zeolite with a rare earth element-substituted framework, comprising at least a zeolite and at least one rare earth element selected from the group consisting of Ce, La, Nd and Pr, wherein a content ratio of the rare earth element is 1 to 15% by mass in total based on the total amount, and one or some of Al and/or Si atoms constituting the framework of the zeolite are replaced with the rare earth element.

The present invention discloses a preparation method of a catalyst with white carbon black modified by ZrNdO and use thereof, and belongs to the field of catalyst technologies. In the present invention, an organic solvent evaporation induced self-assembly method is used to load ZrNdO onto white carbon black to obtain a mesoporous ZrNdO/white carbon black catalyst. The mesoporous ZrNdO/white carbon black catalyst in the present invention has high catalytic activity, contains uniformly distributed mesopores with a relatively large average aperture, and has a simple preparation process, etc.

An exhaust purification system includes an LAF sensor provided in an exhaust pipe and generates a signal corresponding to an air-fuel ratio of exhaust gas. An upstream catalytic converter is downstream of the LAF sensor and has a catalyst to purify the exhaust gas. An O2 sensor is downstream of the upstream catalytic converter, and generates a signal corresponding to the air-fuel ratio of the exhaust gas. A GPF is downstream of a the O2 sensor and purifies the exhaust gas. An ECU controls an air-fuel mixture in an engine using output signal KACT of the LAF sensor and an output signal VO2 of the O2 sensor such that the air-fuel ratio of exhaust gas flowing into the GPF converges to a target value near the stoichiometric ratio. The GPF has a filter substrate and a downstream TWC supported by a partition of the filter substrate.