Systems for abatement of pollutants in an exhaust gas stream of an internal combustion engine including a hydrogen injection article configured to introduce hydrogen upstream of a catalytic article are effective for the abatement of carbon monoxide and/or hydrocarbons and/or nitrogen oxides. The introduction of hydrogen may be intermittent and/or during a cold-start period.

An exhaust after-treatment system includes a first set of exhaust after-treatment components, a second set of exhaust after-treatment components, an inlet to the exhaust after-treatment system, an outlet from the exhaust after-treatment system, and a valve and conduit arrangement configurable in a plurality of modes, in a first mode, exhaust gas entering the inlet flows through the second set of exhaust after-treatment components, then through the first set of exhaust after-treatment components, and then through the outlet. In a second mode, exhaust gas entering the inlet flows through the second set of exhaust after-treatment components without flowing through the first set of exhaust after-treatment components, and then through the outlet in a third mode, exhaust gas entering the inlet flows through the first set of exhaust after-treatment components, then through the second set of exhaust after-treatment components, and then through the outlet.

There is provided an exhaust gas purification system that allows efficient purification of NOx present in exhaust gas emitted from an internal combustion engine. The exhaust gas purification system of the disclosure comprises a first exhaust gas purification device that purifies exhaust gas emitted from an internal combustion engine, wherein the atmosphere alternately switches between a reducing agent-excess atmosphere and an oxidizing agent-excess atmosphere with respect to the stoichiometric atmosphere, and a second exhaust gas purification device that further purifies the exhaust gas that has been purified by the first exhaust gas purification device, wherein the first exhaust gas purification device has a three-way catalyst, and the second exhaust gas purification device has an exhaust gas purifying catalyst that comprises an AMn.sub.2O.sub.4 spinel-type oxide support (A=Mg, Zn or Li) on which a precious metal is supported.

Catalyst for passive NOx absorber to remove NOx from exhaust gas system during engine cold start operation having high storage capacity and ideal desorption properties. The catalyst may include a mixed oxide catalyst system having a Pt promoted Ce.sub.0.5Zr.sub.0.5O.sub.2 catalyst material synthesized by co-precipitation using ammonium carbonate as a precipitation agent.

A NO.sub.x absorber catalyst for treating an exhaust gas from a diesel engine. The NO.sub.x absorber catalyst comprises a first NO.sub.x absorber material comprising a molecular sieve catalyst, wherein the molecular sieve catalyst comprises a noble metal and a molecular sieve, and wherein the molecular sieve contains the noble metal; a second NO.sub.x absorber material comprising palladium (Pd) supported on an oxide of cerium; and a substrate having an inlet end and an outlet end.

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, a second layer, and a third layer.

Provided are novel synthesis techniques for producing pure phase aluminosilicate zeolite and a catalyst comprising the phase pure zeolite in combination with a metal, and methods of using the same.

The exhaust gas purification catalyst device includes an upper layer which includes first carrier particles and rhodium, and a lower layer which includes second carrier particles, and the upper layer includes a rhodium enriched area in the range a, from the upstream end in the exhaust gas flow to 50% of the upper layer length, and a range b from the upper layer top surface to 18 μm in the depth direction. The rhodium enriched area contains at least 50% and less than 100% of all the rhodium in the upper layer.

The present disclosure provides a method for producing an exhaust gas purifying catalyst, in which fine Rh—Pd particles exhibiting high catalytic activity are produced such that a variation in the Pd composition can be reduced. The present disclosure relates to a method for producing an exhaust gas purifying catalyst having fine composite metal particles containing Rh and Pd, comprising: preparing a starting material solution containing Rh and Pd, in which the atomic percentage of Pd to the total of Rh and Pd is 1 atomic % to 15 atomic %; and allowing the prepared starting material solution to react with a neutralizer by a super agitation reactor having a rotation number of 500 rpm or more, to generate fine composite metal particles.

A catalyst for removing nitrogen oxides, and the catalyst for removing the nitrogen oxides includes a first catalyst having a component including Pt, Ba, and Ce supported on a first support, and a second catalyst physically mixed with the first catalyst and having a component including Cu and Ce supported on a second support.