An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NO.sub.x trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction catalyst. The modified LNT comprises a first layer and a second layer. The first layer comprises a NO.sub.x adsorbent component and one or more platinum group metals. The second layer comprises a diesel oxidation catalyst zone and an NO oxidation zone. The diesel oxidation catalyst zone comprises a platinum group metal, a zeolite, and optionally an alkaline earth metal. The NO oxidation zone comprises a platinum group metal and a carrier. The modified LNT stores NO.sub.x at temperatures below about 200 C. and releases at temperatures above about 200 C. The modified LNT and a method of using the modified LNT are also disclosed.

A passive NO.sub.x adsorber is disclosed. The passive NO.sub.x adsorber is effective to adsorb NO.sub.x at or below a low temperature and release the adsorbed NO.sub.x at temperatures above the low temperature. The passive NO.sub.x adsorber comprises a noble metal and a molecular sieve having an LTL Framework Type. The invention also includes an exhaust system comprising the passive NO.sub.x adsorber, and a method for treating exhaust gas from an internal combustion engine utilizing the passive NO.sub.x adsorber.

A NO.sub.x trap catalyst is disclosed. The NO.sub.x trap catalyst comprises a noble metal, a NO.sub.x storage component, a support, and a first ceria-containing material. The first ceria-containing material is pre-aged prior to incorporation into the NOx trap catalyst, and may have a surface area of less than 80 m.sup.2/g. The invention also includes exhaust systems comprising the NO.sub.x trap catalyst, and a method for treating exhaust gas utilizing the NO.sub.x trap catalyst.

The catalytic converter of the vehicle includes: an LNT converter including an LNT catalyst to reduce nitrogen oxides; an SDPF converter including an SDPF catalyst to capture particulate matters and reduce the nitrogen oxides; a connection housing connecting the LNT converter and the SDPF converter to each other; an injection module provided in the connection housing to inject the reducing agent from the LNT converter toward the SDPF converter; an impactor atomizing and vaporizing the reducing agent injected from the injection module; a first guide mixer provided inside the connection housing to form a swirl-direction flow of the exhaust gas mixed with the reducing agent atomized through the impactor; and a second guide mixer provided downstream of the first guide mixer inside the connection housing to form an additional swirl-direction flow of the exhaust gas mixed with the reducing agent.

The invention provides methods for a one-pot synthesis of molecular sieves of the CHA-type. The method uses molecular and non-molecular sieves as sources of silicon and aluminum. A first OSDA is selected from tetraethylenepentamine (TEPA) and triethy-lenepentamine (TETA). The synthesis mixture comprises a first metal selected from copper, iron and zinc. Optionally, the synthesis mixture may furthermore comprise a second OSDA and/or a second metal selected from manganese, cesium, magnesium, calcium, strontium, barium, yttrium, titanium, zirconium, niobium, iron, zinc, silver, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and mixtures thereof. The molecular sieves of the CHA-type obtainable by the method can be used as SCR-catalytically active substances for the removal of nitrogen oxides from exhaust gases of combustion engines.

This disclosure is directed to catalyst compositions, catalytic articles for purifying exhaust gas emissions and methods of making and using the same. In particular, the disclosure relates to a catalytic article including a catalytic material on a substrate, wherein the catalytic material has a first layer and a second layer. The first layer provides effective lean NO.sub.x trap functionality and the second layer provides effective three-way conversion of carbon monoxide, hydrocarbons, and nitrogen oxides (NO.sub.x).

A system includes a catalyst for receiving and treating exhaust gas generated by an engine, a passive NOx adsorber (PNA) positioned upstream of the catalyst, a bypass valve positioned upstream of the catalyst and the PNA, and a controller. The controller is configured to, determine that the catalyst is operating under cold start conditions, control the bypass valve to direct exhaust gas to the PNA, determine that the catalyst is no longer operating under cold start conditions and continue to control the bypass valve to direct exhaust gas to the PNA for a predetermined duration, and after the elapse of the predetermined duration, control the bypass valve to direct exhaust gas to the catalyst bypassing the PNA. The controller is also configured to detect a high transient torque demand while the exhaust gas is provided to the PNA, and split the torque demand between the engine and an electric motor.

The present disclosure provides Low Temperature NO.sub.x-Absorber (LT-NA) catalyst compositions, catalyst articles, and an emission treatment system for treating an exhaust gas, each including the LT-NA catalyst compositions. Further provided are methods for reducing a NO.sub.x level in an exhaust gas stream using the LT-NA catalyst articles. In particular, the LT-NA catalyst compositions include a first zeolite, a first palladium component, and a plurality of platinum nanoparticles. The LT-NA catalyst compositions exhibit enhanced regeneration efficiency with respect to NO.sub.x adsorption capacity, even after hydrothermal aging.

Provided is a novel synthesis technique for producing pure phase small pore zeolites employing a synthesis gel of at least one zeolite, a structure directing agent and an alkaline earth metal source. Additionally provided are a novel form of AFX zeolite, a novel synthesis method for producing a zeolite with an increased Al pair content, a catalyst comprising the AFX zeolite in combination with a metal, and methods of using the same.

A passive NO.sub.X adsorbent includes: palladium, platinum or a mixture thereof and a mixed or composite oxide including the following elements in percentage by weight, expressed in terms of oxide: 10-90% by weight zirconium and 0.1-50% by weight of least one of the following: a transition metal or a lanthanide series element other than Ce. Although the passive NO.sub.X adsorbent can include Ce in an amount ranging from 0.1 to 20% by weight expressed in terms of oxide, advantages are obtained particularly in the case of low-Ce or a substantially Ce-free passive NOx adsorbent.