A catalyst state estimation apparatus includes a first sensor, a memory and a processor. The first sensor is configured to acquire information about a catalyst that removes a toxic substance in an exhaust gas, the first sensor being provided in a main passage into which the exhaust gas flows from an internal combustion engine. The memory is configured to previously store a catalyst state estimation model that includes at least one mathematical model. The processor is configured to estimate a removal performance of the catalyst by applying the information about the catalyst acquired by the first sensor to the catalyst state estimation model.

An exhaust gas purification apparatus for an internal combustion engine includes a filter supporting the catalyst with an oxygen storage capacity, an air fuel ratio sensor to detect an air fuel ratio of exhaust gas at the downstream side of the filter, and a controller configured to change an air fuel ratio of exhaust gas flowing into the filter, to estimate an amount of particulate matter deposited in an interior of a partition wall of the filter, estimate a maximum storable oxygen amount of the catalyst from a change of the air fuel ratio of exhaust gas obtained by the air fuel ratio sensor at the time when the air fuel ratio of exhaust gas is changed by the controller, and correct the maximum storable oxygen amount of the catalyst based on the amount of particulate matter deposited in the interior of the partition wall of the filter.

The present invention relates to a stoichiometric-combustion spark-ignition engine comprising a specific exhaust gas system for reducing harmful exhaust gases resulting from the combustion process. The exhaust gas system consists in the through-flow direction of a three-way catalytic converter close to the engine, an oxidation catalyst and a gasoline particulate filter.

The disclosure relates to a particulate filter for the treatment of exhaust gas from an internal combustion engine, wherein the particulate filter comprises a functional material layer, and the amount of the functional material layer in the region which is around the whole central axis of the particulate filter and accounts for 11.1 vol. % of the total volume of the particulate filter, is in the range from 13 to 40 wt. %, based on the total weight of the functional material layer, relates to the process for preparing the particulate filter and relates to a method for the treatment of exhaust gas from an internal combustion engine. The particulate filter according to the present invention has a centralized-distributed functional material layer in the radial direction, shows excellent filtration efficiency and low backpressure.

To provide a hydrocarbon adsorbent having high hydrocarbon adsorbing properties even after exposed to a high temperature/high humidity reducing atmosphere.

A hydrocarbon adsorbent, which includes a FAU type zeolite having a lattice constant of at least 24.29 and containing copper. Such a hydrocarbon adsorbent may be used for a method for adsorbing hydrocarbons to be exposed to a high temperature/high humidity environment, and may be used particularly for a method for adsorbing hydrocarbons in an exhaust gas of an internal combustion engine, such as an automobile exhaust gas.

Provided herein is a catalytic article including a catalytic coating disposed on a substrate, wherein the catalytic coating comprises a bottom coating on the substrate and a top coating layer on the bottom coating layer, one such coating layer containing a platinum group metal on a refractory metal oxide support and the other such coating layer containing a ceria-containing molecular sieve. Such catalytic articles are effective toward treating exhaust gas streams of internal combustion engines and exhibit outstanding resistance to sulfur.

Passive NO.sub.x adsorption (PNA) compositions have a formula PdNiFe.sub.2O.sub.4 wherein Pd represents a palladium component, such as palladium oxide, that is adsorbed on surfaces of the nickel ferrite. Such compositions can be synthesized by wet impregnation of nickel ferrite with a palladium salt, and exhibit efficient NO.sub.x adsorption at low temperature, with NO.sub.x desorption occurring predominantly at high temperature. Two-stage NO.sub.x abatement catalysts, effective under engine cold start conditions, include a PNA composition upstream from an NO.sub.x conversion catalyst.

A method of controlling an oxygen purge of a three-way catalyst (TWC) may include: rapidly adjusting, by a controller, an air-fuel ratio (AFR) at an upstream of the TWC to a target AFR when the oxygen purge of the TWC after a fuel cut-off is performed; and maintaining the target AFR until an oxygen purge finish time has passed. According to the method, concentration of NOx slipped from the TWC after the oxygen purge may be reduced.

An after treatment method for a lean-burn engine is disclosed. The after treatment method is configured to control an after treatment system sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction (SCR) catalyst, and a CO clean-up catalyst (CUC) on an exhaust pipe through which an exhaust gas flows and which is connected to a lean-burn engine. NH.sub.3 generation in the ammonia production catalyst module is changed according to a temperature and a temperature change rate of the SCR catalyst.

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.