A vehicular exhaust filter (2) comprising a porous substrate having an inlet face and an outlet face with the porous substrate comprising inlet channels extending from the inlet face and outlet channels extending from the outlet face is disclosed. The inlet channels and the outlet channels are separated by a plurality of filter walls having a porous structure. The vehicular exhaust filter (2) is loaded with a refractory powder having a tapped density before loading of less than 0.10 g/cm.sup.3 and the vehicular exhaust filter has a mass loading of the refractory powder of less than 10 g/l.

Subject of the invention is an exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices: a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2), wherein the oxygen storage capacity (OSC) of the TWC2 is greater than the OSC of the GPF, wherein the OSC is determined in mg/l of the volume of the device.

The invention also relates to methods in which the system is used and uses of the system.

An exhaust gas purification system for a gasoline engine is described the system comprising in consecutive order the following devices: •a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2), •wherein the oxygen storage capacity (OSC) of the GPF is greater than the OSC of the TWC1, wherein the OSC is determined in mg/l of the volume of the device.

Described is a method of coating the inside of an exhaust gas purification catalyst filter with a predetermined amount of catalyst slurry while adjusting the distribution of catalyst components in or on a cell wall of the filter. A predetermined amount of catalyst slurry can be injected into an internal channel of a filter to solve conventional problems caused by excess or surplus slurry injection. The predetermined amount of slurry injected into the internal channel of the filter is coated on or in the cell wall, depending on the viscosity and particle size of the slurry. This enables a coating profile in which the slurry distribution at a front portion of the filter and the slurry distribution at a back portion of the filter differ from each other. In addition, the coating profile on the inner surface of the cell wall or in the pores of the cell wall can be adjusted through the subsequent air blowing, so that the back pressure of the filter and the performance of the catalyst filter, such as catalytic activity, can be improved. In addition, the coating length in the filter can be adjusted by controlling the pressure of air during the air blowing.

An exhaust gas purification catalyst device has catalyst coating layers, which extend from the upstream side to the downstream side of the exhaust gas flow. The catalyst coating layers each have at least three zones present in order from the upstream side to the downstream side of the exhaust gas flow, and each of these at least three zones is an oxidation catalyst zone or a reduction catalyst zone. In the uppermost layer of an oxidation catalyst zone, the total number of atoms of platinum and palladium is greater than the number of atoms of rhodium; in the upper most layer of a reduction catalyst zone, the number of atoms of rhodium is greater than the total number of atoms of platinum and palladium. The oxidation catalyst zones and the reduction catalyst zones alternate at least twice in the exhaust gas flow direction.

Systems and methods for controlling a gasoline urea selective catalytic reductant catalyst are described. In one example, an observer is provided that corrects an estimate of an amount of NH.sub.3 that is stored in a SCR. The amount of NH.sub.3 that is stored in the SCR is a basis for generating additional NH.sub.3 or ceasing generation of NH.sub.3.

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 comprising: a substrate comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component supported on a first PGM support material, wherein the first PGM component comprises platinum and rhodium; and wherein the first PGM support material comprises ZrO.sub.2—Al.sub.2O.sub.3.

An internal combustion engine control device and a catalyst deterioration diagnostic method according to the present invention control the amount of fuel to be supplied to an internal combustion engine such that the air-fuel ratio of the exhaust on the downstream side of the exhaust purification catalyst is alternately switched between rich and lean, measure the oxygen storage capability of the exhaust purification catalyst during a measurement period within a reversal period of the air-fuel ratio, and diagnose deterioration of the exhaust purification catalyst based on a measurement value of the oxygen storage capability. A time point at which the output of an exhaust sensor indicates that the air-fuel ratio of the exhaust on the downstream side of the exhaust purification catalyst begins to change from a vicinity of a stoichiometric air-fuel ratio to rich or lean is set as the time of end of the measurement period.

A method is disclosed for making a catalyzed particulate filter with high clean filtration efficiency which may include applying a catalyst material to a filter body having porous filter walls, wherein filtration material comprising filtration particles are disposed on or in or both on and in porous filter walls, and the filtration material is hydrophobic while the catalyst material is applied. A catalyzed particulate filter with high clean filtration efficiency is also disclosed wherein the filter includes porous filter walls with filtration particles disposed on or in or both on and in the porous filter walls, and catalyst material disposed on or in or both on and in the porous filter walls, and wherein the catalyst material substantially does not touch the filtration particles.

A vehicular exhaust filter comprising a porous substrate having an inlet face and an outlet face with the porous substrate comprising inlet channels extending from the inlet face and outlet channels extending from the outlet face is disclosed. The inlet channels and the outlet channels are separated by a plurality of filter walls having a porous structure. The vehicular exhaust filter is loaded with a refractory powder having a tapped density before loading of less than 0.10 g/cm.sup.3 and the vehicular exhaust filter has a mass loading of the refractory powder of less than 10 g/l.