An exhaust aftertreatment system for an internal combustion engine includes an outer casing having an exhaust gas inlet and an exhaust gas outlet between which a fluid flow path for exhaust gases is provided, a selective catalytic reduction unit provided in the fluid flow path for reducing nitrogen oxides, a reductant dosing device for adding reductant to the exhaust flow upstream of the selective catalytic reduction unit, and a rotatable mixer device for mixing the reductant with exhaust gases upstream of the selective catalytic reduction unit, an air inlet valve provided upstream of the mixer device for introducing air into the fluid flow path, and an electric motor arranged for rotating the mixer device to create a suction of air into the fluid flow path via the air inlet valve.

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.

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.

Systems and methods for controlling a regeneration process of catalyst(s) are disclosed. The method includes receiving, via Kalman filter, initial estimation from a previous instance of time. The initial estimation includes one or more first estimated inside temperature(s) and/or first estimated outlet temperature of A/T catalyst. An output from a simulation model may be generated to calculate a mean and covariance. Sensor measurement covariance may be compared against the mean and covariance of the output to update Kalman filter gain and process covariance. A weighted average may be calculated between sensor measurements and mean of the output to generate a second estimation for the next instance of time, wherein weight is based on Kalman filter gain. The second estimation includes one or more second estimated inside temperature(s) and/or second estimated outlet temperature of A/T catalyst to control the mass flow rate in diesel engine via a closed loop control system.

The present invention relates to a catalyst washcoat composition comprising a slurry comprising at least one platinum group metal and/or at least one non-platinum group metal supported on at least one support; and at least one pore forming agent having a particle size ranging from 100 nm to 5.0 μm, wherein the pore forming agent is selected from carbon nano-tubes, carbon nano-fibres, activated carbon, resins, cellulose powder, and polymer spheres. The present invention also provides a catalyst article for capturing particulate matter of size ranging from 1.0 nm to 100 μm, said article comprising the catalyst washcoat deposited on a substrate and calcined to form pores of which 50%-100% have a pore size ranging from 100 nm to 5.0 μm.

The invention concerns a method for unblocking pores in a metal zeolite based selective catalytic reduction (SCR) catalyst. The method includes filling, at least partially, the SCR catalyst with a liquid, the liquid being preferably distilled water. The method includes letting said liquid inside the SCR catalyst enough time to allow said liquid to dissolve, at least partially, the obstructions and to penetrate into the pores. The method includes heating the SCR catalyst at a temperature above the ebullition temperature of the liquid so as to vaporize the part of the liquid remained into the pores, and generate steam flows through the obstructions, the steam flows removing the obstructions and unblocking the pores, wherein no hydrocarbons are injected during the step of heating.

An exhaust system of an internal combustion engine of a motor vehicle includes a particulate filter where particles are filterable out from the exhaust gas by the particulate filter. A selective catalytic reduction (SCR) catalytic converter through which the exhaust gas from the internal combustion engine is flowable for denitrifying the exhaust gas from the internal combustion engine is disposed downstream of the particulate filter. The exhaust gas of the internal combustion engine is heatable by a combustor at a point disposed upstream of the SCR catalytic converter and downstream of the particulate filter where the combustor provides an exhaust gas of the combustor. Particles are filterable out from the exhaust gas of the combustor by a filter element.

A method for controlling urea injection in an exhaust aftertreatment system includes injecting urea at a flow rate upstream of the first catalytic reduction device; measuring a level of nitrogen oxides downstream of the first catalytic reduction device and upstream of the second catalytic reduction device; controlling the flow rate of the urea injection until the measured level of nitrogen oxides fulfils a predetermined condition; if the measured level of nitrogen oxides is decreasing in response to reducing the flow rate of the urea injection, reducing the flow rate of the urea injection, and controlling a flow rate of urea injection using the second urea injector upstream of the second catalytic reduction device according to the measured level of nitrogen oxides downstream of the first catalytic reduction device and upstream of the second catalytic reduction device.

An exhaust aftertreatment arrangement for cleaning exhaust gases includes a fluid channel for providing a fluid pathway for the exhaust gases, a selective catalyst reduction, SCR, catalyst, arranged in or downstream the fluid channel, a heating arrangement for heating the exhaust gases, the heating arrangement being arranged upstream of the SCR catalyst and comprising an electrical heating element, a first fluid pathway for guiding the exhaust gases to the electrical heating element, and a second fluid pathway for guiding the exhaust gases to bypass the electrical heating element, wherein the heating arrangement is removably arranged relative the fluid channel.

An electric gas flow heater has a grid-like heating element through which exhaust gas can flow axially, and which forms an electrical resistance heating. The grid-like heating element includes radially successive layers of band-like material, wherein the layers, in an axial view of the heating element, are bent in an undulating manner and include valleys and peaks. The layers that are located between the radially outermost layer and the radially innermost layer are attached by their peaks and valleys to the respectively radially adjacent layer, so that flow-through openings are formed between the layers. The wavelengths of the layers are increasing radially outwards.