An object of the disclosure is to adjust the ammonia adsorption amount in an SCR catalyst supported on an SCR filter as close as possible to a target adsorption amount in an exhaust gas purification system including the SCR filter. In a system according to the disclosure, the quantity of ammonia supplied by an ammonia supplier is made smaller when a differential pressure change rate at the time when ammonia is supplied by the ammonia supplier is lower than a predetermined threshold than when the differential pressure change rate at the time when ammonia is supplied by the ammonia supplier is equal to or higher than the predetermined threshold. Moreover, when the differential pressure change rate is lower than the predetermined threshold, the change in the quantity of ammonia supplied by the ammonia supplier relative to the change in the filter PM deposition amount is kept equal to zero.

An exhaust gas purification apparatus includes: an oxidation reduction catalytic converter; a selective reduction catalytic converter disposed downstream of the oxidation reduction catalytic converter; and a controller configured to perform a first control or a second control based on mixing ratios when a temperature is higher than a predetermined temperature. The first control is performed when the mixing ratio downstream of the selective reduction catalytic converter is greater than the mixing ratio upstream of the selective reduction catalytic converter so that the mixing ratio upstream of the selective reduction catalytic converter is changed from stoichiometric ratio to lean mixture ratio. The second control is performed when the mixing ratio downstream of the selective reduction catalytic converter is smaller than the mixing ratio upstream of the selective reduction catalytic converter so that the mixing ratio downstream of the selective reduction catalytic converter is changed from stoichiometric ratio to lean mixture ratio.

An ammonia precursor generating system includes: a storage compartment storing at least ammonia precursor granules; a tank storing an ammonia precursor solution; a dissolving compartment configured to store an ammonia precursor solution, and to dissolve ammonia precursor granules in the ammonia precursor solution; a transfer mechanism configured to transfer ammonia precursor granules from the storage compartment to the dissolving compartment; a fluid transfer device configured to transfer the ammonia precursor solution from the tank to the dissolving compartment.

Ammonia gas generator for producing ammonia from a solution of an ammonia precursor substance comprising a catalyst unit, which comprises a catalyst for the decomposition and/or hydrolysis of ammonia precursor substances into ammonia and a mixing chamber arranged upstream of the catalyst, an injection device for introducing the solution of the ammonia precursor substance into the mixing chamber, and an outlet for the ammonia gas formed, wherein the injection device comprises a nozzle which produces droplets having a Sauter mean diameter D.sub.32 of 26 to 100 m.

An exhaust gas system for an engine producing an exhaust gas includes an exhaust gas tube configured to receive the exhaust gas. A particulate filter is in fluid communication with the exhaust gas tube and configured to undergo thermal regeneration when the exhaust gas in the particulate filter is heated above a regeneration temperature. A generator unit is positioned downstream of the particulate filter and includes a first catalyst. A tank is configured to store a precursor material. The generator unit is configured to employ the precursor material and the heat generated for the thermal regeneration of the particulate filter to generate an ammonia gas from the precursor material. The system includes a controller having a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of controlling generation of ammonia gas in the generator unit and injection of ammonia gas in the exhaust gas tube.

An object of the disclosure is to adjust the ammonia adsorption amount in an SCR catalyst supported on an SCR filter as close as possible to a target adsorption amount in an exhaust gas purification system including the SCR filter. In a system according to the disclosure, the quantity of ammonia supplied by an ammonia supplier is made smaller when a differential pressure change rate at the time when ammonia is supplied by the ammonia supplier is lower than a predetermined threshold than when the differential pressure change rate at the time when ammonia is supplied by the ammonia supplier is equal to or higher than the predetermined threshold. Moreover, when the differential pressure change rate is lower than the predetermined threshold, the change in the quantity of ammonia supplied by the ammonia supplier relative to the change in the filter PM deposition amount is kept equal to zero.

A decrease in an NOx removal or reduction rate at the time of filter regeneration is suppressed. To this end, provision is made for an NOx selective reduction catalyst, a filter arranged at the upstream side of the NOx selective reduction catalyst, an NH.sub.3 generation catalyst arranged at the upstream side of the NOx selective reduction catalyst to generate NH.sub.3 when the air fuel ratio of an exhaust gas is equal to or less than a stoichiometric air fuel ratio, a regeneration unit to carry out regeneration of the filter, and a generation unit to make the air fuel ratio of the exhaust gas equal to or less than the stoichiometric air fuel ratio, thereby causing NH.sub.3 to be generated in the NH.sub.3 generation catalyst, wherein the regeneration unit inhibits the regeneration of the filter until the generation of NH.sub.3 by the generation unit is completed.

In an exhaust gas purification apparatus for an internal combustion engine in which a filter for trapping PM, and a deflector for deflecting exhaust gas flowing into the filter, are arranged in an exhaust passage, in cases where a state continues in which the flow rate of the exhaust gas does not change relatively, regeneration processing of the filter is carried out so that a local excessive temperature rise resulting from non-uniform deposition of PM does not occur. When an integrated period of time, which is obtained by integrating a period of time in which an amount of change per unit time of a flow rate of the exhaust gas deflected by the deflector is equal to or less than a predetermined threshold amount of change, becomes equal to or more than a predetermined threshold period of time, during the time the regeneration processing is not carried out, the controller performing the regeneration processing of the filter carries out the regeneration processing before an estimated amount of PM deposited in the filter becomes equal to or more than a predetermined threshold amount of deposition.

A nitrogen oxide (NOx) abatement system is provided. The system includes a power generation device for generating power from a hydrogen-element containing fuel, an exhaust conduit in flow communication with an exhaust stream containing NOx which comes from the power generation device, a plasma reactor for reforming a portion of the hydrogen-element containing fuel with nitrogen to produce ammonia, and a NOx abatement reactor containing ammonia selective catalytic reduction (NH3-SCR) catalyst for receiving the exhaust stream and the ammonia and reducing NOx in the exhaust stream by causing the NOx to react with the ammonia to form nitrogen.

The system for use on board of a vehicle comprises a decomposition unit (2) for decomposing a compound under catalysis of a biological catalyst (3). The compound is for instance an ammonia precursor, and the biological catalyst is in solid form. At least one transfer means is present for transferring one of said compound and biological catalyst towards and/or away from the other one. The transfer means are for instance a moving device (15), for instance in the form of a float.