In an internal combustion engine, a hydrocarbon feed valve and an exhaust purification catalyst are arranged in an engine exhaust passage. A first NO.sub.X removal method which reduces NO.sub.X contained in an exhaust gas by a reducing intermediate which is generated by injecting hydrocarbons from the hydrocarbon feed valve within a predetermined range of period and a second NO.sub.X removal method in which an air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst is made rich by a period which is longer than this predetermined range are used. The switching temperatures ST and ST.sub.0 of the exhaust purification catalyst at which temperature an NO.sub.X removal method is switched from the second NO.sub.X removal method to the first NO.sub.X removal method, are made lower if the amount of NO.sub.X in the exhaust gas flowing into the exhaust purification catalyst increases.

An internal combustion engine, wherein a hydrocarbon supply valve (15) and an exhaust gas purification catalyst (13) are disposed inside an engine exhaust gas passage. When an increase in the temperature of the exhaust gas purification catalyst (13) caused by hydrocarbons supplied from the hydrocarbon supply valve (15) is smaller than a predetermined increase amount, and a decrease in the pressure of fuel supplied to the hydrocarbon supply valve (15) when the hydrocarbons have been injected from the hydrocarbon supply valve (15) is larger than a predetermined decrease amount, the present invention determines that a blockage is occurring in a hydrocarbon injection channel (69) when the hydrocarbons have been injected from the hydrocarbon supply valve (15).

A reducing agent supplying device includes a reforming device, an obtaining section and a controller. The reforming device mixes fuel, which is a hydrocarbon compound, with air, and reforms the fuel by partially oxidizing the fuel with oxygen in the air. A reformed fuel is supplied into the exhaust passage as the reducing agent. The obtaining section obtains a physical quantity as a property index. The physical quantity has a correlation with property of the fuel that is supplied to the reforming device. The controller controls the reforming device according to the property index obtained by the obtaining section.

A reducing agent supplying device is for a fuel combustion system that includes a NOx purifying device with a reducing catalyst arranged in an exhaust passage to purify NOx contained in exhaust gas of an internal combustion engine. The reducing agent supplying device supplies a reducing agent into the exhaust passage at a position upstream of the reducing catalyst. The reducing agent supplying device includes a reforming portion and a reformation suppressing portion. The reforming portion reforms the reducing agent by partially oxidizing the reducing agent. When a temperature of the reducing agent is higher than a first specified temperature that is equal to or higher than an activation temperature of the reducing catalyst, the reformation suppressing portion (i) suppresses the degree of reformation of the reducing agent in comparison with when a temperature of the reducing agent is lower than the first specified temperature, or (ii) stops the reformation of the reducing agent.

An integrated catalyst reformer is described, including a housing which surrounds and defines at least two individualized and adjacent chambers. The first chamber is intended for the catalytic conversion of exhaust gases from the MCI and at least one second chamber intended for reforming fuel, ethanol or others, and the heat generated in the first chamber is transferred to the second chamber by thermal conduction. The first chamber is connected, upstream, to the exhaust manifold of the MCI from the inlet nozzle and is connected to the exhaust of the vehicle from the outlet nozzle, while the plenum of the first chamber is filled with a catalytic mesh. The second chamber includes a plenum filled with a catalytic mesh; an intake nozzle intended to receive both ambient air and the fuel to be reformed; and an exhaust nozzle, connected upstream of the intake manifold, so as to allow the reformed fuel to be aspirated.

Systems and methods directed at removing HCN from an FCC process flue gas (and/or generated in the catalyst system reactions themselves) such that the final HCN output is satisfactory; while, in so doing, avoiding undesirable levels of other pollutants contained in that exhaust gas such as NOx. A system includes an assembly having a fluid catalytic cracking (FCC) unit generating a flue gas with HCN and NOx and a catalyst device placed in the flue gas line to remove HCN and NOx. The catalyst device having one or more SCR catalytic articles, as in one free of platinum group metal material (PGM) or a dual functioning SCR catalyst with PGM, or a combination of each. The assembly can be provided with an ammonia supplier and optionally an H2O supplier with associated injection for supply into the flue gas upstream of a catalytic article(s).

A modular plasma treatment system has interchangeable and easily accessible inner and outer electrodes that concentrically nest within an outer housing of one or more plasma reformers. The inner and outer electrodes have self-centering features that allow for blind-fitting of the interchangeable inner and outer electrodes during electrode replacement and maintenance. A plurality of reformers that generate different types of plasmas are preferably arranged serially to allow for a mixture of separate plasmas within the same reaction area and to increase utilization of short-lived radicals.

A method for exhaust gas post treatment is provided, comprising the following steps: a) providing a nitrogen oxide-containing raw exhaust gas, b) introducing the nitrogen oxide-containing raw exhaust gas into a catalytic evaporator (1), c) introducing a fuel into the catalytic evaporator (1), whereby a converted fuel is obtained, d) mixing urea with the converted fuel, and e) feeding the mixture obtained after step d) into an exhaust gas post treatment system (8). Alternatively or in addition, a device may be provided for exhaust gas post treatment.

A modular plasma treatment system has interchangeable and easily accessible inner and outer electrodes that concentrically nest within an outer housing of one or more plasma reformers. The inner and outer electrodes have self-centering features that allow for blind-fitting of the interchangeable inner and outer electrodes during electrode replacement and maintenance. A plurality of reformers that generate different types of plasmas are preferably arranged serially to allow for a mixture of separate plasmas within the same reaction area and to increase utilization of short-lived radicals.

The disclosure provides a system for treating an exhaust gas stream from a gasoline engine. The system is configured to introduce controlled quantities of hydrogen gas into the exhaust gas stream upstream of a catalyst article during a cold-start period. Further provided are related methods of treating such exhaust streams. Such systems and methods are useful in reducing a level of one or more of hydrocarbons, carbon monoxide, and nitrogen oxide in a gaseous exhaust stream from a gasoline engine.