Abstract: The invention provides a method for purification of exhaust gas from a diesel engine in a system, which comprises a device for selective catalytic reduction and a diesel particulate filter preferably at least partially covered by a catalytic layer installed downstream of the device for selective catalytic reduction. A device for catalytic oxidation is installed upstream of the device for selective catalytic reduction and/or between the device for selective catalytic reduction and the diesel particulate filter. A device for injection of a controlled amount of reductant is installed inlet of the device for selective catalytic reduction, and a device for injection of a controlled amount of hydrocarbon is installed inlet of the catalytic oxidation.

Abstract: The invention provides a method and system for purification of a carbon monoxide, nitrogen oxides, incompletely combusted hydrocarbons and soot containing exhaust gas from a combustion engine comprising the steps of catalytically oxidizing the carbon monoxide in the exhaust gas, retaining soot and remaining amounts of hydrocarbons in the oxidised exhaust gas in a filter, addition of a reducing agent to gas and catalytically reducing nitrogen oxides, and obtaining a purified exhaust gas.

Abstract: The invention provides a method for purification of exhaust gas from a diesel engine in a system, which comprises a device for selective catalytic reduction and a diesel particulate filter preferably at least partially covered by a catalytic layer installed downstream of the device for selective catalytic reduction. A device for catalytic oxidation is installed upstream of the device for selective catalytic reduction and/or between the device for selective catalytic reduction and the diesel particulate filter. A device for injection of a controlled amount of reductant is installed inlet of the device for selective catalytic reduction, and a device for injection of a controlled amount of hydrocarbon is installed inlet of the catalytic oxidation.

Abstract: Process for reducing nitrogen oxides to nitrogen in an exhaust gas comprising passing the exhaust gas in the presence of a reducing agent through a catalyst system comprising at least two catalyst beds, in which a first catalyst bed is an iron-beta-zeolite and a second catalyst bed downstream is silver supported on alumina.

Abstract: A method for removing impurities in exhaust gas from a diesel engine, where the impurities comprise nitrogen oxides, carbon monoxide, particulate matter and incompletely combusted hydrocarbons. The method comprises the steps of injection of a reductant comprising urea or ammonia into the exhaust gas from the engine, selective catalytic reduction of the nitrogen oxides in the exhaust gas by the reductant, and intermittent injection of a hydrocarbon into this effluent. The succeeding steps are oxidation of carbon monoxide, particulate matter, incompletely combusted hydrocarbons and injected hydrocarbon to carbon dioxide and water, and in selectively oxidising possible excess of reductant to free nitrogen, and finally filtration of the effluent by passing the gas through a catalysed filter.

Abstract: The invention provides a method and system for purification of a carbon monoxide, nitrogen oxides, incompletely combusted hydrocarbons and soot containing exhaust gas from a combustion engine comprising the steps of catalytically oxidising the carbon monoxide in the exhaust gas, retaining soot and remaining amounts of hydrocarbons in the oxidised exhaust gas in a filter, addition of a reducing agent to gas and catalytically reducing nitrogen oxides, and obtaining a purified exhaust gas.

Abstract: The invention relates to a method for controlling injection of a reductant into a NOx containing exhaust gas stream from a combustion engine, where combustion of a known fuel takes place and where the NOx is reduced by selective catalytic reduction, SCR, in the presence of a SCR catalyst, comprising establishing signals related to exhaust gas flow, HOx concentration in the exhaust gas stream upstream of the catalyst, exhaust gas temperature upstream of the SCR catalyst, exhaust gas temperature downstream of the SCR catalyst and to input data for catalyst characteristics. From the signals an adjusted amount of the reductant is calculated by using a calculated amount of reductant and a value d(E*T)/dt, where E is the exhaust gas flow, T is the exhaust gas temperature upstream of the catalyst and t is time.

Abstract: The invention relates to a method for controlling injection of a reductant into a NOx containing exhaust gas stream from a combustion engine, where combustion of a known fuel takes place and where the HOx is reduced by selective catalytic reduction, SCR, in the presence of a SCR catalyst, comprising establishing signals related to exhaust gas flow, HOx concentration in the exhaust gas stream upstream of the catalyst, exhaust gas temperature upstream of the SCR catalyst, exhaust gas temperature downstream of the SCR catalyst and to input data for catalyst characteristics. From the signals an adjusted amount of the reductant is calculated by using a calculated amount of reductant and a value d(E*T)/dt, where E is the exhaust gas flow, T is the exhaust gas temperature upstream of the catalyst and t is time.