Provided are: a cleaning agent for a denitration catalyst; and a denitration catalyst regeneration method and a denitration catalyst regeneration system which make it possible to efficiently remove matter adhering to a surface of a catalyst and to greatly restore catalytic performance. The regeneration method includes: a prewashing step (S12) of washing a denitration catalyst with water; a liquid agent cleaning step (S14) of immersing the denitration catalyst washed with water in a liquid agent containing an inorganic acid and a fluorine compound; a step of recovering the denitration catalyst from the liquid agent; and a finish washing step (S16) of washing the denitration catalyst recovered from the liquid agent with a finish cleaning liquid which is water or sulfamic acid-containing water.

An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, a first ammonia injector configured to inject ammonia into the exhaust gas pathway at a first rate, and a first treatment element positioned downstream of the first ammonia injector. A second ammonia injector is positioned downstream of the first treatment element. The second ammonia injector is configured to inject ammonia into the exhaust gas pathway at a second rate. A controller is configured to estimate an amount of particulate present in the exhaust gas and adjust at least one of the first rate or the second rate based on the estimate.

An exhaust gas treatment apparatus which includes a denitration device, a dust collector, and a desulfurization device in order, respectively, in a flow path of exhaust gas discharged from a boiler, wherein a heavy-metal component removal device is provided in the exhaust gas flow path between the dust collector and the desulfurization device. This device is provided with: an absorption tower including a nozzle which sprays acidic absorption liquid on the exhaust gas, a tank which stores liquid which has absorbed a heavy metal, and a pump which supplies the nozzle with the liquid in the tank; a neutralizing tank which neutralizes the liquid drawn from the absorption tower; and a separator which separates the neutralized liquid into a solid and a liquid component. Since a small amount of heavy metal can be removed in the absorption tower, re-emission of the heavy metal by the desulfurization device is prevented.

A system for use in selective catalytic reduction reactor is disclosed. The system may include a catalyst bed and a screen located close to the catalyst bed in a manner so that flow of flue gas to the catalyst bed contacts the screen before it contacts the catalyst bed. The screen may be adapted to support a weight of at least 400 pounds above the catalyst bed so that the weight is not imposed on the catalyst. The screen may have a plurality of holes across its surface in a manner so that the screen is adapted to change the velocity distribution of the flue gas as it flows through the screen.

In one embodiment, a process for the purification of CO.sub.2 from chlorinated and non-chlorinated hydrocarbons, comprising: contacting a CO.sub.2 stream with a metal oxide catalyst, wherein the stream comprises the CO.sub.2 and impurities comprising the non-chlorinated hydrocarbons and the chlorinated hydrocarbons; interacting the impurities with the catalyst to form additional CO.sub.2 and metal chloride; and regenerating the catalyst by contacting the metal chloride with an oxygen containing gas stream. In another embodiment, a process for the purification of CO.sub.2 from chlorinated hydrocarbons and non-chlorinated hydrocarbons, comprising: contacting a CO.sub.2 stream with a metal oxide catalyst, wherein the CO.sub.2 stream comprises the CO.sub.2 and impurities comprising the non-chlorinated hydrocarbons and the chlorinated hydrocarbons; oxidizing the impurities with catalyst oxygen to form additional CO.sub.2 and converting the chlorine to metal chloride; and regenerating the catalyst by contacting the metal chloride with an oxygen containing gas stream.

A dual-layer catalyst includes a substrate, a first layer disposed on the substrate, and a second layer disposed on the first layer. The first layer includes a first catalyst for storing NO.sub.x when the first catalyst has a temperature below an active temperature of a second catalyst. The first catalyst is to release the stored NO.sub.x when the first catalyst is heated to the active temperature of the second catalyst. The second layer includes the second catalyst for ammonia Selective Catalytic Reduction of the released NO.sub.x. The dual-layer catalyst is to be included in a catalytic converter and a catalyst system for reducing NO.sub.x emissions from a diesel engine, the NO.sub.x emissions including NO.sub.x emitted during a predetermined cold-start time period.

The invention contributes to a cost effective way to solve the problem of trace ammonia removal from a hydrogen and nitrogen containing gas. The set of catalysts of the invention selectively oxidized ammonia in ppm concentration even in gas mixtures containing hydrogen gas in concentrations of three orders of magnitude higher than the concentration of ammonia.

A filter incorporates a catalyst for the Selective Catalytic Reduction (SCR) of NO.sub.x gases and removal of particulate matter from the exhaust gas of a lean burn combustion engine, wherein the catalyst includes a vanadate component having an alkaline earth metal, a transition metal, a rare earth metal, or combinations thereof. The vanadate component may be iron vanadate. The filter includes a supported vanadate component disposed on a wall-flow filter. The method of making the filter includes applying an aqueous mixture of the supported vanadate component as a washcoat on the wall-flow filter or extruding a composition containing the supported vanadate component. The method of treating exhaust gases from an engine includes contacting the exhaust gas with the catalyst including the vanadate component.

The present invention relates to a method for regenerating a catalyst that can effectively remove a poison bound to a catalyst without chemical injury while minimizing the loss of catalytically active components through a process with improved efficiency, whereby the regenerated catalyst may exhibit excellent denitrification performance.

The invention relates to a method for the operation of an exhaust gas aftertreatment system in an exhaust tract of an internal combustion engine. The exhaust gas aftertreatment system includes an SCR particle filter, a first reducing agent feed device for introducing the reducing agent into the exhaust tract upstream of the SCR particle filter, continuous regeneration of the SCR particle filter being possible using nitrogen dioxide as oxidizing agent, an SCR catalytic converter element arranged downstream of the SCR particle filter, and a second reducing agent feed device for introducing the reducing agent into the exhaust tract downstream of the SCR particle filter and upstream of the SCR catalytic converter element. A control unit regulates a quantity of reducing agent introduced into the exhaust tract by the first reducing agent feed device and/or by the second reducing agent feed device as a function of the temperature (T.sub.SCR-PF) of the SCR particle filter.