A method of converting nitrogen oxides in a gas to nitrogen by contacting the nitrogen oxides with a nitrogenous reducing agent in the presence of a zeolite catalyst containing at least one transition metal, wherein the zeolite is a small pore zeolite containing a maximum ring size of eight tetrahedral atoms, wherein the at least one transition metal is selected from the group consisting of Cr, Mn, Fe, Co, Ce, Ni, Cu, Zn, Ga, Mo, Ru, Rh, Pd, Ag, In, Sn, Re, Jr and Pt.

A method of converting nitrogen oxides in a gas to nitrogen by contacting the nitrogen oxides with a nitrogenous reducing agent in the presence of a zeolite catalyst containing at least one transition metal, wherein the zeolite is a small pore zeolite containing a maximum ring size of eight tetrahedral atoms, wherein the at least one transition metal is selected from the group consisting of Cr, Mn, Fe, Co, Ce, Ni, Cu, Zn, Ga, Mo, Ru, Rh, Pd, Ag, In, Sn, Re, Jr and Pt.

An oxidation catalyst composition is provided, the composition including a plurality of platinum group metal particles having a multi-modal distribution of particle sizes. The plurality of platinum group metal particles includes a first population of platinum group metal particles having a range of particle sizes of from about 0.5 nm to about 3 nm, and a second population of platinum group metal particles having a range of particle sizes of from about 4 nm to about 15 nm. Methods for the preparation and use of the catalyst composition are also provided, as well as catalyst articles and emission gas treatment systems employing such catalyst articles. The catalyst exhibits enhanced stability with respect to oxidation performance after degreening and/or aging, as compared to conventional oxidation catalysts, in particular less loss of NOx oxidation performance.

An oxidation catalyst composition is provided, the composition including a plurality of platinum group metal particles having a multi-modal distribution of particle sizes. The plurality of platinum group metal particles includes a first population of platinum group metal particles having a range of particle sizes of from about 0.5 nm to about 3 nm, and a second population of platinum group metal particles having a range of particle sizes of from about 4 nm to about 15 nm. Methods for the preparation and use of the catalyst composition are also provided, as well as catalyst articles and emission gas treatment systems employing such catalyst articles. The catalyst exhibits enhanced stability with respect to oxidation performance after degreening and/or aging, as compared to conventional oxidation catalysts, in particular less loss of NOx oxidation performance.

A method for controlling a reductant generation device 100, the reductant generation device 100 including: a sprayer 10 capable of spraying a reductant precursor 50; and a heater 20 comprising a ceramic substrate 21, the heater 20 being arranged on a downstream side of the sprayer 10 and capable of heating the reductant precursor 50 to generate a reductant 60. The method includes: a permeation step of spraying the reductant precursor 50 from the sprayer 10 and permeating the ceramic substrate 21 with the reductant precursor 50 when the heater is not heated; and after the permeation step, a heating step A of heating the reductant precursor 50 by the heater 20 and generating the reductant 60 while spraying the reductant precursor 50 from the sprayer 10.

A method for controlling a reductant generation device 100, the reductant generation device 100 including: a sprayer 10 capable of spraying a reductant precursor 50; and a heater 20 comprising a ceramic substrate 21, the heater 20 being arranged on a downstream side of the sprayer 10 and capable of heating the reductant precursor 50 to generate a reductant 60. The method includes: a permeation step of spraying the reductant precursor 50 from the sprayer 10 and permeating the ceramic substrate 21 with the reductant precursor 50 when the heater is not heated; and after the permeation step, a heating step A of heating the reductant precursor 50 by the heater 20 and generating the reductant 60 while spraying the reductant precursor 50 from the sprayer 10.

An object of the present invention is to increase the reduction performance of nitrogen oxides compared to existing three-way catalysts; simultaneously inhibit the emission of ammonia and nitrous oxide; simplify a process by means of a method of further doping an iridium-ruthenium catalyst into a commercial three-way catalyst; and expand the scope of application. The present invention provides a catalyst for simultaneously inhibiting the emission of ammonia and nitrous oxide by doping an iridium-ruthenium catalyst component into a three-way catalyst (TWC), a diesel oxidation catalyst, or a lean NOx trap supported on a honeycomb support.

An object of the present invention is to increase the reduction performance of nitrogen oxides compared to existing three-way catalysts; simultaneously inhibit the emission of ammonia and nitrous oxide; simplify a process by means of a method of further doping an iridium-ruthenium catalyst into a commercial three-way catalyst; and expand the scope of application. The present invention provides a catalyst for simultaneously inhibiting the emission of ammonia and nitrous oxide by doping an iridium-ruthenium catalyst component into a three-way catalyst (TWC), a diesel oxidation catalyst, or a lean NOx trap supported on a honeycomb support.

A method of manufacturing a catalyst article, the method comprising: providing a complex of a humic acid or derivative thereof, and a PGM; providing a support material; applying the complex to the support material to form a loaded support material; disposing the loaded support material on a substrate; and heating the loaded support material to form nanoparticles of the PGM on the support material.

The devices, systems and techniques disclosed in this patent document include photocatalytic filter devices and can be used to provide a method for manufacturing a photocatalytic filter with improved adhesion. In addition, the present disclosure of this patent document includes technology to provide a method for reactivating a photocatalytic filter. Using the disclosed techniques, even if a photocatalytic filter is contaminated, the contaminated photocatalytic filter is easily reactivated while maintaining improved adhesion.