Catalytic removal of NO

The NH3-SCR activity of the small-pore zeolites, Cu-SSZ-13, Cu-SSZ-16, and Cu-SAPO-34, is investigated using a high-throughput reactor system. These copper exchanged small-pore zeolites have high SCR activity between 150 and 500 °C and are shown to be much more hydrothermally stable than the medium-pore zeolite, Cu-ZSM-5. The degree of copper exchange, the dimensionality of the framework, and heteroatom framework substitution all impact the SCR activity and hydrothermal stability of the materials. Of the small-pore zeolites tested, Cu-SSZ-13 and Cu-SAPO-34 display superior SCR performance, both before and after high-temperature hydrothermal treatment.

The ammonia selective catalytic reduction activity of copper-exchanged small-pore zeolites

A predominant challenge to both industrial and academic research institutions is the selective reduction of NOx during lean exhaust conditions. Despite a proliferation of publications, papers and reviews, a large number of catalysts fall short of a credible and consistent diesel application. Herein are reviewed systems designed specifically with the goal of assisting researchers in their assessment of catalytic performance. By way of conclusion, three principal types of catalysts active for HC-SCR are discussed.

The current state of research on automotive lean NOx catalysis

An internal combustion engine wherein an HC treatment catalyst (12) having the function of adsorbing the HC in the exhaust gas is arranged upstream of the NOx selective reducing catalyst (14), an urea aqueous solution fed from the reducing agent feed valve (15) is arranged upstream of the HC treatment catalyst (12), urea, and NOx contained in the exhaust gas, and HC adsorbed on the HC treatment catalyst 12 are reacted with each other to form intermediate products having cyano groups, oximes, and amino groups, and these intermediate products are sent to the NOx selective reducing catalyst (14).

Exhaust purification device of internal combustion engine

Recent advances in automobile exhaust catalysts

Research on new DeNOx catalysts for automotive engines

A method for purifying an exhaust gas containing an excess amount of oxygen is described, wherein a catalyst is brought into contact with the exhaust gas to remove nitrogen oxides, carbon monoxide and hydrocarbons from the exhaust gas, said catalyst comprises:
 (i) a zeolite having a molar ratio of SiO₂/Al₂O₃ of at least 10; and (ii) at least one copper ion and at least one kind of rare earth ion loaded thereon.

Process for reducing nitrogen oxides from exhaust gas

Nitrogen oxides are removed from an oxygen rich exhaust gas containing nitrogen oxides and hydrocarbons by bringing the oxygen rich exhaust gas into contact with a catalyst composed of phosphorus and at least one active metal contained in a zeolite having a molar ratio of SiO2/Al2O3 of at least 15.

Process for Removing Nitrogen Oxides from Oxygen Rich Exhaust Gas

A method for cleaning an exhaust gas, entailing bringing the exhaust gas into contact with a crystalline aluminosilicate having a primary particle size of not less than 05 micron, containing one or more kinds of metal ions selected from the group of metals of Group Ib and Group VIII of the periodic table in an amount ranging from about 02 to 08 equivalent relative to one gram atom of aluminum, and having a mole ratio of SiO2 /Al2 O3 of not less than about 20

Method for exhaust gas cleaning

A method for purifying an exhaust gas containing an excess amount of oxygen, to remove nitrogen oxides, carbon monoxide and hydrocarbons therefrom, by bringing a catalyst into contact with the exhaust gas, the catalyst comprising a zeolite ion-exchanged with (a) cobalt or (b) both cobalt and at least one metal selected from the group consisting of alkaline earth metals and rare earth metals, the zeolite being selected from the group consisting of ferrierite, ZSM-5, ZSM-11, ZSM-12 and ZSM-20, and having a silica-to-alumina molar ratio of from 15 to 1,000.

Senshi Kasahara

Papers

Research on new DeNOx catalysts for automotive engines

Process for reducing nitrogen oxides from exhaust gas

Process for Removing Nitrogen Oxides from Oxygen Rich Exhaust Gas

Method for exhaust gas cleaning

Method of purifying oxygen-excess exhaust gas