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.

The present disclosure is directed to an emission treatment system for NO.sub.x abatement in an exhaust stream of a lean burn engine. The emission treatment system includes a lean NO.sub.x trap (LNT) in fluid communication with and downstream from the lean burn engine and a low-temperature NO.sub.x adsorber (LT-NA) in fluid communication with and downstream of the LNT. Further provided is a method for abating NO.sub.x in an exhaust stream from a lean burn engine utilizing the disclosed system.

A catalyst composition for treating an exhaust gas, the catalyst composition comprising a molecular sieve, the molecular sieve comprising exchanged copper and exchanged manganese.

A catalytic article for treating exhaust gas comprising: a substrate comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component and a support; a second catalytic region comprising a second PGM component on a support with low ammonia storage and a first SCR catalyst; and wherein the first catalytic region is covered by at least another catalytic region.

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, Ir and Pt.

The present invention relates to a catalytic material for treating an exhaust gas produced by a natural gas engine, which catalytic material comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve, wherein the molecular sieve has a framework comprising silicon, oxygen and germanium, and has a content of heteroatom T-atoms of ≤about 0.20 mol %, wherein the germanium is present in an amount of from 15 to 20 mol %. The present invention further relates to a catalyst article and a compressed natural gas combustion and exhaust system.

The present invention provide a method for purifying exhaust gas in which nitrogen oxides (NOx) gas is removed from a combustion exhaust gas. The method for purifying exhaust gas according to the invention is characterized in that water vapor is further added to raw exhaust gas to be processed to increase the water vapor concentration in the exhaust gas and the resulting moisture-adjusted exhaust gas is introduced into a denitration catalyst layer. The water vapor concentration in the moisture-adjusted exhaust gas is preferably 22.0% by volume or less in the total of the water vapor originally contained in the raw exhaust gas and the added water vapor.

In an exhaust gas purification system provided with a denitration catalyst layer, a reducing agent oxidation catalyst layer is installed together; a reducing agent and air are supplied into the reducing agent oxidation catalyst layer at the time of catalyst regeneration of the denitration catalyst layer; a high-temperature oxidation reaction gas is produced by a reaction heat generated by an oxidation reaction of the reducing agent and the air in this reducing agent oxidation catalyst layer; and this high-temperature oxidation reaction gas is introduced into the denitration catalyst layer to heat the denitration catalyst, thereby recovering a denitration performance of the catalyst.

The honeycomb structure includes a honeycomb structure body made of a zeolite material containing at least a coarse particle zeolite having a large average particle diameter (coarse zeolite particles). A fine particle zeolite having an average particle diameter smaller than that of the coarse particle zeolite (fine zeolite particles), and an inorganic bonding material, the coarse particle zeolite (the coarse zeolite particles) is a chabazite type zeolite in which an average particle diameter of primary particles is 2 μm or more and 6 μm or less, and in the fine particle zeolite (the fine zeolite particles), an average particle diameter of primary particles is 0.02 μm or more and smaller than 2 μm, and in the zeolite material which is comprised the honeycomb structure body, a ratio of a volume of pores having pore diameters of 0.02 to 0.15 μm to a volume of all pores is 42% or less.

The manufacturing method includes a step of mixing a coarse particle zeolite, a fine particle zeolite, and a raw material of an inorganic bonding material to prepare a zeolite raw material; a step of forming the prepared zeolite raw material into a honeycomb shape to prepare a honeycomb formed body; and a step of firing the prepared honeycomb formed body to prepare the honeycomb structure. In the step of preparing the zeolite raw material, as the coarse particle zeolite, a chabazite type zeolite having a specific average particle diameter, the fine particle zeolite having a specific average particle diameter, the raw material of the inorganic bonding material which includes at least basic aluminum lactate is used.