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.

A coke control reactor, and a device and method for preparing low-carbon olefins from an oxygen-containing compound are provided. The coke control reactor includes a coke control reactor shell, a reaction zone I, and a coke controlled catalyst settling zone; a cross-sectional area at any position of the reaction zone I is less than that of the coke controlled catalyst settling zone; n baffles are arranged in a vertical direction in the reaction zone I; the n baffles divide the reaction zone I into m reaction zone I subzones; and a catalyst circulation hole is formed in each of the baffles, such that a catalyst flows in the reaction zone I in a preset manner. A catalyst charge in the present coke control reactor can be automatically adjusted, and an average residence time of a catalyst in the coke control reactor can be controlled by changing process operating conditions.

A passive NO.sub.x adsorber is disclosed. The passive NO.sub.x adsorber is effective to adsorb NO.sub.x at or below a low temperature and release the adsorbed NO.sub.x at temperatures above the low temperature. The passive NO.sub.x adsorber comprises a noble metal and a molecular sieve having an LTL Framework Type. The invention also includes an exhaust system comprising the passive NO.sub.x adsorber, and a method for treating exhaust gas from an internal combustion engine utilizing the passive NO.sub.x adsorber.

A passive NO.sub.x adsorber is disclosed. The passive NO.sub.x adsorber is effective to adsorb NO.sub.x at or below a low temperature and release the adsorbed NO.sub.x at temperatures above the low temperature. The passive NO.sub.x adsorber comprises a noble metal and a molecular sieve having an LTL Framework Type. The invention also includes an exhaust system comprising the passive NO.sub.x adsorber, and a method for treating exhaust gas from an internal combustion engine utilizing the passive NO.sub.x adsorber.

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.

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 disclosure provides a method for preparing a molecular sieve catalyst. A water-in-oil micro-emulsion including a continuous phase containing an organic solvent and a dispersed phase containing an aqueous solution containing one or more metal salts and a water-soluble organic carbon source is prepared, hydrolyzed, and azeotropically distilled to form a mixture solution. The mixture solution is heated to carbonize the water-soluble organic carbon source to form nanoparticles each having a core-shell structure including a carbon-shelled metal-oxide. The nanoparticles containing the carbon-shelled metal-oxide are dispersed in a molecular sieve precursor solution. A nanoparticle-loaded molecular sieve is formed from the molecular sieve precursor solution containing the nanoparticles, and then calcined to remove carbon there-from to form a metal-oxide loaded molecular sieve.

The present disclosure provides a method for preparing a molecular sieve catalyst. A water-in-oil micro-emulsion including a continuous phase containing an organic solvent and a dispersed phase containing an aqueous solution containing one or more metal salts and a water-soluble organic carbon source is prepared, hydrolyzed, and azeotropically distilled to form a mixture solution. The mixture solution is heated to carbonize the water-soluble organic carbon source to form nanoparticles each having a core-shell structure including a carbon-shelled metal-oxide. The nanoparticles containing the carbon-shelled metal-oxide are dispersed in a molecular sieve precursor solution. A nanoparticle-loaded molecular sieve is formed from the molecular sieve precursor solution containing the nanoparticles, and then calcined to remove carbon there-from to form a metal-oxide loaded molecular sieve.

Described are compositions and catalytic articles comprising both a first molecular sieve promoted with copper and a second molecular sieve promoted with iron, the first and second molecular sieves having a d6r unit and the first molecular sieves having cubic shaped crystals with an average crystal size of about 0.5 to about 2 microns. The weight ratio of the copper-promoted molecular sieve to the iron-promoted molecular sieve can be about 1:1 to about 4:1. The catalytic articles are useful in methods and systems to catalyze the reduction of nitrogen oxides in the presence of a reductant.