Provided are the following: an MWW type zeolite which has many Brønsted acid sites when in the form of a proton type and which is highly suitable as a cracking catalyst for cumene; a method for producing same; and an application of same. The present invention provides an MWW type zeolite in which the ratio (B/A) of the peak intensity (B) attributable to tetracoordinate aluminum relative to the peak intensity (A) attributable to hexacoordinate aluminum is 2 or more in .sup.27Al MAS NMR, when measured as an ammonium type. The present invention also provides a method for producing an MWW type zeolite, the method having a step for carrying out a hydrothermal synthesis reaction in the presence of: a seed crystal of an MWW type zeolite containing no organic structure-directing agent; and a reaction mixture containing a silica source, an alumina source, an alkali source, an organic structure-directing agent, and water. The reaction mixture satisfies the following molar ratio: X/SiO.sub.2<0.15 (here, X denotes the number of moles of the organic structure-directing agent).

Provided are the following: an MWW type zeolite which has many Brønsted acid sites when in the form of a proton type and which is highly suitable as a cracking catalyst for cumene; a method for producing same; and an application of same. The present invention provides an MWW type zeolite in which the ratio (B/A) of the peak intensity (B) attributable to tetracoordinate aluminum relative to the peak intensity (A) attributable to hexacoordinate aluminum is 2 or more in .sup.27Al MAS NMR, when measured as an ammonium type. The present invention also provides a method for producing an MWW type zeolite, the method having a step for carrying out a hydrothermal synthesis reaction in the presence of: a seed crystal of an MWW type zeolite containing no organic structure-directing agent; and a reaction mixture containing a silica source, an alumina source, an alkali source, an organic structure-directing agent, and water. The reaction mixture satisfies the following molar ratio: X/SiO.sub.2<0.15 (here, X denotes the number of moles of the organic structure-directing agent).

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

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.

A method for producing a hierarchical mesoporous beta includes mixing a beta zeolite with an aqueous metal hydroxide solution and heating the beta zeolite and the aqueous metal hydroxide mixture to produce a desilicated beta zeolite, contacting the desilicated beta zeolite with an ammonium salt solution to produce an intermediate hierarchical mesoporous beta zeolite, and treating the intermediate hierarchical mesoporous beta zeolite with an acidic solution to produce the hierarchical mesoporous beta zeolite. The hierarchical mesoporous beta zeolite includes a molar ratio of silicon to aluminum of greater than 12.5, a total pore volume of greater than or equal to the total pore volume of the intermediate hierarchical mesoporous beta zeolite, and an average mesopore size of greater than or equal to the average mesopore size of the hierarchical mesoporous beta zeolite. The method may also include calcining the intermediate hierarchical mesoporous beta zeolite.

A method for producing a hierarchical mesoporous beta includes mixing a beta zeolite with an aqueous metal hydroxide solution and heating the beta zeolite and the aqueous metal hydroxide mixture to produce a desilicated beta zeolite, contacting the desilicated beta zeolite with an ammonium salt solution to produce an intermediate hierarchical mesoporous beta zeolite, and treating the intermediate hierarchical mesoporous beta zeolite with an acidic solution to produce the hierarchical mesoporous beta zeolite. The hierarchical mesoporous beta zeolite includes a molar ratio of silicon to aluminum of greater than 12.5, a total pore volume of greater than or equal to the total pore volume of the intermediate hierarchical mesoporous beta zeolite, and an average mesopore size of greater than or equal to the average mesopore size of the hierarchical mesoporous beta zeolite. The method may also include calcining the intermediate hierarchical mesoporous beta zeolite.

A process for the production of a zeolitic material comprising one or more zeolite intergrowth phases of one or more zeolites having a CHA-type framework structure comprising SiO.sub.2 and X.sub.2O.sub.3, and one or more zeolites having an AFT-type framework CT structure comprising SiO.sub.2 and X.sub.2O.sub.3, wherein X is a trivalent element, and wherein said process comprises: (1) preparing a mixture comprising one or more sources for SiO.sub.2, one or more sources for X.sub.2O.sub.3, and seed crystals comprising a zeolitic material, said zeolitic material comprising SiO.sub.2 and X.sub.2O.sub.3 in its framework structure and having a CHA-type framework structure; (2) heating the mixture prepared in (1) for obtaining a zeolitic material comprising one or more zeolite intergrowth phases; and (R) subjecting the zeolitic material obtained in (2) to a procedure for removing at least a portion of X from the framework structure of the zeolitic material.

A process for the production of a zeolitic material comprising one or more zeolite intergrowth phases of one or more zeolites having a CHA-type framework structure comprising SiO.sub.2 and X.sub.2O.sub.3, and one or more zeolites having an AFT-type framework CT structure comprising SiO.sub.2 and X.sub.2O.sub.3, wherein X is a trivalent element, and wherein said process comprises: (1) preparing a mixture comprising one or more sources for SiO.sub.2, one or more sources for X.sub.2O.sub.3, and seed crystals comprising a zeolitic material, said zeolitic material comprising SiO.sub.2 and X.sub.2O.sub.3 in its framework structure and having a CHA-type framework structure; (2) heating the mixture prepared in (1) for obtaining a zeolitic material comprising one or more zeolite intergrowth phases; and (R) subjecting the zeolitic material obtained in (2) to a procedure for removing at least a portion of X from the framework structure of the zeolitic material.