Hydrothermal conversion of Y-zeolite using alkaline earth cations
AssigneeCalifornia Institute of Technology
InventorsOsamu Chiyoda, Mark E. Davis
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Abstract
Hydrothermal synthesis of the natural, alkaline earth zeolites via the alteration of Y-zeolite is presented. Synthetic versions of the zeolites harmotome, heulandite, brewsterite and gmelinite are synthesized from Y-zeolite using alkaline earth cations containing solutions. The effect of the composition of the starting zeolite, the composition of the solution phase, the presence or absence of seeds and the experimental conditions are discussed.
Claims16
A method for synthesizing a zeolite, comprising the steps of:
- a) providing a Y-zeolite having 2.0≦Si/Al≦3.5;
- and
- b) forming said zeolite under hydrothermal reaction conditions from a reaction mixture containing said Y-zeolite and an aqueous solution of a cation selected from the group consisting of Na+, Ba2+, Ca2+ and Sr2+, said reaction mixture being substantially free of an organic base.
A method for preparing synthetic heulandite, gmelinite, brewsterite, analcime or harmotome zeolite product, comprising the steps of:
- a) providing a reaction mixture containing Y-zeolite having 2.0≦Si/Al≦3.5 and a cation selected from the group consisting of Na+, Ba2+, Ca2+ and Sr2+, wherein said cation is in a concentration greater than that of the concentration of any other metal cation present in the reaction mixture;
- and
- b) converting under hydrothermal conditions said Y-zeolite in said reaction mixture to said zeolite product containing said cation, said reaction mixture being substantially free of an organic base.
A method for preparing a zeolite having the analcime topology and the formula in terms of atomic ratios Na2O:Al2O3:4SiO2:2H2O comprising the steps of:
- a) providing a reaction mixture containing Na+ and a Y-zeolite, said Y-zeolite having 2.0≦Si/Al≦3.0 and a cation, said cation being selected from the group consisting of Na+ and Sr2+, the mixture being substantially free of any other alkali or alkaline earth cations and any zeolite structure directing agent;
- and
- b) forming said zeolite from said Y-zeolite under hydrothermal reaction conditions, said zeolite incorporating said Nat, wherein said reaction mixture is substantially free of organic base.
A method for preparing a zeolite having the gmelinite topology and the formula in terms of atomic ratios 8Na2O:4CaO:Al2O3:4SiO2:6H2O, comprising the steps of:
- a) providing a reaction mixture containing Sr2+ and a Y-zeolite, said Y-zeolite having 2.0≦Si/Al≦2.4 and a cation, said second cation being selected from the group consisting of Ca2+ and Sr2+, the mixture being substantially free of any other alkali or alkaline earth cations, an organic base, and any zeolite structure directing agent;
- and
- b) forming said zeolite from said Y-zeolite under hydrothermal reaction conditions, said zeolite incorporating a first cation.
Dependencies are inferred from the claim text.