Methods for making mesostructured zeolitic materials
View Patent ↗A quantity of solution sufficient to dissolve a pH controlling substance and/or substantially dissolve a surfactant without substantial excess solution is controlled under a set of time and temperature conditions to transform an inorganic material having long-range crystallinity to a mesostructure having long-range crystallinity. The method employs concentrated conditions that have a consistency similar to a thick slurry. The economic viability of scaling up such thick slurry methods is improved relative to prior more dilute methods of transforming an inorganic material to a mesostructure.
1. A method of making a mesostructure comprising:
exposing an inorganic material having long-range crystallinity to a solution comprising a pH controlling substance and a surfactant under time and temperature conditions sufficient to define, in said inorganic material, a plurality of mesopores having a controlled cross sectional area forming a mesostructure having long-range crystallinity, wherein the quantity of said solution is in the range of from about 0 volume percent to about 20 volume percent in excess of the amount sufficient to dissolve said pH controlling substance and substantially dissolve said surfactant, wherein said inorganic material is selected from the group consisting of metal oxides, zeolites, zeotypes, aluminophosphates, gallophosphates, zincophosphates, titanophosphates, and mixtures of two or more thereof.
2. The method of claim 1 wherein the ratio of said solution to said inorganic material ranges from about 10 ml/g to about 0.1 ml/g.
3. The method of claim 1 wherein said quantity of said solution produces an autogenous pressure in a closed vessel under said conditions of time and temperature.
4. The method of claim 1 wherein said solution is an aqueous solution.
5. The method of claim 1 wherein said solution and said time and temperature conditions produce a mesostructure having substantially the same hydrothermal stability as said inorganic material.
6. The method of claim 5 wherein the hydrothermal stability of said inorganic material is substantially the same as measured by comparing a property of said inorganic material prior to exposure to steam with said property of said inorganic material after exposure to steam and hydrothermal stability of said mesostructure is measured by comparing said property of said mesostructure prior to exposure to steam with said property of said mesostructure after exposure to steam.
7. The method of claim 1 wherein said pH controlling substance is a base.
8. The method of claim 1 wherein said inorganic material is simultaneously exposed to said pH controlling substance and said surfactant.
9. The method of claim 1 wherein said inorganic material is sequentially exposed to said pH controlling substance and said surfactant resulting in said solution comprising said pH controlling substance and said surfactant.
10. A mesostructure produced by the process of claim 1 .
11. The mesostructure of claim 10 wherein said plurality of mesopores have a pore volume and said pore volume is controlled.
12. The mesostructure of claim 11 wherein said pore volume is from about 0.05 cc/g to about 2 cc/g.
13. The mesostructure of claim 12 wherein said controlled cross sectional area has a diameter ranging from about 2 nm to about 60 nm.
14. The mesostructure of claim 10 wherein said controlled cross sectional area has a diameter and said diameter has a controlled distribution range.
15. The mesostructure of claim 10 wherein said plurality of mesopores have a pore arrangement and said pore arrangement is controlled.
16. The mesostructure of claim 10 wherein said plurality of mesopores have a pore arrangement and said pore arrangement is organized.
17. The mesostructure of claim 10 wherein a wall thickness between adjacent mesopores is from about 1 nm to about 50 nm.
18. The mesostructure of claim 10 wherein said mesostructure has a chemical composition framework substantially the same as the chemical composition framework of said inorganic material prior to defining said plurality of mesopores.
19. The mesostructure of claim 10 wherein said mesostructure has a connectivity substantially the same as the connectivity of said inorganic material prior to defining said plurality of mesopores.
20. The mesostructure of claim 10 wherein said inorganic material is a zeolite and said mesostructure has a tetracoordinated aluminum/octacoordinated aluminum ratio substantially the same as the tetracoordinated aluminum/octacoordinated aluminum ratio of said zeolite prior to defining said plurality of mesopores.
21. The mesostructure of claim 10 wherein said mesostructure has a crystal unit cell substantially the same as the crystal unit cell of said inorganic material prior to defining said plurality of mesopores.