Accelerated aluminosilicate zeolite crystallization
A method for crystallizing aluminosilicate zeolites, including the steps of preparing a mixture containing a silica source, a mineralizing agent, an organic structure directing agent; heating the mixture to form a heated mixture; and adding an alumina source to the heated mixture. The method steps described herein can provide an accelerated aluminosilicate zeolite crystallization process as compared to conventional processes.
1. A method of crystallizing zeolites, comprising:
preparing a mixture comprising a silica source, a mineralizing agent, an organic structure directing agent, and zeolite crystals;
heating the mixture to form a heated mixture; and
adding an alumina source to the heated mixture,
wherein the heated mixture comprises about 75 wt. % or less of alumina source in the heated mixture prior to the adding step, based on a total amount of alumina source employed in the method.
2. The method of claim 1 , wherein the heating is conducted, at least in part, at a pressure of at least 1 atmosphere.
3. The method of claim 1 , wherein the heated mixture is free of alumina prior to the adding step, other than alumina in the zeolite crystals.
4. The method of claim 1 wherein the zeolite crystals have an 8 ring pore size.
5. The method of claim 1 , wherein the alumina source is added continuously at a constant flow rate.
6. The method of claim 1 , wherein the method provides a product having about 80% or more crystallinity in a time period that is less than a comparative time period required to provide a product having about 80% or more crystallinity in a control process, wherein the control process is substantially identical except wherein the heated mixture comprises the alumina source in an amount of about 80 wt. % or more, based on a weight of a total amount of alumina source to be added, the silica source, mineralizing agent, organic structure directing agent, and zeolite crystals.
7. The method of claim 6 , wherein the time period is about 1.5 times shorter than the comparative time period.
8. The method of claim 6 , wherein the time period is about 2 times shorter than the comparative time period.
9. The method of claim 6 , wherein the time period is about 3 times shorter than the comparative time period.
10. The method of claim 6 , wherein the time period is the time required to obtain about 85% or more crystallinity from the mixture and the alumina source.
11. The method of claim 6 , wherein the time period is the time required to obtain about 90% or more crystallinity from the mixture and the alumina source.
12. The method of claim 6 , wherein the time period is the time required to obtain about 95% or more crystallinity from the mixture and the alumina source.
13. The method of claim 6 , wherein the adding step is conducted during about 10% to about 100% of the time period.
14. The method of claim 6 , wherein the adding step is conducted during about 30% to about 100% of the time period.
15. The method of claim 6 , wherein the time period ranges from about 1 hour to about 96 hours.
16. The method of claim 6 , wherein the comparative time period ranges from about 3 hours to about 168 hours.
17. The method of claim 1 , further comprising calcining to form aluminosilicate zeolite crystals with an 8 ring pore size.
18. The method of claim 17 , wherein the aluminosilicate zeolite crystals comprise zeolites with frameworks selected from the group consisting of AEI, AFX, CHA, LEV, AFT, EAB, KFI, SAT, TSC, SAV, ERI, LTA and combinations thereof.
19. The method of claim 17 , wherein the aluminosilicate zeolite crystals comprise zeolites with a CHA framework.
20. The method of claim 17 , wherein the aluminosilicate zeolite crystals have a zeolitic BET surface area ranging from about 200 m2/g to about 900 m2/g.
21. The method of claim 17 , wherein the aluminosilicate zeolite crystals form clusters ranging in size from about 50 nanometers to about 5 micrometers.
22. The method of claim 1 , wherein the alumina source is selected from the group consisting of sodium aluminate, Al(C3H7O)3, Al metal, water-soluble aluminum salts, aluminum oxides, aluminum hydroxides, colloidal suspensions, and combinations thereof.
23. The method of claim 1 , wherein the silica source is selected from the group consisting of colloidal silica, fumed silica, and tetraethyl orthosilicate (TEOS), sodium silicate, precipitated silica, and combinations thereof.
24. The method of claim 1 , wherein the mineralizing agent is selected from the group consisting of NaOH, KOH, F—, quaternary ammonium hydroxides, and combinations thereof.
25. The method of claim 1 , wherein the organic structure directing agent is selected from the group consisting of quaternary ammonium salts, adamantyl, cyclohexyl, aromatic substituents, and combinations thereof.
26. The method of claim 1 , wherein the zeolite crystals are aluminosilicate zeolite crystal seeds with an 8 ring pore size, having structures selected from the group consisting of AEI, AFX, CHA, LEV, AFT, EAB, KFI, SAT, TSC, SAV, ERI, LTA and combinations thereof.
27. The method of claim 26 , wherein the aluminosilicate zeolite crystals with an 8 ring pore size have a CHA structure.
28. The method of claim 1 , wherein the heated mixture comprises about 50 wt. % or less of alumina source in the heated mixture prior to the adding step, based on a total amount of alumina source employed in the method.
29. The method of claim 1 , wherein the heated mixture comprises about 25 wt. % or less of alumina source in the heated mixture prior to the adding step, based on a total amount of alumina source employed in the method.
30. The method of claim 1 , wherein the heated mixture comprises about 5 wt. % or less of alumina source in the heated mixture prior to the adding step, based on a total amount of alumina source employed in the method.