Aluminosilicate AEI zeolite preparation
A method for synthesizing AEI zeolites is provided which results in high relative yields of AEI based on the weight of the reaction mixture and on the structure directing agent. The method also provides for the reduced use of water in the reaction mixture. A reaction mixture composition comprises the following components: at least one source of silica, at least one source of alumina, at least one structure directing agent (SDA), a source of hydroxide ions and water, where the silica sources and the alumina sources are expressed as SiO2 and Al2O3, respectively, and the components are present in the following ratios: SiO 2 /Al 2 O 3 10-100 OH − /SiO 2 0.2-0.9 SDA/SiO 2 0.01-0.20 Alkali metal cation/SiO 2 0.20-1.0 H 2 O/SiO 2 4-60.
1. A method of preparing a zeolite having an AEI framework, the method comprising:
a. forming a reaction mixture comprising one or more sources of silica, one or more sources of alumina, a base and one or more organic structure directing agents (SDA), where at least a portion of the alumina source is an FAU topological type zeolite and wherein the reaction mixture comprises less than 600 moles of water per mole of alumina, and wherein the silica source and the alumina source are expressed as SiO 2 and Al 2 O 3 , respectively, and the components are present in the following ratios, where the endpoints are included:
SiO 2 /Al 2 O 3
25-75
OH−/SiO 2
0.35-0.75
SDA/SiO 2
0.01-0.12
Alkali metal cation/SiO 2
0.30-0.60
H 2 O/SiO 2
6-30
and
b. reacting the reaction mixture at an elevated temperature for a period of time sufficient to form zeolite crystals having an AEI framework and a silica-to-alumina ratio (SAR) of about 10 to about 30, wherein the reacting step, prior to removal of SDAs from the zeolite crystals, has a relative yield based on the weight of the AEI to the weight of the reaction mixture of ≥about 5%.
2. The method of claim 1 , wherein the structure directing agents comprises one or more cations selected from the group consisting of N,N-dimethyl-3,5-dimethylpiperidinium, N,N-dimethyl-2-(2-hydroxyethyl)piperidinium, N,N-dimethyl-2-ethylpiperidinium, and 2,2,4,6,6-pentamethyl-2-azoniabycyclo[3.2.1]octane.
3. The method of claim 1 , wherein the silica source is selected from the group consisting of a solid silica, waterglass (sodium silicate), dealuminated Y, NaY and USY.
4. The method of claim 1 , wherein the relative yield is ≥about 8%.
5. The method of claim 1 where the yield of AEI zeolite based on the structure directing agent is ≥about 30%.
6. The method of claim 1 where the yield of AEI zeolite based on the structure directing agent is ≥about 65%.
7. The method of claim 1 wherein the reaction mixture is substantially free of fluorine, fluorine ions, and fluorine containing compounds.
8. The method of claim 1 wherein the SAR of the AEI zeolite crystals is about 10 to about 20.
9. A composition comprising the following components: one or more sources of silica, one or more sources of alumina, one or more structure directing agents (SDA), a source of hydroxide ions and water, where the silica source and the alumina source are expressed as SiO 2 and Al 2 O 3 , respectively, and the components are present in the following ratios, where the endpoints are included:
SiO 2 /Al 2 O 3
25-75
OH − /SiO 2
0.35-0.75
SDA/SiO 2
0.01-0.12
Alkali metal cation/SiO 2
0.30-0.60
H 2 O/SiO 2
6-30
wherein the composition, upon reacting at a temperature of between about 75 to about 220° C. for between 0.1 and 20 days, produces AEI zeolite crystals having a silica-to-alumina ratio (SAR) of about 10 to about 30.