Zeolite synthesis with dominant and secondary templates

Patent metadata

Field	Value
Publication number	US-10155665-B2
Application number	US-201514887464-A
Country	US
Kind code	B2
Filing date	Oct 20, 2015
Priority date	Nov 3, 2014
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

Methods are provided for synthesis of various types of zeolites using synthesis mixtures that contain a dominant structure directing agent and one or more secondary structure directing agents. Advantageously, the secondary structure directing agents may substantially not alter the crystal structure and/or morphology of the crystals generated by a synthesis mixture in the presence of the dominant structure directing agent.

First claim

What is claimed is:

1. A method of synthesizing ZSM-48 zeolite crystals, the method comprising:
crystallizing a reaction mixture to form ZSM-48 zeolite crystals under effective synthesis conditions, the reaction mixture comprising a source of water, a source of silicon, a source of aluminum, a source of an alkali metal, M, a source of a dominant structure directing agent in the form of an organic cation Q 1 , and a source of a secondary structure directing agent in the form of an organic cation Q 2 , a combined amount of dominant structure directing agent cation Q 1 and secondary structure directing agent cation Q 2 corresponding to a combined amount of structure directing agent cation Q,
wherein the dominant structure directing agent Q 1 is a salt comprising a dihalide anion component and a cation component comprising is a diquaternary ammonium cation represented by the formula RR′R″—N + —R 3 —N + —RR′R″, wherein each R, R′, and R″ are the same or different and each R, R′, and R″ is an alkyl group having from 1 to 10 carbons and R 3 is a polymethylene group of formula (CH 2 ) n , where n=5 or 6,
wherein the secondary structure directing agent cation does not enable formation of the zeolite crystals under the effective synthesis conditions, the secondary structure directing agent being a tetraalkyl ammonium hydroxide, and
wherein the amount of secondary structure directing agent cation Q 2 is at least about 20 mol % of the combined amount of structure directing agent cation Q.

2. The method of claim 1 , wherein the reaction mixture further comprises seeds of the zeolite crystals in an amount such that a weight percent of seeds relative to total weight of silicon measured as SiO 2 in said reaction mixture is between about 0.1 wt % and about 20 wt %.

3. The method of claim 1 , wherein the secondary structure directing agent is tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, or a combination thereof.

4. The method of claim 3 , wherein the secondary structure directing agent cation is tetraethyl ammonium.

5. The method of claim 1 , wherein a molar ratio of the amount of secondary structure directing agent Q 2 to the amount of hydroxyl ions is at least about 1:10.

6. The method of claim 1 , wherein the amount of secondary structure directing agent cation Q 2 is at least about 25 mol % of the combined amount of structure directing agent cation Q.

7. An as-synthesized zeolite crystal made according to the method of claim 1 , and further comprising both the dominant structure directing agent cation Q 1 and the secondary structure directing agent cation Q 2 within its pore structure, wherein the dominant structure directing agent cation Q 1 comprises a diquat-5, a diquat-6, or a combination thereof, and wherein the secondary structure directing agent cation Q 2 comprises tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, or a combination thereof.

8. The as-synthesized zeolite crystal according to claim 7 , wherein the secondary structure directing agent cation Q 2 comprises tetraethyl ammonium hydroxide.

9. A method of synthesizing ZSM-48 crystals, the method comprising:
crystallizing a reaction mixture to form ZSM-48 crystals under effective synthesis conditions, the reaction mixture comprising a source of water, a source of silicon, a source of aluminum, a source of an alkali metal, M, a source of a dominant structure directing agent in the form of an organic cation Q 1 , and a source of a secondary structure directing agent in the form of an organic cation Q 2 , a combined amount of dominant structure directing agent cation Q 1 and secondary structure directing agent cation Q 2 corresponding to a combined amount of structure directing agent cation Q,
the reaction mixture having a molar ratio of combined structure directing agent cation Q to silicon measured as SiO 2 in said reaction mixture from about 0.01 to about 0.20; a molar ratio of silicon measured as SiO 2 to aluminum measured as Al 2 O 3 in said reaction mixture from about 50 to about 200; a molar ratio of water to silicon measured as SiO 2 in said reaction mixture from about 1 to about 500; a molar ratio of hydroxyl group concentration to silicon measured as silica SiO 2 in said reaction mixture is from about 0.1 to about 0.3; and a molar ratio of alkali metal, M, to silicon measured as SiO 2 in said reaction mixture is from about 0.05 to about 0.4,
wherein the dominant structure directing agent is a salt comprising a dihalide anion component and a cation component comprising is a diquaternary ammonium cation represented by the formula RR′R″—N + —R 3 —N + —RR′R″, wherein each R, R′, and R″ are the same or different and each R, R′, and R″ is an alkyl group having from 1 to 10 carbons and R 3 is a polymethylene group of formula (CH 2 ) n , where n=5 or 6,
wherein the secondary structure directing agent cation does not enable formation of ZSM-48 under the effective synthesis conditions, the secondary structure directing agent being a tetraalkyl ammonium hydroxide, and
wherein an amount of secondary structure directing agent cation Q 2 is at least about 20 mol % of the combined amount of structure directing agent cation Q.

10. The method of claim 9 , wherein the secondary structure directing agent is tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, or a combination thereof.

11. The method of claim 9 , wherein the secondary structure directing agent cation is tetraethyl ammonium.

12. The method of claim 9 , wherein a molar ratio of the amount of secondary structure directing agent Q 2 to the amount of hydroxyl ions is at least about 1:10.

13. The method of claim 9 , wherein the amount of secondary structure directing agent cation Q 2 is at least about 25 mol % of the combined amount of structure directing agent cation Q.

14. The method of claim 9 , wherein the reaction mixture further comprises seeds of ZSM-48 in an amount such that a weight percent of seeds relative to total weight of silicon measured as SiO 2 in said reaction mixture is between about 0.1 wt % and about 20 wt %.

15. The method of claim 9 , wherein at least 50 vol % of the as-synthesized ZSM-48 crystals have a fibrous morphology.

16. The method of claim 9 , wherein at least 50 vol % of the as-synthesized ZSM-48 crystals have a needle-like morphology.

17. The method of claim 9 , wherein the reaction mixture has a molar ratio of combined structure directing agent cation Q to silicon measured as SiO 2 in said reaction mixture from about 0.01 to about 0.05; a molar ratio of silicon measured as SiO 2 to aluminum measured as Al 2 O 3 in said reaction mixture from about 50 to about 150; a molar ratio of water to silicon measured as SiO 2 in said reaction mixture from about 1 to about 500; a molar ratio of hydroxyl group concentration to silicon measured as SiO 2 in said reaction mixture is from about 0.1 to about 0.3; and a molar ratio of alkali metal, M, to silicon measured as SiO 2 in said reaction mixture is from about 0.05 to about 0.4.

18. The method of claim 17 , wherein the molar ratio of silicon measured as SiO 2 to aluminum measured as Al 2 O 3 in said reaction mixture is from about 65 to about 120.

19. An as-synthesized ZSM-48 crystal made according to the method of claim 9 , and further comprising both the dominant structure directing agent cation Q 1 and the seconda

Assignees

• Lai Wenyih Frank
• Rollman Nicholas S
• Walp Jenna L
• Lonergan William W
• Exxonmobil Res & Eng Co

Inventors

• Lai Wenyih Frank
• Rollman Nicholas S
• Walp Jenna L
• Lonergan William W

Classifications

• C01B39/04

  using at least one organic template directing agent, e.g. an ionic quaternary ammonium compound or an aminated compound · CPC title

• C01B39/48 Primary

  using at least one organic template directing agent · CPC title

• B01J29/703

  MRE-type, e.g. ZSM-48 · CPC title