Small crystallite zeolite CHA

• US 20030069449A1
• Filed: 08/30/2001
• Published: 04/10/2003
• Est. Priority Date: 08/30/2001
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Miller, Stephen J., Zones, Stacey I., Yuen, Lun-Teh
• Granted Patent: US 6,709,644 B2
• Time in Patent Office: Days
• US Class Current: 564/463
• CPC Class Codes: B01D 2323/12 Specific ratios of components used
• CPC Class Codes: B01D 67/0051 by controlled crystallisation, e,.g. hydrothermal growth
• CPC Class Codes: B01D 71/028 Molecular sieves carbon B01D71/021
• CPC Class Codes: B01D 71/0281 Zeolites
• CPC Class Codes: B01J 29/7015 CHA-type, e.g. Chabazite, LZ-218
• CPC Class Codes: C01B 39/48 using at least one organic template directing agent
• CPC Class Codes: C07C 1/20 starting from organic compounds containing only oxygen atoms as heteroatoms
• CPC Class Codes: C07C 11/02 Alkenes
• CPC Class Codes: C07C 209/16 with formation of amino groups bound to acyclic carbon atoms or to carbon atoms of rings other than six-membered aromatic rings
• CPC Class Codes: C07C 2529/70 of types characterised by their specific structure not provided for in groups C07C2529/08 - C07C2529/65

Abstract

The present invention relates to zeolites having the crystal structure of chabazite (CHA) and having small crystallite size, to processes using the small crystallite CHA as a catalyst, and to gas separation processes using the small crystallite CHA.

Claims

1. A zeolite having the CHA crystal structure, a mole ratio greater than about 10 of an oxide of a first tetravalent element to an oxide of a second tetravalent element which is different from said first tetravalent element, trivalent element, pentavalent element or mixture thereof and having a crystallite size of 0.5 micron or less.

5. A zeolite according to claim 1 wherein said zeolite is predominantly in the hydrogen form.

6. A zeolite according to claim 1 wherein said zeolite is substantially free of acidity.

2. A zeolite having the CHA crystal structure, a mole ratio greater than about 10 of silicon oxide to aluminum oxide, and having a crystallite size of 0.5 micron or less.

3. A zeolite according to claim 2 wherein the mole ratio of silicon oxide to aluminum oxide is at least 30.

4. A zeolite according to claim 2 wherein the crystallite size is 0.1 micron or less.

7. A method of preparing an aluminosilicate crystalline material having the CHA crystal structure and a crystallite size of 0.5 micron or less, said method comprising contacting under crystallization conditions an aluminum hydroxide gel dried to about 50 wt. % Al₂O₃, precipitated silica with a water content of about 5-15 wt. % and a templating agent comprising a N,N,N-trimethyl-1-adamantammonium cation.

8. The method of claim 7 wherein the aluminum hydroxide has a particle density of less than about 1.0 g/cm³.

9. The method of claim 7 wherein the aluminum hydroxide has a particle size of less than about 40 microns.

10. The method of claim 7 wherein the aluminum hydroxide has an alkali content of less than about 0.12 wt. %.

11. A process for converting lower alcohols and other oxygenated hydrocarbons comprising contacting said lower alcohol or other oxygenated hydrocarbon under conditions to produce liquid products with a catalyst comprising a zeolite having the CHA crystal structure, a mole ratio greater than about 10 of silicon oxide to aluminum oxide and having a crystallite size of about 0.5 micron or less.

12. The process of claim 11 wherein the lower alcohol is methanol.

13. In a process for the reduction of oxides of nitrogen contained in a gas stream in the presence of oxygen wherein said process comprises contacting the gas stream with a zeolite, the improvement comprising using as the zeolite a zeolite having the CHA crystal structure, a mole ratio greater than about 10 of silicon oxide to aluminum oxide and having a crystallite size of 0.5 micron or less.

14. The process of claim 13 wherein said zeolite contains a metal or metal ions capable of catalyzing the reduction of the oxides of nitrogen.

15. The process of claim 14 wherein the metal is copper, cobalt or mixtures thereof.

16. The process of claim 14 wherein the gas stream is the exhaust stream of an internal combustion engine.

17. A process for producing dimethylamine comprising reacting methanol and/or dimethyl ether and ammonia in the gaseous phase in the presence of a catalyst comprising a zeolite having the CHA crystal structure, a mole ratio greater than about 10 of silicon oxide to aluminum oxide and having a crystallite size of 0.5 micron or less.

18. The process of claim 17 wherein the methanol and/or dimethylether and ammonia are present in amounts sufficient to provide a carbon/nitrogen ratio from about 0.2 to about 1.5.

19. The process of claim 17 conducted at a temperature of from about 250°

C. to about 450°

C.

20. In a process for separating gasses using a membrane containing a zeolite, the improvement comprising using a zeolite having the CHA crystal structure, a mole ratio greater than about 10 of silicon oxide to aluminum oxide and having a crystallite size of 0.5 micron or less.

21. The process of claim 20 wherein the process separates carbon dioxide from natural gas.