High-silica molecular sieve CHA
AssigneeChevron U.S.A. Inc.
InventorLun-Teh Yuen
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Abstract
A method is disclosed for synthesizing high-silica molecular sieves having the CHA crystal structure using a structure directing agent comprising a cation derived from 1-adamantamine, 3-quinuclidinol or 2-exo-aminonorbornane. The synthesis is conducted in the absence of fluorine.
Claims9
A method for preparing a molecular sieve having the CHA crystal structure and a mole ratio of greater than 50:1 of (1) silicon oxide, germanium oxide and mixtures thereof to (2) aluminum oxide, iron oxide, titanium oxide, gallium oxide and mixtures thereof said method comprising:
- A. forming an aqueous reaction mixture comprising a composition in terms of mole ratios falling within the following ranges:
- YO2/WaOb
- 400–∞
- OH—/YO2
- 0.19–0.52
- Q/YO2
- 0.15–0.25
- M2/nO/YO2
- 0.04–0.10
- H2O/YO2
- 10–50
- wherein Y is silicon, germanium or mixtures thereof, W is aluminum, iron, titanium, gallium or mixtures thereof, a is 1 or 2, b is 2 when a is 1 or b is 3 when a is 2;
- M is an alkali metal or alkaline earth metal, n is the valence of M, and Q is a cation derived from 1-adamantamine, 3-quinuclidinol or 2-exo-aminonorbornane;
- and
- B. maintaining said aqueous mixture under sufficient crystallization conditions until crystals are formed
- wherein the molecular sieve is prepared in the absence of fluorine.
A molecular sieve having the CHA crystal structure and having a composition, as-synthesized and in the anhydrous state, in terms of mole ratios of oxides as follows:
- YO2/WcOd
- 200–∞
- M2/nO/YO2
- 0.04–0.15
- Q/YO2
- 0.15–0.25
- wherein Y is silicon, germanium or mixtures thereof, W is aluminum, iron, titanium, gallium or mixtures thereof;
- c is 1 or 2;
- d is 2 when c is 1 or d is 3 or 5 when c is 2;
- M is an alkali metal cation, alkaline earth metal cation or mixtures thereof;
- n is the valence of M;
- and Q is a cation derived from 1-adamantamine, 3-quinuclidinol or 2-exo-aminonorbornane and wherein the as-synthesized molecular sieve does not contain fluorine.
Dependencies are inferred from the claim text.