METHOD FOR SYNTHESIZING MOLECULAR SIEVE SSZ-13

Abstract

A method for synthesizing a crystalline molecular sieve SSZ-13, characterized in that the method comprises bringing the following raw materials into contact in water under a crystallization condition: at least one tetravalent silicon source, at least one trivalent aluminium source, at least one alkali metal compound, choline cations and/or SSZ-13 seed crystals, and hydroxide ions. The method avoids using benzyl trimethyl quaternary ammonium ions (BzTMA.sup.+) or N,N,N-trimethyl-1-amantadine cations as structure-directing agents, and obtains high-quality crystal molecular sieve SSZ-13. Due to the use of a low-cost nontoxic structure-directing agent, the method has low production price by employing a low-cost nontoxic template, and can be popularized for application.

Claims

1. A method for synthesizing a crystalline molecular sieve SSZ-13, characterized in that, the method comprises bringing the following raw materials into contact in water under a crystallization condition: (1) at least one tetravalent silicon source; (2) at least one trivalent aluminium source; (3) at least one alkali metal compound; (4) choline cation and/or SSZ-13 seed crystal; and (5) hydroxide ion.

2. The method according to claim 1, characterized in that, the tetravalent silicon source includes, but is not limited to, silicon-containing oxide and silicate.

3. The method according to claim 2, characterized in that, the tetravalent silicon source is one or more selected from the group consisting of silicate, silica sol, tetraethyl orthosilicate, deposited silicon dioxide and clay.

4. The method according to claim 3, characterized in that, the tetravalent silicon source is silica sol.

5. The method according to claim 1, characterized in that, the trivalent aluminium source is trivalent aluminum oxide or aluminate.

6. The method according to claim 5, characterized in that, the trivalent aluminium source is sodium metaaluminate, aluminium oxide or aluminium hydroxide.

7. The method according to claim 1, characterized in that, the alkali metal compound is a sodium-containing compound.

8. The method according to claim 7, characterized in that, the alkali metal compound is sodium hydroxide or sodium chloride.

9. The method according to claim 1, characterized in that, the choline cation is choline hydroxide and/or choline chloride.

10. The method according to claim 9, characterized in that, the choline cation is choline chloride.

11. The method according to claim 1, characterized in that, the SSZ-13 seed crystal is a molecular sieve SSZ-13 synthesized by using the choline cation as a structure-directing agent.

12. The method according to claim 1, characterized in that, the molar ratios of individual raw material are: tetravalent silicon source/trivalent aluminium source 10-60; alkali metal compound/ tetravalent silicon source 0.33-0.47; choline cation/tetravalent silicon source 0.05-0.1; and hydroxide ion/tetravalent silicon source 0.3-0.6.

13. The method according to claim 11, characterized in that, the molar ratios of individual raw material are: tetravalent silicon source/trivalent aluminium source 10-60; alkali metal compound/tetravalent silicon source 0.33-0.47; hydroxide ion/tetravalent silicon source 0.3-0.6; and the SSZ-13 seed crystal is 1%-10% of the tetravalent silicon source by mass.

14. The method according to claim 1, characterized in that, when the choline cation and the SSZ-13 seed crystal are simultaneously used for synthesizing the crystalline molecular sieve SSZ-13, the mass ratio of the choline cation to the SSZ-13 seed crystal is (2-3):1.

15. The method according to claim 1, characterized in that, after the end of feeding, the reaction mixture is heated for crystallization, wherein the reaction temperature is maintained at 100-200 C.; the crystallization process lasts for at least 4 days; and the product crystals after water-washing are dried at 90-150 C. for 8-12 hours, and then calcined in a muffle furnace at 500-600 C. for 6-10 hours to give crystals of the molecular sieve SSZ-13.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0089] FIG. 1 shows the XRD spectra of the molecular sieve SSZ-13 sample prepared in Example 1(A).

[0090] FIG. 2 shows the XRD spectra for the molecular sieve SSZ-13 sample prepared in Example 1(B).

[0091] FIG. 3 shows the XRD spectra for the molecular sieve SSZ-13 sample prepared in Example 2(A).

[0092] FIG. 4 shows the XRD spectra for the molecular sieve SSZ-13 sample prepared in Example 2(B).

[0093] FIG. 5 shows the XRD spectra for the molecular sieve SSZ-13 sample prepared in Example 3.

[0094] FIG. 6 shows the XRD spectra for the molecular sieve SSZ-13 sample prepared in Example 4.

BEST MODE OF THE INVENTION

[0095] The following examples are described for the purpose of illustrating the present invention rather than limiting the scope of the present invention.

[0096] The chemical reagents used in the following examples are commercially available.

Example 1

[0097] 0.492 g of sodium metaaluminate (aluminum source) and 3.6 g of sodium hydroxide were dissolved in 15.8 g of deionized water and stirred to dissolve completely. 2.3 g of choline chloride was added into the obtained mixture and stirred for 15 minutes to dissolve completely. 18 g of LUDOX-AS-40 silica sol (silicon source) was slowly added dropwise under rapid stirring.

[0098] After stirring at room temperature for one hour, the final colloid was divided into two parts (A and B), then A and B were respectively transferred into a stainless steel high-pressure reactor with a polytetrafluoroethylene lining, placed in an oven at 140 C. and kept for 4 days (for A) and 6 days (for B) respectively.

[0099] The obtained product was washed with deionized water, collected after filtration, dried in a vacuum oven at 100 C. for 12 hours, and then calcined in a muffle furnace at 550 C. for 8 hours to remove the structure-directing agent so as to give the molecular sieve SSZ-13. Wherein, FIGS. 1 and 2 showed the XRD spectra of the molecular sieve SSZ-13 prepared in the two groups, A and B.

Example 2

[0100] 0.853 g of sodium metaaluminate (aluminum source) and 3.0 g of sodium hydroxide were dissolved in 15.8 g of deionized water and stirred to dissolve completely. 1.8 g of choline chloride was added into the obtained mixture and stirred for 15 minutes to dissolve completely. 17.25 g of LUDOX-AS-40 colloided silica (silicon source) was slowly added dropwise under rapid stirring.

[0101] After stirring at room temperature for one hour, the final colloid was divided into two parts (A and B), then A and B were respectively transferred into a stainless steel high-pressure reactor with a polytetrafluoroethylene lining, placed in an oven at 130 C. (for A) and 150 C. (for B) respectively and kept for 6 days.

[0102] The obtained product was washed with deionized water, collected after filtration, dried in a vacuum oven at 100 C. for 12 hours, and then calcined in a muffle furnace at 550 C. for 8 hours to remove the structure-directing agent so as to give the molecular sieve SSZ-13. Wherein, FIGS. 3 and 4 showed the XRD spectra of the molecular sieve SSZ-13 prepared in the two groups, A and B.

Example 3

[0103] 0.492 g of sodium metaaluminate (aluminum source) and 3.0 g of sodium hydroxide were dissolved in 15.8 g of deionized water and stirred to dissolve completely. 1.2 g of choline chloride was added into the obtained mixture and it took 15 minutes to mix completely. 0.36 g of SSZ-13 seed crystal was added and it took 5 minutes to mix completely. 18.0 g of LUDOX-AS-40 silica sol (silicon source) was slowly added dropwise under rapid stirring.

[0104] After stirring at room temperature for one hour, the mixture was transferred into a stainless steel high-pressure reactor with a polytetrafluoroethylene lining, placed in an oven at 140 C. and kept for 4 days.

[0105] The obtained product was washed with deionized water, collected after filtration, dried in a vacuum oven at 100 C. for 12 hours, and then calcined in a muffle furnace at 550 C. for 8 hours to remove the structure-directing agent so as to give the molecular sieve SSZ-13. Wherein, FIG. 5 showed the XRD spectra of the molecular sieve SSZ-13.

Example 4

[0106] 0.492 g of sodium metaaluminate (aluminum source) and 3.0 g of sodium hydroxide were dissolved in 15.8 g of deionized water and stirred to dissolve completely. 0.72 g of SSZ-13 seed crystal was added into the obtained mixture and stirred for 15 minutes to dissolve completely. 18.0 g of LUDOX-AS-40 silica sol (silicon source) was slowly added dropwise under rapid stirring.

[0107] After stirring at room temperature for one hour, the mixture was transferred into a stainless steel high-pressure reactor with a polytetrafluoroethylene lining, placed in an oven at 140 C. and kept for 6 days.

[0108] The obtained product was washed with deionized water, collected after filtration, dried in a vacuum oven at 100 C. for 12 hours, and then calcined in a muffle furnace at 550 C. for 8 hours to remove the structure-directing agent so as to give the molecular sieve SSZ-13. Wherein, FIG. 6 showed the XRD spectra of the molecular sieve SSZ-13.

Example 5

[0109] The difference of Example 5 compared with Example 4 merely lied in the specific selection and molar quantity of individual raw material, which were specifically as follows:

[0110] tetravalent silicon source/trivalent aluminium source 10;

[0111] alkali metal compound/tetravalent silicon source 0.33;

[0112] hydroxide ion/tetravalent silicon source 0.33;

[0113] H.sub.2O/tetravalent silicon source 3; and

[0114] seed crystal/tetravalent silicon source (Wt. %) 4.

[0115] In this example, the tetravalent silicon source was deposited silicon dioxide, the trivalent aluminium source was pseudo-bohemite, the alkali metal compound was sodium hydroxide, and the hydroxide ion was provided in the form of sodium hydroxide. The XRD spectrum of the molecular sieve SSZ-13 prepared in this example, as compared with FIGS. 1-6, showed characteristic diffraction peaks at the same positions, which confirmed that the preparation method as described in this example obtained the same molecular sieve SSZ-13. The spectrum was not provided here due to the space constraints. Those skilled in the art may predict that using the above-mentioned technical solution can achieve the object of the present invention, obtaining the expected molecular sieve SSZ-13.

Example 6

[0116] The difference of Example 6 compared with Example 4 merely lied in the specific selection and molar quantity of individual raw material, which were specifically as follows:

[0117] tetravalent silicon source/trivalent aluminium source 60;

[0118] alkali metal compound/tetravalent silicon source 0.47;

[0119] hydroxide ion/tetravalent silicon source 0.47;

[0120] H.sub.2O/SiO.sub.2 11; and

[0121] seed crystal/tetravalent silicon source (Wt. %) 10.

[0122] In this example, the tetravalent silicon source was tetraethyl orthosilicate, the trivalent aluminium source was sodium metaaluminate, the alkali metal compound was sodium hydroxide, and the hydroxide ion was provided in the form of sodium hydroxide. The XRD spectrum of the molecular sieve SSZ-13 prepared in this example, as compared with FIGS. 1-6, showed characteristic diffraction peaks at the same positions, which confirmed that the preparation method as described in this example obtained the same molecular sieve SSZ-13.

Example 7

[0123] The difference of Example 7 compared with Example 1 merely lied in the specific selection and molar quantity of individual raw material, which were specifically as follows:

[0124] tetravalent silicon source/trivalent aluminium source 20;

[0125] alkali metal compound/tetravalent silicon source 0.4;

[0126] hydroxide ion/tetravalent silicon source 0.4;

[0127] H.sub.2O/tetravalent silicon source 11; and

[0128] choline chloride/tetravalent silicon source 0.08.

[0129] In this example, the tetravalent silicon source was sodium silicate, the trivalent aluminium source was pseudo-bohemite, the alkali metal compound was sodium hydroxide, and the hydroxide ion was provided in the form of sodium hydroxide. The XRD spectrum of the molecular sieve SSZ-13 prepared in this example, as compared with FIGS. 1-6, showed characteristic diffraction peaks at the same positions, which confirmed that the preparation method as described in this example obtained the same molecular sieve SSZ-13.

Example 8

[0130] The difference of Example 8 compared with Example 1 merely lied in the specific selection and molar quantity of individual raw material, which were specifically as follows:

[0131] tetravalent silicon source/trivalent aluminium source 40;

[0132] alkali metal compound/trivalent aluminium source 2.3;

[0133] hydroxide ion/tetravalent silicon source 0.5;

[0134] H.sub.2O/tetravalent silicon source 5; and

[0135] choline hydroxide/tetravalent silicon source 0.1.

[0136] In this example, the tetravalent silicon source was silica sol, the trivalent aluminium source was aluminum oxide, the alkali metal compound was sodium chloride, and the hydroxide ion was provided in the form of ammonia water. The XRD spectrum of the molecular sieve SSZ-13 prepared in this example, as compared with FIGS. 1-6, showed characteristic diffraction peaks at the same positions, which confirmed that the preparation method as described in this example obtained the same molecular sieve SSZ-13.

Example 9

[0137] The difference of Example 9 compared with Example 3 merely lied in that the mass ratio of choline chloride to SSZ-13 seed crystal was 2:1.

Example 10

[0138] The difference of Example 10 compared with Example 3 merely lied in that the mass ratio of choline chloride to SSZ-13 seed crystal was 3:1.

Example 11

[0139] The difference of Example 11 compared with Example 3 merely lied in that the mass ratio of choline chloride to SSZ-13 seed crystal was 2.5:1.

[0140] Although the present invention has been described in detail through the general descriptions and detailed embodiments above, it is obvious to those skilled in the art to make modifications or improvements based on the present invention. Hence, the modifications or improvements which are made without departing from the spirits of the present invention fall into the protection scope claimed by the present invention.

INDUSTRIAL APPLICABILITY

[0141] Disclosed is a novel method for synthesizing a crystalline molecular sieve SSZ-13, the method comprises bringing the following raw materials into contact in water under a crystallization condition: (1) at least one tetravalent silicon source, (2) at least one trivalent aluminium source, (3) at least one alkali metal compound, (4) choline cations and/or SSZ-13 seed crystals, and (5) hydroxide ions. The novel method for synthesizing a crystalline molecular sieve SSZ-13 according to the present invention may avoid the use of benzyl trimethyl quaternary ammonium ion (BzTMA.sup.+) or N,N,N-trimethyl-1-amantadine cation as the structure-directing agent, and may finally obtain high-quality crystalline molecular sieve SSZ-13. In view of the use of a low-cost and nontoxic structure-directing agent in the present invention, the preparation method according to the present invention also has the following advantages: a low production price due to the use of a low-cost and nontoxic template agent and easy popularization for application, and thus has strong industrial applicability.