A method for making a pansilicalite ratio ssz-39 molecular sieve

Abstract

The application provides a method for preparing a general silicon-aluminum ratio SSZ-39 molecular sieve, and relates to the technical field of molecular sieves. A template agent, water, an alkali source, seeds and a silicon source are mixed to obtain a gel; the alkali source is an alkali metal hydroxide, and the seeds are small-pore SAPO molecular sieves; the gel is subjected to hydrothermal crystallization to obtain a crystallization product; and the crystallization product is calcined to obtain the SSZ-39 molecular sieve. A series of SSZ-39 with different silicon-aluminum ratios are synthesized by an aluminum-free seed method for the first time. In the application, the alkali metal cations in the alkali source play a structure guiding role. The amount of the template agent is reduced by adjusting the amount of the alkali metal cations. The specific seeds can significantly improve the yield of the molecular sieve. The silicon-to-molecular ratio of the preparation method is only 0.02, the highest yield can reach 34%, and the preparation cost can be controlled at a very low level.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve technology, and in particular to a method for preparing a silicon-to-aluminum ratio (SBR) SSZ-39 molecular sieve. Background Technology

[0002] As a new generation of small-pore catalysts, SSZ-39 molecular sieve has shown excellent performance in reactions such as denitration and methanol-to-olefins, and therefore has very high commercial potential.

[0003] However, the synthesis of traditional SSZ-39 molecular sieves faces three problems: (1) high dosage of expensive template agents; (2) use of commercial molecular sieves as the aluminum source; and (3) low yield. These three problems result in high synthesis costs for SSZ-39 molecular sieves, making industrialization and commercial application difficult. Currently, the lowest template agent dosage in related technologies is a template-to-silicon ratio (i.e., the molar ratio of template agent to silicon) of 0.1, with an average yield of 20%. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing SSZ-39 molecular sieves with a silicon-to-aluminum ratio. This invention uses an aluminum-free seed crystal method to synthesize a series of SSZ-39 molecular sieves with a silicon-to-aluminum ratio of only 0.02, achieving a maximum yield of 34%, and significantly reducing preparation costs.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing SSZ-39 molecular sieves with a silicon-to-aluminum ratio, comprising the following steps:

[0007] A gel is obtained by mixing a template agent, water, an alkali source, a seed crystal, and a silicon source; the alkali source is an alkali metal hydroxide, and the seed crystal is a small-pore SAPO molecular sieve; the composition of the gel satisfies the molar ratio of SiO2:template agent:alkali metal hydroxide:Al2O3:H2O = 1:0.02:0.58:0.002~0.012:7.5, wherein the molar amount of SiO2 is obtained by converting the silicon element in the silicon source to SiO2, and the molar amount of Al2O3 is obtained by converting the aluminum element in the seed crystal to Al2O3;

[0008] The gel was subjected to hydrothermal crystallization to obtain a crystallized product;

[0009] The crystallized product was calcined to obtain SSZ-39 molecular sieve.

[0010] Preferably, the template agent is 1,1,3,5-tetramethylpiperidine hydroxide.

[0011] Preferably, the alkali source is sodium hydroxide and / or potassium hydroxide.

[0012] Preferably, the silicon source is one or more of silica gel, silica sol, and silica fume.

[0013] Preferably, the small-pore SAPO molecular sieve is one or more of the following: AEI type SAPO molecular sieve, CHA type SAPO molecular sieve, LEV type SAPO molecular sieve, RHO type SAPO molecular sieve, ERI type SAPO molecular sieve, and KFI type SAPO molecular sieve.

[0014] Preferably, the hydrothermal crystallization temperature is 130–160°C, and the time is 1–5 days.

[0015] Preferably, after hydrothermal crystallization, the process further includes sequentially performing solid-liquid separation and drying on the obtained crystallization reaction solution to obtain the crystallization product.

[0016] Preferably, the calcination temperature is 550–750°C and the time is 4–10 hours.

[0017] Preferably, the silicon-aluminum molar ratio of the SSZ-39 molecular sieve is 7 to 19.

[0018] Preferably, after calcination, the calcined molecular sieve is subjected to ammonium ion exchange and calcination again to obtain hydrogen-form SSZ-39 molecular sieve.

[0019] This invention provides a method for preparing a silicon-to-aluminum ratio (SiO2) SSZ-39 molecular sieve, comprising the following steps: mixing a template agent, water, an alkali source, a seed crystal, and a silicon source to obtain a gel; wherein the alkali source is an alkali metal hydroxide, and the seed crystal is a small-pore SAPO molecular sieve; the composition of the gel satisfies the molar ratio of SiO2:template agent:alkali metal hydroxide:Al2O3:H2O = 1:0.02:0.58:0.002~0.012:7.5, wherein the molar amount of SiO2 is obtained by converting silicon in the silicon source to SiO2, and the molar amount of Al2O3 is obtained by converting aluminum in the seed crystal to Al2O3; subjecting the gel to hydrothermal crystallization to obtain a crystallized product; and calcining the crystallized product to obtain the SSZ-39 molecular sieve. This invention is the first to synthesize a series of SSZ-39 molecular sieves with varying silicon-to-aluminum ratios using an aluminum-free seed crystal method. In this invention, the alkali metal cations in the alkaline source play a structure-directing role. The amount of template agent is reduced by controlling the amount of these alkali metal cations. The use of specific seed crystals significantly improves the yield of the molecular sieves. Furthermore, the silicon-to-aluminum ratio of the SSZ-39 molecular sieves can be easily and conveniently controlled by adjusting the amount of seed crystals added. The preparation method provided by this invention has a silicon-to-aluminum ratio of only 0.02, a maximum yield of 34%, and keeps the preparation cost at a very low level. Attached Figure Description

[0020] Figure 1XRD patterns of SSZ-39 molecular sieves (S1-S6) prepared in Examples 1-6;

[0021] Figure 2 XRD patterns of SSZ-39 molecular sieves (S3, S7-S11) prepared in Examples 3 and 7-11;

[0022] Figure 3 XRD patterns of SSZ-39 molecular sieves (S3, S12-S15) prepared in Examples 3 and 12-15;

[0023] Figure 4 XRD patterns of SSZ-39 molecular sieves (S3, S16-S19) prepared in Examples 3 and 16-19;

[0024] Figure 5 XRD patterns of SSZ-39 molecular sieves (S3, S20-S24) prepared in Examples 3 and 20-24;

[0025] Figure 6 The XRD pattern of the molecular sieve (S25-S30) prepared in Comparative Example 1 is shown. Detailed Implementation

[0026] This invention provides a method for preparing SSZ-39 molecular sieves with a silicon-to-aluminum ratio, comprising the following steps:

[0027] A gel is obtained by mixing a template agent, water, an alkali source, a seed crystal, and a silicon source; the alkali source is an alkali metal hydroxide, and the seed crystal is a small-pore SAPO molecular sieve; the composition of the gel satisfies the molar ratio of SiO2:template agent:alkali metal hydroxide:Al2O3:H2O = 1:0.02:0.58:0.002~0.012:7.5, wherein the molar amount of SiO2 is obtained by converting the silicon element in the silicon source to SiO2, and the molar amount of Al2O3 is obtained by converting the aluminum element in the seed crystal to Al2O3;

[0028] The gel was subjected to hydrothermal crystallization to obtain a crystallized product;

[0029] The crystallized product was calcined to obtain SSZ-39 molecular sieve.

[0030] Unless otherwise specified, all raw materials involved in this invention are commercially available products well known in the art.

[0031] This invention mixes a template agent, water, an alkali source, a seed crystal, and a silicon source to obtain a gel.

[0032] In this invention, the alkali source is an alkali metal hydroxide, preferably sodium hydroxide and / or potassium hydroxide. When the alkali source is sodium hydroxide and potassium hydroxide, the ratio of sodium hydroxide to potassium hydroxide is not particularly important, as long as it meets the molar ratio of the alkali metal hydroxide in the subsequent gel. In this invention, the alkali metal hydroxide serves as both an alkali source and, simultaneously, the alkali metal cations therein play a structural guiding role.

[0033] In this invention, the silicon source is preferably one or more of silica gel, silica sol and fumed silica, such as column chromatography silica gel or silica gel powder, and the silica sol is such as 30wt% silica sol or HS-40.

[0034] In this invention, the template agent is preferably 1,1,3,5-tetramethylpiperidine hydroxide (DMDMPOH). In an embodiment of this invention, the 1,1,3,5-tetramethylpiperidine hydroxide is added in the form of an aqueous solution of 1,1,3,5-tetramethylpiperidine hydroxide, and the mass fraction of the aqueous solution of 1,1,3,5-tetramethylpiperidine hydroxide is 25%.

[0035] In this invention, the water is preferably distilled water.

[0036] In this invention, the seed crystal is a small-pore SAPO molecular sieve. Preferably, the small-pore SAPO molecular sieve is one or more of the following types: AEI-type SAPO molecular sieve, CHA-type SAPO molecular sieve, LEV-type SAPO molecular sieve, RHO-type SAPO molecular sieve, ERI-type SAPO molecular sieve, and KFI-type SAPO molecular sieve. In embodiments of this invention, the AEI-type SAPO molecular sieve, CHA-type SAPO molecular sieve, LEV-type SAPO molecular sieve, RHO-type SAPO molecular sieve, ERI-type SAPO molecular sieve, and KFI-type SAPO molecular sieve are respectively designated as SAPO-AEI seed crystal, SAPO-CHA seed crystal, SAPO-LEV seed crystal, SAPO-RHO seed crystal, SAPO-ERI seed crystal, and SAPO-KFI seed crystal. This invention does not have any particular requirements regarding the source of the small-pore SAPO molecular sieve; it can be obtained from commercially available products or prepared using methods well-known to those skilled in the art. In this embodiment of the invention, the AEI type SAPO molecular sieve is SAPO-18 molecular sieve; the CHA type SAPO molecular sieve is SAPO-34 molecular sieve; the LEV type SAPO molecular sieve is SAPO-35 molecular sieve; the ERI type SAPO molecular sieve is SAPO-17 molecular sieve; and the RHO type SAPO molecular sieve and KFI type SAPO molecular sieve are prepared by the following methods respectively:

[0037] Preparation of RHO-type SAPO molecular sieve: Orthophosphoric acid (85 wt%), tetraethyl orthosilicate, aluminum isopropoxide solution, and deionized water were mixed. After stirring the synthesis solution for 2 hours, N,N′-dimethylethylenediamine, a template agent, was added to make the gel ratio tetraethyl orthosilicate:Al2O3:P2O5:N,N′-dimethylethylenediamine:water = 1.3:1.3:1:5:167. The mixture was stirred for another 4 hours. The mixture was then placed in an autoclave and crystallized at 200℃ for 12 hours. The solid product was filtered and recovered, washed three times with deionized water, and dried overnight at 110℃. Finally, the mixture was calcined at 550℃ for 4 hours to remove organic matter, yielding the RHO-type SAPO molecular sieve.

[0038] Preparation of KFI-type SAPO molecular sieve: Orthophosphoric acid (85wt%), dipropylamine, and deionized water were mixed. After stirring the synthesis solution for 2 hours, tetraethyl orthosilicate and aluminum isopropoxide were added and stirred for 12 hours. Then, hexadecyltrimethylammonium bromide was added and stirred for 12 hours to make the gel ratio of tetraethyl orthosilicate:Al2O3:P2O5:dipropylamine:CTAB:water = 0.3:1:1:2:0.15:50. The mixture was then placed in a reactor and crystallized at 200℃ for 24 hours. The solid product was recovered by filtration, washed three times with deionized water, and dried overnight at 110℃. Finally, the mixture was calcined at 550℃ for 4 hours to remove organic matter, thus obtaining KFI-type SAPO molecular sieve.

[0039] In this invention, the seed crystal also serves as an aluminum source. By employing the specific seed crystal described above, this invention can improve the yield of SSZ-39 molecular sieve. In this invention, the mass of the seed crystal is preferably 1-6% of the mass of the silicon source, and can be 1%, 2%, 3%, 4%, 5%, or 6%, where the mass of the silicon source is SiO2.

[0040] In this invention, the preferred method for mixing the template agent, water, alkali source, seed crystal, and silicon source is as follows: the template agent, water, alkali source, and seed crystal are added to a reaction vessel and stirred evenly under sealed, room temperature conditions; then the silicon source is added, and the mixture is stirred thoroughly until a uniform gel is formed. This mixing method first forms an aluminum-rich gel, and then the silicon source is added to form small particles with an aluminum gel coating the silicon core structure, which is beneficial for crystal formation.

[0041] In this invention, the composition of the gel satisfies the molar ratio of SiO2:templative agent:alkali metal hydroxide:Al2O3:H2O = 1:0.02:0.58:0.002~0.012:7.5, which can be 1:0.02:0.58:0.002:7.5, 1:0.02:0.58:0.004:7.5, 1:0.02:0.58:0.006:7.5, 1:0.02:0.58:0.008:7.5, 1:0.02:0.58:0.010:7.5 or 1:0.02:0.58:0.012:7.5, wherein the molar amount of SiO2 is obtained by converting the silicon element in the silicon source to SiO2, and the molar amount of Al2O3 is obtained by converting the aluminum element in the seed crystal to Al2O3. In this invention, the alkali metal cations in the alkali metal hydroxide play a structure-directing role, overlapping with the role of the template agent. Therefore, by controlling the amount of alkali metal cations in the system, the amount of template agent can be reduced, enabling the preparation of SSZ-39 molecules using trace amounts of template agent. In this invention, the silicon-to-silicon ratio is only 0.02. Furthermore, this invention can easily and conveniently control the silicon-to-aluminum ratio of SSZ-39 molecular sieves by adjusting the amount of seed crystals added. Specifically, a larger amount of seed crystals results in a lower silicon-to-aluminum ratio in the product, while a smaller amount results in a higher silicon-to-aluminum ratio. This invention controls the silicon-to-aluminum ratio range of SSZ-39 using a simple method.

[0042] After obtaining the gel, the present invention performs hydrothermal crystallization on the gel to obtain the crystallized product.

[0043] In this invention, the temperature of the hydrothermal crystallization is preferably 130-160°C, which can be 130, 140, 150 or 160°C, and the time is preferably 1-5 days, which can be 1 day, 2 days, 3 days, 4 days or 5 days.

[0044] Following the hydrothermal crystallization, the present invention preferably involves sequentially performing solid-liquid separation and drying on the resulting crystallization reaction solution to obtain the crystallized product. The present invention does not have particular requirements for the solid-liquid separation method; any solid-liquid separation method well-known to those skilled in the art, such as centrifugation, can be used. In the present invention, the drying temperature is preferably 90°C.

[0045] After obtaining the crystallized product, the present invention calcines the crystallized product to obtain SSZ-39 molecular sieve. In the present invention, the calcination temperature is preferably 550-750℃, which can be 550, 600, 650, 700 or 750℃, and the time is preferably 4-10h, which can be 4, 5, 6, 7, 8, 9 or 10h, to remove the template agent in the molecular sieve.

[0046] After calcination, the present invention can further subject the calcined molecular sieve to ammonium ion exchange and calcination again to obtain hydrogen-form SSZ-39 molecular sieve (H-SSZ-39). Preferably, the calcined molecular sieve is placed in an ammonium chloride solution under water bath conditions for ammonium ion exchange; the concentration of the ammonium chloride solution is preferably 1 mol / L, the temperature of the ammonium ion exchange is preferably 80°C, and the time is preferably 2 hours. After the ammonium ion exchange is completed, the resulting reaction solution is preferably separated into solid and liquid phases (e.g., by filtration), and the resulting solid is dried before being calcined again; the drying temperature is preferably 90°C, the calcination temperature is preferably 500°C, and the time is preferably 4 hours.

[0047] In this invention, the silicon-aluminum molar ratio (Si / Al) of the SSZ-39 molecular sieve is 7 to 19, and it has an AEI topology.

[0048] This invention provides a method for preparing SSZ-39 molecular sieves with a silicon-to-aluminum atomic ratio in the range of 7 to 19 using only trace amounts of template agents. The silicon-to-silicon ratio is only 0.02, and the highest yield can reach 34%, keeping the preparation cost at a very low level.

[0049] To further illustrate the present invention, the method for preparing the SSZ-39 molecular sieve with a silicon-to-aluminum ratio provided by the present invention will be described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0050] In various embodiments:

[0051] The template agent was an aqueous solution of 1,1,3,5-tetramethylpiperidine hydroxide (25 wt%).

[0052] The SAPO-AEI seed crystal is: SAPO-18 molecular sieve seed crystal;

[0053] SAPO-CHA seed crystals are: SAPO-34 molecular sieve seed crystals;

[0054] SAPO-LEV seed crystals are: SAPO-35 molecular sieve seed crystals;

[0055] The SAPO-ERI seed crystal is: SAPO-17 molecular sieve seed crystal;

[0056] The preparation method of SAPO-RHO seed crystals is as follows:

[0057] Phosphoric acid (85 wt%), tetraethyl orthosilicate, aluminum isopropoxide solution, and deionized water were mixed. After stirring the synthesis solution for 2 hours, the template agent N,N′-dimethylethylenediamine was added to make the gel ratio tetraethyl orthosilicate:Al2O3:P2O5:N,N′-dimethylethylenediamine:water = 1.3:1.3:1:5:167. The mixture was stirred for another 4 hours. The mixture was then placed in a reactor and crystallized at 200°C for 12 hours. The solid product was filtered and recovered, washed three times with deionized water, and dried overnight at 110°C. Finally, the mixture was calcined at 550°C for 4 hours to remove organic matter.

[0058] The preparation method of SAPO-KFI seed crystals is as follows:

[0059] Phosphoric acid (85 wt%), dipropylamine, and deionized water were mixed. After stirring the synthesis solution for 2 hours, tetraethyl orthosilicate and aluminum isopropoxide were added, and the mixture was stirred for 12 hours. Then, hexadecyltrimethylammonium bromide was added, and the mixture was stirred for 12 hours to achieve a gel ratio of tetraethyl orthosilicate:Al₂O₃:P₂O₅:dipropylamine:CTAB:water = 0.3:1:1:2:0.15:50. The mixture was then placed in a reactor and crystallized at 200°C for 24 hours. The solid product was recovered by filtration, washed three times with deionized water, and dried overnight at 110°C. Finally, the mixture was calcined at 550°C for 4 hours to remove organic matter.

[0060] Example 1

[0061] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, silica gel for column chromatography was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.002:7.5, and the mass of the seed crystals was 1% of the mass of SiO2.

[0062] The gel was placed in a 150℃ oven for 5 days to crystallize. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S1).

[0063] The prepared SSZ-39 molecular sieve was placed in a 1 mol / L ammonium chloride aqueous solution, bathed in an 80℃ water bath for 2 h, filtered, dried at 90℃, and then calcined at 500℃ for 4 h to obtain H-SSZ-39 molecular sieve.

[0064] Example 2

[0065] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.004:7.5, and the mass of the seed crystals was 2% of the mass of SiO2.

[0066] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S2).

[0067] Example 3

[0068] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0069] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S3).

[0070] Example 4

[0071] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.008:7.5, and the mass of the seed crystals was 4% of the mass of SiO2.

[0072] The gel was placed in a 150℃ oven for 5 days to crystallize. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S4).

[0073] Example 5

[0074] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.010:7.5, and the mass of the seed crystals was 5% of the mass of SiO2.

[0075] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S5).

[0076] Example 6

[0077] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.012:7.5, and the mass of the seed crystals was 6% of the mass of SiO2.

[0078] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S6).

[0079] Figure 1 The XRD patterns are of the SSZ-39 molecular sieves (S1-S6) prepared in Examples 1-6.

[0080] The silicon-to-aluminum ratio and yield of the SSZ-39 molecular sieve products prepared in Examples 1 to 6 are listed in Table 1. The silicon-to-aluminum ratio of the products was obtained by inductively coupled plasma atomic emission spectrometry (ICP). The yield was calculated as: mass of product / (mass of SiO2 in raw material + mass of Al2O3 in raw material). The testing and calculation methods for other examples were the same.

[0081] Table 1. Silica-to-alumina ratios and yields of SSZ-39 molecular sieve products prepared in Examples 1-6

[0082]

[0083] As shown in Table 1, with the increase of seed crystal dosage, the silicon-to-aluminum ratio of the product decreases and the yield increases until a small amount of impurities (MFI, less than 5%) appear after 6%. In Table 1, the SSZ-39 molecular sieve product S6 formed an AEI+MFI structure because only the amount of seed crystal was increased in the synthesis, but the amount of hydroxide was not increased.

[0084] Example 7

[0085] Template agent, distilled water, sodium hydroxide, potassium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, KOH, Al2O3, and H2O in the gel was 1:0.02:0.464:0.116:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0086] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S7).

[0087] Example 8

[0088] Template agent, distilled water, sodium hydroxide, potassium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed, room temperature conditions. Then, silica gel for column chromatography was added and stirred thoroughly until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, KOH, Al2O3, and H2O in the gel was 1:0.02:0.348:0.232:0.006:7.5, and the seed crystal mass was 3% of the SiO2 mass.

[0089] The gel was placed in a 150℃ oven for 5 days to crystallize. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S8).

[0090] Example 9

[0091] Template agent, distilled water, sodium hydroxide, potassium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, KOH, Al2O3, and H2O in the gel was 1:0.02:0.232:0.348:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0092] The gel was placed in a 150℃ oven for 5 days to crystallize. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S9).

[0093] Example 10

[0094] Template agent, distilled water, sodium hydroxide, potassium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, KOH, Al2O3, and H2O in the gel was 1:0.02:0.116:0.464:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0095] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S10).

[0096] Example 11

[0097] Template agent, distilled water, sodium hydroxide, potassium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, KOH, Al2O3, and H2O in the gel was 1:0.02:0:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0098] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S11).

[0099] Figure 2 The XRD patterns are of the SSZ-39 molecular sieves (S3, S7-S11) prepared in Examples 3 and 7-11.

[0100] The silica-alumina ratios and yields of the SSZ-39 molecular sieve products from Examples 3 and 7-11 are listed in Table 2.

[0101] Table 2. Silica-to-alumina ratios and yields of SSZ-39 molecular sieve products from Examples 3 and 7-11.

[0102]

[0103] As shown in Table 2, as the proportion of KOH in the metal hydroxide increases, the silicon-to-aluminum ratio of the product gradually decreases, while the yield remains almost unchanged.

[0104] Example 12

[0105] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0106] The gel was placed in a 150℃ oven for crystallization for 1 day. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S12).

[0107] Example 13

[0108] Template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed, room temperature conditions. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the seed crystal mass was 3% of the mass of SiO2.

[0109] The gel was placed in a 150℃ oven for 2 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S13).

[0110] Example 14

[0111] Template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed, room temperature conditions. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the seed crystal mass was 3% of the mass of SiO2.

[0112] The gel was placed in an oven at 150℃ for 3 days to crystallize. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S14).

[0113] Example 15

[0114] Template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed, room temperature conditions. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the seed crystal mass was 3% of the mass of SiO2.

[0115] The gel was placed in a 150℃ oven for 4 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S15).

[0116] Figure 3 XRD patterns of SSZ-39 molecular sieves (S3, S12-S15) prepared in Examples 3 and 12-15.

[0117] The silicon-to-aluminum ratio and yield of the SSZ-39 molecular sieve products prepared in Examples 3 and 12-15 are listed in Table 3.

[0118] Table 3. Silica-to-alumina ratios and yields of the SSZ-39 molecular sieve products prepared in Examples 3 and 12-15.

[0119]

[0120] As can be seen from Table 3, the yield increases with the extension of crystallization time, but the increase is not significant from the fourth to the fifth day, indicating that the yield has reached the critical point.

[0121] Example 16

[0122] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred evenly under sealed conditions at room temperature. Then, 30 wt% silica sol was added and stirred until a uniform gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0123] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S16).

[0124] Example 17

[0125] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred evenly under sealed conditions at room temperature. Then, silica was added and stirred until a uniform gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0126] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S17).

[0127] Example 18

[0128] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred evenly under sealed conditions at room temperature. Then, 90 wt% silica gel powder was added and stirred until a uniform gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0129] The gel was placed in a 150℃ oven for 5 days to crystallize. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S18).

[0130] Example 19

[0131] The template agent, distilled water, sodium hydroxide, and SAPO-AEI seed crystals were added to a reaction vessel and stirred evenly under sealed conditions at room temperature. Then, HS-40 was added and stirred until a uniform gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0132] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S19).

[0133] Figure 4 XRD patterns of SSZ-39 molecular sieves (S3, S16-S19) prepared in Examples 3 and 16-19.

[0134] The silicon-to-aluminum ratio and yield of the SSZ-39 molecular sieve products prepared in Examples 3 and 16-19 are listed in Table 4.

[0135] Table 4. Silica-to-alumina ratios and yields of the SSZ-39 molecular sieve products prepared in Examples 3 and 16-19.

[0136]

[0137] As can be seen from Table 4, the type of silicon source has little impact on the product.

[0138] Example 20

[0139] The template agent, distilled water, sodium hydroxide, and SAPO-CHA seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0140] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S20).

[0141] Example 21

[0142] The template agent, distilled water, sodium hydroxide, and SAPO-LEV seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0143] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S21).

[0144] Example 22

[0145] The template agent, distilled water, sodium hydroxide, and SAPO-ERI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0146] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S22).

[0147] Example 23

[0148] The template agent, distilled water, sodium hydroxide, and SAPO-RHO seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0149] The gel was placed in a 150℃ oven for 5 days to crystallize. The product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S23).

[0150] Example 24

[0151] The template agent, distilled water, sodium hydroxide, and SAPO-KFI seed crystals were added to a reaction vessel and stirred until homogeneous under sealed conditions at room temperature. Then, column chromatography silica gel was added and stirred until a homogeneous gel was formed. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5, and the mass of the seed crystals was 3% of the mass of SiO2.

[0152] The gel was placed in a 150℃ oven for 5 days to crystallize. The resulting product was centrifuged, dried at 90℃, and then calcined at 600℃ for 5 hours to obtain SSZ-39 molecular sieve (denoted as S24).

[0153] Figure 5 The XRD patterns are of the SSZ-39 molecular sieves (S3, S20-S24) prepared in Examples 3 and 20-24. Figure 5 It can be seen that all small-pore SAPO molecular sieve seeds can synthesize SSZ-39 molecular sieve.

[0154] Comparative Example 1

[0155] The molecular sieve product was synthesized according to Example 3, except that H-SSZ-39 molecular sieve was used as the seed crystal, as detailed below:

[0156] H-SSZ-39 molecular sieve with a silicon-to-aluminum ratio of 5 was used as seed crystals and added at 1%, 2%, 3%, 4%, 5%, and 6% of the silicon source mass (based on SiO2), respectively. The molar ratio of the effective components SiO2, template agent, NaOH, Al2O3, and H2O in the gel was 1:0.02:0.58:0.006:7.5. The insufficient aluminum was supplemented with aluminum sulfate. The resulting molecular sieve products were denoted as S25, S26, S27, S28, S29, and S30, respectively.

[0157] Figure 6 The XRD patterns of the molecular sieves (S25–S30) prepared in Comparative Example 1 are shown below. Figure 6 It can be seen that, under this gel ratio, SSZ-39 molecular sieve cannot be synthesized when using silica-alumina molecular sieve as a seed crystal.

[0158] Comparative Example 2

[0159] Compared with a paper published in the authoritative journal *ACS Applied Materials & Interfaces* (ACS Appl. Mater. Interfaces 2019, 11, 26, 23112–23117), the cost of synthesizing one ton of sample was calculated based on the market price of raw materials. The silicon-to-molecular ratio was 0.12, sodium aluminate was used as the aluminum source, and the yield was only 21%. The calculated cost was 364,000 yuan / ton, more than double the cost of this invention.

[0160] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing SSZ-39 molecular sieve with a silica-to-alumina ratio, characterized in that, Includes the following steps: A gel is obtained by mixing a template agent, water, an alkali source, a seed crystal, and a silicon source; the template agent is 1,1,3,5-tetramethylpiperidine hydroxide; the alkali source is an alkali metal hydroxide, specifically sodium hydroxide and / or potassium hydroxide; and the seed crystal is a small-pore SAPO molecular sieve. The composition of the gel satisfies the molar ratio of SiO2:template agent:alkali metal hydroxide:Al2O3:H2O = 1:0.02:0.58:0.002~0.012:7.5, where the molar amount of SiO2 is calculated by converting silicon in the silicon source to SiO2, and the molar amount of Al2O3 is calculated by converting aluminum in the seed crystal to Al2O3. The small-pore SAPO molecular sieve is one or more of the following types: AEI-type SAPO molecular sieve, CHA-type SAPO molecular sieve, LEV-type SAPO molecular sieve, RHO-type SAPO molecular sieve, ERI-type SAPO molecular sieve, and KFI-type SAPO molecular sieve. The gel was subjected to hydrothermal crystallization to obtain a crystallized product; The crystallized product was calcined to obtain SSZ-39 molecular sieve.

2. The method according to claim 1, characterized in that, The silicon source is one or more of silica gel, silica sol, and fumed silica.

3. The method according to claim 1, characterized in that, The hydrothermal crystallization temperature is 130~160℃, and the time is 1~5 days.

4. The method according to claim 1 or 3, characterized in that, After hydrothermal crystallization, the process further includes sequentially performing solid-liquid separation and drying on the obtained crystallization reaction solution to obtain the crystallization product.

5. The method according to claim 1, characterized in that, The calcination temperature is 550~750℃, and the time is 4~10h.

6. The method according to claim 1, characterized in that, The silica-alumina molar ratio of the SSZ-39 molecular sieve is 7~19.

7. The method according to claim 1, characterized in that, The calcination process further includes sequentially subjecting the calcined molecular sieve to ammonium ion exchange and calcining it again to obtain the hydrogen-type SSZ-39 molecular sieve.

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