Preparation method of SSZ-13 molecular sieve

Abstract

The invention provides a preparation method of an SSZ-13 molecular sieve, and relates to the technical field of molecular sieve preparation. The preparation process of the SSZ-13 molecular sieve comprises the following steps: mixing an aluminum source and an alkali source in a water environment, adding a tetravalent silicon source to obtain a reaction gel, carrying out a hydrothermal crystallization reaction, and filtering, washing, drying and roasting reaction slurry obtained after the reaction is completed to obtain the SSZ-13 molecular sieve. The SSZ-13 molecular sieve preparation method provided by the invention does not need to use an organic structure template agent, simplifies the process flow, reduces the production cost, improves the product quality and environmental protection property, meets the green chemical requirements, and has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieve preparation, and in particular to a method for preparing SSZ-13 molecular sieve. Background Art

[0002] SSZ-13 is a CHA (Chabazite) type zeolite structure molecular sieve, whose crystal structure is composed of an 8-membered ring channel system, which makes it highly selective and stable. At the same time, the high specific surface area and silicon-aluminum ratio make it have good catalytic performance, good hydrothermal stability, more surface proton acidity and exchangeable cations, so it has excellent performance in diesel exhaust NOx removal (DeNOx), methanol to olefins (MTO) and CO2 adsorption separation.

[0003] SSZ-13 was originally invented by Zones of Chevron in 1985 and was prepared by a conventional hydrothermal method using N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH) as a template.

[0004] U.S. Patent No. 4544538 first disclosed a method for synthesizing SSZ-13 molecular sieves, which uses N,N,N-trimethyl-1-adamantanamine (TMAA + ) organic cations are used as templates to synthesize SSZ-13 molecular sieves. However, N,N,N-trimethyl-1-adamantanamine is expensive, which leads to high cost of synthesizing SSZ-13 molecular sieves, severely limiting the industrial application of SSZ-13 molecular sieves.

[0005] In the patent US60 / 826882 filed by Zone on September 25, 2006, a method for reducing the use of N,N,N-trimethyl-1-adamantanamine organic cations as templates is introduced. The method significantly reduces the use of N,N,N-trimethyl-1-adamantanamine cations by adding a template agent benzyltrimethylammonium cation (such as benzyltrimethylammonium hydroxide). Although this method can reduce the use of N,N,N-trimethyl-1-adamantanamine cations and thus reduce the synthesis cost of synthesizing SSZ-13 molecular sieves, it still cannot completely avoid TMAA. + Use of.

[0006] The invention patent with publication number CN111484037A discloses a method for synthesizing SSZ-13 molecular sieves with different silicon-to-aluminum ratios by crystallization of Y molecular sieve. The method comprises adding Y molecular sieves with different silicon-to-aluminum ratios into the initial gel, and adding a structure directing agent N,N,N-trimethyl-1-adamantyl ammonium hydroxide under high-temperature hydrothermal conditions to crystallize the Y molecular sieve into SSZ-13 molecular sieves with different silicon-to-aluminum ratios. Similarly, the method still cannot avoid the use of an organic structure directing agent. Summary of the invention

[0007] In view of this, the present invention provides a method for preparing SSZ-13 molecular sieve, which does not require the use of an organic structure template and has significant advantages in process simplification, cost reduction, product quality improvement and environmental protection, and has good application prospects compared to the existing technology.

[0008] The preparation method of the SSZ-13 molecular sieve of the present invention comprises the following steps:

[0009] The aluminum source and the alkali source are mixed evenly in an aqueous environment, and then a tetravalent silicon source is added and stirred to react to obtain a reaction gel, and then the reaction gel is subjected to a hydrothermal crystallization reaction. After the reaction is completed, the reaction slurry obtained is filtered, washed, dried, and calcined to obtain the SSZ-13 molecular sieve.

[0010] Preferably, the aluminum source is at least one of sodium aluminate, aluminum sulfate, aluminum nitrate, pseudo-boehmite, and aluminum chloride.

[0011] Preferably, the alkali source is NaOH and / or KOH.

[0012] Preferably, the tetravalent silicon source is at least one of silicate, silica sol, tetraethyl orthosilicate, precipitated silica, and clay. More preferably, the tetravalent silicon source is silica sol.

[0013] Preferably, the molar ratio of the tetravalent silicon source to the aluminum source is 1:(2-50), the molar ratio of the tetravalent silicon source to the alkali metal element is 1:(0.05-0.2), and the molar ratio of the tetravalent silicon source to the hydroxide ion is 1:(0.2-0.7).

[0014] Preferably, the stirring reaction time is 1 to 3 hours.

[0015] Preferably, the hydrothermal crystallization reaction temperature is 100° C. to 200° C., and the hydrothermal crystallization reaction time is 72 to 96 hours.

[0016] Preferably, the drying temperature is 80° C. to 120° C., and the drying time is 10 to 20 hours.

[0017] Preferably, the calcination temperature is 450° C. to 600° C., and the calcination time is 2 to 6 hours.

[0018] The SSZ-13 molecular sieve preparation method of the present invention does not need to use the traditional template agents of N, N, N-trimethyl-1-adamantanamine cation and benzyltrimethylammonium cation, avoids the pollution problem caused by the template agent, reduces the production cost, and simplifies the process flow. The present invention improves the process flexibility by selecting different combinations of aluminum sources, alkali sources and tetravalent silicon sources, and can adjust the reaction conditions according to specific needs to obtain the required SSZ-13 molecular sieve. At the same time, the present invention optimizes the temperature, time, drying and roasting temperature of the hydrothermal crystallization reaction by accurately controlling the ratio of the aluminum source, tetravalent silicon source and alkali source, effectively improves the crystallinity and yield, and ensures the consistency of product quality. The present invention uses common aluminum sources and alkali sources to not only reduce the cost of raw materials, but also further reduce the production cost by not using expensive template agents. In addition, since no organic template agent is used, the risk of environmental pollution is reduced, which meets the requirements of green chemistry and improves environmental protection performance. In the preparation process of the SSZ-13 molecular sieve of the present invention, the reaction time and temperature of hydrothermal crystallization and roasting are controllable, which helps to improve production efficiency and ensure product consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Figure 1 The PXRD spectrum of the SSZ-13 molecular sieve synthesized in Example 1;

[0021] Figure 2 The PXRD spectrum of the SSZ-13 molecular sieve synthesized in Example 2;

[0022] Figure 3 The PXRD spectrum of the SSZ-13 molecular sieve synthesized in Example 3;

[0023] Figure 4 The PXRD spectrum of the SSZ-13 molecular sieve synthesized in Example 4;

[0024] Figure 5 This is the PXRD spectrum of the SSZ-13 molecular sieve synthesized in Example 5. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The present invention provides a method for preparing SSZ-13 molecular sieve, comprising the following steps:

[0027] S1, mixing the aluminum source and the alkali source in a water environment, and then adding the tetravalent silicon source and stirring to react to obtain a reaction gel;

[0028] S2, subjecting the reaction gel to a hydrothermal crystallization reaction and then separating the crystals;

[0029] S3. Wash the crystals with water until they are neutral, then dry and calcine to obtain SSZ-13 molecular sieve.

[0030] The aluminum source of the present invention is preferably at least one of sodium aluminate, aluminum sulfate, aluminum nitrate, pseudo-boehmite, and aluminum chloride.

[0031] The alkali source of the present invention is preferably NaOH and / or KOH.

[0032] The tetravalent silicon source of the present invention is preferably at least one of silicate, silica sol, tetraethyl orthosilicate, precipitated silica, and clay. In some specific embodiments of the present invention, the tetravalent silicon source is silica sol. In some preferred embodiments of the present invention, the silica sol is AS-40 silica sol.

[0033] The molar ratio of the tetravalent silicon source to the aluminum source of the present invention is preferably 1:(2-50), the molar ratio of the tetravalent silicon source to the alkali metal element is 1:(0.05-0.2), and the molar ratio of the tetravalent silicon source to the hydroxide ion is 1:(0.2-0.7).

[0034] The stirring reaction time of the present invention is preferably 1 to 3 hours.

[0035] In some preferred embodiments of the present invention, the aluminum source and the alkali source are mixed uniformly in an aqueous environment and stirred for 1 hour, and then a tetravalent silicon source is added and stirred for reaction to obtain a reaction gel.

[0036] The hydrothermal crystallization reaction temperature of the present invention is preferably 100°C to 200°C, and the hydrothermal crystallization reaction time is preferably 72 to 96 hours. In some preferred embodiments of the present invention, the hydrothermal crystallization reaction time is 140°C to 160°C, and the hydrothermal crystallization reaction time is 72 hours. In some more preferred embodiments of the present invention, the hydrothermal crystallization reaction temperature is 150°C, and the hydrothermal crystallization reaction time is 72 hours.

[0037] The hydrothermal crystallization reaction of the present invention is preferably a dynamic hydrothermal crystallization reaction.

[0038] The hydrothermal crystallization reaction of the present invention is preferably carried out in an autoclave.

[0039] The drying temperature of the present invention is preferably 80° C. to 120° C., and the drying time is preferably 10 to 20 hours. In some preferred embodiments of the present invention, the drying temperature is 100° C., and the drying time is 12 hours.

[0040] The calcination temperature of the present invention is preferably 450°C to 600°C, and the calcination time is preferably 2 to 6 hours. In some preferred embodiments of the present invention, the calcination temperature is 550°C, and the calcination time is 4 hours.

[0041] In order to further illustrate the present invention, the following examples are provided for detailed description. The raw materials used in the following examples of the present invention are all commercially available.

[0042] Example 1 A method for preparing SSZ-13 molecular sieve, the steps are as follows:

[0043] S1. Mix 7.78 g KOH and 0.35 g NaOH in 81.6 g deionized water;

[0044] S2, add 4.13 g of pseudo-boehmite to step S1 and stir for 1 h;

[0045] S3, add 18.66g AS-40 to step S2 and stir for 2h;

[0046] S4, transferring the reaction gel of step S3 into a crystallization kettle for crystallization treatment, and dynamically crystallizing at 150° C. for 72 hours;

[0047] S5. Filter the reaction slurry after the crystallization in step S4, wash with water until neutral, dry at 100° C. for 12 h, and calcine at 550° C. for 4 h to obtain SSZ-13 molecular sieve. The PXRD results of the sample are as follows: Figure 1 .

[0048] Example 2 A method for preparing SSZ-13 molecular sieve, the steps are as follows:

[0049] S1. Mix 8.2 g KOH and 0.3 g NaOH in 81.6 g deionized water;

[0050] S2, add 3.6 g of pseudo-boehmite to step S1 and stir for 1 h;

[0051] S3, add 18.66g AS-40 to step S2 and stir for 2h;

[0052] S4, transferring the reaction gel of step S3 into a crystallization kettle for crystallization treatment, and dynamically crystallizing at 150° C. for 72 hours;

[0053] S5. Filter the reaction slurry after the crystallization in step S4, wash with water until neutral, dry at 100° C. for 12 h, and calcine at 550° C. for 4 h to obtain SSZ-13 molecular sieve. The PXRD results of the sample are as follows: Figure 2 .

[0054] Example 3 A method for preparing SSZ-13 molecular sieve, the steps are as follows:

[0055] S1. Mix 8.2 g KOH and 0.3 g NaOH in 81.6 g deionized water;

[0056] S2, add 4.13 g of pseudo-boehmite to step S1 and stir for 1 h;

[0057] S3, add 18.66g AS-40 to step S2 and stir for 2h;

[0058] S4, transferring the reaction gel of step S3 into a crystallization kettle for crystallization treatment, and dynamically crystallizing at 150° C. for 72 hours;

[0059] S5. Filter the reaction slurry after the crystallization in step S4, wash with water until neutral, dry at 100° C. for 12 h, and calcine at 550° C. for 4 h to obtain SSZ-13 molecular sieve. The PXRD results of the sample are as follows: Figure 3 .

[0060] Example 4 A method for preparing SSZ-13 molecular sieve, the steps are as follows:

[0061] S1. Mix 8.2 g KOH and 0.3 g NaOH in 81.6 g deionized water;

[0062] S2, add 4.38g pseudo-boehmite to step S1, and stir for 1h;

[0063] S3, add 15.3g of white carbon black to step S2, and stir for 2h;

[0064] S4, transferring the reaction gel of step S3 into a crystallization kettle for crystallization treatment, and dynamically crystallizing at 150° C. for 72 hours;

[0065] S5. Filter the reaction slurry after the crystallization in step S4, wash with water until neutral, dry at 100° C. for 12 h, and calcine at 550° C. for 4 h to obtain SSZ-13 molecular sieve. The PXRD results of the sample are as follows: Figure 4 .

[0066] Example 5 A method for preparing SSZ-13 molecular sieve, the steps are as follows:

[0067] S1. Mix 7.5 g KOH and 0.2 g NaOH in 81.6 g deionized water;

[0068] S2, add 4.38g pseudo-boehmite to step S1, and stir for 1h;

[0069] S3, add 15.3g of white carbon black to step S2, and stir for 2h;

[0070] S4, transferring the reaction gel of step S3 into a crystallization kettle for crystallization treatment, and dynamically crystallizing at 150° C. for 72 hours;

[0071] S1. The reaction slurry after the crystallization in step S4 is filtered, washed with water until neutral, dried at 100°C for 12h, and calcined at 550°C for 4h to obtain SSZ-13 molecular sieve. The PXRD of the sample is as follows: Figure 5 .

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing SZ-13 molecular sieve, characterized in that: The following steps are involved: The aluminum source and the alkali source are mixed evenly in an aqueous environment, and then a tetravalent silicon source is added and stirred to react to obtain a reaction gel, and then the reaction gel is subjected to a hydrothermal crystallization reaction. After the reaction is completed, the reaction slurry obtained is filtered, washed, dried, and calcined to obtain the SSZ-13 molecular sieve.

2. The preparation method according to claim 1, characterized in that: The aluminum source is at least one of sodium aluminate, aluminum sulfate, aluminum nitrate, pseudo-boehmite, and aluminum chloride.

3. The preparation method according to claim 1, characterized in that: The alkali source is NaOH and / or KOH.

4. The preparation method according to claim 1, characterized in that: The tetravalent silicon source is at least one of silicate, silica sol, tetraethyl orthosilicate, precipitated silica, and clay.

5. The preparation method according to claim 4, characterized in that: The tetravalent silicon source is silica sol.

6. The preparation method according to claim 1, characterized in that: The molar ratio of the tetravalent silicon source to the aluminum source is 1:(2-50), the molar ratio of the tetravalent silicon source to the alkali metal element is 1:(0.05-0.2), and the molar ratio of the tetravalent silicon source to the hydroxide ion is 1:(0.2-0.7).

7. The preparation method according to claim 1, characterized in that: The stirring reaction time is 1 to 3 hours.

8. The preparation method according to claim 1, characterized in that: The hydrothermal crystallization reaction temperature is 100° C. to 200° C., and the hydrothermal crystallization reaction time is 72 to 96 hours.

9. The preparation method according to claim 1, characterized in that: The drying temperature is 80° C. to 120° C., and the drying time is 10 to 20 hours.

10. The preparation method according to claim 1, characterized in that: The calcination temperature is 450° C. to 600° C., and the calcination time is 2 to 6 hours.

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