阅读说明：本技术 一种循环利用母液水热合成ssz-13分子筛的方法 (Method for hydrothermally synthesizing SSZ-13 molecular sieve by recycling mother liquor ) 是由 陈培榕 熊梧琬 刘林辉 付名利 叶代启 于 2021-01-29 设计创作，主要内容包括：本发明涉及分子筛合成领域,尤其涉及一种循环利用母液水热合成SSZ-13分子筛的方法。本发明通过对SSZ-13分子筛晶化后分离得到的母液进行回收,不对母液进行进一步处理,将其作为SSZ-13分子筛合成原料的一部分,再根据合成配比相应地补加新鲜原料然后晶化合成SSZ-13分子筛,进而循环利用母液。回收利用SSZ-13分子筛母液合成SSZ-13分子筛能有效地利用合成原料,降低原料的浪费,减轻对环境的污染,减少母液的排放处理成本。本发明通过对母液中各组分进行分析,选择有机模板剂的添加量,减少新鲜昂贵的有机模板剂的投入量,进一步有效地降低SSZ-13分子筛合成成本。(The invention relates to the field of molecular sieve synthesis, in particular to a method for synthesizing an SSZ-13 molecular sieve by recycling mother liquor in a hydrothermal mode. The method comprises the steps of recovering mother liquor obtained by separating after the SSZ-13 molecular sieve is crystallized, not further treating the mother liquor, using the mother liquor as a part of raw materials for synthesizing the SSZ-13 molecular sieve, correspondingly supplementing fresh raw materials according to a synthesis ratio, crystallizing and synthesizing the SSZ-13 molecular sieve, and further recycling the mother liquor. The SSZ-13 molecular sieve synthesized by recycling the SSZ-13 molecular sieve mother liquor can effectively utilize the synthesized raw materials, reduce the waste of the raw materials, reduce the pollution to the environment and reduce the discharge and treatment cost of the mother liquor. According to the invention, through analyzing each component in the mother liquor and selecting the addition amount of the organic template agent, the input amount of the fresh and expensive organic template agent is reduced, and the synthesis cost of the SSZ-13 molecular sieve is further effectively reduced.)

1. A method for hydrothermally synthesizing an SSZ-13 molecular sieve by recycling mother liquor is characterized by comprising the following steps:

(1) separating SSZ-13 molecular sieve solid products synthesized by a hydrothermal method, and recovering mother liquor after the molecular sieve is synthesized;

(2) analysis of SiO in mother liquor₂、Al₂O₃The content of the organic template;

(3) synthesizing a precursor formula of the SSZ-13 molecular sieve according to the hydrothermal method adopted in the step (1), adding a silicon source and an aluminum source into mother liquor, selectively adding an organic template agent, filling the obtained mixture into a polytetrafluoroethylene-lined high-pressure reaction kettle, and synthesizing by the hydrothermal method to obtain a corresponding molecular sieve crystallization liquid;

(4) separating the molecular sieve crystallization liquid obtained in the step (3) to obtain a molecular sieve solid and a mother liquid;

(5) washing, drying and roasting the molecular sieve solid obtained in the step (4) to obtain the SSZ-13 molecular sieve;

(6) and (5) repeating the steps (2) to (5) repeatedly to realize the preparation of the SSZ-13 molecular sieve and the recycling of the SSZ-13 molecular sieve mother liquor.

2. The method for hydrothermally synthesizing SSZ-13 molecular sieve by recycling mother liquor as claimed in claim 1, wherein in step (1) and step (3), the silicon source used in the hydrothermally synthesizing SSZ-13 molecular sieve is at least one of silica sol, fumed silica or water glass; the aluminum source is at least one of sodium aluminate, aluminum sulfate, pseudo-boehmite or aluminum hydroxide; the organic template agent is N, N, N-trimethyl-1-adamantyl ammonium hydroxide (TMADAOH), and the molar ratio of the silicon source, the aluminum source, the organic template agent and the water is SiO₂:Al₂O₃:TMADaOH:H₂O＝1:0.01～0.1:0.01～1:10～100。

3. The method for hydrothermally synthesizing the SSZ-13 molecular sieve by recycling the mother liquor as claimed in claim 1, wherein in step (1) and step (3), the reaction temperature of the hydrothermal reaction is as follows: 100-200 ℃; the reaction time of the hydrothermal reaction is 1-10 days.

4. The method for hydrothermally synthesizing the SSZ-13 molecular sieve by recycling the mother liquor as claimed in claim 1, wherein in the step (3), additional deionized water is not required.

5. The method for hydrothermally synthesizing the SSZ-13 molecular sieve by recycling the mother liquor as claimed in claim 1, wherein in the step (3), the selectively added organic template agent is: when the molar ratio of the organic template to the silicon dioxide in the mother solution is more than 0.2, the organic template does not need to be supplemented.

6. The method for hydrothermally synthesizing the SSZ-13 molecular sieve by recycling the mother liquor as claimed in claim 1, wherein in the step (5), the drying temperature is 60-160 ℃, and the drying time is 8-36 h.

7. The method for hydrothermally synthesizing the SSZ-13 molecular sieve by recycling the mother liquor as claimed in claim 1, wherein in step (5), the calcination conditions are as follows: the temperature is 400-800 ℃, and the time is 5-20 h.

Technical Field

The invention relates to the technical field of molecular sieve synthesis, in particular to a method for synthesizing an SSZ-13 molecular sieve by recycling mother liquor in a hydrothermal mode.

Background

The SSZ-13 molecular sieve with CHA topological structure is SiO₄And AlO₄Tetrahedron is used as skeleton base and is connected with oxygen atom to form ordered eight-membered ring channel and three-dimensional crossed channel. The SSZ-13 molecular sieve has uniform pore channels with the pore channel size ofBelongs to a small pore molecular sieve. The structural characteristics of the SSZ-13 molecular sieve enable the molecular sieve to be widely applied to ammonia selective catalytic reduction (NH)₃-SCR), Methanol To Olefins (MTO) and CO₂Adsorption separation and the like.

The most commonly used organic template for SSZ-13 molecular sieves, TMADAOH, contains 13 carbon atoms and plays a role in space filling during crystallization. During the nucleation of molecular sieve precursor gel or liquid phase nucleation, TMADAOH takes self molecules as core tissue SiO₄、AlO₄Tetrahedra or some basic structural units, and form a certain geometrical configuration around the tetrahedra or some basic structural units, so as to form the framework structure of the molecular sieve. In order to prepare the SSZ-13 molecular sieve with excellent performance, in the actual industrial production process, a feeding mode with a high modulus silicon ratio is selected in the SSZ-13 synthesis process, namely the input amount of the organic template is far larger than a theoretical value, so that the high TMADAOH concentration is kept in the molecular sieve mother liquor. After the hydrothermal synthesis reaction, the mother liquor contains Al which is not utilized yet₂O₃、SiO₂And a large amount of water, if the mother liquor is directly discharged, the raw material loss and the environmental pollution are caused.

The method for synthesizing the molecular sieve by using the molecular sieve mother liquor as the raw material has been reported, and the characteristics of the method are that part or all of the synthetic raw materials are from the molecular sieve crystallization mother liquor of the same type. The method effectively reduces the production cost of the molecular sieve and reduces the pollution of the mother liquor to the environment. For example: CN101121522A discloses a method for utilizing a synthesis mother liquor of a phosphorus aluminum molecular sieve, which recycles the mother liquor for synthesis of phosphorus aluminum molecular sieves of the same type, and from the examples, it can be found that the amount of the mother liquor of the phosphorus aluminum molecular sieve added in the synthesis is only a proper amount, and the addition amount is not described in detail. CN105668587B introduces a recycling method of SAPO-34 molecular sieve synthesis mother liquor, the mother liquor is concentrated, the concentrated mother liquor is regarded as an independent whole, and is added into crystallized liquid after semi-crystallization to synthesize the SAPO-34 molecular sieve. Most of domestic patents related to the utilization of the CHA molecular sieve synthesis mother liquor are mother liquor treatment of a phosphorus-silicon-aluminum molecular sieve (SAPO-34), the mother liquor composition and the property difference of an organic template agent between the CHA molecular sieve synthesis mother liquor and the SSZ-13 molecular sieve are large, the recycling and utilization guidance of the SSZ-13 molecular sieve mother liquor is not large, and the introduction of the method for synthesizing the molecular sieve by recycling the SSZ-13 molecular sieve mother liquor is not involved in all the disclosed CHA molecular sieve mother liquor utilization methods.

Disclosure of Invention

In order to solve the technical problem, the invention provides a method for hydrothermally synthesizing an SSZ-13 molecular sieve by recycling mother liquor. The method has high economic value and environmental protection benefit on the efficient utilization of the organic template agent, the saving of raw materials, the effective reduction of the synthesis cost of the molecular sieve, the reduction of the discharge treatment cost of the industrial molecular sieve mother liquor and the reduction of the pollution to the environment.

A method for hydrothermally synthesizing an SSZ-13 molecular sieve by recycling mother liquor comprises the following steps:

(1) separating SSZ-13 molecular sieve solid products synthesized by a hydrothermal method, and recovering mother liquor after the molecular sieve is synthesized;

(2) analysis of SiO in mother liquor₂、Al₂O₃The content of the organic template;

(3) synthesizing a precursor formula of the SSZ-13 molecular sieve by a hydrothermal method adopted in the step (1), adding a silicon source and an aluminum source into a certain amount of mother liquor, selectively adding part of an organic template agent, filling the obtained mixture into a polytetrafluoroethylene-lined high-pressure reaction kettle, and synthesizing by the hydrothermal method to obtain a corresponding molecular sieve crystallization liquid;

(4) separating the molecular sieve crystallization liquid obtained in the step (3) to obtain a molecular sieve solid and a mother liquid;

(5) washing, drying and roasting the molecular sieve solid obtained in the step (4) to obtain the SSZ-13 molecular sieve;

(6) and (5) repeating the steps (2) to (5) repeatedly to realize the preparation of the SSZ-13 molecular sieve and the recycling of the SSZ-13 molecular sieve mother liquor.

In the above method, the silicon source used in the hydrothermal synthesis of the SSZ-13 molecular sieve in steps (1) and (3) is at least one of silica sol, fumed silica and water glass; the aluminum source is at least one of sodium aluminate, aluminum sulfate, pseudo-boehmite and aluminum hydroxide; the organic template agent is N, N, N-trimethyl-1-adamantyl ammonium hydroxide (TMADAOH), and the molar ratio of the silicon source, the aluminum source, the organic template agent and the water is SiO₂:Al₂O₃:TMADaOH:H₂O＝1:0.01～0.1:0.01～1:10～100。

In the above method, in the step (1) and the step (3), the reaction temperature of the hydrothermal reaction by the hydrothermal method is: 100-200 ℃; the reaction time of the hydrothermal reaction is 1-10 days.

In the method, in the step (3), deionized water is not required to be supplemented.

In the above method, in the step (3), the selectively added organic template is: when the molar ratio of the organic template to the silicon dioxide in the mother solution is more than 0.2, the organic template does not need to be supplemented.

In the method, in the step (5), the drying temperature is 60-160 ℃, and the drying time is 8-36 h.

In the method, in the step (5), the roasting conditions are as follows: the temperature is 400-800 ℃, and the time is 5-20 h.

According to the technical scheme provided by the invention, the preparation method can recycle the SSZ-13 molecular sieve mother liquor to synthesize the SSZ-13 molecular sieve. Compared with the method for directly discharging the molecular sieve mother liquor, the method can recycle a large amount of unreacted organic template agent, silicon source, aluminum source and deionized water in the mother liquor, and the microcrystals in the molecular sieve mother liquor can be beneficial to the synthesis of the SSZ-13 molecular sieve, thereby effectively reducing the waste of raw materials, lightening the pollution to the environment and reducing the discharge treatment cost of the mother liquor. Meanwhile, by analyzing each component in the mother solution and selecting the addition amount of the organic template agent, the invention reduces the input amount of the expensive organic template agent and effectively reduces the synthesis cost of the SSZ-13 molecular sieve.

The invention has the beneficial effects that:

(1) the SSZ-13 molecular sieve is synthesized by recycling the SSZ-13 molecular sieve mother liquor. Compared with the traditional hydrothermal method for synthesizing the SSZ-13 molecular sieve, the unreacted raw material components in the molecular sieve mother liquor are used, so that the consumption of the synthetic raw materials is effectively reduced, and theoretical and technical bases are provided for the development of the SSZ-13 molecular sieve industrial production.

(2) The SSZ-13 molecular sieve is synthesized by recycling the SSZ-13 molecular sieve mother liquor, so that the expensive organic template agent can be efficiently utilized, the waste of the organic template agent and the environmental pollution are prevented, and the high synthesis cost of the molecular sieve can be greatly reduced.

Drawings

FIG. 1 is a phase structure representation diagram of molecular sieves SSZ-13-1, SSZ-13-2, SSZ-13-3 and SSZ-13-4 prepared in comparative example 1, example 2 and example 3;

FIG. 2 is a scanning electron micrograph of the molecular sieve SSZ-13-1 prepared in comparative example 1;

FIG. 3 is a scanning electron micrograph of molecular sieve SSZ-13-2 prepared in example 1.

Detailed Description

The technical solutions in the embodiments are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and these are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

Comparative example 1

30g N, N, N-trimethyl-1-adamantyl ammonium hydroxide solution was weighed and added to 28g of deionized water, and the resulting mixture was stirred for 15 min. 0.3g of aluminum hydroxide powder was then weighed into the above solution and stirred and mixed for 30 min. Finally, 11g of silica sol (40 wt%) was weighed into the above solution and stirred at room temperature for 2h to a homogeneous solution. The mixture was transferred to a 100mL reaction vessel and statically crystallized in an oven at 160 ℃ for 6 days. After the crystallization reaction is finished, separating a solid product and recovering a mother solution. The solid product was washed until the pH of the supernatant was neutral, collected by filtration, and then dried at 100 ℃ for 24 hours. And finally, placing the solid product in a tubular furnace, and calcining for 10 hours at 580 ℃ in a dry air atmosphere to obtain the SSZ-13 molecular sieve which is marked as SSZ-13-1.

Example 1

The mother liquor obtained in comparative example 1 was analyzed to obtain SiO₂、Al₂O₃And relative molar values of TMADAOH were 0.30, 0.008, and 0.39, respectively. 0.3g of aluminum hydroxide powder is weighed and added into 52g of mother liquor, and the mixture is mixed and stirred for 30 min. Finally, 11g of silica sol (40 wt%) was weighed into the above solution and stirred at room temperature for 2h to a homogeneous solution. The mixture was transferred to a 100mL reaction vessel and statically crystallized in an oven at 160 ℃ for 6 days. After the crystallization reaction is finished, separating a solid product and recovering a mother solution. The solid product was washed until the pH of the supernatant was neutral, collected by filtration, and then dried at 100 ℃ for 24 hours. And finally, placing the solid product in a tubular furnace, and calcining for 10 hours at 580 ℃ in a dry air atmosphere to obtain the SSZ-13 molecular sieve which is marked as SSZ-13-2.

Example 2

Analysis of the mother liquor obtained in example 1 gave SiO₂、Al₂O₃And relative molar values of TMADAOH were 0.24, 0.008, and 0.28, respectively. 0.3g of aluminum hydroxide powder is weighed and added into 52g of mother liquor, and the mixture is mixed and stirred for 30 min. Finally, 11g of silica sol (40 wt%) was weighed into the above solution and stirred at room temperature for 2h to a homogeneous solution. The mixture was transferred to a 100mL reaction vessel and statically crystallized in an oven at 160 ℃ for 6 days. After the crystallization reaction is finished, separating a solid product and recovering a mother solution. The solid product was washed until the pH of the supernatant was neutral, collected by filtration, and then dried at 100 ℃ for 24 hours. And finally, placing the solid product in a tubular furnace, and calcining for 10 hours at 580 ℃ in a dry air atmosphere to obtain the SSZ-13 molecular sieve which is marked as SSZ-13-3.

Example 3

The mother liquor obtained in example 2 was analyzed to obtain SiO₂、Al₂O₃And TMADAOH were 0.15, 0.007 and 0.17 in relative molar ratio, respectively. 10g N, N, N-trimethyl-1-adamantyl ammonium hydroxide solution was weighed and added to 44g of the mother liquor, and the resulting mixture was stirred for 15 min. 0.3g of aluminum hydroxide powder was then weighed into the above solution and stirred and mixed for 30 min. Finally, 11g of silica sol (40 wt%) was weighed into the above solution and stirred at room temperature for 2h to a homogeneous solution. The mixture was transferred to a 100mL reaction vessel and statically crystallized in an oven at 160 ℃ for 6 days. After the crystallization reaction is finished, separating a solid product and recovering a mother solution. The solid product was washed until the pH of the supernatant was neutral, collected by filtration, and then dried at 100 ℃ for 24 hours. And finally, placing the solid product in a tubular furnace, and calcining for 10 hours at 580 ℃ under a dry air atmosphere to obtain the SSZ-13 molecular sieve which is marked as SSZ-13-4.

The molecular sieve SSZ-13-1 prepared in comparative example 1 and the molecular sieves SSZ-13-2, SSZ-13-3 and SSZ-13-4 prepared in examples 1, 2 and 3 are subjected to phase structure characterization, and the test results are shown in FIG. 1. As can be seen from FIG. 1, the SSZ-13-2, SSZ-13-3 and SSZ-13-4 molecular sieves have good crystallinity, and compared with the SSZ-13-1 molecular sieve, the crystal structures of the SSZ-13-2, SSZ-13-3 and SSZ-13-4 are not changed, which shows that the SSZ-13 molecular sieve can be effectively synthesized by recycling the mother liquor of the SSZ-13 molecular sieve, and the prepared molecular sieve has high crystallinity.

The molecular sieve SSZ-13-1 prepared in comparative example 1 and the molecular sieve SSZ-13-2 prepared in example 1 were subjected to a scanning electron microscope test, and the test results are shown in FIGS. 2 and 3. Wherein FIG. 2 is a scanning electron micrograph of molecular sieve SSZ-13-1 prepared in comparative example 1, and FIG. 3 is a scanning electron micrograph of molecular sieve SSZ-13-2 prepared in example 1. As can be seen from FIGS. 2 and 3, the SSZ-13-2 molecular sieve material synthesized by recovering and utilizing SSZ-13 molecular sieve mother liquor to obtain the SSZ-13 molecular sieve has the same morphology as the SSZ-13-1 molecular sieve synthesized by the conventional hydrothermal method.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and it should be understood that various modifications, equivalents and improvements can be made by those skilled in the art without departing from the principle of the present invention, and the modifications and improvements should also be considered as the protection scope of the present invention.