阅读说明：本技术 合成分子筛的方法 (Method for synthesizing molecular sieve ) 是由 史静 朱慧芬 徐建军 于 2019-10-21 设计创作，主要内容包括：本发明公开了一种合成分子筛的方法。该方法包括：分别配制物料A和物料B,其中物料A含有水、硅源和有机模板剂R,物料B含铝源和水；物料A和物料B作为两股物流分别加入超重力反应器进行反应和老化,然后排出超重力反应器,得到老化后的浆液；老化后的浆液进行晶化,得到分子筛。该方法用于合成分子筛时,超少模板剂用量,减少环境污染,合成步骤简便,易于工业化,且老化时间与晶化时间大幅度缩短,晶化温度大幅度降低,晶化效率高,得到的分子筛具有粒度均匀的特点。(The invention discloses a method for synthesizing a molecular sieve. The method comprises the following steps: respectively preparing a material A and a material B, wherein the material A contains water, a silicon source and an organic template agent R, and the material B contains an aluminum source and water; respectively adding the material A and the material B as two material flows into a supergravity reactor for reaction and aging, and then discharging the supergravity reactor to obtain aged slurry; crystallizing the aged slurry to obtain the molecular sieve. When the method is used for synthesizing the molecular sieve, the dosage of the template agent is extremely small, the environmental pollution is reduced, the synthesis steps are simple and convenient, the industrialization is easy, the aging time and the crystallization time are greatly shortened, the crystallization temperature is greatly reduced, the crystallization efficiency is high, and the obtained molecular sieve has the characteristic of uniform granularity.)

1. A method of synthesizing a molecular sieve, comprising:

(1) respectively preparing a material A and a material B, wherein the material A contains water, a silicon source and an organic template agent R, and the material B contains an aluminum source and water, and preferably also contains a phosphorus source;

(2) respectively adding the material A and the material B as two material flows into a supergravity reactor for reaction and aging, and then discharging the supergravity reactor to obtain aged slurry;

(3) crystallizing the aged slurry obtained in the step (2) to obtain a molecular sieve;

in the material A, the dosage of the organic template agent R and the silicon source are SiO₂Calculated as R/SiO₂Is less than 0.6, and the crystallization conditions are as follows: the crystallization temperature is not more than 140 ℃, and the crystallization time is less than 360 min.

2. The method of claim 1, wherein: the molecular sieve is one or more of ZSM-5, ZSM-11, X-type molecular sieve, Y-type molecular sieve, Beta, mordenite and SAPO-34, and preferably the molecular sieve is one or more of ZSM-5, ZSM-11 and SAPO-34.

3. The method of claim 1, wherein: in the material A, the dosage of the organic template agent R and the silicon source are SiO₂Calculated as R/SiO₂Is prepared from (A) and (B)The molar ratio is 0.4 or less, and further 0.3 or less.

4. A method according to claim 1 or 3, characterized by: in the material A, H₂O/SiO₂In a molar ratio of 5 to 1000.

5. The method of claim 1, wherein: in the material B, the silicon source in the material A is used as SiO₂Based on the added amount of Al₂O₃/SiO₂Is 0-2 and is not 0, P/SiO₂In a molar ratio of 0 to 50; h₂O/SiO₂In a molar ratio of 1 to 1000.

6. The method of claim 1, wherein: in the step (2), the rotation speed of the high gravity reactor is 10-3000rpm, preferably 1000-2500 rpm.

7. The method of claim 1 or 6, wherein: in the step (2), the reaction conditions of the hypergravity reactor are as follows: the residence time is less than 120min, preferably less than 30min, more preferably 3min to 8 min.

8. The method of claim 1, wherein: in the step (2), the feeding volume ratio of the material A to the material B is 0.1-10.

9. The method of claim 1, wherein: the crystallization conditions in the step (3) are as follows: the crystallization time is 240min or less, preferably 180min or less, and more preferably 120min or less, and the crystallization time is 10min or more; the crystallization temperature is not more than 130 ℃, preferably not more than 95 ℃, and the crystallization temperature is above 60 ℃.

10. The method of claim 1, wherein: the template agent R is at least one of n-propylamine, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide, tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide; the silicon source is at least one of silica sol, ethyl orthosilicate and silicate, and the aluminum source is at least one of aluminum sulfate, aluminum isopropoxide and aluminate; the phosphorus source is at least one of phosphate.

Technical Field

The invention relates to a method for synthesizing a molecular sieve, belonging to the technical field of zeolite molecular sieve synthesis.

Background

In 1979, a supergravity separation technology originated from the national space administration (NASA) space experiment is a typical chemical process strengthening technology, and is realized by simulating a supergravity environment on the earth through a centrifugal force field which is generated by a Rotating Packed Bed (RPB) and is higher than the gravitational acceleration of the earth. CN200610114439.2 discloses a method for preparing a nano NaY molecular sieve. The preparation of the directing agent, the preparation of the mother liquor, the mixing of the directing agent and the mother liquor and the subsequent crystallization of reaction products are respectively carried out under the condition of the supergravity of the rotating bed, so that the method for preparing the high-quality nano NaY molecular sieve, which shortens the crystallization reaction time and simplifies the process flow, is provided, but the crystallization time is still longer. CN201210287914.1 discloses a preparation method of a mesoporous zeolite molecular sieve, which is characterized in that tetraethoxysilane is used as a silicon source, sodium metaaluminate is used as an aluminum source, a bifunctional triammonium quaternary ammonium salt cationic surfactant is used as a template agent, and the mesoporous zeolite molecular sieve with micropore crystallization pore walls is prepared by a hydrothermal synthesis method under an alkaline condition. The quaternary ammonium salt surfactant adopted by the method is used as a zeolite structure guiding agent to generate micropores, and the aggregation of long hydrophobic alkyl groups at two ends of the micropores forms mesopores. The method effectively changes the amorphous pore wall structure of the traditional mesoporous material, enables the mesoporous material to have crystallized pore walls, greatly improves the acidity and hydrothermal stability of the mesoporous material, and the prepared mesoporous zeolite molecular sieve has a special mesopore/micropore multiple pore structure, can avoid the defect of a single pore structure, improves the mass transfer efficiency, and has wide application prospects in the aspects of macromolecule catalysis, adsorption, separation and the like. CN201310020530.8 discloses a zeolite synthesis method, which comprises the steps of intercalating layered silicate Na-kenyaite by using polar molecules, namely hexadecyl trimethyl ammonium bromide to obtain a Na-kenyaite-CTAB intercalation compound, synthesizing a molecular sieve by using tetraalkyl ammonium hydroxide as a template agent, and carrying out delamination treatment on a product to obtain a flaky molecular sieve crystal. The intercalation process enlarges the interlayer spacing and keeps a certain distance to avoid mutual fusion, the growth speed is controlled in the crystallization process to ensure that the molecular sieve can nucleate and grow along the laminate of the layered substance, after the reaction is finished, the template agent and the polar molecules are removed, and finally, the two-dimensional structure of the layered substance is also kept while the molecular sieve is obtained, thereby greatly improving the contactability of the macromolecular reactant and the active acid center and improving the reaction performance. CN200910072747.7 discloses a method for preparing a molecular sieve, adding pre-crystallized seed crystals into a gel system for synthesizing a nano molecular sieve without a template agent, crystallizing at 160-180 ℃ for 24 hours, cooling to room temperature, centrifugally filtering, washing, drying and roasting a product to obtain a molecular sieve impurity-free crystalline phase.

Among the methods described in the above patents, some methods use a supergravity reactor but the crystallization time is still long, while some methods do not use a supergravity reactor for strengthening the micro process, the crystallization process is basically static crystallization, the content of the template agent used is high, and the zeolite growth process is not stirred. Some methods have the disadvantages of long aging time and crystallization time, high crystallization temperature and complex synthesis process for preparing the molecular sieve although the dosage of the template agent is reduced.

Disclosure of Invention

Aiming at the problems of large dosage, long aging time, long crystallization time, high crystallization temperature and low synthesis efficiency of the organic template agent for synthesizing the zeolite molecular sieve in the prior art, the invention provides a novel method for synthesizing the molecular sieve. When the method is used for synthesizing the molecular sieve, the dosage of the template agent is extremely small, the environmental pollution is reduced, the synthesis steps are simple and convenient, the industrialization is easy, the aging time and the crystallization time are greatly shortened, the crystallization temperature is greatly reduced, the crystallization efficiency is high, and the obtained molecular sieve has the characteristic of uniform granularity.

In order to solve the technical problems, the method for synthesizing the molecular sieve provided by the invention comprises the following steps:

(1) respectively preparing a material A and a material B, wherein the material A contains water, a silicon source and an organic template agent R, and the material B contains an aluminum source and water, and preferably also contains a phosphorus source;

(2) respectively adding the material A and the material B as two material flows into a supergravity reactor for reaction and aging, and then discharging the supergravity reactor to obtain aged slurry;

(3) crystallizing the aged slurry obtained in the step (2) to obtain a molecular sieve;

in the material A, the dosage of the organic template agent R and a silicon source (SiO is used)₂Calculated) is R/SiO₂Is less than 0.6, and the crystallization conditions are as follows: the crystallization temperature is not more than 140 ℃, and the crystallization time is less than 360 min.

Further, the molecular sieve is one or more of ZSM-5, ZSM-11, X-type molecular sieve, Y-type molecular sieve, Beta, mordenite and SAPO-34, and preferably, the molecular sieve is one or more of ZSM-5, ZSM-11 and SAPO-34.

Furthermore, in the material A, the dosage of the organic template agent R and a silicon source (SiO is used as SiO)₂Calculated) is R/SiO₂The molar ratio of (a) is less than 0.6, may be less than 0.5, may be 0.4 or less, may be 0.3 or less, and may be 0.2 or less.

Further, in the material A, H₂O/SiO₂In a molar ratio of 5 to 1000.

Further, in the material B, the silicon source in the material A is SiO₂Based on the added amount of Al₂O₃/SiO₂Is 0 to 2 and is not 0 and may be 0.1 to 2, P/SiO₂The molar ratio of (A) to (B) is from 0 to 50, and may be from 0.1 to 50.

Further, in the material B, H₂O/SiO₂In a molar ratio of 1 to 1000.

Further, in the step (2), the rotation speed of the high gravity reactor is 10-3000rpm, preferably 1000-2500 rpm.

Further, in the step (2), the reaction conditions of the hypergravity reactor are as follows: the residence time is less than 120min, preferably less than 30min, more preferably 3min to 8 min.

Further, in the step (2), the feeding volume ratio of the material A to the material B is 0.1-10.

Further, the crystallization conditions in step (3) are as follows: the crystallization time is less than 360min, preferably less than 240min, preferably less than 180min, and preferably less than 120min, and the crystallization time is more than 10 min; the crystallization temperature is not more than 140 ℃, preferably not more than 130 ℃, more preferably not more than 95 ℃, and the crystallization temperature is above 60 ℃.

Further, after the crystallization in the step (3), conventional post-treatment steps, namely cooling, washing and separating, drying, roasting and the like, can be further included to prepare the molecular sieve.

Further, the template agent R is at least one of n-propylamine, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide, tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide. The silicon source is at least one of silica sol, ethyl orthosilicate and silicate, and the aluminum source is at least one of aluminum sulfate, aluminum isopropoxide and aluminate. The water may be deionized water. The phosphorus source is at least one of phosphate.

The method for synthesizing the molecular sieve provided by the invention has the advantages that two materials are adopted to enter the hypergravity reactor for reaction and aging, and the aged slurry is crystallized in the crystallization kettle, so that the aging time is short, the low-temperature crystallization and the crystallization time are short under the condition of greatly reducing the dosage of the template, the synthesis efficiency can be effectively improved, the obtained molecular sieve has the characteristic of uniform granularity, and the molecular sieve has the characteristics of good parallelism, repeatability, operability and the like, and has better practicability and effectiveness.

The ZSM-5 molecular sieve prepared by the method for synthesizing the molecular sieve is applied to the reaction of a butylene cracking fixed bed, the reaction temperature is 550 ℃, and the volume space velocity is 10h^-1In the process, after the reaction time is 6 hours, the catalyst has a good catalytic effect, the conversion rate of the butylene reaches over 76 percent, the selectivity of the propylene reaches over 30 percent, and an unexpected technical effect is obtained.

Drawings

FIG. 1 is an XRD spectrum of the molecular sieve obtained in example 1;

FIG. 2 is an SEM photograph of the molecular sieve obtained in example 1;

FIG. 3 is an XRD spectrum of the molecular sieve obtained in comparative example 1.

Detailed Description

The following examples further illustrate the synthesis of the molecular sieve provided by the present invention, but the scope of the present invention is not limited by these examples.

The analysis (XRD) of the crystal phases of the starting materials and the products was carried out on an X' pert PRO X-ray powder diffractometer from Pasacaceae, using Cu Ka rays as the X-ray source, at a tube pressure of 40kV and a tube flow of 40 mA. Scanning Electron Microscope (SEM) photographs of the samples were taken on a scanning electron microscope, type S-4800II, Hitachi.

[ example 1 ]

The synthesis method comprises the following steps: preparing a material A: 2g of tetrapropylammonium hydroxide and 6.7g of silica sol were added to 7.5g of water, and the mixture was stirred uniformly. Preparing a material B: 0.09g of aluminum sulfate octadecahydrate is added into 7.5g of water and stirred evenly. Introducing the materials into a supergravity reactor in two paths, adjusting the supergravity rotating speed to 1500rpm, circularly introducing into the supergravity reactor, and recovering the solution after 8min to obtain the liquid to be crystallized. Then placing the mixture into a crystallization kettle, heating to 120 ℃, stirring at 150rpm for crystallization for 2 hours, cooling to room temperature after the reaction is finished, washing and centrifuging for 3 times by deionized water, drying for 12 hours at 80 ℃, and roasting to obtain the final product.

FIG. 1 is an XRD spectrum of the product obtained in example 1, and it can be seen that the product has a characteristic diffraction peak of ZSM-5 and has a higher crystallinity. FIG. 2 is an SEM photograph of the product obtained in example 1, and it can be seen that the sample exhibits a uniform morphology.

[ example 2 ]

Using the same conditions as in example 1, the amount of tetrapropylammonium hydroxide used was changed to 1.2g, and the rotational speed of the supergravity reactor was adjusted to 1800rpm, to obtain the final product. The XRD characterization result of the sample shows that the product has a ZSM-5 characteristic diffraction peak, and the SEM picture shows that the sample is a uniform nano ZSM-5 molecular sieve.

[ example 3 ]

Using the same conditions as in example 1, the amount of tetrapropylammonium hydroxide used was changed to 0.5g, and the rotational speed of the supergravity reactor was adjusted to 2500rpm, to obtain a final product. The XRD characterization result of the sample shows that the product has a ZSM-5 characteristic diffraction peak, and the SEM picture shows that the sample is a uniform nano ZSM-5 molecular sieve.

[ example 4 ]

The same conditions as in example 1 were used, with a crystallization time of 3h being varied, to obtain the final product. The XRD characterization result of the sample shows that the product has a ZSM-5 characteristic diffraction peak, and the SEM picture shows that the sample is a uniform nano ZSM-5 molecular sieve.

[ example 5 ]

The synthesis method comprises the following steps: preparing a material A: according to H₂O/SiO₂＝25；R/SiO₂Weighing TBAOH and tetraethyl orthosilicate and dissolving the TBAOH and the tetraethyl orthosilicate in deionized water to prepare a material B: according to Si/Al of 200, H₂O/SiO₂Weighing sodium metaaluminate according to the weight percentage of 500, adding the sodium metaaluminate into water, uniformly stirring, introducing the materials into a supergravity reactor in two ways, adjusting the supergravity rotating speed to 1600rpm, circularly entering the supergravity reactor, and recovering the solution after 8min to obtain the liquid to be crystallized. Then placing the mixture into a crystallization kettle, heating to 90 ℃, stirring at 150rpm for crystallization for 1h, cooling to room temperature after the reaction is finished, washing and centrifuging for 3 times by deionized water, drying for 12h at 80 ℃, and roasting to obtain the final product. The sample XRD is characterized, and the product can be seen to have a ZSM-11 characteristic diffraction peak.

[ example 6 ]

The synthesis method comprises the following steps: preparing a material A: according to H₂O/SiO₂＝133；R/SiO₂Weighing TEAOH and silica sol and dissolving in deionized water to prepare a material B: according to H₂O/SiO₂＝500，Si/Al＝0.5，P/SiO₂Weighing aluminum isopropoxide and phosphoric acid in water, uniformly stirring, introducing the materials into a supergravity reactor in two paths, adjusting the supergravity rotating speed to 1600rpm, circularly entering the supergravity reactor, and recovering the solution after 8min to obtain the liquid to be crystallized. Then placing the mixture into a crystallization kettle, heating to 120 ℃, stirring at 150rpm for crystallization for 2 hours, cooling to room temperature after the reaction is finished, washing and centrifuging for 3 times by deionized water, drying for 12 hours at 80 ℃, and roasting to obtain the final product. Sample XRD, the result is characterized, and the product can be seen to have a SAPO-34 characteristic diffraction peak.

[ example 7 ]

The synthesis method comprises the following steps: preparing a material A: 1.8g of tetrapropylammonium bromide and 7.7g of silica sol were added to 6g of water to prepare a material B: adding 0.014g of aluminum isopropoxide into 6g of water, introducing the materials into a supergravity reactor in two paths, adjusting the supergravity rotating speed to be 1500rpm, circularly entering the supergravity reactor, and recovering the solution after 3min to obtain the liquid to be crystallized. Then placing the mixture into a crystallization kettle, heating to 90 ℃, stirring at 150rpm for crystallization for 2 hours, cooling to room temperature after the reaction is finished, washing and centrifuging for 3 times by deionized water, drying for 12 hours at 80 ℃, and roasting to obtain the final product. The XRD characterization result of the sample shows that the product has a ZSM-5 characteristic diffraction peak, and the SEM picture shows that the sample is a uniform nano ZSM-5 molecular sieve.

[ COMPARATIVE EXAMPLE 1 ]

For comparison, no hypergravity reactor was introduced. The synthesis method comprises the following steps: preparing a material A: 2g of tetrapropylammonium hydroxide and 6.7g of silica sol were added to 7.5g of water, and the mixture was stirred uniformly. Preparing a material B: 0.09g of aluminum sulfate octadecahydrate is added into 7.5g of water and stirred evenly. And (3) uniformly mixing the material A and the material B, aging for 30min, then placing the mixture into a crystallization kettle, heating to 120 ℃, crystallizing for 2h under stirring of 150rpm, cooling to room temperature after the reaction is finished, washing and centrifuging for 3 times by using deionized water, drying for 12h at 80 ℃, and roasting to obtain a final product. The XRD pattern of the resulting product is shown in FIG. 3, and the product is seen to be amorphous.

[ COMPARATIVE EXAMPLE 2 ]

2g of tetrapropylammonium hydroxide, 6.7g of silica sol and 0.09g of aluminum sulfate octadecahydrate are added into 15g of water and stirred uniformly. Directly introducing into a hypergravity reactor, adjusting the rotational speed of the hypergravity to 1500rpm, circularly introducing into the hypergravity reactor, and recovering the solution after 8min to obtain the liquid to be crystallized. Then placing the mixture into a crystallization kettle, heating to 120 ℃, stirring at 150rpm for crystallization for 2 hours, cooling to room temperature after the reaction is finished, washing and centrifuging for 3 times by deionized water, drying for 12 hours at 80 ℃, and roasting to obtain the final product. XRD showed the sample to be amorphous.

[ COMPARATIVE EXAMPLE 3 ]

In comparative example 3, a silicon source and water were used as material B, and an aluminum source, a templating agent, an auxiliary agent and water were used as material A. Weighing 1.3g of aluminum sulfate, 90g of silica sol, 3.5g of sodium chloride, 6g of sodium hydroxide, 100g of tetrapropyl ammonium hydroxide and 200g of deionized water to respectively prepare a material A and a material B. And (3) introducing the material A and the material B into a supergravity reactor, adjusting the supergravity rotating speed to be 1500rpm, circularly entering the supergravity reactor, and recovering the solution after 8min to obtain the liquid to be crystallized. Then placing the mixture into a crystallization kettle, heating to 120 ℃, stirring at 150rpm for crystallization for 2 hours, cooling to room temperature after the reaction is finished, washing and centrifuging for 3 times by deionized water, drying for 12 hours at 80 ℃, and roasting to obtain the final product. XRD showed the sample to be amorphous.