阅读说明：本技术 一种suz-4分子筛的制备方法 (Preparation method of SUZ-4 molecular sieve ) 是由 高杭 杜艳泽 秦波 柳伟 张晓萍 于 2019-10-28 设计创作，主要内容包括：本发明公开一种SUZ-4型分子筛的制备方法,包括如下内容：将铝源、硅源、碱源、去离子水和HZSM-5型分子筛混合,经晶化、过滤、干燥制得SUZ-4型分子筛。所述方法无需采用模板剂、制备成本低,适于工业应用。(The invention discloses a preparation method of an SUZ-4 type molecular sieve, which comprises the following steps: mixing an aluminum source, a silicon source, an alkali source, deionized water and the HZSM-5 type molecular sieve, and crystallizing, filtering and drying the mixture to obtain the SUZ-4 type molecular sieve. The method does not need to adopt a template agent, has low preparation cost and is suitable for industrial application.)

1. A preparation method of SUZ-4 type molecular sieve is characterized by comprising the following steps: the method comprises the following steps: mixing an aluminum source, a silicon source, an alkali source, deionized water and the HZSM-5 type molecular sieve, and crystallizing, filtering and drying the mixture to obtain the SUZ-4 type molecular sieve.

2. The method of claim 1, wherein: the silicon source is one or more of silica sol, water glass, white carbon black and silicon dioxide; the aluminum source is one or more of aluminum sheet, aluminum oxide, aluminum hydroxide, pseudo-boehmite and aluminate; the alkali source is at least potassium hydroxide.

3. The method of claim 2, wherein: the silicon source is silica sol; the aluminum source is a metal aluminum sheet or aluminum oxide; the alkali source is KOH.

4. The method of claim 1, wherein: mixing and stirring an aluminum source, a silicon source, an alkali source, deionized water and the HZSM-5 type molecular sieve according to a certain ratio to a uniform state, crystallizing for 1-7 days at 100-200 ℃ in a sealed condition, filtering the obtained mixture after crystallization, washing and drying the obtained white solid to obtain the SUZ-4 molecular sieve.

5. The method of claim 4, wherein: weighing a proper amount of alkali source, dissolving in water, adding an aluminum source for dissolving, weighing a proper amount of HZSM-5 type molecular sieve, putting into the mixed solution, stirring, adding a silicon source after uniformly stirring, stirring for 1-2 hours, and crystallizing.

6. The method of claim 1, wherein: the crystallization temperature and the crystallization time are respectively 140-180 ℃ and 2-4 days.

7. The method of claim 1, wherein: the aluminum source is Al₂O₃The silicon source is SiO₂Calculated as H, deionized water₂Calculated by O, the alkali source is calculated by potassium hydroxide, and the molar ratio of the raw materials is SiO₂：Al₂O₃：KOH：H₂O=5~65:0.4~5:2.5~25:165~1495。

8. The method of claim 7, wherein: the molar ratio of the raw materials is as follows: SiO 2₂：Al₂O₃：KOH：H₂O=15~30:0.8~1.8:4.0~14.0:400~900。

9. The method of claim 1, wherein: the crystallization process is dynamic crystallization or static crystallization.

10. The method of claim 1, wherein: the adding amount of the HZSM-5 type molecular sieve is 1-25% of the total mass of a mixed material system for synthesizing the SUZ-4 molecular sieve, and preferably 5-10%.

Technical Field

The invention belongs to the field of molecular sieve synthesis, and particularly relates to a preparation method of an SUZ-4 molecular sieve.

Background

The SUZ-4 molecular sieve has similar pore channel structure to ZSM-5 and FER molecular sieves, and the three-dimensional pore channel mainly consists of four, five, six, eight and ten membered rings, and comprises a pore channel which consists of eight membered rings and is parallel to the XY plane and a pore opening which consists of ten membered rings and is parallel to the XY planezTwo cross-shaped channels of the straight channels of the shaft. The SUZ-4 molecular sieve is applied to a plurality of catalytic fields of n-butene isomerization, selective catalytic reduction of nitrogen oxides and the like, and has potential industrial application prospects.

Currently, the reported conventional method for synthesizing SUZ-4 requires dynamic crystallization at a relatively high temperature (typically 150 ℃ C. and 180 ℃ C.) with the addition of a large amount of an expensive organic template for about 4 to 7 days. This makes the SUZ-4 molecular sieve impossible to be produced in large scale, and limits the application prospect of the molecular sieve. Meanwhile, the use of a large amount of organic template agent causes environmental pollution, and green and environment-friendly production cannot be achieved.

Zhou Hualan et al, in the Journal of Chinese Journal of Chemical Engineering, 22(1) 120-126 (2014), published a method for preparing SUZ-molecular sieves without a template, but with a longer crystallization time. The preparation process of a SUZ-4 molecular sieve membrane is published in Lei ya Meng et al, Liaoning university of engineering technology, journal of science, Vol.38, No. 2, and is successfully applied to the process of pervaporation ethyl acetate dehydration reaction, but the preparation process is complex and is not beneficial to large-scale production. Jianshan et al published a paper in university of maritime university, university of Dalian province 33, No. 4, to study the influence of the framework dealumination process of the SUZ-4 molecular sieve on the catalytic performance, and found that the acid center on the surface of the SUZ-4 molecular sieve is mainly the B acid center.

CN102241407 discloses a method for synthesizing the molecular sieve by SUZ-4 seed crystal glue, which greatly reduces the dosage of an organic template agent and shortens the synthesis time, but the molecular sieve needs to be synthesized under dynamic conditions. CN107285340 discloses a preparation method for obtaining SUZ-4 zeolite by using mother liquor. The method is characterized in that the mother liquor is evaporated to dryness to obtain dry glue, and the dry glue on the upper part of a reaction kettle is converted into the zeolite molecular sieve through mass transfer of a vapor phase, so that the preparation process of the method is complex. CN102249257 discloses a method for obtaining SUZ-4 molecular sieve by circulating and crystallizing mother liquor, and the crystallization time in the synthesis process is greatly shortened, and the SUZ-4 molecular sieve with template agent is reduced or not used.

At present, most of synthesis methods of the SUZ-4 molecular sieve are further synthesized by using an expensive and environmentally-friendly organic template and seed crystals or seed gels generated in the synthesis process of the SUZ-4 molecular sieve, and no relevant report about the synthesis of the SUZ-4 molecular sieve by using secondary structural units in heterogeneous seed crystals exists.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method of SUZ-4. The method does not need to adopt a template agent, has low preparation cost and is suitable for industrial application.

The invention relates to a preparation method of an SUZ-4 type molecular sieve, which comprises the following steps: mixing an aluminum source, a silicon source, an alkali source, deionized water and the HZSM-5 type molecular sieve, and crystallizing, filtering and drying the mixture to obtain the SUZ-4 type molecular sieve.

In the method of the invention, the silicon source can be silica sol, water glass and white carbon black (SiO)₂) Silica, preferably silica sol, white carbon; the aluminum source can be a mixture of one or more of aluminum metal sheets, aluminum oxide, aluminum hydroxide, pseudo-boehmite and aluminate, preferably aluminum metal sheets and aluminum oxide; the alkali source is at least potassium hydroxide, preferably KOH.

In the method, an aluminum source, a silicon source, an alkali source, deionized water and an HZSM-5 type molecular sieve are preferably mixed and stirred according to a certain proportion to be in a uniform state, the mixture is crystallized for 1 to 7 days under the sealing condition of 100-200 ℃, the mixture obtained after crystallization is filtered, and the obtained white solid is washed and dried to obtain the SUZ-4 molecular sieve.

In the method, the feeding sequence in the synthesis process is as follows: weighing a proper amount of alkali source, dissolving in water, adding an aluminum source for dissolving, weighing a proper amount of HZSM-5 type molecular sieve, putting into the mixed solution, stirring, adding a silicon source after uniformly stirring, stirring for 1-2 hours, and crystallizing.

In the method, when the crystallization temperature is lower, the corresponding crystallization time is longer; on the contrary, when the crystallization temperature is higher, the crystallization time corresponding thereto is shorter. The optimal crystallization temperature and crystallization time are 140-180 ℃ and 2-4 days respectively.

In the method of the invention, the aluminum source is Al₂O₃The silicon source is SiO₂Calculated as H, deionized water₂Calculated by O, the alkali source is calculated by potassium hydroxide, and the molar ratio of the raw materials is SiO₂：Al₂O₃：KOH：H₂O = 5-65: 0.4-5: 2.5-25: 165-1495; the preferable molar ratio of the raw materials is as follows: SiO 2₂：Al₂O₃：KOH：H₂O=15~30:0.8~1.8:4.0~14.0:400~900。

In the method, the crystallization process can be dynamic crystallization or static crystallization, the crystallization time of the static crystallization is longer, and the dynamic crystallization is preferably used as a crystallization mode.

In the method, the addition amount of the HZSM-5 type molecular sieve is 1-25%, preferably 5-10% of the total mass of a mixed material system for synthesizing the SUZ-4 molecular sieve.

The method adopts the conventional ZSM-5 type molecular sieve as the seed crystal to prepare the SUZ-4 molecular sieve under the condition of not adding a template agent. The channel structure of the SUZ-4 molecular sieve is very similar to that of the ZSM-5 molecular sieve, the three-dimensional channel structure of the SUZ-4 is composed of four, five, six, eight and ten membered rings, and the ZSM-5 molecular sieve is a topological structure composed of four, five, six and ten membered rings. The three-dimensional pore channel structure of the SUZ-4 molecular sieve comprises two mutually crossed pore channels, wherein one pore channel is a pore channel which is composed of eight-membered rings and is parallel to an XY plane; the other is a straight channel parallel to the z-axis, the orifice consisting of ten-membered rings. Unlike the structure of the SUZ-4 molecular sieve, the openings of both channels of the ZSM-5 molecular sieve are ten-membered rings, and the straight channel opening parallel to the z-axis is slightly larger than that of SUZ-4. The ZSM-5 molecular sieve is used as a seed crystal to be dissolved into a secondary structural unit with a metastable state consisting of four, five and six-membered rings in a synthesis system of the SUZ-4 molecular sieve, and the secondary structural unit is rearranged and combined according to the growth process of the SUZ-4 molecular sieve to prepare the SUZ-4 molecular sieve. The secondary structural unit in the metastable state plays a guiding role in the synthesis process of the SUZ-4 molecular sieve, and accelerates the synthesis process of the SUZ-4 molecular sieve. In the synthesis process of SUZ-4 molecular sieve, Na⁺The presence of (a) may cause the formation of a competitive MOR phase in the system, and therefore the H-type ZSM-5 molecular sieve is used as seed in the preparation process. The SUZ-4 molecular sieve prepared by the method has short crystallization time, does not adopt a template agent, reduces the preparation cost and reduces the environmental pollution.

Compared with the prior art, the method provides a novel preparation method for the synthesis process of the SUZ-4 molecular sieve, and also provides a basis for the generation of secondary structure units of the heterogeneous seed crystals in the synthesis process of the zeolite and the guiding effect. The method does not use an organic template agent for preparing the SUZ-4 molecular sieve conventionally, and the used heterogeneous seed crystal HZSM-5 type molecular sieve has mature synthesis technology and lower purchase cost, thereby greatly reducing the preparation cost.

Drawings

FIG. 1 is an XRD diffractogram of the product synthesized in example 1 of the present invention.

FIG. 2 is a Scanning Electron Microscope (SEM) photograph of a synthesized product of example 3 of the present invention.

FIG. 3 is an XRD diffraction pattern of a synthesized product of comparative example 1 of the present invention.

Detailed Description

The following detailed description of the embodiments of the present invention is provided, but it should be noted that the scope of the present invention is not limited by the embodiments.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, including definitions, will control.

When the specification concludes with claims with the heading "known to those skilled in the art", "prior art", or the like, deriving materials, substances, methods, steps, etc., the subject matter that is derived from the heading encompasses those conventionally used in the art as proposed in the present application, but also includes those that are not currently in use, but would become known in the art to be suitable for a similar purpose.

The X-ray diffraction spectrum in the embodiment is measured by an X' Pert Powder X-ray diffractometer in the Pastinaceae family. The operating conditions were: CuK alpha target, tube current of 40 mA, tube voltage of 40 kV, and scanning range of 3-80^oAt a scanning speed of 5^o/min。

Scanning Electron microscopy in this example was carried out on a QUNATA200 FEG field emission electron scanning electron microscope, manufactured by KANTA, USA. Fixing the sample on a copper table by conductive adhesive, and using N₂Purging and performing evacuation measurement.

Example 1

Aluminum sheet, potassium hydroxide, silica sol (26.5% SiO)₂) SiO and water according to a molar ratio₂：Al₂O₃：KOH：H₂O =16.5:1:11.5:585.0 was added to the beaker, the HZSM-5 type molecular sieve was added in an amount of 9% by mass of the total mass of the initial gel mixture for synthesizing the SUZ-4 molecular sieve, and stirred for 2 hours,the solution is in a uniform state, is put into a reaction kettle and is placed at 150 ℃ for dynamic crystallization for 3 days (the rotating speed is 20 r/min). The reaction vessel was taken out and rapidly cooled to room temperature with cold water, and the resulting mixture was separated by filtration. And drying the obtained solid sample at 110 ℃ for 24 hours to obtain the SUZ-4 molecular sieve which does not contain mixed crystals and has relative crystallinity of 96%.

Example 2

Example 1 was repeated, but with white carbon black as the silicon source and with a reduced amount of deionized water. In this example, aluminum flake, potassium hydroxide, silica sol and water were mixed in a molar ratio of SiO₂：Al₂O₃：KOH：H₂O =27.5:1.5:12.8:765.0, the amount of the HZSM-5 type molecular sieve added is 6.5% of the total mass of the initial gel mixture for synthesizing the SUZ-4 molecular sieve, the mixture is stirred for 2 hours, the solution is in a uniform state, and the solution is placed in a reaction kettle and is dynamically crystallized for 2 days at 170 ℃ (the rotating speed is 20 r/min). Taking out the reaction kettle, rapidly cooling to room temperature with cold water, filtering and separating the obtained mixture, and drying at 110 ℃ for 24 hours to obtain the solid SUZ-4 molecular sieve which does not contain mixed crystals and has relative crystallinity of 98%.

Example 3

Example 1 was repeated, but using alumina as the aluminium source, alumina, potassium hydroxide, silica sol (26.5% SiO)₂) SiO and water according to a molar ratio₂：Al₂O₃：KOH：H₂Adding O =18.8:1.8:1:6.5:500.0 into a beaker, adding HZSM-5 type molecular sieve with the addition of 14% of the total mass of the initial gel mixture for synthesizing the SUZ-4 molecular sieve, stirring for 2 hours to form a uniform solution, placing the uniform solution into a reaction kettle, and placing the reaction kettle at 160 ℃ for dynamic crystallization for 3 days (the rotating speed is 20 r/min) to obtain the SUZ-4 molecular sieve without mixed crystals, wherein the relative crystallinity is 96%.

Example 4

Example 1 was repeated, but using white carbon black as the silicon source and alumina as the aluminum source. In this example, alumina, potassium hydroxide, silica and water are in a molar ratio of SiO₂：Al₂O₃：KOH：H₂O =20.0:1.5:5.5:900.0, in an amount of 7.5% by mass of the total mass of the initial gel mixture for synthesizing the SUZ-4 molecular sieve, was added to the beaker, and stirredAfter 2 hours, the solution is in a uniform state, is put into a reaction kettle and is placed at 180 ℃ for 2 days of dynamic crystallization (the rotating speed is 20 r/min), and the SUZ-4 molecular sieve without mixed crystals is obtained, and the relative crystallinity is 96 percent.

Example 5

Aluminum sheet, potassium hydroxide, white carbon black and water are mixed according to the mol ratio SiO₂：Al₂O₃：KOH：H₂Adding O =20.6:1.4:9.5:900.0 into a beaker, adding the HZSM-5 type molecular sieve with the addition amount being 6% of the total mass of the initial gel mixture for synthesizing the SUZ-4 molecular sieve, stirring for 2 hours to enable the solution to be in a uniform state, placing the solution into a reaction kettle, and standing the solution for static crystallization at 180 ℃ for 7 days to obtain the SUZ-4 molecular sieve without mixed crystals, wherein the relative crystallinity is 86%.

Comparative example 1

Example 1 was repeated, but dynamic crystallization was carried out for 7 days without adding HZSM-5 type molecular sieve. The resulting product was amorphous.

Comparative example 2

Example 1 was repeated, 12.68g of template tetraethylammonium hydroxide was added instead of the HZSM-5 type molecular sieve, dynamic crystallization was carried out for 4 days, and the obtained product was the SUZ-4 molecular sieve, containing no mixed crystals, and having a crystallinity of 98%.

Comparative example 3

Example 1 was repeated to change potassium hydroxide to sodium hydroxide, aluminum flake, sodium hydroxide, white carbon black and water to SiO in molar ratio₂：Al₂O₃：NaOH：H₂O =21.2:1:9.5:900.0 was added to a beaker and dynamic crystallized at 180 ℃ for 4 days to obtain the MOR molecular sieve.