Method for preparing mesoporous zeolite under normal pressure and mild conditions and application thereof

Abstract

The application discloses a method for preparing mesoporous zeolite under normal temperature and pressure and application thereof, and the preparation method comprises the following steps: (1) preparation of a functional protein biomodule: cationic polypeptide is loaded on yeast to obtain a biomodule aqueous solution; (2) deposition of silicon and aluminum: the pH of the biomodule solution obtained in the step (1) is adjusted to neutral, then a silicon source, an aluminum source and a titanium source are added into the solution, and the solution is incubated on a shaking table for 3 days; (3) calcination: the solid obtained in the step (2) is collected by centrifugation, washed with ethanol and water alternately for 3 times, and calcined at 500 DEG C for 4h under an air atmosphere to obtain a zeolite molecular sieve adsorption material. The application can prepare porous molecular sieve small balls by using a simple method, and can provide a brand-new thought for synthesizing molecular sieve materials.

Description

A method for preparing mesoporous zeolites under normal pressure and mild conditions and its application Technical Field

[0001] This invention relates to the field of inorganic material synthesis technology, and in particular to a method for preparing mesoporous zeolite under normal pressure and mild conditions and its application. Background Technology

[0002] Zeolite molecular sieves have attracted increasing attention due to their high specific surface area, large pore size, and ease of surface functionalization, and are widely used in catalyst supports, separation materials, biomedicine, and many other fields. Volatile organic compounds (VOCs) generally refer to easily volatile organic compounds with boiling points between 50-260℃, posing serious health and ecological risks to humans and the environment. The tobacco processing route in tobacco factories is long, involving multiple steps such as adding sugar and flavoring. The complex chemical composition of tobacco, flavorings, and sugars causes VOC odor problems in tobacco processing workshops. Treating VOCs can improve air quality in production workshops, which is of great and far-reaching significance for the large number of employees in the industry.

[0003] Zeolite molecular sieve adsorption is a common method for treating VOCs. Zeolite molecular sieves have a silicon-oxygen or aluminum-oxygen tetrahedral framework structure. Traditional methods typically synthesize them from inorganic materials such as silica sol and aluminum sulfate under alkaline conditions via hydrothermal crystallization. For example, patents CN103848439 and CN106185977B disclose a method for synthesizing ZSM-5 molecular sieves, using natural minerals as silicon and aluminum sources, and carrying out a crystallization reaction under hydrothermal conditions to obtain the product ZSM-5. The crystallinity and silicon-aluminum ratio of the molecular sieve are adjustable. However, current technologies all require pressurized and high-temperature conditions, posing challenges to production equipment and safety. Therefore, developing a process technology for preparing molecular sieves under normal pressure and temperature is of great significance.

[0004] Cationic peptides are a class of bio-inspired peptide sequences that, due to their unique nucleophilicity and biocatalytic effects, can be used to prepare inorganic silica materials. For example, silicin in sponges and silicophilic proteins in diatoms both possess the ability to catalyze the synthesis of silica. However, there are few reports on the technology of synthesizing molecular sieves using cationic peptides under normal pressure. Since cell surfaces are negatively charged, cationic peptides can be adsorbed onto the cell surface through layer-by-layer electrostatic assembly, forming biological templates that are beneficial for the preparation of zeolite microspheres. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and application for preparing mesoporous zeolite under normal pressure and mild conditions. It overcomes the shortcomings of the prior art by utilizing the nucleophilic attack ability and biocatalytic effect of functional cationic polypeptides, combined with yeast as a template, to synthesize porous molecular sieve microspheres with uniform particle size and controllable size under normal pressure and mild conditions for the concentration of VOCs gas.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solution:

[0007] A method for preparing mesoporous zeolites under normal pressure and mild conditions includes the following steps:

[0008] (1) Preparation of functional protein biological templates: Cationic peptides were loaded onto yeast to obtain an aqueous solution of biological templates;

[0009] (2) Deposition of silicon and aluminum: The pH of the biotemplate solution obtained in step (1) was adjusted to neutral, and then the silicon source, aluminum source and titanium source were added to the above solution and incubated on a shaker for 3 days;

[0010] (3) Calcination: The solid obtained in step (2) is collected by centrifugation, washed three times with alternating ethanol and water, and then calcined at 500°C for 4 hours in air atmosphere to obtain zeolite molecular sieve adsorbent material.

[0011] Preferably, in step (1), the cationic polypeptide sequence is SSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRI.

[0012] Preferably, in step (1), the cationic polypeptide is loaded onto yeast by physical adsorption or chemical grafting.

[0013] Preferably, in step (2), the silicon source is tetraethyl orthosilicate or tetramethyl orthosilicate, and the aluminum source is a soluble aluminum salt composed of trivalent aluminum ions and acid radical anions.

[0014] Preferably, in step (2), the molar ratio of the silicon source, aluminum source and titanium source is (500~75):(15~35):(1-5).

[0015] Preferably, in step (2), the silicon and aluminum precursors are added in one or more of the following ways: one-time addition, slow dripping, or batch addition in equal amounts.

[0016] The above-described technical solution of the present invention has the following beneficial effects:

[0017] (1) This invention uses a biomimetic cationic polypeptide sequence to achieve the preparation of porous molecular sieves under normal pressure and temperature and aqueous phase conditions in a simple way, without the use of additional surfactants and catalysts, which has the advantages of being green and low-consumption.

[0018] (2) The present invention yields porous zeolite molecular sieve microspheres with controllable particle size and adjustable specific surface area, and the dispersion is relatively uniform and the mechanical strength is high.

[0019] (3) This invention does not require acids, bases or other organic solvents, the post-processing is simple, it is more green and environmentally friendly, and the energy consumption is low.

[0020] (4) The molecular sieve prepared by the present invention has excellent concentration effect on VOCs such as toluene and xylene. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0022] Figure 1 is a SEM image of the zeolite microspheres prepared in Example 1;

[0023] Figure 2 shows the BET curve of the zeolite microspheres prepared in Example 1;

[0024] Figure 3 shows the BET curve of the zeolite microspheres prepared in Example 2;

[0025] Figure 4 shows the BET curve of the zeolite microspheres prepared in Example 3. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0027] All experimental instruments and reagents used in the following examples are commercially available.

[0028] Example 1

[0029] Preparation of functional protein biological templates: The cationic polypeptide SSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRI was dissolved in 5 mM phosphate buffer, yeast was added, and the OD value was controlled at 1.0 and pH 7.4. After incubation for 2 h, an aqueous solution of the biological template was obtained.

[0030] Deposition of silicon and aluminum: 10 mL of the above-obtained biological template aqueous solution was added to 3.3 mL of tetraethyl orthosilicate, 1 mL of aluminum isopropoxide, and 0.5 mL of tetrabutyl titanate. The mixture was incubated on a shaker for 3 days. After centrifugation, a solid was obtained, which was washed three times alternately with ethanol and water. The solid was then calcined at 400 °C for 4 h in air to obtain the zeolite molecular sieve adsorbent material (Figure 1). BET experiments showed that its specific surface area was approximately 450 m². 2 / g (Figure 2). This material is designated as sample number 1.

[0031] Example 2

[0032] Preparation of functional protein biological templates: The cationic polypeptide SSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRI was dissolved in 5 mM phosphate buffer, yeast was added, the OD value was controlled at 1.0 and pH at 7.4, 5 mM dopamine was added, and the mixture was incubated for 2 h to obtain an aqueous solution of the biological template.

[0033] Deposition of silicon and aluminum: 10 mL of the above-obtained biological template aqueous solution was added to 3.3 mL of tetraethyl orthosilicate, 1 mL of aluminum isopropoxide, and 0.5 mL of tetrabutyl titanate. The mixture was incubated on a shaker for 3 days. After centrifugation, a solid was obtained, which was washed three times alternately with ethanol and water. The solid was then calcined at 500 °C for 4 h in air to obtain the zeolite molecular sieve adsorbent material (Figure 1). BET experiments showed that its specific surface area was approximately 660 m². 2 / g (Figure 3). This material is designated as sample number 2.

[0034] Example 3

[0035] Preparation of functional protein biological templates: The cationic polypeptide SSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRI was dissolved in 5 mM phosphate buffer, yeast was added, and the OD value was controlled at 1.0 and pH 7.4. After incubation for 2 h, an aqueous solution of the biological template was obtained.

[0036] Deposition of silicon and aluminum: 10 mL of the above-obtained biological template aqueous solution was added to 3.3 mL of tetraethyl orthosilicate, 1 mL of aluminum isopropoxide, and 0.5 mL of tetrabutyl titanate. The mixture was incubated on a shaker for 3 days. After centrifugation, a solid was obtained, which was washed three times alternately with ethanol and water. The solid was then calcined at 600 °C for 4 h in air to obtain the zeolite molecular sieve adsorbent material (Figure 1). BET experiments showed that its specific surface area was approximately 1226 m². 2 / g (Figure 4). This material is designated as sample number 3.

[0037] The three zeolite samples prepared in Examples 1-3 were used for VOCs gas adsorption, with commercial zeolite 5A molecular sieve (purchased from Zhuoran Environmental Protection Technology Co., Ltd.) used as a control group. The results showed that the three samples prepared in this patent all had excellent VOCs gas adsorption performance, significantly higher than that of commercial molecular sieves.

[0038] Table 1. Adsorption effects of the three zeolite samples prepared in Examples 1-3 on benzene, methanol, and n-hexane.

[0039]

[0040] This invention utilizes a simple method to prepare porous molecular sieve microspheres, providing a novel approach for the synthesis of molecular sieve materials.

[0041] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various different choices and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing mesoporous zeolites under normal pressure and mild conditions, characterized in that, Includes the following steps: (1) Preparation of functional protein biotemplate: The cationic polypeptide with the sequence: SSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSKRRILSSKKSGSYSGSKGSK RRI was loaded onto yeast by physical adsorption or chemical grafting to obtain an aqueous biotemplate solution; (2) Deposition of silicon and aluminum: The pH of the biotemplate solution obtained in step (1) was adjusted to neutral, and then silicon source, aluminum source and titanium source with a molar ratio of (500~75):(15~35):(1-5) were added to the above solution and incubated on a shaker for 3 days; (3) Calcination: The solid obtained in step (2) is collected by centrifugation, washed three times with ethanol and water alternately, and then calcined at 600°C for 4 hours in air atmosphere to obtain zeolite molecular sieve adsorbent material.

2. The method for preparing mesoporous zeolite under normal pressure and mild conditions according to claim 1, characterized in that, In step (2), the silicon source is tetraethyl orthosilicate or tetramethyl orthosilicate, and the aluminum source is a soluble aluminum salt composed of trivalent aluminum ions and acid radical anions.

3. The method for preparing mesoporous zeolite under normal pressure and mild conditions according to claim 1, characterized in that, In step (2), the silicon and aluminum precursors are added in one or more of the following ways: one-time addition, slow drop addition, or batch addition in equal amounts.

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