阅读说明：本技术 一种改性分子筛的制备方法 (Preparation method of modified molecular sieve ) 是由 冯新 万俊杰 何锦强 杨创鑫 梁志澎 莫松斌 吴依霓 颜俊标 梁婉琪 江瑞龙 郑 于 2020-04-02 设计创作，主要内容包括：本发明公开了一种改性分子筛的制备方法,所述方法包括以下步骤：称量1.0g七水硫酸亚铁加入装有60mL蒸馏水的三口烧瓶中,加入60nl乙醇；搅拌均匀,在氮气的保护下,缓慢滴加2mol/L的硼氢化钠,加至过量,搅拌反应30min；加入3mL正硅酸乙酯,搅拌反应1h；再加入10mL正丁胺,搅拌反应1h；最后加入20mL甲苯和2mL硅烷或季铵盐溶液,搅拌反应6h-48h后获得。(The invention discloses a preparation method of a modified molecular sieve, which comprises the following steps of weighing 1.0g of ferrous sulfate heptahydrate, adding the ferrous sulfate heptahydrate into a three-neck flask filled with 60m L distilled water, adding 60nl of ethanol, stirring uniformly, slowly dropwise adding 2 mol/L of sodium borohydride under the protection of nitrogen until the sodium borohydride is excessive, stirring for reaction for 30min, adding 3m L of ethyl orthosilicate, stirring for reaction for 1h, adding 10m L of n-butylamine, stirring for reaction for 1h, finally adding 20m L of toluene and 2m L of silane or quaternary ammonium salt solution, and stirring for reaction for 6h-48h to obtain the modified molecular sieve.)

1. A method for preparing a modified molecular sieve, comprising the steps of:

s1 weighing 1.0g of ferrous sulfate heptahydrate, adding the ferrous sulfate heptahydrate into a three-neck flask filled with 60m L of distilled water, and adding 60nl of ethanol;

s2, stirring uniformly, slowly and dropwise adding 2 mol/L of sodium borohydride under the protection of nitrogen, adding the sodium borohydride to an excessive amount, and stirring to react for 30 min;

s3, adding 3m of ethyl orthosilicate L, and stirring to react for 1 h;

s4, adding 10m L n-butylamine, and stirring to react for 1 h;

s5, finally adding 20m of L of toluene and 2m of L of silane or quaternary ammonium salt solution, and stirring for reaction for 6-48 h.

2. The method of claim 1, wherein the silane is one of dimethyldimethoxysilane, vinyltriethoxysilane or vinyltrimethoxysilane.

3. The method of claim 1, wherein the quaternary ammonium salt is methacryloyloxyethyl trimethyl ammonium chloride, cetyl trimethyl ammonium bromide, or tetraethyl ammonium chloride.

4. The method for preparing modified molecular sieve of claim 2, wherein the silane is dimethyldimethoxysilane, the stirring time is 0.5m L and the stirring time is 9h, the silane is vinyltriethoxysilane, the stirring time is 1.5m L and the stirring time is 9h, and the silane is vinyltrimethoxysilane, the stirring time is 2.0m L and the stirring time is 48 h.

5. The method for preparing modified molecular sieve of claim 3, wherein the quaternary ammonium salt is methacryloyloxyethyl trimethyl ammonium chloride, and the stirring time is 2.0m L, and the stirring time is 48h, the quaternary ammonium salt is cetyl trimethyl ammonium bromide, and the stirring time is 3.0m L, and the stirring time is 6h, and the quaternary ammonium salt is tetraethylammonium chloride, and the stirring time is 0.5m L, and the stirring time is 48 h.

Technical Field

The invention relates to the technical field of molecular sieve preparation, in particular to a preparation method of a modified molecular sieve.

Background

Nanometer zero-valent iron (nZVI) is widely used for removing various environmental pollutants such as heavy metals (cadmium, arsenic, cobalt, zinc, chromium, copper, lead, uranium and the like), organic matters (mainly halogenated organic matters, dyes and pesticides) and inorganic matters (nitrate, bromate, high aluminate and the like) due to small particle size, large specific surface area, good adsorbability and strong reducibility.

However, the following problems exist in the practical application of the nano-iron: (1) physical and chemical properties: easy oxidation and easy particle agglomeration (poor dispersibility), resulting in a decrease in reactivity. (2) In the application aspect: the selectivity is poor. Because the nZVI can remove various pollutants in an adsorption and reduction mode, and the adsorption and reduction degradation functions of the nZVI can be applied to various pollutants without specific selectivity, the nZVI is interfered and limited by coexisting substances existing in a matrix when used for treating the pollutants difficult to degrade, and the application is influenced due to the fact that the dosage is too large and unnecessary waste occurs.

To solve the above problems, the improvement of the nZVI function is achieved by adding a modifier. The main method comprises (1) wrapping nZVI with organic matter, which proves that the dispersion and reduction effect of nZVI are greatly improved. (2) The development of bimetallic nZVI can effectively improve the reduction efficiency of nZVI. (3) The nZVI is loaded on a specific carrier, so that the dispersity of the nZVI is improved. (4) The nZVI is coated by the mesoporous material, so that the dispersibility and the selective adsorption to target pollutants are improved.

The molecular sieve is a silicon-oxygen tetrahedron (SiO)₄)^4-]And alundum tetrahedron [ (AIO)₄)^5-]Is a primary structural unit and is arranged according to a certain rule to form the crystal framework material with a regular pore channel structure. The molecular sieve has large specific surface area, uniform aperture and good shape-selective catalysis, and is widely applied to the fields of chemical catalysis, adsorption separation and the like. Research shows that the surface modification of the molecular sieve on the nanometer scale is proved to be an effective method for endowing the molecular sieve with selective adsorption function.

Wang et Al load Al in the mesoporous molecular sieve SBA-5 by vacuum self-assembly method, change its Si/Al ratio, get A L-SBA-5 mesoporous molecular sieve with high specific surface area and narrow particle size distribution, change Si/Al ratio in the molecular sieve, thus can modify the pore canal and space structure of the molecular sieve, improve its hydrophilic and hydrophobic properties, pore wall structure and surface area, make the molecular sieve have special space structure, make the selectivity of the molecular sieve different, make the molecular sieve have specific function.

Disclosure of Invention

The invention discusses a preparation method of the modified molecular sieve, and the performance of the modified molecular sieve is improved by optimizing the addition amount of silane and quaternary ammonium salt and the stirring time.

Furthermore, the active substance nano-iron material is coated in the center by virtue of the mesoporous silicon-based molecular sieve to form a core-shell structure, and molecules or ions with different sizes are controlled by virtue of the mesoporous silicon-based molecular sieve with controllable and regular pore channels to enter the core through the pore channels to complete the chemical reaction with the nano-iron, so that the selective permeation degradation of the molecules and ions with different sizes is realized; meanwhile, hydroxyl groups which are easy to be crosslinked and modified are arranged in the pore canal and on the surface of the mesoporous material, alkyl modification is carried out in the pore canal and on the surface of the mesoporous material, so that the mesoporous material can inhibit hydrophilic substances, and only hydrophobic substances are allowed to carry out degradation reaction with nano iron through the mesoporous material. Compared with other inventions and researches, the water treatment agent has higher permeability to hydrophobic molecules and ions with certain sizes, and the interference of hydrophilic matrix substances is removed, so that the water treatment agent is more favorable for being applied to adsorption degradation and removal of micro hydrophobic organic matters in water.

In order to achieve the purpose, the technical scheme includes that the preparation method of the modified molecular sieve comprises the following steps of S1 weighing 1.0g of ferrous sulfate heptahydrate, adding 60nl of ethanol into a three-neck flask containing 60m L of distilled water, S2 stirring uniformly, slowly and dropwise adding 2 mol/L of sodium borohydride under the protection of nitrogen, adding the mixture to an excess amount, stirring for reaction for 30min, S3 adding 3m L of ethyl orthosilicate, stirring for reaction for 1h, S4 adding 10m L of n-butylamine, stirring for reaction for 1h, S5 finally adding 20m L of toluene and 2m L of silane or a quaternary ammonium salt solution, and stirring for reaction for 6h to 48h to obtain the modified molecular sieve, preferably, the silane is one of dimethyl dimethoxy silane, vinyl triethoxy silane or vinyl trimethoxy silane, preferably, the quaternary ammonium salt is methacryloyloxyethyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium bromide and tetraethyl, preferably, when the silane is dimethyl dimethoxy silane, 0.5m of vinyl triethoxy silane or vinyl trimethoxy silane, and when the vinyl 639 h of the vinyl trimethoxy silane is added, and the stirring for reaction time is L h, and the vinyl 639 h of ammonium chloride is 2.9 h.

Preferably, 2.0m L is added and the stirring time is 48h when the quaternary ammonium salt is methacryloyloxyethyl trimethyl ammonium chloride, 3.0m L is added and the stirring time is 6h when the quaternary ammonium salt is cetyl trimethyl ammonium bromide, and 0.5m L is added and the stirring time is 48h when the quaternary ammonium salt is tetraethyl ammonium chloride.

Drawings

FIG. 1 shows the preparation of molecular sieves with different Si/Al ratios according to the present invention, in which the stirring time is related to Cr⁶⁺Removing the influence test chart;

FIG. 2 shows the volume ratio of different hydroalcoholic solutions to Cr according to the present invention⁶⁺Removing the influence test chart;

FIG. 3 shows different amounts of NaOH added versus Cr according to the present invention⁶⁺Removing the influence test chart;

FIG. 4 shows the different amounts of dodecylamine added versus Cr in accordance with the present invention⁶⁺Removing the influence test chart;

FIG. 5 shows different amounts of isopropanolamine added to Cr⁶⁺Removing the influence test chart;

FIG. 6 shows different amounts of tetramethylethylenediamine added to Cr⁶⁺The removed influence is tested.

FIG. 7 is a graph showing the removal rate of hexavalent chromium by adding a molecular sieve prepared by adding tetraethylammonium chloride and stirring for 48 hours according to the present invention;

FIG. 8 is a graph showing the removal rate of hexavalent chromium by the molecular sieve prepared by adding vinyltriethoxysilane according to the present invention;

FIG. 9 is a graph showing the removal rate of hexavalent chromium by the molecular sieve prepared by adding vinyltrimethoxysilane according to the present invention;

FIG. 10 is a graph showing the removal rate of hexavalent chromium in a molecular sieve prepared by adding methacryloyloxyethyl trimethyl ammonium chloride according to the present invention;

FIG. 11 is a graph showing the removal rate of hexavalent chromium by using the molecular sieve prepared by adding cetyltrimethylammonium bromide according to the present invention;

FIG. 12 is a test chart of the removal rate of hexavalent chromium by the molecular sieve prepared by adding tetraethylammonium chloride.

Detailed Description

The present invention will be further described with reference to the accompanying drawings, and it should be noted that the following examples are provided to illustrate the detailed embodiments and specific operations based on the technical solutions of the present invention, but the scope of the present invention is not limited to the examples.

The invention relates to a preparation method of a modified molecular sieve, which comprises the following steps of S1 weighing 1.0g of ferrous sulfate heptahydrate, adding 60nl of ethanol into a three-neck flask containing 60m L of distilled water, S2 stirring uniformly, slowly adding 2 mol/L mol of sodium borohydride dropwise under the protection of nitrogen gas until the sodium borohydride is excessive, stirring and reacting for 30min, S3 adding 3m L of ethyl orthosilicate, stirring and reacting for 1h, S4 adding 10m L of n-butylamine, stirring and reacting for 1h, S5 finally adding 20m L of toluene and 2m L of silane or a quaternary ammonium salt solution, and stirring and reacting for 6h to 48h to obtain the modified molecular sieve, wherein the silane is preferably one of dimethyl dimethoxy silane, vinyl triethoxy silane or vinyl trimethoxy silane, the quaternary ammonium salt is preferably methacryloyloxyethyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium bromide and tetraethyl ammonium chloride, the silane is preferably 0.5m L when the silane is dimethyl dimethoxy silane, the stirring time is 9h, the vinyl triethoxy silane is preferably 0.9 h, and the vinyl 639 h is 0.2 h when the vinyl trimethoxy silane is added, and the vinyl 632 h is L h, and the vinyl L h is added when the vinyl trimethoxy silane is added.

Preferably, 2.0m L is added and the stirring time is 48h when the quaternary ammonium salt is methacryloyloxyethyl trimethyl ammonium chloride, 3.0m L is added and the stirring time is 6h when the quaternary ammonium salt is cetyl trimethyl ammonium bromide, and 0.5m L is added and the stirring time is 48h when the quaternary ammonium salt is tetraethyl ammonium chloride.