Synthesis method of petal-shaped mordenite

Abstract

The invention discloses a synthesis method of petal-shaped mordenite, which is characterized in that under the condition of not using a template agent, C-type silica gel is used as a silicon source, sodium hydroxide is used as an alkali source, and the mordenite is obtained through the steps of batching, crystallization, solid-liquid separation, washing, drying and roasting under the condition of adding an assistant ammonium acetate. The mordenite synthesized by the method is petal-shaped in crystal appearance, crystallized materials are easy for solid-liquid separation, the raw materials are low in price, and industrial production is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of molecular sieve material preparation and relates to a method for synthesizing petal-shaped mordenite. Background Art

[0002] Mordenite (MOR) is a silica-alumina zeolite molecular sieve. In its crystal structure, a large number of double five-membered rings are connected by oxygen bridges to form four-membered rings. Along the c-axis direction of MOR, there are two straight channels, twelve-membered rings and eight-membered rings. These two channels are parallel to each other and interconnected through the eight-membered ring side pockets along the b-axis direction. The diameter of the twelve-membered ring channel is 0.67×0.70nm, and the diameter of the eight-membered ring side pocket is 0.34×0.48 nm. The pore structure and special topological structure of 8-MR have unique catalytic activity for carbonylation reactions. MOR has excellent heat resistance, acid resistance and water vapor resistance. It is widely used as an adsorbent for separation of gas or liquid mixtures in industry. Acidic mordenite is often used as a catalyst for catalytic reactions such as isomerization, alkylation, and transalkylation. Mordenite can also be used as a catalyst carrier, such as the preparation of Ti-MOR for oximation reactions.

[0003] Nowadays, more and more research is being carried out around MOR molecular sieves, mainly focusing on metal modification, morphology, pore regulation, acid distribution regulation and other aspects of MOR molecular sieves.

[0004] Patent document with publication number CN107963637A uses hexadecyl N-dimethylethyl-N,N-dimethylammonium bromide as a template and obtains a sheet-like mordenite molecular sieve with a thickness of 10-40nm in the c-axis direction through dynamic hydrothermal synthesis. Beatriz et al. synthesized nano-needle-shaped mordenite molecular sieves by directly adjusting the synthesis parameters under template-free conditions. The basic grain width is 63 nm and the length is 240nm. Li Xiaofeng et al. used the synthesis strategy of solid-phase in-situ crystallization to prepare small-grain mordenite with novel morphology. The morphology is completely different from the regular grain morphology synthesized by hydrothermal method. The sample has irregular strip-shaped grains with a particle size of 100-500 nm and 10-30μm ellipsoidal particles formed by their accumulation. The patent document with the publication number CN 1847046A obtains spherical aggregates of mordenite with an average size of 42-90nm by adding seed crystals, using sodium chloride or sodium sulfate metal salt as an additive, aging at 100°C and hydrothermal crystallization at 130-150°C. The patent document with the publication number CN102060308A hydrothermally synthesizes fibrous mordenite with a C axis length of 1-8μm and a width of 20-100nm at 130-200°C by adding seed crystals and adding inorganic acid. R.Ryoo et al. use special quaternary ammonium salts as templates to synthesize nanorod-shaped and sheet-shaped mordenite respectively. The Chinese patent document with the publication number CN111573691A discloses a flower-shaped mordenite, which first ages the gel mixture formed by mixing the raw materials at room temperature, then adds seed crystals to the gel mixture for hydrothermal crystallization, and successfully obtains flower-shaped mordenite with a flower-shaped cluster morphology formed by the aggregation of nanorod-shaped crystals. This method must use a template and a cationic surfactant as a growth modifier. A Chinese patent document with publication number CN112850738A discloses a method for preparing petal-shaped clinoptilolite, wherein a petal-shaped zeolite is obtained by adding a non-ionic surfactant and a seed.

[0005] In summary, the shape control of mordenite usually requires the addition of templates, surfactants or additives, and there is no clear rule for the effect of different additives on the shape of mordenite. The study of obtaining a specific shape of mordenite by using different additives is of great significance for expanding the morphology of mordenite and studying the catalytic performance of mordenite with different morphologies. Summary of the invention

[0006] The present invention provides a method for synthesizing petal-shaped mordenite. In the case of not using a template agent, the mordenite is synthesized by adding an auxiliary agent ammonium acetate, the crystal morphology is petal-shaped, the crystallized material is easy to separate solid from liquid, the raw material price is low, and it is convenient for industrial production. The synthesized mordenite can be used to prepare a Ti-MOR catalyst.

[0007] In order to achieve the above purpose and effect, the following scheme is adopted: A method for synthesizing petal-shaped mordenite is characterized in that, under the condition of adding auxiliary agent ammonium acetate, C-type silica gel is used as a silicon source, sodium hydroxide is used as an alkali source, and an aluminum source is mixed to obtain a mixture to be crystallized, and the mixture is subjected to a crystallization reaction at 180-190° C. for 20-30 hours to synthesize the mordenite.

[0008] The mass ratio of each material in the mixture to be crystallized is silicon oxide: aluminum oxide: sodium oxide: ammonium acetate: water = 1: 0.08~0.15: 0.2~0.3: 0.01~0.02: 5~8.

[0009] A specific method for synthesizing petal-shaped mordenite, the specific preparation steps are as follows: (1) After deionized water and sodium hydroxide are mixed and dissolved, ammonium acetate is added under stirring; (2) adding aluminum source and type C silica gel in sequence and stirring for 30 to 60 minutes to obtain a mixture to be crystallized; (3) The materials are loaded into the crystallization kettle, heated to 180-190°C, and kept warm for 20-30 hours; (4) After the insulation is completed, the temperature is lowered, the kettle is taken out, the solid and liquid are separated, the zeolite is washed with water until it is neutral, and then dried and roasted to obtain the mordenite.

[0010] The drying temperature of step 4 is 100-120°C, the roasting temperature is 500-520°C, and the roasting time is 5-10 h.

[0011] Furthermore, in the above-mentioned method for synthesizing mordenite, the mass ratio of the materials in the mixture to be crystallized is silicon oxide: aluminum oxide: sodium oxide: ammonium acetate: water = 1: 0.08~0.15: 0.2~0.3: 0.01~0.02: 5~8.

[0012] Furthermore, in the above-mentioned method for synthesizing mordenite, the aluminum source is one of aluminum oxide powder and sodium aluminate.

[0013] The present invention provides a mordenite synthesized by the above method.

[0014] The present invention provides that the mordenite can be used for preparing Ti-MOR catalyst.

[0015] The Ti-MOR catalyst is used in catalyzing the oximation reaction of cyclohexanone.

[0016] Beneficial effects of the present invention: The present invention provides a method for synthesizing petal-shaped mordenite. In the method, a petal-shaped mordenite is synthesized by adding an auxiliary agent, ammonium acetate, without using a template agent. The Ti-MOR catalyst prepared by the petal-shaped mordenite can reach the catalytic level of the existing Ti-MOR catalyst in catalyzing the oximation reaction of cyclohexanone. The synthesis method of the present invention has a simple process, cheap raw materials, and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the XRD spectrum of mordenite MOR-1; Figure 2 is the SEM picture of mordenite MOR-1; Figure 3 is the XRD spectrum of mordenite MOR-5; Figure 4 is the SEM picture of mordenite MOR-5; Figure 5 is the SEM picture of mordenite MOR-D1; Figure 6 is the SEM picture of mordenite MOR-D2; Figure 7 This is the SEM picture of mordenite MOR-D3. DETAILED DESCRIPTION

[0018] The present invention is further described in the following examples, but the present invention is not limited thereto.

[0019] The materials used in the examples are all industrial products.

[0020] Type C silica gel (100 mesh, silica content 95%) was purchased from Shandong Xinhua Silica Gel Co., Ltd.

[0021] Alumina powder (alumina content 70%) was purchased from Yangzhou Zhongtianli New Materials Co., Ltd.

[0022] Sodium aluminate (alumina content 50%, sodium oxide content 40%) was purchased from Zibo Tongjie Chemical Co., Ltd.

[0023] Sodium hydroxide (purity greater than 99%) was purchased from Dalian Shengjia Chemical.

[0024] The XRD characterization of the catalyst was measured by an X-ray diffraction analyzer (PANalytical, X'Pert3 Powder).

[0025] Scanning electron microscopy (SEM) characterization of the catalysts was measured by scanning electron microscope (Hitachi, SU5000). Example 1

[0026] After 134.9g of deionized water and 6.5g of sodium hydroxide were mixed and dissolved, 0.3g of ammonium acetate was added under stirring. After the ammonium acetate was dissolved, 3.3g of alumina powder (alumina content 70%, the same below) and 21g of C-type silica gel (100 mesh, silica content 95%, the same below) were added in sequence and stirred for 30min. The above mixture was placed in a 200ml crystallization kettle, heated to 185℃ and kept warm for 30h. After the end of the insulation, the temperature was lowered, the kettle was taken out, the solid-liquid separation was carried out, and the water was washed until neutral, dried at 100℃, and roasted at 500℃ for 6h to obtain mordenite, which was recorded as MOR-1.

[0027] The XRD spectrum and SEM photos of sample MOR-1 are attached. Figure 1 and attached Figure 2 . Example 2

[0028] After 148.2g of deionized water and 7.4g of sodium hydroxide were mixed and dissolved, 0.2g of ammonium acetate was added under stirring. After the ammonium acetate was dissolved, 2.28g of alumina powder and 21g of C-type silica gel were added in sequence and stirred for 30min. The above mixture was placed in a 200ml crystallization kettle, heated to 180℃ and kept warm for 30h. After the end of the heat preservation, the temperature was lowered, the kettle was taken out, the solid and liquid were separated, and the water was washed until neutral, dried at 100℃, and roasted at 500℃ for 6h to obtain mordenite, which was recorded as MOR-2. Example 3

[0029] After 119.7 g of deionized water and 6.1 g of sodium hydroxide were mixed and dissolved, 0.3 g of ammonium acetate was added under stirring. After the ammonium acetate was dissolved, 4.1 g of alumina powder and 21 g of C-type silica gel were added in sequence and stirred for 30 min. The above mixture was placed in a 200 ml crystallization kettle, heated to 185 ° C and kept warm for 28 h. After the end of the heat preservation, the temperature was lowered, the kettle was taken out, the solid and liquid were separated, and the water was washed until neutral, dried at 100 ° C, and roasted at 500 ° C for 6 h to obtain mordenite, which was recorded as MOR-3. Example 4

[0030] After 134.9g of deionized water and 6.5g of sodium hydroxide were mixed and dissolved, 0.399g of ammonium acetate was added under stirring. After the ammonium acetate was dissolved, 3.3g of alumina powder and 21g of C-type silica gel were added in sequence and stirred for 30min. The above mixture was placed in a 200ml crystallization kettle, heated to 190℃ and kept warm for 20h. After the end of the heat preservation, the temperature was lowered, the kettle was taken out, the solid-liquid separation was carried out, and the water was washed until neutral, dried at 100℃, and roasted at 500℃ for 6h to obtain mordenite, which was recorded as MOR-4. Example 5

[0031] After 134.9g of deionized water and 4.2g of sodium hydroxide were mixed and dissolved, 0.3g of ammonium acetate was added under stirring. After the ammonium acetate was dissolved, 4.6g of sodium aluminate (alumina content 50%, sodium oxide content 40%) and 21g of C-type silica gel were added in sequence and stirred for 30min. The above mixture was placed in a 200ml crystallization kettle, heated to 185℃ and kept warm for 30h. After the insulation was completed, the temperature was lowered, the kettle was taken out, the solid-liquid separation was carried out, and the water was washed until neutral, dried at 100℃, and roasted at 500℃ for 6h to obtain mordenite, which was recorded as MOR-5.

[0032] The XRD spectrum and SEM photos of sample MOR-5 are attached. Figure 3 and attached Figure 4 .

[0033] Comparative Example 1: After 134.9g of deionized water and 6.5g of sodium hydroxide were mixed and dissolved, 3.3g of alumina powder and 21g of C-type silica gel were added in sequence and stirred for 30min. The above mixture was placed in a 200ml crystallization kettle, heated to 185℃ and kept warm for 30h. After the end of the warming, the mixture was cooled, removed from the kettle, solid-liquid separation was performed, washed with water until neutral, dried at 100℃, and calcined at 500℃ for 6h to obtain mordenite, which was recorded as MOR-D1.

[0034] See the attached SEM photo of sample MOR-D1 Figure 5 .

[0035] Comparative Example 2: After 89.4g of deionized water and 4.2g of sodium hydroxide were mixed and dissolved, 0.3g of ammonium acetate was added under stirring. After the ammonium acetate was dissolved, 4.6g of sodium aluminate and 66.5g of silica sol (silicon oxide content 30%) were added in sequence and stirred for 30min. The above mixture was placed in a 200ml crystallization kettle, heated to 185℃ and kept warm for 30h. After the insulation was completed, the temperature was lowered, the kettle was taken out, the solid-liquid separation was carried out, and the water was washed until neutral, dried at 100℃, and roasted at 500℃ for 6h to obtain mordenite, which was recorded as MOR-D2.

[0036] See the attached SEM photo of sample MOR-D2 Figure 6 .

[0037] Comparative Example 3: After 134.9g of deionized water and 6.5g of sodium hydroxide were mixed and dissolved, 0.3g of ammonium acetate was added under stirring. After the ammonium acetate was dissolved, 3.3g of alumina powder and 21g of C-type silica gel were added in sequence and stirred for 30min. The above mixture was placed in a 200ml crystallization kettle, heated to 170℃ and kept warm for 30h. After the end of the heat preservation, the temperature was lowered, the kettle was taken out, the solid-liquid separation was carried out, and the water was washed until neutral, dried at 100℃, and roasted at 500℃ for 6h to obtain mordenite, which was recorded as MOR-D3.

[0038] See attached for the SEM photo of sample MOR-D3 Figure 7 .

[0039] Application examples: The uncalcined sample MOR-1 of Example 1 of the present application was used as a raw material, and the ammonium exchange, deep dealumination and Ti-MOR parent synthesis steps in Example 1 of the patent document CN 104310425 B (using the sodium type product in the sample replacement step of the present application) were referred to prepare a Ti-MOR catalyst. The obtained Ti-MOR catalyst was used to catalyze the ammoximation reaction of cyclohexanone. The specific implementation process of the catalytic reaction and the equipment used were referred to the patent document CN205562489U. The reactant ratio and the device were the same as those in Example 1 of this patent document CN205562489U. After the reaction was carried out for 6 hours, the sample was taken for analysis. The conversion rate of cyclohexanone catalyzed by the Ti-MOR catalyst prepared in this example reached 99.58%, and the chromaticity of the reaction solution was 42.2.

Claims

1. A method for synthesizing petal-shaped mordenite, characterized in that: Under the condition of adding auxiliary agent ammonium acetate, C-type silica gel is used as silicon source, sodium hydroxide is used as alkali source, and the mixture to be crystallized is mixed with aluminum source at 180-190°C for 20-30h to synthesize mordenite; The mass ratio of each material in the mixture to be crystallized is silicon oxide: aluminum oxide: sodium oxide: ammonium acetate: water = 1: 0.08~0.15: 0.2~0.3: 0.01~0.02: 5~8.

2. The method for synthesizing petal-shaped mordenite according to claim 1, characterized in that: The specific preparation steps are as follows: (1) After deionized water and sodium hydroxide are mixed and dissolved, ammonium acetate is added under stirring; (2) adding aluminum source and type C silica gel in sequence and stirring for 30 to 60 minutes to obtain a mixture to be crystallized; (3) The materials are loaded into the crystallization kettle, heated to 180-190°C, and kept warm for 20-30 hours; (4) After the insulation is completed, the temperature is lowered, the kettle is taken out, the solid and liquid are separated, the zeolite is washed with water until it is neutral, dried, and roasted to obtain the mordenite.

3. The method for synthesizing petal-shaped mordenite according to claim 1, characterized in that: The drying temperature of step 4 is 100-120°C, the roasting temperature is 500-520°C, and the roasting time is 5-10 h.

4. The method for synthesizing petal-shaped mordenite according to claim 2, characterized in that: The aluminum source is one of aluminum oxide powder and sodium aluminate.

5. A mordenite synthesized by the method according to any one of claims 1 to 4.

6. A Ti-MOR catalyst, characterized in that The mordenite according to claim 5 is used to prepare the zeolite.

7. Use of the Ti-MOR catalyst according to claim 6 in catalyzing oximation of cyclohexanone.

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