阅读说明：本技术 一种丝光沸石分子筛的制备方法 (Preparation method of mordenite molecular sieve ) 是由 裴仁彦 杨冬荣 吕新新 夏春晖 赵文广 任晓光 于 2019-10-18 设计创作，主要内容包括：本申请公开了一种丝光沸石分子筛的制备方法,所述方法至少包含以下步骤：(1)将包括铝源、硅源、碱源、矿化剂、模板剂M和水的原料混合,得到具有如下摩尔配比的凝胶I：SiO<Sub>2</Sub>：Al<Sub>2</Sub>O<Sub>3</Sub>＝30～60；Na<Sub>2</Sub>O：SiO<Sub>2</Sub>＝0.01～0.5；M：Al<Sub>2</Sub>O<Sub>3</Sub>＝1～8；(2)将凝胶I密封陈化、除水,得到干胶；(3)将所述干胶蒸汽辅助晶化,焙烧,得到所述丝光沸石分子筛。所得到的丝光沸石分子筛具有针状堆积结构,有利于反应物快速扩散,明显降低积碳和副产物,具有较好的开发价值与应用前景。(The application discloses a preparation method of a mordenite molecular sieve, which at least comprises the following steps: (1) mixing raw materials including an aluminum source, a silicon source, an alkali source, a mineralizer, a template agent M and water to obtain gel I with the following molar ratio: SiO 2 2 ：Al 2 O 3 ＝30～60；Na 2 O：SiO 2 ＝0.01～0.5；M：Al 2 O 3 1-8; (2) sealing, aging and dewatering the gel I to obtain dry gel; (3) steaming the dry glueAnd (3) auxiliary crystallization and roasting to obtain the mordenite molecular sieve. The obtained mordenite molecular sieve has a needle-shaped stacking structure, is beneficial to rapid diffusion of reactants, obviously reduces carbon deposition and byproducts, and has good development value and application prospect.)

1. A process for the preparation of a mordenite molecular sieve, characterized in that said process comprises at least the steps of:

(1) mixing raw materials including an aluminum source, a silicon source, an alkali source, a mineralizer, a template agent M and water to obtain gel I with the following molar ratio:

SiO₂：Al₂O₃＝30～60；

Na₂O：SiO₂＝0.01～0.5；

M：Al₂O₃＝1～8；

(2) sealing, aging and dewatering the gel I to obtain dry gel;

(3) and (3) carrying out steam assisted crystallization on the dried gel, and roasting to obtain the mordenite molecular sieve.

2. The method of claim 1, wherein the silicon source and the aluminum source in step (1) are independently selected from at least one of pretreated natural silica-alumina minerals;

preferably, the natural silica-alumina mineral comprises at least one of kaolin, montmorillonite, bentonite and diatomite;

preferably, the pre-treatment comprises: and activating the object to be treated, and performing acid treatment and/or alkali treatment to obtain the pretreated natural silicon-aluminum mineral.

3. The method according to claim 2, wherein the activation conditions are: calcining and activating for 4-8 hours at 600-900 ℃;

the acid treatment conditions are as follows: the temperature is 60-90 ℃, and the treatment time is 2-5 hours;

the conditions of the alkali treatment are as follows: the temperature is 60-90 ℃, and the treatment time is 2-5 hours.

4. The method of claim 2, wherein the acid treatment comprises:

treating the object to be treated in acid liquor with the mass fraction of 5-20%;

the acid solution comprises at least one of hydrochloric acid and nitric acid;

the alkali treatment comprises the following steps:

treating the object to be treated in 2-8% of alkali liquor by mass;

the alkali liquor comprises at least one of sodium hydroxide solution and potassium hydroxide solution.

5. The method of claim 1, wherein the alkali source in step (1) comprises at least one of sodium hydroxide and potassium hydroxide;

the mineralizer is selected from at least one of NaCl and NaF;

the template agent M is at least one selected from cetyl trimethyl ammonium bromide and dodecyl trimethyl ammonium bromide.

6. The method of claim 1, wherein the removing water in step (2) comprises: aging and drying the gel I to obtain the dry gel;

the aging conditions are as follows: the aging temperature is 100-150 ℃, and the aging time is 12-48 hours;

the drying conditions are as follows: the drying temperature is 60-100 ℃, and the drying time is 12-24 hours.

7. The method according to claim 1, wherein the auxiliary steam in the steam-assisted crystallization in the step (3) is steam containing a template M;

the steam assisted crystallization conditions include: steam assisted crystallization is carried out at the temperature of 150-220 ℃ for 24-72 hours;

preferably, the steam-assisted crystallization in step (3) comprises: placing the dry glue in a container filled with a solution containing a template agent M, and statically crystallizing;

wherein the dry glue is not contacted with a solution containing a template agent M;

preferably, the roasting conditions in step (3) are as follows: and roasting at 400-600 ℃.

8. Method according to claim 1, characterized in that it comprises at least the following steps:

step 1: crushing natural silica-alumina minerals, calcining, and carrying out dealuminization by acid solution or desilication by alkali solution to respectively obtain a silicon source and an aluminum source;

step 2: mixing an aluminum source, a silicon source, an alkali source, a mineralizer, a template agent M and water to obtain gel I with the following molar ratio:

SiO₂：Al₂O₃＝30～60

Na₂O：SiO₂＝0.1～0.5

M：Al₂O₃＝1～5；

and step 3: sealing the gel I in a reactor, aging at 40-70 ℃ for 12-48 hours, and drying at 60-100 ℃ for 12-24 hours to remove water to obtain dry glue;

and 4, step 4: placing the open container filled with the dry glue into a reactor filled with the template agent M, not contacting with the template agent M, and performing static steam crystallization for 24-72 hours at 150-220 ℃;

and 5: and after crystallization is finished, washing the product to be neutral, and drying and roasting to obtain the mordenite molecular sieve.

9. A mordenite molecular sieve whenever prepared by a process as claimed in any one of claims 1 to 8,

preferably, the mordenite molecular sieve has a needle-shaped stacking structure of 10-40 x 100-300 nm.

10. Use of a mordenite molecular sieve prepared by a process as claimed in any one of claims 1 to 8 or a mordenite molecular sieve as claimed in claim 9 as a catalyst in a carbonylation reaction of dimethyl ether.

Technical Field

The invention relates to a preparation method of a mordenite molecular sieve, belonging to the field of inorganic molecular sieve materials.

Background

Mordenite molecular sieve is a silicon-aluminum framework porous material, and is divided into a high silicon-aluminum ratio type and a low silicon-aluminum ratio type according to the content of silicon-aluminum elements, and is also divided into a sodium type and a hydrogen type according to the type of sodium-containing condition. The mordenite has a twelve-membered ring (0.65 multiplied by 0.70nm) and eight-membered ring (0.26 multiplied by 0.57nm) channel structure, and shows excellent catalytic performance in the chemical fields of alcohol dehydration, arene isomerization, alkylation, transalkylation and the like.

CN107963637A uses hexadecyl N-dimethylethyl-N, N-dimethylammonium bromide as a template agent to synthesize a flaky nano mordenite molecular sieve with the thickness of 10-40 nm along the c-axis direction and the size of 3-10 mu m along the a-b axis direction by a dynamic hydrothermal synthesis method. CN102060308A takes an aluminum source, a silicon source, inorganic acid, deionized water and molecular sieve seed crystals as raw materials, and synthesizes the c-axis fibrous mordenite with the width of 20-100 nanometers and the length of 1-8 micrometers by a hydrothermal synthesis method. CN102659134A synthesizes 6 μm spherical mordenite particles by using zeolite molecular sieve containing five-membered ring as seed crystal and adjusting the type, component ratio and reaction condition of the system seed crystal without adding template agent.

The reported mordenite has the shape structures of spheres, rods, sheets and the like, and the preparation method of the acicular mordenite is not reported yet.

Disclosure of Invention

According to one aspect of the application, the preparation method of the mordenite molecular sieve is provided, the raw material pretreatment and activation operation is simple, the silicon-aluminum source is cheap and easy to obtain, the obtained mordenite molecular sieve has a special b-axis oriented needle-shaped stacking structure, the pore channels of the mordenite in the c-axis direction and the a-axis direction are greatly shortened, the rapid diffusion of reactants is facilitated, carbon deposition and byproducts are obviously reduced, and the method has good development value and application prospect.

The preparation method of the mordenite molecular sieve is characterized by at least comprising the following steps:

(1) mixing raw materials including an aluminum source, a silicon source, an alkali source, a mineralizer, a template agent M and water to obtain gel I with the following molar ratio:

SiO₂：Al₂O₃＝30～60；

Na₂O：SiO₂＝0.01～0.5；

M：Al₂O₃＝1～8；

(2) sealing, aging and dewatering the gel I to obtain dry gel;

(3) and (3) carrying out steam assisted crystallization on the dried gel, and roasting to obtain the mordenite molecular sieve.

Optionally, the molar ratio of Na in the gel I is₂O：SiO₂＝0.01～0.4。

Optionally, the natural silica-alumina mineral comprises at least one of kaolin, montmorillonite, bentonite, and diatomaceous earth.

Optionally, the pre-processing comprises: and activating the object to be treated, and performing acid treatment and/or alkali treatment to obtain the pretreated natural silicon-aluminum mineral.

Optionally, the conditions of activation are: calcining and activating for 4-8 hours at 600-900 ℃.

Optionally, the acid treatment conditions are: the temperature is 60-90 ℃, and the treatment time is 2-5 hours.

Optionally, the alkali treatment conditions are: the temperature is 60-90 ℃, and the treatment time is 2-5 hours.

Optionally, the acid treatment comprises: treating the object to be treated in acid liquor with the mass fraction of 5-20%.

Optionally, the acid solution comprises at least one of hydrochloric acid and nitric acid.

Optionally, the alkali treatment comprises: treating the object to be treated in 2-8% of alkali liquor by mass percent.

Optionally, the lye comprises at least one of a sodium hydroxide solution, a potassium hydroxide solution.

Optionally, the alkali source in step (1) comprises sodium hydroxide.

Optionally, the mineralizer is selected from at least one of NaCl, NaF.

Optionally, the template agent M is selected from at least one of cetyl trimethyl ammonium bromide and dodecyl trimethyl ammonium bromide.

Optionally, the removing water in step (2) comprises: and aging and drying the gel I to obtain the dry gel.

Optionally, the aging conditions are: the aging temperature is 100-150 ℃, and the aging time is 12-48 hours.

Optionally, the upper limit of the aging temperature is selected from 150 ℃, 140 ℃, 130 ℃ or 120 ℃, and the lower limit is selected from 100 ℃, 110 ℃, 120 ℃ or 130 ℃.

Optionally, the drying conditions are: the drying temperature is 60-100 ℃, and the drying time is 12-24 hours.

Optionally, the auxiliary steam in the steam-assisted crystallization in the step (3) is steam containing a template agent M.

Optionally, the conditions of the steam assisted crystallization include: steam assisted crystallization at 150-220 ℃ for 24-72 hours.

Optionally, the upper limit of the temperature of the steam assisted crystallization is selected from 220 ℃, 210 ℃, 200 ℃ or 180 ℃, and the lower limit is selected from 150 ℃, 160 ℃, 170 ℃ or 180 ℃.

Optionally, the steam assisted crystallization in step (3) comprises: and (3) placing the dry glue into a container filled with a solution containing a template agent M, and statically crystallizing.

Wherein the dry glue is not contacted with the solution containing the template M.

Optionally, the dry glue is crystallized with steam of a solution containing a template agent M through static steam assistance.

Optionally, the roasting conditions in step (3) are: and roasting at 400-600 ℃.

Optionally, the temperature of the calcination has an upper limit selected from 600 ℃, 580 ℃, 560 ℃ or 500 ℃ and a lower limit selected from 400 ℃, 420 ℃, 450 ℃ or 500 ℃.

Optionally, the method comprises at least the following steps:

step 1: crushing natural silica-alumina minerals, calcining, and carrying out dealuminization by acid solution or desilication by alkali solution to respectively obtain a silicon source and an aluminum source;

step 2: mixing an aluminum source, a silicon source, an alkali source, a mineralizer, a template agent M and water to obtain gel I with the following molar ratio:

SiO₂：Al₂O₃＝30～60

Na₂O：SiO₂＝0.1～0.5

M：Al₂O₃＝1～5；

and step 3: sealing the gel I in a reactor, aging at 100-150 ℃ for 12-48 hours, and drying at 60-100 ℃ for 12-24 hours to remove water to obtain dry glue;

and 4, step 4: placing the open container filled with the dry glue into a reactor filled with the template agent M, not contacting with the template agent M, and performing static steam crystallization for 24-72 hours at 150-220 ℃;

and 5: and after crystallization is finished, washing the product to be neutral, and drying and roasting to obtain the mordenite molecular sieve.

According to a further aspect of the present application there is provided a mordenite molecular sieve prepared according to the process as described above.

Preferably, the mordenite molecular sieve has a needle-shaped stacking structure of 10-40 x 100-300 nm.

According to a further aspect of the present application there is provided the use of an acicular mordenite molecular sieve prepared as hereinbefore described or an acicular mordenite molecular sieve as hereinbefore described as a catalyst in a carbonylation reaction of dimethyl ether.

The beneficial effects that this application can produce include:

according to the preparation method of the acicular mordenite molecular sieve, the obtained mordenite molecular sieve has a special acicular stacking structure, and is beneficial to rapid diffusion of reactants and obvious reduction of carbon deposition and byproducts. In the dimethyl ether carbonylation reaction, the mordenite molecular sieve obtained by the method is used as a catalyst, shows better product selectivity and catalytic stability, and has better development value and application prospect.

Drawings

FIG. 1 is an X-ray powder diffraction (XRD) pattern of the acicular mordenite molecular sieve synthesized in example 1 of the present application.

FIG. 2 is a Scanning Electron Micrograph (SEM) of the acicular mordenite molecular sieve synthesized in example 1 of the present application.

Figure 3 is an X-ray powder diffraction pattern (XRD) of the acicular mordenite molecular sieve synthesized in example 3 of the present application.

FIG. 4 is a Scanning Electron Micrograph (SEM) of the acicular mordenite molecular sieve synthesized in example 3 of the present application.

Figure 5 is an X-ray powder diffraction pattern (XRD) of the acicular mordenite molecular sieve synthesized in example 4 of the present application.

FIG. 6 is a Scanning Electron Micrograph (SEM) of the acicular mordenite molecular sieve synthesized in example 4 of the present application.

Figure 7 is a graph of selectivity and conversion of dimethyl ether carbonylation catalysts prepared from acicular mordenite molecular sieves provided in examples 1, 3 and 4 herein.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.

The analysis method in the examples of the present application is as follows:

XRD analysis characterization was performed using X' Pert PRO X-ray diffractometer from PANalytical, netherlands, Cu target, ka radiation source (λ ═ 0.15418nm), voltage 40KV, current 40 mA; the instrument used for SEM test is a Hitachi SU8020 field emission scanning electron microscope, and the accelerating voltage is 2 kV.

According to an embodiment of the application, the preparation method of the acicular mordenite molecular sieve takes natural silicon-aluminum minerals as all silicon sources and all aluminum sources, and obtains the acicular mordenite molecular sieve with the structure of 10-40 × 100-300 nm by using static water vapor to assist dry gel crystallization, and the method comprises the following steps:

(1) the natural silicon-aluminum mineral is pretreated, namely, crushing, high-temperature roasting, dealumination treatment by using acid solution and silicon treatment by using alkali solution.

(2) Weighing natural silicon-aluminum mineral according to a certain silicon-aluminum ratio, and adding deionized water, sodium hydroxide and a template agent to obtain gel. Transferring the gel into a tetrafluoroethylene lining of a reaction kettle, sealing, aging and drying to obtain dry glue.

(3) And (3) placing the tetrafluoroethylene lining of the reaction kettle filled with the dry glue into the tetrafluoroethylene lining of the reaction kettle filled with a proper amount of template agent water solution, and crystallizing to obtain the needle-shaped mordenite molecular sieve.

The preparation method of the mordenite molecular sieve comprises the following steps of:

drying and crushing commercially available kaolin, montmorillonite and bentonite to obtain 100-150 mesh powder. Roasting the powder at 800 ℃ for 4 h; 100g of each calcined powder is added into 400g of 8 wt% sodium hydroxide aqueous solution, mechanically stirred at 95 ℃ for 5 hours, filtered, washed with deionized water until the pH value of the filtrate is 7-8, and dried at 120 ℃ for 12 hours for later use.

Commercial diatomaceous earth is dried, crushed to obtain 100-150 mesh powder, and calcined at 800 ℃ for 4 h. And adding 500g of calcined diatomite into 2000g of 20% nitric acid solution, mechanically stirring at 90 ℃ for 5 hours, filtering, washing with deionized water until the pH value of the filtrate is 6-7, and drying at 120 ℃ for 12 hours for later use.

The pretreated silica-alumina minerals mainly consist of: diatomite SiO₂97.40wt.％，Al₂O₃1.30 wt.%, kaolin SiO₂6.70wt.％，Al₂O₃91.30 wt.%, montmorillonite SiO₂5.50wt.％，Al₂O₃94.20 wt.%, bentonite SiO₂3.20wt.％，Al₂O₃96.50wt.％。