A method for the synthesis of a mww molecular sieve

Abstract

The application provides a method for synthesizing MWW molecular sieves by using a double template agent, and belongs to the technical field of molecular sieve synthesis, and specifically comprises the following steps: triethylenediamine and piperazine are used as the double template agent, a silicon source, an aluminum source, boric acid, sodium hydroxide and deionized water are used as raw materials, a reaction gel is prepared after mixing, and a crystalline molecular sieve is obtained through hydrothermal crystallization. The method breaks through the template agent involved in the original synthesis system, can adjust the silicon-aluminum ratio by adjusting the proportion of the template agent and the content of a structure aid, has smaller toxicity in the synthesis process, has lower synthesis cost, and has high product purity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of MWW molecular sieve synthesis method, and particularly relates to a low-cost and low-toxicity method for synthesizing MWW molecular sieve by using double templates. BACKGROUND

[0002] In 1990, a new type of high-silicon molecular sieve, MCM-22, was synthesized by using hexamethyl imine (HMI) as a template agent by the United States Mobil Company (US4954325); in 1994, Leonowicz proposed a structural model of MCM-22 molecular sieve; in 1997, the International Zeolite Association (IZA) named the structure code of the molecular sieve as MWW. The MWW molecular sieve has a layered structure, and the layers are connected by oxygen bridges and are perpendicular to the c-axis of the unit cell. The MWW molecular sieve has two independent and non-communicating pore systems, one is a two-dimensional sinusoidal pore in the layer, and the effective pore size is a ten-membered ring (0.40 nm x 0.59 nm); the other is composed of a supercage containing a twelve-membered ring (0.71 nm x 1.82 nm), and the opening is also a ten-membered ring. The unique pore structure of the MWW molecular sieve makes it exhibit the characteristics of 10MR and 12MR in some catalytic reactions, and it works independently or cooperatively, thereby providing different reaction sites for different catalytic reaction requirements. The MWW molecular sieve exhibits good catalytic performance in the fields of catalytic cracking, olefin isomerization, and hydrocarbon alkylation, and has realized industrialization of the alkylation reaction of olefins and benzene (US4992606, US5334795), and has shown high catalytic activity in low-temperature toluene disproportionation reaction, 1-butene skeletal isomerization, and isobutane / butene alkylation reaction. After the MCM-22 molecular sieve, MCM-36, MCM-49, MCM-56, ITQ-1, ITQ-2, SSZ-25, SSZ-70, PSH-3, ERB-1, IEZ-MWW, UZM-8, SCM-1, SCM-2, SCM-6, SRZ-21, EMM-10, EMM-12, EMM-13, ECNU-7, and MIT-1 structure molecular sieves have been discovered and synthesized. The main difference between them is the different degrees of interlayer combination. Different molecular sieves have different characteristics, and thus exhibit different catalytic performance in catalytic reactions.

[0003] MWW molecular sieves are mainly synthesized by dynamic or static hydrothermal crystallization, and the synthesis conditions are relatively harsh. When the hydrothermal temperature is high, ZSM-5, ZSM-35 and the like may compete with the crystallization, and the extension of the reaction time will also promote the crystal transformation. In summary, the conditions of dynamic crystallization are more controllable, and the product quality is more stable. The synthesis of MCM-22 molecular sieves mostly uses nitrogen-containing organic amine template. HMI is the most frequently used template. However, HMI is a highly toxic chemical, which is harmful to the human body and the environment. With the continuous deepening of research work, the range of templates involved in the MWW system is continuously widened, as shown in Table 1.

[0004] Most of the MWW molecular sieves such as PSH-3, MCM-22, MCM-49, MCM-56, ITQ-1 can be synthesized by using HMI as a template. Trimethyladamantammonium (TMAdaOH), piperidine (PI) and long-chain quaternary ammonium salt are also commonly used templates for synthesizing Al-MWW molecular sieves. In addition, Mobil Corporation first reported that UZM-8 molecular sieve with MWW topology structure was synthesized by using dimethyl diethyl ammonium hydroxide (DEDMAOH) as a template; and EMM-10 molecular sieve was first prepared by using double (N, N, N-trimethyl)-1, 5-pentanediammonium bromide as a long-chain double quaternary ammonium salt. Chevron Corporation obtained a new SSZ-70 molecular sieve by using N, N'-diisopropyl imidazolium cation as a template. Roman-Leshkov et al. obtained MIT-1 molecular sieve with single-layer structure by reasonably designing the template by combining adamantylamine with long-chain quaternary ammonium salt. ITQ-30 usually exists in the form of germanosilicate, which can be synthesized by using a template with a larger volume and stronger rigidity as shown in Table 1.

[0005] Table 1 Commonly used templates in MWW system

[0006]

[0007] It can be seen that there is still a lack of non-toxic or low-toxic and cheap and easily available templates in the synthesis of MWW molecular sieves. From the perspective of basic research or practical application, it is very meaningful to find new templates and expand the synthesis system of MWW molecular sieves. SUMMARY

[0008] The purpose of the present application is to provide a method for synthesizing MWW molecular sieves by using boric acid-assisted double templates; MWW molecular sieves are successfully synthesized by using a mixture of triethylenediamine and piperazine as a template, which expands the synthesis system of MWW molecular sieves and effectively reduces the synthesis cost and environmental pollution.

[0009] The synthesis method of MWW molecular sieves provided by the present application has the following preparation steps:

[0010] (1) the silicon source, the aluminum source, boric acid, sodium hydroxide, deionized water and double template agents are mixed uniformly to prepare a gel A, and the molar ratio of various materials is xNa2O:SiO2:yAl2O3:zB2O3:wR1:vR2:sH2O;

[0011] wherein R1 is triethylenediamine, R2 is piperazine, x = 0.025-0.1, preferably 0.035-0.075; y = 0.02-0.06, z = 0.02-0.6, w = 0.1-1.2, v = 0.1-1.2, and s = 12.5-50.

[0012] (2) the gel A is aged at 25-80℃ for 0.5-24 hours, and then is hydrothermally crystallized at 135-180℃ for 3-20 days;

[0013] (3) the crystallization product of step 2 is centrifuged, washed with water until neutral, dried, and calcined at 550℃ in air for 10 hours to remove the template agent, to obtain the MWW molecular sieve.

[0014] The aging process in step 2 of the present application has the following conditions: the aging temperature is 25-80℃, the optimized temperature is 30-70℃, and the more optimized temperature is 40-60℃; and the aging time is 0.5-24 hours, the optimized time is 1-12 hours, and the more optimized time is 2-8 hours.

[0015] The hydrothermal crystallization process in step 2 of the present application has the following conditions: the crystallization temperature is 135-180℃, the optimized temperature is 140-165℃, and the more optimized temperature is 150-160℃; and the crystallization time is 3-20 days, the optimized time is 5-15 days, and the more optimized time is 8-13 days.

[0016] The hydrothermal crystallization method in step 2 of the present application is dynamic crystallization, and the rotation speed is maintained at 20-30 rpm.

[0017] The present method breaks through the template agent involved in the original synthesis system, and can adjust the silicon-aluminum ratio by adjusting the proportion of the template agent and the content of the structure aid, has smaller toxicity in the synthesis process, has lower synthesis cost, and has high product purity. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The XRD spectrum of the MWW molecular sieve prepared in the present application (Example 4);

[0019] Figure 2 The scanning electron microscope image of the MWW molecular sieve prepared in the present application (Example 4); IMPLEMENTATION

[0020] The application will be further described by the following examples, but the application is not limited by the examples.

[0021] The dynamic crystallization method described in the application is implemented by using a commercially available homogeneous reactor which can rotate along the central axis. The specific structure can be described as follows: a horizontal rotating shaft is arranged in a reaction oven which penetrates the wall of the oven, a support (the support arm is 15 cm long) is fixed vertically to the horizontal rotating shaft, a cylindrical hydrothermal reactor with an inner diameter of 8 cm is fixed to the support (one end of the support is fixed to the horizontal rotating shaft, and the other end is fixed to the outer wall of the middle part of the hydrothermal reactor), the horizontal rotating shaft is driven by a motor to rotate, and the reactor in the oven moves in a circular motion (so that the axis of the reactor rotates around the horizontal rotating shaft), and the disturbance to the reactants in the reactor can be realized under the action of centrifugal force and gravity.

[0022] Example 1

[0023] 0.524 g of sodium metaaluminate, 0.4 g of sodium hydroxide and 36 g of deionized water were weighed and stirred until clear; 10 g of TEDA (R1) and 10 g of PIP (R2) were added and stirred until dissolved; 0.4 g of boric acid was added and stirred until the solution was clear; 20 g of silica sol with a SiO2content of 40 wt% was added and stirred to obtain a gel, wherein the composition of the reactant gel was: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.02:0.035:0.024:0.667:0.872:20; the gel was aged at 25°C for 24 hours; then the temperature was raised to 145°C in the homogeneous reactor, and dynamic crystallization was carried out at a rotation speed of 30 revolutions per minute for 20 days; after the crystallization was completed, the product was centrifuged, washed with water until neutral, dried at 120°C for 6 hours, and calcined at 550°C in an air atmosphere for 10 hours to remove the template agent. XRD detection showed that MWW molecular sieve was obtained, which was pure MWW molecular sieve crystal.

[0024] Example 2 0.699 g of sodium metaaluminate, 0.45 g of sodium hydroxide, 18 g of deionized water were weighed, stirred until homogeneous and clear; 12 g of TEDA (R1), 6 g of PIP (R2) were added, stirred until dissolved; 0.45 g of boric acid was added, stirred until the solution was clear; 20 g of silica sol with SiO2content of 40 wt% was added, stirred to obtain a gel, wherein the composition of the reactant gel was: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1 :0.027:0.041 :0.027:0.750:0.523:12.5; aged at 40 °C for 10 hours; then heated to 150 °C in a homogeneous reactor, dynamic crystallization for 15 days, rotation speed 50 rpm; after crystallization, the product was centrifuged, washed with water until neutral, dried at 120 °C for 8 hours, calcined at 550 °C in air atmosphere for 10 hours to remove the template agent. XRD detection showed that the MWW molecular sieve was a pure MWW molecular sieve crystal.

[0025] Example 3

[0026] 0.874 g of sodium metaaluminate, 0.5 g of sodium hydroxide, 36 g of deionized water were weighed, stirred until homogeneous and clear; 15 g of TEDA (R1), 10 g of PIP (R2) were added, stirred until dissolved; 0.66 g of boric acid was added, stirred until the solution was clear; 20 g of silica sol with SiO2content of 40 wt% was added, stirred to obtain a gel, wherein the composition of the reactant gel was: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1 :0.034:0.047:0.040:1:0.872:20; aged at 60 °C for 4 hours; then heated to 150 °C in a homogeneous reactor, dynamic crystallization for 12 days, rotation speed 60 rpm; after crystallization, the product was centrifuged, washed with water until neutral, dried at 120 °C for 4 hours, calcined at 550 °C in air atmosphere for 10 hours to remove the template agent. XRD detection showed that the MWW molecular sieve was a pure MWW molecular sieve crystal.

[0027] Example 4

[0028] Weigh 1.180 g sodium metaaluminate, 0.55 g sodium hydroxide, 60 g deionized water, stir until clear; add 10 g TEDA, 8.3 g PIP, stir until dissolved; add 2.0 g boric acid, stir until solution clear; add 20 g 40 wt% silica sol in SiO2, stir to obtain a gel, wherein the reactant gel composition is: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.046:0.062:0.122:0.668:0.724:30; age at 50°C for 5 hours; then heat to 155°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm; after crystallization, centrifuge the product, wash with water until neutral, dry at 120°C for 6 hours, calcine at 550°C in air for 10 hours to remove the template. XRD detection shows that the MWW molecular sieve is a pure MWW molecular sieve crystal.

[0029] Example 5

[0030] Weigh 1.285 g sodium metaaluminate, 0.6 g sodium hydroxide, 78 g deionized water, stir until clear; 15 g TEDA (R1), 10 g PIP (R2), stir until dissolved; add 2.4 g boric acid, stir until solution clear; add 20 g 40 wt% silica sol in SiO2, stir to obtain a gel, wherein the reactant gel composition is: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.05:0.07:0.146:1:0.872:37.5; age at 70°C for 3 hours; then heat to 160°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 80 rpm; after crystallization, centrifuge the product, wash with water until neutral, dry at 120°C for 10 hours, calcine at 550°C in air for 10 hours to remove the template. XRD detection shows that the MWW molecular sieve is a pure MWW molecular sieve crystal.

[0031] Example 6

[0032] Weigh 1.542 g sodium metaaluminate, 0.75 g sodium hydroxide, 102 g deionized water, stir until clear; add 18 g TEDA (R1), 13.8 g PIP (R2), stir until dissolved; add 4.8 g boric acid, stir until solution clear; add 20 g silica sol with SiO2content of 40 wt%, stir to get gel, where the reactant gel composition is: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.06:0.075:0.365:1.2:1.2:50; age at 50°C for 5 hours; then heat up to 160°C in a homogeneous reactor, dynamic crystallization for 8 days, rotation speed 100 rpm; after crystallization, centrifuge the product, wash with water until neutral, dry at 120°C for 4 hours, calcine at 550°C in air atmosphere for 10 hours to remove template agent. XRD detection shows that MWW molecular sieve is obtained, which is pure MWW molecular sieve crystal.

[0033] Example 7

[0034] Weigh 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until clear; add 10 g TEDA, 8.3 g PIP, stir until dissolved; add 0.66 g boric acid, stir until solution clear; add 20 g silica sol with SiO2content of 40 wt%, stir to get gel, where the reactant gel composition is: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0.040:0.668:0.724:20; age at 60°C for 5 hours; then heat up to 165°C in a homogeneous reactor, dynamic crystallization for 7 days, rotation speed 60 rpm; after crystallization, centrifuge the product, wash with water until neutral, dry at 120°C for 5 hours, calcine at 550°C in air atmosphere for 10 hours to remove template agent. XRD detection shows that MWW molecular sieve is obtained, which is pure MWW molecular sieve crystal.

[0035] Example 8

[0036] Weigh 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until homogeneous and clear; add 10 g TEDA, 13.8 g PIP, stir until dissolved; add 0.66 g boric acid, stir until solution is clear; add 20 g 40 wt% silica sol in SiO2, stir to obtain a gel, wherein the reactant gel composition is: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0.040:0.668:1.2:20; age at 30 °C for 15 hours; then heat to 155 °C in a homogeneous reactor, dynamic crystallization for 10 days at 60 rpm; after crystallization is complete, centrifuge the product, wash with water until neutral, dry at 120 °C for 2 hours, calcine at 550 °C for 10 hours in air atmosphere to remove the template. XRD detection shows that the MWW molecular sieve is a pure MWW molecular sieve crystal.

[0037] Example 9

[0038] Weigh 0.774 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until homogeneous and clear; add 10 g TEDA, 9.6 g PIP, stir until dissolved; add 0.66 g boric acid, stir until solution is clear; add 20 g 40 wt% silica sol in SiO2, stir to obtain a gel, wherein the reactant gel composition is: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.030:0.047:0.040:0.668:0.840:20; age at 40 °C for 10 hours; then heat to 165 °C in a homogeneous reactor, dynamic crystallization for 10 days at 60 rpm; after crystallization is complete, centrifuge the product, wash with water until neutral, dry at 120 °C for 12 hours, calcine at 550 °C for 10 hours in air atmosphere to remove the template. XRD detection shows that the MWW molecular sieve is a pure MWW molecular sieve crystal.

[0039] Comparative Example 1

[0040] Take 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until clear; add 15 g TEDA, stir until dissolved; add 20 g SiO2content 40 wt% silica sol, stir to get gel, wherein the reactant gel composition: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0:1:0:20; age at 50°C for 3 hours; then heat to 155°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm; after crystallization, the product is centrifuged, washed with water to neutral, dried at 120°C for 8 hours, calcined at 550°C in air atmosphere for 10 hours to remove the template agent. XRD detection, ZSM-5 molecular sieve is obtained. It can be seen that, in the absence of boric acid as a crystallization aid, and only triethylenediamine exists, only ZSM-5 molecular sieve can be obtained.

[0041] Comparative Example 2

[0042] Take 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until clear; add 15 g TEDA, stir until dissolved; add 20 g SiO2content 40 wt% silica sol, stir to get gel, wherein the reactant gel composition: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0:1:0:20; age at 50°C for 3 hours; then heat to 155°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm; after crystallization, the product is centrifuged, washed with water to neutral, dried at 120°C for 8 hours, calcined at 550°C in air atmosphere for 10 hours to remove the template agent. XRD detection, ZSM-5 molecular sieve is obtained. It can be seen that, in the absence of boric acid as a crystallization aid, and only triethylenediamine exists, only ZSM-5 molecular sieve can be obtained.

[0043] Comparative Example 3

[0044] Take 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until clear; add 10 g PIP, stir until dissolved; add 20 g SiO2content 40 wt% silica sol, stir to get a gel, wherein the reactant gel composition: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0:0:0.872:20; age at 50°C for 3 hours; then heat up to 155°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm; after crystallization, the product is centrifuged, washed with water to neutral, dried at 120°C for 6 hours, calcined at 550°C in air atmosphere for 10 hours to remove the template agent. By XRD detection, ZSM-35 molecular sieve is obtained. It can be seen that without boric acid as a crystallization aid, and only piperazine exists, only ZSM-35 molecular sieve can be obtained.

[0045] Comparative Example 4

[0046] Take 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until clear; add 15 g TEDA, stir until dissolved; add 0.66 g boric acid, stir until the solution is clear; add 20 g SiO2content 40 wt% silica sol, stir to get a gel, wherein the reactant gel composition: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0.040:1:0:20; age at 50°C for 3 hours; then heat up to 155°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm; after crystallization, the product is centrifuged, washed with water to neutral, dried at 120°C for 12 hours, calcined at 550°C in air atmosphere for 10 hours to remove the template agent. By XRD detection, a mixture containing 30% ZSM-5 molecular sieve and 70% amorphous is obtained. Compared with Comparative Example 2, it can be seen that only triethylenediamine exists, boric acid as a crystallization aid is not conducive to the crystallization of ZSM-5 molecular sieve.

[0047] Comparative Example 5

[0048] Take 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until clear; add 10 g PIP, stir until dissolved; add 0.66 g boric acid, stir until the solution is clear; add 20 g SiO2content 40 wt% silica sol, stir to get a gel, wherein the reactant gel composition: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0.040:0:0.872:20; age at 50°C for 3 hours; then heat to 155°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm; after crystallization, the product is centrifuged, washed with water to neutral, dried at 120°C for 3 hours, calcined at 550°C in air atmosphere for 10 hours to remove the template agent. By XRD detection, ZSM-35 molecular sieve is obtained. It can be seen that without triethylenediamine as a co-template, the crystalline product is ZSM-35, and MWW molecular sieve cannot be obtained.

[0049] Comparative Example 6

[0050] Take 0.699 g sodium metaaluminate, 0.45 g sodium hydroxide, 18 g deionized water, stir until clear; add 12 g TEDA (R1), 6 g PIP (R2), stir until dissolved; add 9.2 g boric acid, stir until the solution is clear; add 20 g SiO2content 40 wt% silica sol, stir to get a gel, wherein the reactant gel composition: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.027:0.041:0.7:0.750:0.523:12.5; age at 40°C for 10 hours; then heat to 150°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm; after crystallization, the product is centrifuged, washed with water to neutral, dried at 120°C for 12 hours, calcined at 550°C in air atmosphere for 10 hours to remove the template agent. By XRD detection, a mixture of 90% amorphous and 10% MWW molecular sieve crystals is obtained. It can be seen that the amount of boric acid added exceeds the ratio range described in the case, which is not conducive to the crystallization of MWW molecular sieve.

[0051] Comparative Example 7

[0052] Take 0.874 g sodium metaaluminate, 0.5 g sodium hydroxide, 36 g deionized water, stir until clear; add 25 g TEDA (template agent one), 16 g PIP (template agent two), stir until dissolved; add 2.4 g boric acid, stir until the solution is clear; add 20 g SiO2content 40 wt% silica sol, stir to get the gel, wherein the composition of the reactant gel is: SiO2:Al2O3:Na2O:B2O3:TEDA:PIP:H2O = 1:0.034:0.047:0.146:1.667:1.395:20; age at 70°C for 3 h; then heat to 160°C in a homogeneous reactor, dynamic crystallization for 10 days, rotation speed 60 rpm / d; after crystallization, the product is centrifuged, washed with water to neutral, dried at 120°C for 5 h, calcined at 550°C for 10 h in air atmosphere to remove the template agent. XRD detection shows that 80% of the product is amorphous and 20% of the product is MWW molecular sieve crystals. It can be seen that the amount of triethylenediamine and piperazine exceeds the range of the proportions described in the case, which is not conducive to the crystallization of MWW molecular sieve.

Claims

1. A method for the synthesis of a MWW molecular sieve, characterized in that, The method comprises the following steps: (1) uniformly mixing a silicon source, an aluminum source, boric acid, sodium hydroxide, deionized water, and double templates to prepare a gel A, and the molar ratio of various materials is xNa2O:SiO2:yAl2O3:zB2O3:wR1:vR2:sH2O; wherein R1 is triethylenediamine, R2 is piperazine, R1 and R2 are triethylenediamine (TEDA) and piperazine (PIP) in the double templates respectively; x = 0.025-0.1, y = 0.02-0.06, z = 0.02-0.6, w = 0.1-1.2, v = 0.1-1.2, s = 12.5-50; (2) aging the gel A at 25-80 ℃ for 0.5-24 hours, and then increasing the temperature to 135-180 ℃ for hydrothermal crystallization for 3-20 days; (3) centrifuging the crystallization product of step 2, washing to neutral with water, drying, and calcining at 500-650 ℃ in an air atmosphere for 6-24 hours to remove the templates to obtain a MWW molecular sieve.

2. The synthesis method according to claim 1, characterized in that, wherein, x = 0.035-0.075, y = 0.025-0.05, z = 0.05-0.5, w = 0.3-0.8, v = 0.3-0.8, s = 15-40.

3. The method of synthesis of claim 1, wherein, The silicon source in step (1) is silica sol, and the aluminum source is sodium metaaluminate.

4. The method of synthesis of claim 1, wherein, The hydrothermal crystallization mode in step (2) is dynamic crystallization, and the rotation speed is maintained at 20-100 revolutions per minute.

5. The synthesis method according to claim 1, characterized in that, In step (2), the aging process: the aging temperature is 30-70 ℃; and the aging time is 1-10 hours.

6. The synthesis method according to claim 5, characterized in that, In step (2), the aging process: the aging temperature is 40-60 ℃; and the aging time is 2-6 hours.

7. The method of synthesis of claim 1, wherein, In step (2), the hydrothermal crystallization process: the crystallization temperature is 140-165 ℃; and the crystallization time is 5-15 days.

8. The method of synthesis of claim 7, wherein, In step (2), the hydrothermal crystallization process: the crystallization temperature is 150-160 ℃; and the crystallization time is 8-13 days.

Images