Method for directly synthesizing and molding SAPO-11 molecular sieve and application of SAPO-11 molecular sieve

Abstract

The invention belongs to the technical field of molecular sieve preparation, and discloses a method for directly synthesizing and forming an SAPO-11 molecular sieve and application, and the method is mainly characterized by comprising the following steps: mixing an aluminum source, a phosphorus source, a silicon source, organic amine, ionic liquid and water according to a certain proportion to prepare gel, then processing and forming the obtained gel according to an expected shape, crystallizing the formed gel under a certain condition to obtain the SAPO-11 molecular sieve. And the molded body completely composed of the SAPO-11 molecular sieve can be obtained. The molded molecular sieve is prepared in one step and is directly used as a catalyst carrier, so that the catalyst preparation process is simplified. Compared with a traditional method, the method is simple in preparation process, high in raw material utilization rate, low in waste liquid discharge amount and wide in application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieve preparation, and relates to a method and application of directly synthesizing and forming SAPO-11 molecular sieve, and specifically to a preforming synthesis method of an alkane isomerization catalyst carrier composed of SAPO-11 molecular sieve. Background Art

[0002] With the increasing awareness of environmental protection and increasingly stringent regulatory requirements, people are increasingly demanding high-octane gasoline, diesel and lubricants with good low-temperature fluidity. The main components of gasoline, diesel and lubricants are alkane compounds. Among them, the light normal alkanes in the gasoline fraction have a low octane value, and the long-chain normal alkanes in the diesel and lubricant fractions have poor low-temperature fluidity. In order to obtain high-quality oil, these normal alkanes need to be removed from the fractions. At present, the main industrial processes for removing normal alkanes from oil products are solvent dewaxing, catalytic dewaxing and isomerization dewaxing. Compared with the first two processes, the isomerization dewaxing process is to isomerize the wax molecules, thereby converting the wax into ideal components. This process has the advantages of high product yield and good quality. The selective isomerization of long-chain normal alkanes into short-chain isoalkanes with fewer side chains can effectively improve the low-temperature fluidity of diesel and lubricants (Journal of Catalysis, 1999, 187(1): 167-76.). In isomerization technology, the isomerization catalyst plays a core role.

[0003] SAPO-n is a non-neutral molecular sieve framework composed of AlO4, PO4 and SiO4 tetrahedrons formed by replacing P or Al atoms in the AlPO4-n framework with Si atoms. SAPO-11 molecular sieve, as a member of the SAPO-n molecular sieve family, is a molecular sieve with good isomerism. It has a one-dimensional non-crossed ten-membered ring channel with a pore size of 0.39×0.64nm. In recent years, SAPO-11 molecular sieve has shown high activity and selectivity in the isomerization reaction of normal alkanes due to its unique pore structure and adjustable acidity. It can be used in the isomerization reaction of alkanes to improve the octane number of gasoline (Catalysis Today, 2018, 316(15): 43-50). In recent years, with the rapid development of the national economy, the market demand for SAPO-11 molecular sieve has gradually increased. When SAPO-11 molecular sieve is used as a catalyst in actual industrial applications, it is often necessary to make it into finished particles of specific shapes and sizes. The finished product preparation process includes the synthesis of molecular sieve powder and the processing and molding of catalyst particles.

[0004] The synthesis of SAPO-11 molecular sieve powder is industrially carried out by hydrothermal synthesis, which uses water as solvent and mixes materials in a certain ratio to obtain sol. The sol is crystallized at 80-200 °C and under the autogenous pressure of water. After the crystallization, the product is filtered, washed and dried to obtain molecular sieve powder. Catalyst molding requires mixing molecular sieve powder with additives such as binders, plasticizers, extrusion aids, pore-forming agents, etc. to obtain a plastic body, which is then kneaded, cured, dried and calcined to obtain the finished product.

[0005] For example, patent CN1843625A discloses a catalyst for alkane hydroisomerization reaction and its preparation method, in which molecular sieve powder is mixed with a binder, a pore-forming agent, an extrusion aid, water, etc. and squeezed into a clover-shaped strip, and then dried and calcined to obtain a catalyst carrier. Pt is loaded on the carrier, and the finished catalyst is obtained after drying and calcining. The catalyst is used in the hydroisomerization reaction of n-dodecane.

[0006] The above method first prepares the molecular sieve powder, and then shapes, dries and roasts it to obtain the finished catalyst. The process is long and complicated. In addition, the hydrothermal crystallization process of the molecular sieve is carried out under high pressure, which poses a safety hazard; the filtration and washing process of the powder produces a large amount of wastewater, causing environmental pollution; the catalyst molding requires the addition of additives such as binders. Due to the introduction of additives, the content of molecular sieve in the finished catalyst is generally 60~80%, and cannot reach 100%, which affects the performance of the molecular sieve.

[0007] In order to solve the above problems, people have done a lot of research on simplifying the preparation process of molecular sieve catalysts and increasing the content of molecular sieve in the molded body.

[0008] The researchers used raw materials with a certain shape to directly produce molecular sieves with the same shape as the raw materials without the need for reshaping, which can simplify the molecular sieve catalyst preparation process.

[0009] For example, Barg, S. et al. prepared a molded X-type molecular sieve adsorbent using aluminum foam monolithic material as raw material. This method placed the aluminum foam monolithic material at 820℃ in an air atmosphere for 2 h to convert part of the Al into Al3O2, and then placed it in a solution with a molar ratio of Na2O:K2O:SiO2:H2O=70:20:10:1500 and crystallized it at 80℃. The resulting molded adsorbent was composed of X-type molecular sieve and Al2O3 (J. Porous Mat., 2011, 18(1): 89-98).

[0010] Franziska Scheffler et al. prepared a shaped ZSM-5 catalyst using aluminum foam monolithic material as raw material. The method placed the aluminum foam monolithic material in a solution with a molar ratio of Na2O:TPABr:SiO2:H2O=0:423:0.055:1:72.4, and crystallized it at 150 °C for 24 h to obtain a shaped catalyst. The method used aluminum foam monolithic material as the aluminum source, and other raw materials were still in the aqueous solution. The content of ZSM-5 was only 13% (Micropor. Mesopor. Mater., 2004, 67(1):53-9).

[0011] The above methods crystallize part of the raw materials in the form of integral materials under hydrothermal conditions, and obtain an integral catalyst in one step, which simplifies the preparation process. However, other raw materials still exist in the aqueous solution, and crystallization is still a hydrothermal process, which poses a safety hazard; the reaction raw materials are divided into solid and liquid phases, the reaction process is limited by mass transfer, the finished product contains unconverted raw materials, and the molecular sieve content is not high. In addition, these methods use raw materials in the shape of integral materials, which are limited by the raw material material and have a single shape. At present, the actual finished products of the molded catalyst are rich in shapes, including spheres, strips, cylinders, honeycombs, four-leaf clover shapes, three-leaf clover shapes, external gear shapes, non-porous external gear shapes, plum blossom shapes, porous plum blossom shapes, seven-hole spheres, non-porous spheres, seven-rib wheel shapes, four-hole shapes, four-leaf butterfly shapes, etc.

[0012] Nevertheless, there is no similar work on preparing SAPO-11 molecular sieve carrier using monolithic materials as raw materials.

[0013] In order to increase the content of molecular sieve in the finished molecular sieve catalyst, researchers have done a lot of work to crystallize additives such as binders added during the molding process into molecular sieves.

[0014] For example, patent CN101348260A discloses a method for preparing an MFI / FAU composite molecular sieve catalyst. In this method, after MFI seed crystals, FAU molecular sieves, silicon sources and aluminum sources are mixed and formed, an integrated MFI / FAU composite molecular sieve catalyst is prepared by dry gel conversion in steam containing organic amines, and then the catalyst product is obtained by recrystallization and calcination.

[0015] The above method is to mix the molecular sieve powder and the binder to obtain a molded body, and then crystallize it again to convert the binder into the molecular sieve. Although this method can obtain a molded body composed entirely of molecular sieves, it still requires the synthesis of molecular sieve raw powder; the molding process adds a crystallization step, which increases the manufacturing cost. Summary of the invention

[0016] The present invention aims to simplify the process of preparing molecular sieve catalysts and directly prepare pure molecular sieve materials with desired shapes, which can simultaneously achieve the goals of simplifying the molecular sieve catalyst preparation process and increasing the molecular sieve content in the molded body. Catalysts based on SAPO-11 molecular sieves show excellent catalytic performance in the hydroisomerization reaction of long-chain normal alkanes. The present invention is particularly directed to SAPO-11 molecular sieves and provides a preformed synthesis method.

[0017] The solution of the present invention to solve the above technical problems is as follows: A method for directly synthesizing a SAPO-11 molecular sieve having an AEL structure confirmed by the International Zeolite Association, wherein the synthetic gel is processed and shaped into a desired shape, and recrystallized to obtain a shaped molecular sieve having the same shape as the shaped gel, comprising the following steps: (1) mixing an aluminum source, a phosphorus source, a silicon source, an organic amine, an ionic liquid and water in a molar ratio of Al2O3:P2O5:SiO2:organic amine:ionic liquid:H2O=1:0.2-3:0.05-1:0.1-2:0.1-2:30-45 to prepare a gel; (2) processing the gel prepared in step (1) into a shaped gel having a desired shape; (3) The molded gel obtained in step (2) is placed in a sealed container and crystallized at 175-210°C for 30 min-24 h to obtain a molded SAPO-11 molecular sieve.

[0018] The characteristic is that the synthetic gel is pre-processed into a desired shape, and a molded body composed of molecular sieves is directly crystallized in one step. Step (1) is carried out in a self-made ultrasonic oscillation high-pressure reactor, and steps (2) and (3) are carried out in a self-made ultrasonic oscillation microwave reactor.

[0019] Furthermore, a reactor ultrasonic oscillator is installed at the lower part of the shell of the ultrasonic oscillation high-pressure reactor, a feeding port is opened at the upper part, a discharging port is opened at the bottom, a middle mixer extends into the reactor, and the mixer is connected to the reactor motor.

[0020] Furthermore, the ultrasonic oscillation high-pressure reactor is also provided with a thermocouple and a pH meter.

[0021] Furthermore, the oscillation frequency of the ultrasonic oscillator of the reactor is: 120KHZ in the early stage, 60KHZ in the middle stage, and 30KHZ in the final stage. Each oscillation time is 10-30 minutes, and the interval period is 4-8 hours. Under the action of high-frequency ultrasonic oscillation, the gel can produce more crystal nuclei, which is conducive to crystal growth, shortens the synthesis time, and improves the crystallinity of the product. The production cost of the catalyst can be reduced by 24-38% compared with the traditional production process synthesis + molding energy consumption.

[0022] Furthermore, a plurality of microwave reaction ultrasonic oscillators are installed at the bottom of the cavity of the ultrasonic oscillation microwave reactor, the rear of which is connected to the receiving hopper, and the front of which is connected to the conveyor belt, and the microwave reaction motor provides power for the conveyor belt.

[0023] Furthermore, the microwave reaction motor is provided with an operation panel, and the cavity is supported by a plurality of brackets.

[0024] Furthermore, the oscillation frequency of the microwave reaction ultrasonic oscillator is 20 MHZ to 3000 MHZ to prevent adhesion between particles.

[0025] The organic amine described in the present invention is di-n-propylamine, diisopropylamine, or one or both.

[0026] The synthetic gel of the present invention needs to add an ionic liquid, and the anion of the added ionic liquid is One or more of the following; the cation is an alkyl-substituted imidazolium ion , alkyl-substituted pyridinium ion , alkyl quaternary ammonium salt ion One or more of the following, R is a C1-C16 alkyl group.

[0027] The aluminum source described in the present invention is one or both of pseudo-boehmite and activated alumina.

[0028] The phosphorus source described in the present invention is one or more of phosphoric acid, monoammonium hydrogen phosphate, diammonium hydrogen phosphate and triammonium phosphate.

[0029] The silicon source described in the present invention is silica sol.

[0030] The gel molding described in the present invention is a conventional operation in the art, such as extrusion molding, compression molding, oil column molding, rotation molding, spray molding, and granulation. The shape of the obtained molded gel can be spherical, strip, cylindrical, honeycomb, four-leaf clover, three-leaf clover, external gear, non-porous external gear, plum blossom, porous plum blossom, seven-hole sphere, non-porous sphere, seven-rib wheel, four-hole, four-leaf butterfly, etc. The specific shape and size adopted are selected and determined according to the actual use conditions. The gel described in the present invention can be pre-treated in a certain form before the molding operation to improve its plasticity to ensure convenient operation of the molding process. For example, the gel can be appropriately aged, or treated at a temperature not exceeding 110°C to remove part of the water in the gel to obtain a plastic solid, and then molded.

[0031] The crystallization process of the present invention can also be carried out by placing the formed gel in a conventional pressure container in the art, and a certain amount of water can be placed in the container in advance, but it is not necessary to directly contact the water with the formed gel. The crystallization process adopts a conventional heating method in the art, such as oil bath heating, oven heating and microwave heating.

[0032] After the crystallization is completed, the molded product prepared by the present invention does not need to be filtered or washed. The crystallized product maintains the same shape and size as the molded gel and is completely composed of molecular sieves, and the molecular sieve framework structure is the AEL structure confirmed by the International Zeolite Association.

[0033] The invention discloses an application of directly synthesized SAPO-11 molecular sieve, which is mainly used in the isomerization reaction of alkanes.

[0034] To help understand the present invention, the term "preform" is defined below. The defined terms have the meanings commonly understood by those of ordinary skill in the art to which the present invention relates.

[0035] Unless otherwise specified, "preforming" herein refers to the process or step of processing the gel used for synthesizing molecular sieves into a shaped gel with a certain shape, size and mechanical strength by compression, extrusion, rotation, spraying, etc.

[0036] In summary, the present invention provides a preforming method for synthesizing SAPO-11 molecular sieve, which has the following advantages: The one-step preparation of the molded molecular sieve simplifies the catalyst preparation process. The molded body is completely composed of molecular sieves, which increases the content of molecular sieves per unit volume of the catalyst and can improve its catalytic activity. The method directly obtains the molded molecular sieve, avoids the filtering and washing steps in the conventional molecular sieve production process, has low waste liquid discharge, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is the XRD spectrum of the sample in Example 1 of the present invention; Figure 2 is a SEM image of the cross section of the sample in Example 1 of the present invention; Figure 3 The actual photographs are of the cylindrical SAPO-11 molecular sieve synthesized by the molded dry gel and pre-molding method in Example 1 of the present invention; Figure 4 It is a schematic diagram of the structure of an ultrasonic oscillation high-pressure reactor; Figure 5 This is a schematic diagram of the structure of an ultrasonic oscillation microwave reactor.

[0038] Among them, 1. discharge port, 2. mixer, 3. shell, 4. feeding port, 5. reactor motor, 6. thermocouple, 7. pH meter, 8. reactor ultrasonic oscillator, 9. conveyor belt, 10. microwave reaction motor, 11. operation panel, 12. microwave reaction ultrasonic oscillator, 13. bracket, 14. box shell, 15. hopper, 16. cavity. DETAILED DESCRIPTION

[0039] The present invention will be further described in the following examples, but the present invention is not limited thereto.

[0040] Table 1 Synthesis conditions of Examples 1-4 of the present invention (crystallization at 175-210 °C for 30 min-24 h)

[0041] Comparative Example 1 Conventional SAPO-11 molecular sieve was synthesized according to the method provided in patent CN 102381716 A, and the hydroisomerization reaction of n-dodecane was evaluated.

[0042] A: Weigh 10.85g pseudo-boehmite (Wenzhou Jingjing Alumina Co., Ltd., water content 25% by weight), dissolve it in 18.00g deionized water to prepare a solution, heat and stir for 0.5h; B: Weigh 9.7mL di-n-propylamine (98% by weight) and add it dropwise to the solution obtained in step A, stir for 2h, then weigh 10.30g silica sol (Qingdao Chengyu Chemical Co., Ltd., containing 25% by weight of silicon dioxide) and add it to the above solution, stir for 2h to obtain an aqueous slurry; C: When the aqueous slurry obtained in step B is heated to 80°C, add 16.45g An acid solution of H3PO4 (concentration is 85 weight %) in 18.00g of deionized water is added dropwise to the aqueous slurry at a rate of adding 2.8% phosphoric acid per minute. During the whole process, the pH of the slurry is 7.3. Water is added and stirred for another 1h to obtain a colloidal mixture with a molar composition of R: Al2O3: P2O5: 0.6SiO2: 50H2O, wherein R is di-n-propylamine; D: the colloidal mixture obtained in step C is crystallized at 180°C for 24h; E: the crystallized product obtained in step D is filtered out, cooled, washed, and then dried at 120°C for 12h; F: the product obtained in step E is placed in a muffle furnace and calcined at 550°C for 6h to obtain SAPO-11 molecular sieve.

[0043] 180g of the SAPO-11 molecular sieve prepared above was mixed evenly with 100g of SB powder and 15g of sesbania powder. 110g of 10 wt% nitric acid and 110 ml of water were measured and mixed evenly, and then the mixed powder was added. After fully kneading, cylindrical strips were extruded on an extruder, and then baked at 110°C for 24 hours and calcined at 600°C for 24 hours to obtain a catalyst formed carrier.

[0044] Take 10 g of the above-mentioned shaped carrier, crush it into 20-40 mesh, and use the usual filling hole impregnation method to impregnate 3.76 mL of H2PtCl solution (containing 0.0133 g of Pt per mL) for 16 hours, then bake at 120°C for 4 hours and calcine at 480°C for 8 hours to prepare a catalyst containing 0.5 wt% Pt.

[0045] 100 mL of the catalyst was loaded into a stainless steel tube reactor and evaluated by the hydroisomerization reaction of n-dodecane. The reaction conditions were: reaction pressure of 0.1 MPa, liquid space velocity of n-dodecane of 1.0 h -1 The molar ratio of hydrogen to n-dodecane is 15. The reaction products are analyzed by online gas chromatography. The results are listed in Table 2.

[0046] Table 2 Hydroisomerization results of n-dodecane over 0.5 wt% Pt / SAPO-11 catalyst

[0047] n-dodecane conversion rate (%) = 1-unconverted n-dodecane amount / n-dodecane feed amount × 100% Isomerization selectivity (%) = amount of converted isomerized (branched) dodecane / total amount of all converted normal dodecane × 100% Isomerization yield (%) = isomerization selectivity (%) × n-dodecane conversion (%) × 100% Example 1

[0048] 17.39g pseudo-boehmite (78.35wt% Al2O3) was placed in a 250mL beaker, 58.4g deionized water was added, and the mixture was stirred at room temperature for 30 minutes; 30.82g 85wt% phosphoric acid was added and stirred for 3 hours; 13.34g 30w% silica sol was added and stirred for 30 minutes; 27.05g di-n-propylamine was added and stirred for 30 minutes; finally, 25.54g 1-ethyl-3-methyl imidazolium bromide ionic liquid was added. The above mixture was stirred evenly into a gel state, and then baked at 90℃ for 30 minutes. The plastic gel mixture obtained by the above operation was extruded into a cylindrical strip with a diameter of 2mm using a twin-screw extruder. The obtained cylindrical strip gel was placed in a crystallization reactor with a polytetrafluoroethylene reactor liner and crystallized in a closed state at 200℃ for 24h.

[0049] After the crystallization is completed, the crystallization reactor is cooled to room temperature to obtain a cylindrical strip-shaped molecular sieve with a diameter of about 2 mm. The shaped molecular sieve is ground into powder for XRD analysis. The molecular sieve is SAPO-11, such as Figure 1 The electron microscope photo shows that the molded body is completely composed of inter-grown molecular sieve crystals and contains large pores, such as Figure 2 The shaped molecular sieve maintains the shape of the shaped gel, as shown in Figure 3 shown.

[0050] Take 2 g of the above-mentioned SAPO-11 molecular sieve, crush it to 20-40 mesh, take 0.27 mL of H2PtCl6 solution (containing 0.037 g of Pt per mL) and mix it with 1.73 mL of deionized water to make a solution, use the usual pore filling impregnation method to impregnate for 12 h, dry it at room temperature under vacuum conditions, and reduce it at 400 °C in H2 atmosphere (25 mL / min) for 4 h to prepare a 0.5 wt% Pt / SAPO-11 catalyst.

[0051] 100 mL of the catalyst was loaded into a stainless steel tube reactor and evaluated by the hydroisomerization reaction of n-dodecane. The reaction conditions were: reaction pressure of 0.1 MPa, liquid space velocity of n-dodecane of 1.0 h -1 , the molar ratio of hydrogen to n-dodecane is 15, and the reaction products are analyzed by online gas chromatography, and the results are listed in Table 3. In the range of 260-320 °C, the 0.5 wt% Pt / SAPO-11 catalyst prepared in this patent has high n-dodecane conversion rate, isomerization selectivity and isomerization yield.

[0052] Table 3 Hydroisomerization results of n-dodecane over 0.5 wt% Pt / SAPO-11 catalyst

[0053] Compared with the method provided by patent CN 102381716 A, the method of preparing the molecular sieve carrier by using the synthesized shaped SAPO-11 as the carrier is simpler. The synthesized carrier has a high molecular sieve content, and the catalyst has more excellent catalytic performance. Example 2

[0054] 17.39g pseudo-boehmite (78.35wt% Al2O3) was placed in a 250mL beaker, 84.2g deionized water was added, and stirred for 30 minutes at room temperature; 61.64g 85wt% phosphoric acid and 30.75g diammonium phosphate were added, and stirred for 3 hours; 1.33g 30w% silica sol was added, and stirred for 30 minutes; 6.76g di-n-propylamine and 6.76g diisopropylamine were added, and stirred for 30 minutes; finally, 2.6g 1-ethyl-3-methyl imidazolium bromide ionic liquid was added. The above mixture was stirred evenly into a gel state, and then baked at 90℃ for 30 minutes. The plastic gel mixture obtained by the above operation was extruded into a clover shape with a diameter of 2mm using a twin-screw extruder. The obtained molded clover-shaped gel was placed in a crystallization kettle with a polytetrafluoroethylene kettle liner and crystallized in a closed state at 210℃ for 30 minutes.

[0055] After the crystallization is completed, the crystallization kettle is cooled to room temperature to obtain a clover-shaped molecular sieve. The molded molecular sieve is ground into powder for XRD analysis, and the molecular sieve is SAPO-11. Example 3

[0056] 17.39g pseudo-boehmite (78.35wt% Al2O3) was placed in a 250mL beaker, 89g deionized water was added, and the mixture was stirred at room temperature for 30 minutes; 3.1g 85wt% phosphoric acid and 3.53g diammonium hydrogen phosphate were added, and the mixture was stirred for 3 hours; 26.68g 30w% silica sol was added, and the mixture was stirred for 30 minutes; 13.52g di-n-propylamine was added, and the mixture was stirred for 30 minutes; finally, 50g 1-ethyl-3-methyl imidazolium bromide ionic liquid was added. The mixture was stirred evenly into a gel state, and then baked at 90°C for 30 minutes. The mixture was stirred evenly into a gel state, and then baked at 75°C for 30 minutes. The plastic gel mixture obtained by the above operation was rolled into a ball. The obtained spherical gel was placed in a crystallization kettle with a polytetrafluoroethylene kettle liner, and crystallized at 175°C for 24 hours in a closed manner.

[0057] After the crystallization is completed, the crystallization kettle is cooled to room temperature to obtain a spherical molecular sieve. The spherical molecular sieve is ground into powder for XRD analysis, and the molecular sieve is SAPO-11. Example 4

[0058] 17.39g pseudo-boehmite (78.35wt% Al2O3) was placed in a 250mL beaker, 96.5g deionized water was added, and stirred at room temperature for 30 minutes; 33.9g 85wt% phosphoric acid was added and stirred for 3 hours; 8.03g 30w% silica sol was added and stirred for 30 minutes; 8.18g di-n-propylamine was added and stirred for 30 minutes; finally, 25.54g 1-ethyl-3-methyl imidazolium bromide ionic liquid was added. The above mixture was stirred evenly into a gel state, and then baked at 90°C for 30 minutes. The plastic gel mixture obtained by the above operation was extruded into a honeycomb shape using a single screw extruder. The obtained molded honeycomb gel was placed in a crystallization kettle with a polytetrafluoroethylene kettle liner and crystallized in a closed state at 200°C for 18 hours.

[0059] After the crystallization is completed, the crystallization kettle is cooled to room temperature to obtain a honeycomb-shaped molecular sieve. The formed molecular sieve is ground into powder for XRD analysis, and the molecular sieve is SAPO-11.

[0060] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A method for directly synthesizing a SAPO-11 molecular sieve, characterized in that: The synthetic gel is pre-processed into a desired shape and directly crystallized in one step to obtain a shaped body composed of a molecular sieve, comprising the following steps: (1) mixing an aluminum source, a phosphorus source, a silicon source, an organic amine, an ionic liquid and water in a molar ratio of Al2O3:P2O5:SiO2:organic amine:ionic liquid:H2O=1:0.2-3:0.05-1:0.1-2:0.1-2:30-45 to prepare a gel; (2) processing the gel prepared in step (1) into a shaped gel having a desired shape; (3) placing the formed gel obtained in step (2) in a sealed container and crystallizing at 175-210°C for 30 min-24 h to obtain a formed SAPO-11 molecular sieve; Step (1) is carried out in a self-made ultrasonic oscillation high-pressure reactor, and step (2) and step (3) are carried out in a self-made ultrasonic oscillation microwave reactor. A reactor ultrasonic oscillator (8) is installed at the lower part of the shell (3) of the ultrasonic oscillation high-pressure reactor.

2. The method for directly synthesizing SAPO-11 molecular sieve according to claim 1, characterized in that: The upper part of the ultrasonic oscillation high-pressure reactor is provided with a feeding port (4), the lower part is provided with a discharging port (1), the middle part of the stirrer (2) extends into the reactor, and the stirrer (2) is connected to the reactor motor (5); the oscillation frequency of the reactor ultrasonic oscillator (8) is: 120KHZ in the early stage, 60KHZ in the middle stage, and 30KHZ in the final stage, each oscillation time is 10-30 minutes, and the interval period is 4-8 hours.

3. The method for directly synthesizing SAPO-11 molecular sieve according to claim 2, characterized in that: The ultrasonic oscillation high-pressure reactor is also provided with a thermocouple (6) and a pH meter (7).

4. The method for directly synthesizing SAPO-11 molecular sieve according to claim 1, characterized in that: A plurality of microwave reaction ultrasonic oscillators (12) are installed at the bottom of the cavity (16) of the ultrasonic oscillation microwave reactor, the rear of which is connected to a material receiving hopper (15) and the front of which is connected to a conveyor belt (9). A microwave reaction motor (10) provides power for the conveyor belt (9); the oscillation frequency of the microwave reaction ultrasonic oscillators (12) is 20 MHZ to 3000 MHZ.

5. The method for directly synthesizing SAPO-11 molecular sieve according to claim 4, characterized in that: The microwave reaction motor (10) is provided with an operation panel (11), and the cavity (16) is supported by a plurality of brackets (13).

6. The method for directly synthesizing SAPO-11 molecular sieve according to claim 1, characterized in that: The organic amine is di-n-propylamine, diisopropylamine, one or both; the anion of the ionic liquid is One or more of the following: the cation is an alkyl-substituted imidazolium ion , alkyl-substituted pyridinium ion , alkyl quaternary ammonium salt ion One or more of the following, R is a C1-C16 alkyl group; the aluminum source is one or two of pseudo-boehmite and activated alumina; the phosphorus source is one or more of phosphoric acid, monoammonium hydrogen phosphate, diammonium phosphate, and triammonium phosphate; and the silicon source is silica sol.

7. The method for directly synthesizing SAPO-11 molecular sieve according to claim 1, characterized in that: The gel molding is extrusion molding, compression molding, oil column molding, rotation molding, spray molding, and granulation; the shape of the obtained molded gel is any one of sphere, strip, cylinder, honeycomb, four-leaf clover, three-leaf clover, external gear, non-porous external gear, plum blossom, porous plum blossom, seven-hole sphere, non-porous sphere, seven-rib wheel, four-hole, and four-leaf butterfly.

8. The method for directly synthesizing SAPO-11 molecular sieve according to claim 1, characterized in that: The gel is pretreated before molding, and the gel is properly aged or treated at a temperature not exceeding 110° C. to remove a portion of the water in the gel to obtain a plastic solid, which is then molded.

9. The method for directly synthesizing SAPO-11 molecular sieve according to claim 1, characterized in that: The crystallization process of step (3) is carried out by placing the formed gel in a pressure container. A certain amount of water is placed in the container in advance, and the water is not in direct contact with the formed gel. The crystallization process adopts oil bath heating, oven heating or microwave heating.

10. An application of directly synthesized SAPO-11 molecular sieve, characterized in that: Applied to the isomerization reaction of alkanes.

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