Synthesis method of Y-type molecular sieve with low salt discharge

Abstract

The invention discloses a low-salt-discharge Y-type molecular sieve synthesis method, which comprises: uniformly mixing a silicon source, a guiding agent and a silica-alumina gel, sequentially adding an aluminum source and a sodium metaaluminate solution to form a gel, and carrying out crystallization and post-treatment to obtain a Y-type molecular sieve, the guiding agent is obtained by mixing and aging a sodium metaaluminate solution, silicon powder, a silicon source and an alkaline compound; the same sodium metaaluminate solution is adopted when the gel is formed and the guiding agent is prepared, the sodium metaaluminate solution contains a stabilizer, and the molar ratio of Na2O to Al2O3 to SiO2 in the gel is (1.0-1.9): 1: (6-7). The Y-type molecular sieve synthesis method provided by the invention not only can reduce the emission of sodium salt, but also can be effectively and continuously implemented in an industrial device, the crystallinity of the finally prepared Y-type molecular sieve is 90-99%, and the Y-type molecular sieve is an industrial product with stable product quality.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve synthesis, and in particular relates to a method for synthesizing a Y-type molecular sieve with low salt emission. Background Art

[0002] Catalytic cracking is the core process technology for the lightening of heavy oil and the integration of refining and chemical industry in refineries, accounting for about 19.0% of the primary processing capacity of crude oil. With the growth of catalytic cracking processing capacity, its proportion of primary processing capacity of crude oil is still the largest, and it is also the most important means of heavy oil processing; moreover, refining technology tends to develop in a large-scale, clean and integrated way.

[0003] Catalysts are the core of catalytic cracking technology, with strong control capabilities, large control range and quick results. Due to the complex and changeable raw materials, various processes and large differences in production equipment of catalytic cracking, catalysts need to meet the requirements of operational adaptability, product distribution adjustment and product quality upgrade. Therefore, catalysts determine the product structure and economic benefits of refineries to a large extent.

[0004] Y-type molecular sieve is one of the most important molecular sieves in catalytic cracking catalysts and is also the main source of activity. At present, the most important method for preparing NaY molecular sieve is to synthesize by hydrothermal method under alkaline silica-alumina colloid system, so that the synthesized molecular sieve has the characteristics of high molecular sieve content and high silicon-aluminum ratio. Although this process is relatively mature, the quality of the product is relatively stable, and it is widely used in industrial devices, especially the full circulation use of crystallization mother liquor, which significantly improves the utilization rate of SiO2. However, since NaY synthetic raw materials are all chemical synthesis raw materials, including silicon sources, such as water glass, silica sol, etc., also including acidic aluminum sources (such as aluminum sulfate, aluminum nitrate, aluminum chloride, etc.), etc., therefore, a large amount of sodium salts will inevitably be produced in NaY synthesis, which brings very great pressure to subsequent sewage discharge and environmental protection treatment. Based on this, it is of great practical significance to develop a preparation method of Y-type molecular sieve with low salt discharge of environmental protection.

[0005] Chinese patent document CN111320184A discloses a method for preparing NaY molecular sieve by recycling NaY mother liquor, specifically, the mixture of NaY mother liquor and supplementary silicon source is fully dissolved and homogenized at 30-80°C to obtain high modulus water glass as silicon source for synthesis. The method can realize 100% recycling of NaY mother liquor and reduce the environmental pollution caused by waste liquid and waste residue caused by mother liquor discharge. However, the method does not mention how to reduce salt discharge during the synthesis of Y-type molecular sieve.

[0006] Chinese patent document CN108609633A discloses a method for synthesizing NaY molecular sieves without containing an acidic aluminum source in the raw material. The specific steps are to add silicon aluminum powder as the silicon source and aluminum source for NaY synthesis, and the NaY molecular sieve crystallization mother liquor is directly reused in the synthesis of NaY molecular sieve. The method provided by the present invention reduces the environmental problems caused by the discharge of sodium salts, but the NaY mother liquor cannot be fully reused using this method, which means that although certain salt discharges are reduced, the mother liquor containing sodium, silicon and aluminum will still be discharged, increasing the cost of wastewater treatment, bringing new environmental pollution, and the silicon aluminum powder preparation process is complicated, and the energy consumption is very high, which is not conducive to implementation in industrial devices.

[0007] Chinese patent document CN101112996A discloses a method for rapid synthesis of NaY molecular sieves. Compared with the traditional NaY synthesis process, it does not require the preparation of a directing agent, and the synthesis process does not require the addition of a directing agent. However, it first requires the silicon source, aluminum source, alkali and water to be mixed in a certain proportion and stirred evenly at 0-60°C for 2-10 hours, and then the mixture is placed in a high-pressure reactor, aged at 5-40°C for 0.5-24 hours, and finally the aged mixture is crystallized at 80-120°C in the reactor for 8-48 hours. The entire synthesis process does not involve salt reduction technology.

[0008] Chinese patent document CN111410206A discloses a method for preparing a high silicon-aluminum ratio Y-type molecular sieve, which uses water glass solution, directing agent solution, aluminum sulfate solution, sodium aluminate solution and silica-alumina gel solution as raw materials, and adds them into a gelling reactor in parallel, performs a gelling reaction at equal pH value, ages, and performs post-treatment to obtain the high silicon-aluminum ratio Y-type molecular sieve; wherein the sodium aluminate solution used in the gelling reaction and the preparation of the directing agent solution is the same, the concentrations of Al2O3 and Na2O in the sodium aluminate solution are 80-180g / L and 100-200g / L respectively, and the molar ratio of Na2O, Al2O3, and SiO2 in the gelling reaction is 2-3.5:1:8-10. This method successfully prepares a Y-type molecular sieve with low impurity content, large grains, good adsorption performance, high relative crystallinity, and good stability. However, when using the same sodium aluminate solution, it is necessary to overcome the problems of continuous crystallization synthesis and reprocessing of the mother liquor. The existing sodium aluminate solutions generally have the problem of poor stability, and the relative crystallinity of the molecular sieve obtained by this solution does not meet the requirements of industrial continuous production.

[0009] Chinese patent document CN113149028A discloses a method for preparing NaY molecular sieve using active silicon powder and recycling mother liquor, comprising the following steps: S1. preparing active silicon powder: selecting one or more of waste FCC catalyst, bentonite, kaolin, and fly ash, adding hydrochloric acid or sulfuric acid at 1.0-1.5 times the theoretical acid consumption, stirring and acidolysis activation for 1-6 hours, filtering and separating, and using the solution for use in preparing finished products such as polyaluminum; washing the solid to obtain active silicon slag, drying and crushing to obtain active silicon powder; S2. preparing NaY molecular sieve crystallization directing agent; S 3. Gelling: Mix active silicon powder, low-alkali sodium aluminate and directing agent in a certain proportion, stir evenly at 10-80°C for 0.5-5 hours, then add a calculated amount of water to make the total molar ratio of the mixed solution Na2O: Al2O3: SiO2: H2O = 2-6: 1: 8-15: 90-350, and stir at 10-60°C for 0.5-5 hours; S4. Crystallization: Crystallize the mixture at 80-120°C in a reactor for 6-48 hours, and then filter, wash and dry to obtain the product NaY, and collect the mother liquor after filtration. However, there are two problems in this method: one is that when acid-treating waste FCC catalysts, bentonite, kaolin and fly ash, there are problems of complex process flow and difficulty in filtration; the other is that the quality of the Y-type molecular sieve obtained by this synthesis method is lower than that of the conventional gel method, and there will be impurity crystals, which is not suitable for continuous industrial processes.

[0010] Other Chinese patent documents CN104340990A, CN105621448A, CN105314651A and CN105084387A disclose methods for preparing small-grain NaY molecular sieves by different methods such as directing agent ratios and raw material usage, but none of them mention how to reduce salt emissions during the synthesis stage.

[0011] In summary, the existing research on the preparation method of NaY molecular sieve is mostly focused on the following two aspects: 1) How to efficiently utilize the mother liquor and improve the utilization rate of silicon; 2) How to synthesize NaY molecular sieve with high silicon-aluminum ratio and small crystallite, that is, to improve the crystallinity and crystallite properties of the molecular sieve. There are few studies on how to reduce the emission of sodium salts in the preparation process of Y-type molecular sieve. Summary of the invention

[0012] In view of this, the present invention provides a method for synthesizing a Y-type molecular sieve with low salt emission. Compared with the existing method for synthesizing a Y-type molecular sieve, the method for synthesizing a Y-type molecular sieve provided by the present invention can not only reduce the emission of sodium salt, but also can be effectively and continuously implemented in an industrial device. The final Y-type molecular sieve obtained has a crystallinity of 90% to 99% and is an industrial product with stable product quality.

[0013] To achieve the above object, the present invention provides the following technical solutions:

[0014] A method for synthesizing a Y-type molecular sieve with low salt emission comprises the following steps:

[0015] After the silicon source, the directing agent and the silica-alumina gel are uniformly mixed, the aluminum source and the sodium metaaluminate solution are added in sequence to form a gel, and after crystallization and post-treatment, a Y-type molecular sieve is obtained;

[0016] The guiding agent is obtained by mixing and aging sodium aluminate solution, silicon powder, silicon source and alkaline compound;

[0017] The sodium aluminate solution used in forming the gel and preparing the guiding agent is the same, the sodium aluminate solution contains a stabilizer, and the concentration of Al2O3 is 190-400g / L, and the concentration of Na2O is 210-400g / L; and the molar ratio of Na2O to Al2O3 is controlled to be 0.86-3.46:1.

[0018] The molar ratio of Na2O, Al2O3 and SiO2 in the gel is (1.0-1.9):1:(6-7).

[0019] Optionally, in the low-salt emission Y-type molecular sieve synthesis method provided by the present invention, the sodium aluminate solution is obtained by stirring 25wt% to 50wt% of sodium hydroxide solution and aluminum hydroxide powder with an Al2O3 content of not less than 60wt% at 0.1 to 0.4MPa and 100 to 140°C for 2 to 6 hours, and then adding a stabilizer to obtain it.

[0020] Optionally, in the process for preparing the sodium aluminate solution provided by the present invention, the stabilizer is selected from one or more of sodium carbonate, sodium bicarbonate, and ammonia water.

[0021] Taking the mass of the sodium hydroxide solution and the aluminum hydroxide powder added in the process of preparing the sodium aluminate solution as 100%, the content of the stabilizer is 1% to 10%.

[0022] Optionally, in the method for synthesizing a Y-type molecular sieve with low salt emission provided by the present invention, the molar ratio of Na2O, Al2O3 and SiO2 in the directing agent is (10-20):1:(10-20).

[0023] Optionally, in the method for synthesizing a Y-type molecular sieve with low salt emission provided by the present invention, the preparation of the directing agent comprises the following steps: adding the alkaline compound and the silicon powder to the sodium aluminate solution, adding the silicon source after mixing evenly, and aging at 30 to 40° C. for 6 to 24 hours;

[0024] The mass ratio of the alkaline compound to the directing agent is 0.01 to 0.1 based on Al2O3;

[0025] The molar ratio of the silicon powder to the directing agent is 0.01 to 0.2 based on SiO2;

[0026] The alkaline compound is selected from any one of sodium hydroxide, sodium carbonate and sodium bicarbonate.

[0027] Optionally, in the method for synthesizing a Y-type molecular sieve with low salt emission provided by the present invention, based on the mass of the gel as 100%, the content of the directing agent is 1wt% to 30wt%, preferably 1wt% to 20wt%.

[0028] Optionally, in the low-salt emission Y-type molecular sieve synthesis method provided by the present invention, the SiO2 content in the silica-alumina gel is 55wt%~65wt%, the Al2O3 content is 15wt%~20wt%, and the Na2O content is 12wt%~14wt%; the solid content is 10wt%~12wt%, and the density is 1.090~1.10.

[0029] Optionally, in the low-salt emission Y-type molecular sieve synthesis method provided by the present invention, the silica-alumina gel is obtained by reacting NaY mother liquor with an aluminum source, and the SiO2 concentration in the NaY mother liquor is 40-60 g / L and the Na2O concentration is 20-30 g / L.

[0030] Optionally, in the method for synthesizing a Y-type molecular sieve with low salt emission provided by the present invention, the post-treatment includes the steps of separation, washing and drying; the washing step is carried out with deionized water until the pH value of the filtrate is 10.0-10.5.

[0031] Optionally, in the method for synthesizing a Y-type molecular sieve with low salt emission provided by the present invention, the crystallization is hydrothermal crystallization, and the temperature of the hydrothermal crystallization is 92 to 100° C., and the time is 16 to 40 hours.

[0032] Optionally, in the method for synthesizing a Y-type molecular sieve with low salt emission provided by the present invention, the silicon source is selected from one or more of silicon aluminum powder, silica sol, water glass, white carbon black and sodium silicate; the SiO2 concentration in the water glass is 260-350 g / L and the modulus is 2.96-3.40;

[0033] The aluminum source is selected from one or more of aluminum sulfate, aluminum phosphate, aluminum chloride, aluminum nitrate, aluminum fluoride, aluminum formate and aluminum acetate.

[0034] Optionally, the method for synthesizing the Y-type molecular sieve with low salt emission provided by the present invention comprises the following steps:

[0035] Add the directing agent and silica-alumina gel to the silicon source in sequence, mix evenly (such as stirring and mixing for 30 to 60 minutes), then add the aluminum source and mix thoroughly (such as mixing for 30 to 60 minutes), and finally add the sodium aluminate solution to form a gel, and obtain the Y-type molecular sieve through crystallization, filtration, washing and drying.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] Beneficial effect 1: The Y-type molecular sieve synthesis method with low salt emission provided by the present invention achieves the ultimate goal of low salt emission through the mutual coordination between various raw materials. Compared with the existing conventional formula, the feeding amount of sodium oxide in the synthesis process provided by the present invention is reduced by 50% to 55%, the feeding amount of aluminum oxide is reduced by 5% to 8%, and the feeding amount of silicon oxide is reduced by 20% to 30%. The total synthesis cost is reduced by 30% to 50%, and the salt emission is reduced by 40% to 50%.

[0038] Beneficial effect 2: The Y-type molecular sieve synthesis method with low salt emission provided by the present invention starts from changing the properties of the synthetic raw materials, adopting a new synthesis formula and combining hydrothermal crystallization to synthesize high-quality Y-type molecular sieves, which minimizes the amount of salt emissions while reducing costs and energy consumption, and successfully realizes industrial application. Specifically, 1) In the traditional Y-type molecular sieve synthesis process, different concentrations of sodium aluminate solutions are used in the directing agent configuration process and the gel preparation process, respectively, which increases the complexity of the process operation, energy consumption and various raw material consumption. The present invention only uses a sodium aluminate solution of one concentration when preparing the directing agent and the gel, which reduces the introduction of sodium and the type of synthetic solution from the source, thereby reducing the sodium, sulfate and other ions that may form salts brought in by the synthesis, while reducing the types of synthetic solutions and the sodium oxide brought in by the synthesis. It greatly reduces the energy consumption of production enterprises, various raw material consumption and transportation, and significantly reduces the synthesis cost. 2) Sodium aluminate solution is a very important aluminum source in the synthesis of Y-type molecular sieves. Under normal conditions, the preparation of the solution requires strict temperature control, and the concentration control of the sodium oxide and aluminum oxide ratio in the solution is very strict. In addition, since sodium aluminate exists in the form of Na[Al(OH)4] (sodium tetrahydroxyaluminate) in aqueous solution, it is in an unstable state and is easily precipitated in the form of Al(OH)3, causing the sodium aluminate solution to decompose and deteriorate. Therefore, the stability of the sodium aluminate solution is poor, and the general storage time cannot exceed 72 hours, which greatly limits the continuity and efficiency of the molecular sieve synthesis, resulting in energy consumption and waste of raw materials. The present invention starts from the root cause of the poor stability of the sodium aluminate solution. It is found through research that by adding a stabilizer, the stabilizer dissociates into OH in the solution. -Preventing the decomposition of Na[Al(OH)4] greatly improves the stability of the sodium aluminate solution, and facilitates storage and transportation, providing guarantees for the continuity and efficiency of molecular sieve synthesis, while reducing raw material and production costs, and reducing the amount of wastewater and waste residue generated. 3) The present invention adds silicon powder to the directing agent, which not only plays a role in supplementing the silicon source, but more importantly, after the silicon powder is added, countless "silicon islands" are formed. During the aging stage of the directing agent, aluminum ions are more easily adsorbed on the silicon islands to form the initial structural units of silicon and aluminum, thereby increasing the crystal nucleus, promoting crystal growth, and improving the relative crystallinity of the molecular sieve. 4) On the basis of the above two raw materials, a gel ratio with lower sodium is adopted, the utilization rate of the silicon and aluminum source is high, the crystallization time is short, the entire process operation is simple and efficient, and the obtained Y-type molecular sieve has a high degree of crystallinity. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the XRD diagram of the Y-type molecular sieve prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0040] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0041] If no specific experimental steps or conditions are specified in the examples and comparative examples, the conventional experimental steps or conditions described in the literature in the art can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be purchased commercially.

[0042] Source of raw materials or equipment:

[0043] Sodium silicate: industrial product, sourced from the Catalyst Division of Lanzhou Petrochemical Company (SiO2: 19.60%, Na2O: 6.86%)

[0044] Sodium aluminate: industrial product, sourced from the catalyst division of Lanzhou Petrochemical Company (Na2O: 12.10%, Al2O3: 8.06%)

[0045] Aluminum sulfate: industrial product, sourced from the Catalyst Division of Lanzhou Petrochemical Company (Al2O3: 7.10%)

[0046] Sodium hydroxide, aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum phosphate, aluminum nitrate, aluminum acetate, aluminum formate, aluminum fluoride, sodium carbonate, sodium bicarbonate, silica sol, ammonia water: chemically pure, Sinopharm Chemical Reagent Co., Ltd.

[0047] Silica fume: chemically pure, Qingdao Jinyang Fine Chemical Co., Ltd.

[0048] Preparation of sodium aluminate solution

[0049] Sodium aluminate solution 1: 25wt% sodium hydroxide solution and aluminum hydroxide powder with Al2O3 content of 60wt% were reacted in an autoclave at 0.4MPa and 140℃ for 6 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:0.86. The Al2O3 concentration in the sodium aluminate solution was 400g / L, and the Na2O concentration was 210g / L. Then, solid sodium hydroxide accounting for 1% of the total mass of the sodium aluminate solution was added, and the mixture was fully stirred and mixed for use.

[0050] Sodium aluminate solution 2: 50wt% sodium hydroxide solution and aluminum hydroxide powder with Al2O3 content of 80wt% were reacted in an autoclave at 0.1MPa and 100℃ for 2 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:3.46. The Al2O3 concentration in the sodium aluminate solution was 190g / L, and the Na2O concentration was 400g / L. Then, solid sodium bicarbonate accounting for 5% of the total mass of the sodium aluminate solution was added, and the mixture was fully stirred and mixed for use.

[0051] Sodium aluminate solution 3: 40wt% sodium hydroxide solution and aluminum hydroxide powder with Al2O3 content of 90wt% were reacted in an autoclave at 0.3MPa and 100℃ for 2 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:1.08. The Al2O3 concentration in the sodium aluminate solution was 380g / L, and the Na2O concentration was 250g / L. Then, solid sodium carbonate accounting for 10% of the total mass of the sodium aluminate solution was added, and the mixture was fully stirred and mixed for use.

[0052] Sodium aluminate solution 4: 30wt% sodium hydroxide solution and aluminum hydroxide powder with an Al2O3 content of 95wt% were reacted in an autoclave at 0.2MPa and 100°C for 4 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:1.84. The Al2O3 concentration in the sodium aluminate solution was 250g / L, and the Na2O concentration was 280g / L.

[0053] Then add an ammonia solution (mass concentration 20%) accounting for 8% of the total mass of the sodium aluminate solution, and stir and mix thoroughly for use.

[0054] Sodium aluminate solution 5: 35wt% sodium hydroxide solution and aluminum hydroxide powder with an Al2O3 content of 95wt% are reacted in an autoclave at 0.1MPa and 120°C for 5 hours, and the molar ratio of Al2O3 to Na2O is controlled to be 1:2.08. The Al2O3 concentration in the sodium aluminate solution is 210g / L, and the Na2O concentration is 265g / L.

[0055] Then add an ammonia solution (mass concentration 20%) accounting for 7% of the total mass of the sodium aluminate solution, and stir and mix thoroughly for use.

[0056] Sodium aluminate solution 6: 45wt% sodium hydroxide solution and aluminum hydroxide powder with an Al2O3 content of 60wt% were reacted in an autoclave at 0.4MPa and 140°C for 2 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:1.65. The Al2O3 concentration in the sodium aluminate solution was 300g / L, and the Na2O concentration was 300g / L.

[0057] Then add solid sodium hydroxide accounting for 3% of the total mass of the sodium aluminate solution, stir and mix thoroughly for use.

[0058] Sodium aluminate solution 7: 33wt% sodium hydroxide solution and aluminum hydroxide powder with an Al2O3 content of 70wt% are reacted in an autoclave at 0.3MPa and 130°C for 3 hours, and the molar ratio of Al2O3 to Na2O is controlled to be 1:1.88. The Al2O3 concentration in the sodium aluminate solution is 280g / L, and the Na2O concentration is 320g / L.

[0059] Then add 2% of the mass of solid sodium bicarbonate in the total sodium aluminate solution, stir and mix thoroughly for later use.

[0060] Sodium aluminate solution 8: 37wt% sodium hydroxide solution and aluminum hydroxide powder with an Al2O3 content of 77wt% are reacted in an autoclave at 0.2MPa and 110°C for 5 hours, and the molar ratio of Al2O3 to Na2O is controlled to be 1:1.72. The Al2O3 concentration in the sodium aluminate solution is 330g / L, and the Na2O concentration is 345g / L.

[0061] Then add solid sodium carbonate accounting for 4% of the total mass of the sodium aluminate solution, stir and mix thoroughly for use.

[0062] Sodium aluminate solution 9: 32wt% sodium hydroxide solution and aluminum hydroxide powder with Al2O3 content of 73wt% were reacted in an autoclave at 0.1MPa and 135°C for 5 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:1.79. The Al2O3 concentration in the sodium aluminate solution was 350g / L, and the Na2O concentration was 380g / L. Then, an ammonia solution (mass concentration 20%) accounting for 6% of the total mass of the sodium aluminate solution was added, and the mixture was fully stirred and mixed for use.

[0063] Sodium aluminate solution 10: 25wt% sodium hydroxide solution and aluminum hydroxide powder with Al2O3 content of 72wt% were reacted in an autoclave at 0.1MPa and 135℃ for 6 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:1.69. The Al2O3 concentration in the sodium aluminate solution was 365g / L, and the Na2O concentration was 375g / L. Then, solid sodium hydroxide accounting for 9% of the total mass of the sodium aluminate solution was added, and the mixture was fully stirred and mixed for use.

[0064] Preparation of silica-alumina gel

[0065] The element content in silica-alumina gel is calculated after being determined by chemical titration, and the density is determined by a pycnometer.

[0066] Silica-alumina gel 1: NaY mother liquor with SiO2 concentration of 40g / L and Na2O concentration of 20g / L and aluminum sulfate solution with Al2O3 concentration of 88g / L were reacted in a synthesis reactor for 1h, filtered and washed with deionized water to obtain. After testing, the quality data of the silica-alumina gel are: SiO2 55%, Al2O3 15%, Na2O 12%, solid content 10%, density 1.09.

[0067] Silica-alumina gel 2: NaY mother liquor with SiO2 concentration of 60g / L and Na2O concentration of 30g / L was reacted with aluminum chloride in a synthesis reactor for 5h, filtered, and washed with deionized water to obtain the silica-alumina gel. After testing, the quality data of the silica-alumina gel are: SiO2 65%, Al2O3 20%, Na2O 14%, solid content 12%, and density 1.10.

[0068] Silica-alumina gel 3: NaY mother liquor with SiO2 concentration of 50g / L and Na2O concentration of 20 / L was reacted with aluminum phosphate in a synthesis reactor for 2h, filtered, and washed with deionized water to obtain the silica-alumina gel. After testing, the quality data of the silica-alumina gel are: SiO2 60%, Al2O3 18%, Na2O 13%, solid content 11%, and density 1.10.

[0069] Silica-alumina gel 4: NaY mother liquor with SiO2 concentration of 40g / L and Na2O concentration of 30 / L was reacted with aluminum nitrate in a synthesis reactor for 3h, filtered, and washed with deionized water to obtain the silica-alumina gel. After testing, the quality data of the silica-alumina gel are: SiO2 58%, Al2O3 16%, Na2O 12%, solid content 12%, and density 1.10.

[0070] Silica-alumina gel 5: NaY mother liquor with SiO2 concentration of 45g / L and Na2O concentration of 25 / L was reacted with aluminum acetate in a synthesis reactor for 4 hours, filtered, and washed with deionized water to obtain the silica-alumina gel. After testing, the quality data of the silica-alumina gel are: SiO2 63%, Al2O3 19%, Na2O 12%, solid content 12%, and density 1.10.

[0071] Silica-alumina gel 6: NaY mother liquor with SiO2 concentration of 53g / L and Na2O concentration of 27 / L was reacted with aluminum formate in a synthesis reactor for 5h, filtered, and washed with deionized water to obtain the silica-alumina gel. After testing, the quality data of the silica-alumina gel are: SiO2 62%, Al2O3 15%, Na2O 12%, solid content 12%, and density 1.09.

[0072] Silica-alumina gel 7: NaY mother liquor with SiO2 concentration of 43g / L and Na2O concentration of 23 / L was reacted with aluminum sulfate solution in a synthesis reactor for 2h, filtered, and washed with deionized water to obtain. After testing, the quality data of the silica-alumina gel are: SiO2 58%, Al2O3 16%, Na2O 12%, solid content 12%, and density 1.10.

[0073] Silica-alumina gel 8: NaY mother liquor with SiO2 concentration of 44g / L and Na2O concentration of 24 / L was reacted with aluminum fluoride in a synthesis reactor for 1h, filtered, and washed with deionized water to obtain the silica-alumina gel. After testing, the quality data of the silica-alumina gel are: SiO2 59%, Al2O3 17%, Na2O 12%, solid content 12%, and density 1.10.

[0074] Silica-alumina gel 9: NaY mother liquor with SiO2 concentration of 60g / L and Na2O concentration of 30g / L was reacted with aluminum formate in a synthesis reactor for 3h, filtered, and washed with deionized water to obtain the silica-alumina gel. After testing, the quality data of the silica-alumina gel are: SiO2 64%, Al2O3 19%, Na2O 14%, solid content 12%, and density 1.10.

[0075] Silica-alumina gel 10: NaY mother liquor with SiO2 concentration of 56g / L and Na2O concentration of 26g / L was reacted with aluminum nitrate in a synthesis reactor for 4h, filtered, and washed with deionized water to obtain. After testing, the quality data of the silica-alumina gel are: SiO2 55%, Al2O3 16%, Na2O 12%, solid content 12%, and density 1.10.

[0076] Preparation of directing agent

[0077] Directing agent 1: Weigh 100g of the above-mentioned fresh sodium aluminate solution 1, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.2), water glass, solid sodium hydroxide (calculated as alumina as the directing agent, the amount of the alkali added accounts for 1% of the total mass of the directing agent), and age at 35°C for 23 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 10:1:10.

[0078] Directing agent 2: Weigh 130g of the above-mentioned fresh sodium aluminate solution 2, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.1), water glass, solid sodium carbonate (the directing agent is calculated as alumina, and the amount of the alkali added accounts for 10% of the total mass of the directing agent), and age at 30°C for 20 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 20:1:20.

[0079] Directing agent 3: Weigh 180g of the above-mentioned fresh sodium aluminate solution 3, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.01), water glass, solid sodium bicarbonate (the directing agent is calculated as alumina, and the amount of the alkali added accounts for 5% of the total mass of the directing agent), and age at 33°C for 18 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 20:1:15.

[0080] Directing agent 4: Weigh 140 g of the above-mentioned fresh sodium aluminate solution 4, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.03), water glass, solid sodium carbonate (the directing agent is calculated as alumina, and the amount of this alkali added accounts for 8% of the total mass of the directing agent), and age at 30°C for 16 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 15:1:10.

[0081] Directing agent 5: Weigh 170g of the above-mentioned fresh sodium aluminate solution 5, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.15), water glass, solid sodium hydroxide (the directing agent is calculated as alumina, and the amount of the alkali added accounts for 6% of the total mass of the directing agent), and age at 37°C for 12 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 15:1:20.

[0082] Directing agent 6: Weigh 130 g of the above-mentioned fresh sodium aluminate solution 6, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.18), water glass, solid sodium carbonate (calculated as alumina as the directing agent, the amount of the alkali added accounts for 4% of the total mass of the directing agent), and age at 40°C for 8 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 10:1:20.

[0083] Directing agent 7: Weigh 200 g of the above-mentioned fresh sodium aluminate solution 7, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.05), water glass, solid sodium bicarbonate (the directing agent is calculated as alumina, and the amount of the alkali added accounts for 3% of the total mass of the directing agent), and age at 32°C for 13 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 18:1:16.

[0084] Directing agent 8: Weigh 400 g of the above-mentioned fresh sodium aluminate solution 8, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.08), water glass, solid sodium carbonate (the directing agent is calculated as alumina, and the amount of this alkali added accounts for 9% of the total mass of the directing agent), and age at 36°C for 10 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 13:1:18.

[0085] Directing agent 9: Weigh 500 g of the above-mentioned fresh sodium aluminate solution 9, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.17), water glass, solid sodium bicarbonate (the directing agent is calculated as alumina, and the amount of this alkali added accounts for 7% of the total mass of the directing agent), and age at 38°C for 22 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 19:1:13.

[0086] Directing agent 10: Weigh 300 g of the fresh sodium aluminate solution 10, add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.12), water glass, solid sodium hydroxide (calculated as alumina for the directing agent, the amount of alkali added accounts for 2% of the total mass of the directing agent), and age at 31°C for 24 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 12:1:17.

[0087] Specific analysis method:

[0088] The crystallinity of the Y-type molecular sieve is determined by X-ray diffraction method on a D / max-3C X-ray powder diffractometer manufactured by Rigaku Corporation of Japan. The specific operation method refers to the standard Q / SYLS 0596-2002.

[0089] Example 1

[0090] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0091] Weigh 500g of silica sol, slowly add 400g of the above-mentioned silica-alumina gel 1, then add 123g of the above-mentioned directing agent 1, fully stir for 30min, then slowly add an aluminum sulfate solution with a concentration of 88g / L, stir for 20min, and finally add sodium aluminate solution 1 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1:1:7; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 100°C for 40 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.5, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0092] The Y-type molecular sieve was subjected to XRD test, and the results were as follows Figure 1 As shown by Figure 1 It can be seen that the Y-type molecular sieve has a complete crystal form and does not contain other impurity crystals.

[0093] Example 2

[0094] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0095] Weigh 200g of white carbon black, slowly add 100g of the above-mentioned silica-alumina gel 2, then add 78g of the above-mentioned directing agent 2, stir thoroughly for 30min, then slowly add aluminum chloride, stir for 20min, finally add sodium aluminate solution 2 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.9:1:6.8; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 96°C for 36 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.2, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0096] Example 3

[0097] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0098] Weigh 300g of water glass, slowly add 140g of the above-mentioned silica-alumina gel 3, then add 112g of the above-mentioned directing agent 3, stir thoroughly for 30min, then slowly add aluminum phosphate, stir for 20min, and finally add sodium aluminate solution 3 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.5:1:6.5; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 96°C for 36 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.1, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0099] Example 4

[0100] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0101] Weigh 500g of water glass, slowly add 300g of the above-mentioned silica-alumina gel 4, then add 132g of the above-mentioned directing agent 4, fully stir for 30min, then slowly add aluminum nitrate, stir for 20min, and finally add sodium aluminate solution 4 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.3:1:6.0; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 98°C for 32 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.3, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0102] Example 5

[0103] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0104] Weigh 500g of water glass, slowly add 340g of the above-mentioned silica-alumina gel 5, then add 148g of the above-mentioned directing agent 5, stir thoroughly for 30min, then slowly add aluminum acetate, stir for 20min, and finally add sodium aluminate solution 5 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.6:1:6.3; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 97°C for 26 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.4, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0105] Example 6

[0106] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0107] Weigh 350g of water glass, slowly add 167g of the above-mentioned silica-alumina gel 6, then add 102g of the above-mentioned directing agent 6, stir thoroughly for 30min, then slowly add aluminum formate, stir for 20min, and finally add sodium aluminate solution 6 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.8:1:6.9; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 95°C for 22 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.5, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0108] Example 7

[0109] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0110] Weigh 550g of water glass, slowly add 345g of the above-mentioned silica-alumina gel 7, then add 190g of the above-mentioned directing agent 7, fully stir for 30min, then slowly add a 90g / L aluminum sulfate solution, stir for 20min, and finally add sodium aluminate solution 7 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.4:1:6.2; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 97°C for 20 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.0, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0111] Example 8

[0112] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0113] Weigh 350g of water glass, slowly add 167g of the above-mentioned silica-alumina gel 8, then add 100g of the above-mentioned directing agent 8, stir thoroughly for 30min, then slowly add aluminum fluoride, stir for 20min, and finally add sodium aluminate solution 8 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.7:1:6.4; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 92°C for 38 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.3, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0114] Example 9

[0115] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0116] Weigh 390g of water glass, slowly add 160g of the above-mentioned silica-alumina gel 9, then add 140g of the above-mentioned directing agent 9, stir thoroughly for 30min, then slowly add aluminum formate, stir for 20min, and finally add sodium aluminate solution 9 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.7:1:6.7; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 100°C for 20 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.2, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0117] Example 10

[0118] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0119] Weigh 290g of water glass, slowly add 120g of the above-mentioned silica-alumina gel 10, then add 110g of the above-mentioned directing agent 10, stir thoroughly for 30min, then slowly add aluminum nitrate, stir for 20min, and finally add sodium aluminate solution 10 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.2:1:6.6; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 94°C for 30 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.4, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0120] Embodiment 11

[0121] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0122] Weigh 500g of silica sol, slowly add 400g of the above-mentioned silica-alumina gel 1, then add 123g of the above-mentioned directing agent 1, stir thoroughly for 30min, then slowly add an aluminum sulfate solution with a concentration of 88g / L, stir for 20min, and finally add a sodium aluminate solution 1 that has been placed at room temperature for 1 month to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1:1:7; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 100°C for 40 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.5, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0123] Example 12

[0124] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0125] Weigh 200g of white carbon black, slowly add 100g of the above-mentioned silica-alumina gel 2, then add 78g of the above-mentioned directing agent 2, stir thoroughly for 30min, then slowly add aluminum chloride, stir for 20min, and finally add sodium aluminate solution 2 that has been left at room temperature for 1 month to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.9:1:6.8; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 96°C for 36 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.2, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0126] Embodiment 13

[0127] This embodiment provides a method for synthesizing a Y-type molecular sieve, and the specific steps are as follows:

[0128] Weigh 350g of water glass, slowly add 167g of the above-mentioned silica-alumina gel 8, then add 100g of the above-mentioned directing agent 8, stir thoroughly for 30min, then slowly add aluminum fluoride, stir for 20min, finally add sodium aluminate solution 8 that has been left at room temperature for 1 month to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.7:1:6.4; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 92°C for 38 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.3, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0129] Comparative Example 1

[0130] The Y-type molecular sieve synthesis method provided in this comparative example is similar to that in Example 3, except that the sodium aluminate solution is different, and the sodium aluminate solution in this comparative example is used when preparing the directing agent. The Y-type molecular sieve synthesis method provided in this comparative example comprises the following steps:

[0131] Sodium aluminate solution D-1: 40wt% sodium hydroxide solution and aluminum hydroxide powder with an Al2O3 content of 90wt% were reacted in an autoclave at 0.3MPa and 100°C for 2 hours, and the molar ratio of Al2O3 to Na2O was controlled to be 1:1.08. The Al2O3 concentration in the sodium aluminate solution was 150g / L, and the Na2O concentration was 99g / L.

[0132] Directing agent D-1: Weigh 180g of the above-mentioned fresh sodium aluminate solution D-1, and add silicon powder (calculated as SiO2, the molar ratio of silicon powder to directing agent is 0.01), water glass, solid sodium bicarbonate (directing agent calculated as alumina, the amount of alkali added accounts for 5% of the total mass of the directing agent), and age at 33°C for 18 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 20:1:15.

[0133] Weigh 300g of water glass, slowly add 140g of the above-mentioned silica-alumina gel 3, then add 112g of the above-mentioned directing agent D-1, stir thoroughly for 30min, then slowly add aluminum phosphate, stir for 20min, and finally add the above-mentioned fresh sodium aluminate solution D-1 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.5:1:6.5; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 96°C for 36 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.1, and then dry at 120°C for 12h to obtain a Y-type molecular sieve.

[0134] Comparative Example 2

[0135] This comparative example is similar to Example 8, except that silicon powder is not added when preparing the directing agent. The Y-type molecular sieve synthesis method provided in this comparative example includes the following steps:

[0136] Directing agent D-2: Weigh 400 g of the fresh sodium aluminate solution 8, slowly add water glass and solid sodium carbonate (the amount of the directing agent based on alumina accounts for 9% of the total mass of the directing agent), and age at 36° C. for 10 hours to prepare a directing agent with a molar ratio of Na2O, Al2O3, and SiO2 of 13:1:18.

[0137] Weigh 350g of water glass, slowly add 167g of the above-mentioned silica-alumina gel 8, then add 100g of the above-mentioned directing agent D-2, fully stir for 30min, then slowly add aluminum fluoride, stir for 20min, and finally add the above-mentioned sodium aluminate solution 8 to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.7:1:6.4; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 92°C for 38 hours, and wash the filtered solid with deionized water until the pH of the washing liquid is 10.3, and then dry at 120°C to obtain a Y-type molecular sieve.

[0138] Comparative Example 3

[0139] The Y-type molecular sieve synthesis method provided in this comparative example is similar to that in comparative example 1, except that a sodium aluminate solution D-1 that has been left for a period of time is used to prepare the molecular sieve. The Y-type molecular sieve synthesis method provided in this comparative example comprises the following steps:

[0140] Weigh 300g of water glass, slowly add 140g of the above-mentioned silica-alumina gel 3, then add 112g of the above-mentioned directing agent D-1, stir thoroughly for 30min, then slowly add aluminum phosphate, stir for 20min, and finally add the above-mentioned sodium aluminate solution D-1 that has been left at room temperature for 7 days to form a gel, and control the molar ratio of Na2O, Al2O3, and SiO2 in the gel to be 1.5:1:6.5; after rapid stirring for 30min, transfer to a synthesis kettle, crystallize at 96°C for 36 hours, wash the filtered solid with deionized water until the pH of the washing liquid is 10.1, and then dry at 120°C to obtain a Y-type molecular sieve.

[0141] Comparative Example 4

[0142] The Y-type molecular sieve synthesis method provided in this comparative example comprises the following steps:

[0143] Sodium aluminate solution D-2: 500 ml of a 31.8% sodium hydroxide solution and 223.8 g of aluminum hydroxide powder with an Al2O3 content of 62.7% were added to a stirred reactor at a pressure of 0.2 MPa; the reaction temperature was 125°C, and the reaction time was 6 hours to prepare the sodium aluminate solution used.

[0144] Silica-alumina gel D-4: The filtered filtrate of the aged qualified material in the NaY preparation step with a SiO2 concentration of 45.8 g / L and a Na2O concentration of 25.2 g / L was reacted with an aluminum sulfate solution with an Al2O3 concentration of 90.2 g / L, and silica-alumina gel was prepared after filtration and washing. The quality data of the silica-alumina gel are: SiO2 61.9%, Al2O3 16.6%, Na2O 13.7%, solid content 11.9%, and density 1.0956.

[0145] Directing agent D-3: 135.6 ml of sodium aluminate solution with an Al2O3 concentration of 150.5 g / L and a Na2O concentration of 180.3 g / L and 270.6 ml of liquid caustic soda with a concentration of 31% are added to a stirred reactor. After stirring evenly, 718.2 ml of water glass solution with a SiO2 concentration of 250.6 g / L and a modulus of 3.25 are added. The aging temperature is controlled at 28°C and the product is aged for 20 hours. After aging, 169 ml of chemical water is added. The resulting product is the directing agent solution.

[0146] Take 255.9 ml of the above-mentioned silica-alumina gel D-4, 294.2 ml of water glass solution (the SiO2 concentration in the water glass solution is 250.6 g / L and the modulus is 3.25), 52.8 ml of the above-mentioned fresh sodium aluminate solution D-2, 50 ml of the directing agent D-3 and 65.8 ml of aluminum sulfate solution with an Al2O3 concentration of 90.5 g / L, and add them into the colloid reaction kettle at a certain flow rate to ensure that the molar ratio of Na2O, Al2O3 and SiO2 is 2-3.5:1:8-10. The stirring time is 40 minutes, the temperature is raised to 98°C, and it is aged for 28 hours. The obtained product is washed and filtered to obtain a Y-type molecular sieve.

[0147] The Y-type molecular sieves of the above-mentioned embodiments and comparative examples and their synthesis effects were compared in detail, and compared with the above-mentioned comparative example 4 as a benchmark, and the salt emission and cost were calculated. The effects are listed in Table 1.

[0148] Table 1 Effect

[0149]

[0150]

[0151] As can be seen from the data in the above table, Example 3 is compared with Comparative Example 1. After adding a stabilizer, the instability problem of the sodium aluminate solution is fundamentally solved. While ensuring the high crystallinity of the molecular sieve, the salt discharge and total cost are reduced by 10% and 17% respectively compared with Comparative Example 1. In addition, it can be seen from the comparison results of Example 8 and Comparative Example 2 that after adding silicon powder to the preparation process of the guiding agent, the role of "silicon island" aggregation and promoting crystallization synthesis is fully exerted, so that the crystallinity of the Y-type molecular sieve is increased by 8 units. And from the comparison results of the different placement times of sodium aluminate in Example 3 and Comparative Example 3, it can be seen that if no stabilizer is added, the sodium aluminate solution is easy to parse out aluminum-containing compounds, thereby causing failure, and the synthesis efficiency is deteriorated, thereby affecting the synthesis effect, and the crystallinity is reduced from 97% to 76%, which significantly affects the synthesis effect, and the total cost reduction rate is low. Although Comparative Example 4 can ensure smooth crystallization, since it is not a low sodium gel ratio, it has no advantage over the present invention in terms of salt discharge and total cost reduction, which further proves that the present invention has the advantages of comprehensive sodium reduction from the source and reducing salt emissions.

[0152] In summary, the synthesis method of the Y-type molecular sieve provided by the present invention greatly reduces the salt emission and the total synthesis cost while ensuring the high-quality synthesis of NaY, showing very good results, reducing costs and increasing efficiency while having a broader application prospect.

[0153] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for synthesizing a Y-type molecular sieve with low salt emission, characterized in that: The steps include: After the silicon source, the directing agent and the silica-alumina gel are uniformly mixed, the aluminum source and the sodium metaaluminate solution are added in sequence to form a gel, and the Y-type molecular sieve is obtained through crystallization and post-treatment; Wherein, the guiding agent is obtained by mixing and aging sodium aluminate solution, silicon powder, silicon source and alkaline compound; The sodium aluminate solution used in forming the gel and preparing the guiding agent is the same, the sodium aluminate solution contains a stabilizer, and the concentration of Al2O3 is 190-400g / L, the concentration of Na2O is 210-400g / L, and the molar ratio of Na2O to Al2O3 is controlled to be 0.86-3.46:

1. The molar ratio of Na2O, Al2O3 and SiO2 in the gel is (1.0-1.9):1:(6-7).

2. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: The sodium aluminate solution is obtained by reacting 25wt% to 50wt% sodium hydroxide solution with aluminum hydroxide powder having an Al2O3 content of not less than 60wt% at 0.1 to 0.4MPa and 100 to 140°C, and then adding a stabilizer.

3. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 2, characterized in that: The stabilizer is selected from one or more of sodium carbonate, sodium bicarbonate, and ammonia water; Based on the mass of the sodium hydroxide solution and the aluminum hydroxide powder being 100%, the content of the stabilizer is 1% to 10%.

4. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: The molar ratio of Na2O, Al2O3 and SiO2 in the directing agent is (10-20):1:(10-20).

5. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: The preparation of the directing agent comprises the following steps: adding the alkaline compound, the silicon powder and the silicon source to the sodium aluminate solution, mixing them evenly, and then aging them at 30 to 40° C. for 6 to 24 hours; The mass ratio of the alkaline compound to the directing agent is 0.01 to 0.1 based on Al2O3; Calculated in terms of SiO2, the molar ratio of the silicon powder to the directing agent is 0.01 to 0.

2.

6. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: Based on the mass of the gel being 100%, the content of the directing agent is 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%.

7. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: The SiO2 content of the silica-alumina gel is 55wt%-65wt%, the Al2O3 content is 15wt%-20wt%, and the Na2O content is 12wt%-14wt%; the solid content is 10wt%-12wt%, and the density is 1.090-1.

10.

8. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: The silica-alumina gel is obtained by reacting a NaY mother liquor with an aluminum source, wherein the SiO2 concentration in the NaY mother liquor is 40-60 g / L and the Na2O concentration is 20-30 g / L.

9. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: The post-treatment comprises the steps of separation, washing and drying; the washing step is carried out with deionized water until the pH value of the filtrate is 10.0-10.

5.

10. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1, characterized in that: The crystallization is hydrothermal crystallization, the temperature of the hydrothermal crystallization is 92-100° C., and the time is 16-40 hours.

11. The method for synthesizing a Y-type molecular sieve with low salt emission according to claim 1 or 8, characterized in that: The silicon source is selected from one or more of silicon aluminum powder, silica sol, water glass, white carbon black and sodium silicate; The aluminum source is selected from one or more of aluminum sulfate, aluminum phosphate, aluminum chloride, aluminum nitrate, aluminum fluoride, aluminum formate and aluminum acetate.

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