Method for preparing saPO-5 molecular sieve from phosphosilicate aluminums molecular sieve crystallization mother liquor, saPO-5 molecular sieve and application thereof
SAPO-5 molecular sieves were prepared by using SAPO-34 crystallization mother liquor through gas-solid phase crystallization, which solved the problems of high treatment cost and low resource utilization rate of crystallization mother liquor, achieved zero wastewater generation and good adsorption performance, and reduced production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-08-09
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies for treating SAPO-34 crystallization mother liquor have high costs, low resource utilization rates, and are prone to causing secondary pollution, especially in the hydrothermal crystallization method, which generates a large amount of wastewater.
SAPO-5 molecular sieves were prepared by using SAPO-34 crystallization mother liquor as raw material through gas-solid phase crystallization, drying, crystallization and calcination, avoiding the addition of water and template agent, and realizing resource utilization and zero emission.
Production costs were reduced and the yield per batch was increased. The prepared SAPO-5 molecular sieve has good adsorption performance, with a cyclohexane adsorption capacity of more than 24%. It also realizes the resource utilization of crystallization mother liquor and the generation of no wastewater.
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Figure CN117619340B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of molecular sieve preparation, specifically relating to a method for preparing SAPO-5 molecular sieves using crystallization mother liquor of silica-alumina molecular sieves, SAPO-5 molecular sieves and their application as adsorbents. Background Technology
[0002] In the early 1980s, UOP Corporation in the United States developed the AlPO4-n series of aluminum phosphate molecular sieves. Introducing silicon atoms into the aluminum phosphate framework yields SAPO molecular sieves. SAPO molecular sieves can be used in the catalytic reactions of various hydrocarbons, especially SAPO-34, which is widely used in methanol-to-olefins processes. Currently, the commonly used method for synthesizing SAPO-34 molecular sieves is hydrothermal crystallization. This process generates large amounts of wastewater containing organic amines / quaternary ammonium bases, which is very difficult to treat. Typically, the SAPO-34 crystallization mother liquor is treated physically or chemically before being discharged as wastewater, resulting in resource waste and increased production costs. Therefore, it is necessary to develop new methods for resource utilization.
[0003] Patent CN103170361B discloses a method for using SAPO-34 molecular sieve synthesis liquid to produce a methanol-to-olefins catalyst. The method involves directly or indirectly mixing the SAPO-34 molecular sieve synthesis liquid with a small amount of silicon- and aluminum-based clay and binder. After processing through grinding, degassing, spraying, and calcination, the methanol-to-olefins catalyst is obtained. This method enables the reuse of the liquid generated during SAPO-34 molecular sieve synthesis, saving on the amount of aluminum sol and water added during catalyst synthesis. However, this method cannot utilize the residual template agent in the crystallized molecular sieve synthesis liquid, which can easily cause secondary pollution.
[0004] Patent CN103172083B discloses a method for the comprehensive utilization of the synthesis liquid of silica-alumina-phosphorus molecular sieves. This method involves mixing the liquid generated during the crystallization synthesis of SAPO molecular sieves with a template agent, silicon source, aluminum source, phosphorus source, and water, and then synthesizing different SAPO molecular sieves via hydrothermal crystallization. This method reduces the amount of some raw materials added during molecular sieve synthesis, saves water resources, and lowers wastewater treatment costs. However, this method uses the traditional hydrothermal crystallization method to prepare SAPO molecular sieves, which still generates a large amount of wastewater during crystallization and washing, and the utilization rate of the template agent in the synthesis liquid is relatively low.
[0005] Patent CN106542623B discloses a method for preparing polyphosphate aluminum sulfate flocculant using SAPO-34 crystallization mother liquor. The method involves alkali distillation, water washing separation, water treatment, acid leaching, measurement, hydrolysis polymerization, aging, and drying of the SAPO-34 crystallization mother liquor to obtain the polyphosphate aluminum sulfate flocculant. This method achieves the recycling of wastewater resources and has high environmental and economic benefits. However, the method is cumbersome and has low wastewater resource utilization efficiency.
[0006] Therefore, developing a method for the resource utilization of SAPO-34 crystallization mother liquor is of great significance to the sustainable development of the economy and the environment. Summary of the Invention
[0007] This invention provides a method for preparing SAPO-5 molecular sieves using SAPO-34 crystallization mother liquor. This method uses gas-solid phase crystallization with SAPO-34 crystallization mother liquor as raw material to prepare SAPO-5 molecular sieves with good adsorption performance, and the cyclohexane adsorption capacity is greater than 24%. This invention mainly solves the problems of high treatment cost, low resource utilization rate and easy secondary pollution of existing molecular sieve crystallization mother liquor, avoids the addition of water and template agent, and realizes the resource utilization and zero emission of crystallization mother liquor.
[0008] To achieve the above objectives, the present invention provides a method for preparing SAPO-5 molecular sieve using SAPO-34 crystallization mother liquor. The method includes: drying a mixture containing SAPO-34 molecular sieve crystallization mother liquor, a phosphorus source, an aluminum source, a silicon source, and water to obtain a precursor; and crystallizing and calcining the precursor to obtain the SAPO-5 molecular sieve.
[0009] SAPO-34 crystallization mother liquor contains small molecules produced by the decomposition of template agents, resulting in a complex composition. During reuse, it is prone to generating impurities, affecting product quality. This invention employs a gas-solid phase crystallization method, directly using the SAPO-34 crystallization mother liquor for molecular sieve preparation, generating virtually no wastewater and improving yield. By controlling the crystallization process, impurities can be eliminated, yielding a pure-phase molecular sieve product.
[0010] Preferably, the crystallization is gas-solid phase crystallization, wherein the gas phase consists of water vapor and a template agent, which can improve the yield and generate virtually no wastewater.
[0011] Optionally, the drying temperature is 90–150°C.
[0012] Optionally, the drying time is 5 to 12 hours.
[0013] Optionally, the weight loss of the precursor at 120°C is 3% to 21%; preferably 6% to 17%.
[0014] Optionally, the crystallization temperature is 170-1210℃, and the crystallization time is 12-148h.
[0015] The roasting temperature is 500-1600℃, the roasting time is 316h, and the roasting atmosphere is air.
[0016] Optionally, in the SAPO-34 molecular sieve crystallization mother liquor, the mass ratio of phosphorus (as P2O5), aluminum (as Al2O3), silicon (as SiO2), and template agent (as triethylamine) is 2.3111.8:0.915.6:114.3:10120.
[0017] Optionally, in the mixture, the mass ratio of SAPO-34 molecular sieve crystallization mother liquor, phosphorus source, aluminum source and silicon source is (40160):(20135):(14122):(4116).
[0018] Optionally, the phosphorus source is selected from at least one of phosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate, polyphosphoric acid, and phosphates; preferably, phosphoric acid.
[0019] Optionally, the aluminum source is selected from at least one of boehmite, aluminum hydroxide, aluminum isopropoxide, aluminum oxide, and aluminum sol; preferably silica sol or ethyl silicate.
[0020] Optionally, the silicon source is selected from at least one of silica sol, ethyl silicate, propyl silicate, silica, silica gel; preferably boehmite or aluminum hydroxide.
[0021] Optionally, the template agent is selected from at least one of triethylamine, diethylamine, quaternary ammonium base, and morpholine.
[0022] As a preferred embodiment, the method for preparing SAPO-5 molecular sieve includes the following steps:
[0023] S1 provides a mixture containing SAPO-34 molecular sieve crystallization mother liquor, phosphorus source, aluminum source, silicon source and water, wherein the mixture is in a gel state;
[0024] S2. The mixture is dried to obtain the precursor;
[0025] S3 crystallizes the precursor to obtain a crystallized molecular sieve; the crystallization process is gas-solid phase crystallization.
[0026] S4 involves calcining the crystallized molecular sieve to obtain the SAPO-5 molecular sieve.
[0027] Optionally, before calcination, the crystallized molecular sieve powder can be washed, filtered, and dried.
[0028] Optionally, the filtration method is selected from centrifugal filtration, plate and frame filter press, differential pressure filtration, etc.; the drying temperature is 80-130℃, and the drying time is 5-16h.
[0029] The present invention also provides SAPO-5 molecular sieves prepared by any of the methods described above.
[0030] The present invention also provides the application of the above-mentioned SAPO-5 molecular sieve as an adsorbent.
[0031] Optionally, the SAPO-5 molecular sieve has a cyclohexane adsorption capacity of 24% to 27% and a water absorption rate of 24% to 26%.
[0032] This invention utilizes SAPO-34 crystallization mother liquor to prepare SAPO-5 molecular sieves, achieving resource utilization and reducing production costs. The method of this invention improves single-reactor yield, reduces crystallization pressure, and generates virtually no waste liquid, making it a green and environmentally friendly molecular sieve production method. Furthermore, the SAPO-5 molecular sieve prepared by this invention exhibits a water absorption rate and cyclohexane adsorption capacity greater than 24%, making it a high-performance adsorbent.
[0033] Compared with the prior art, the present invention has at least the following beneficial effects:
[0034] The present invention utilizes SAPO-34 crystallization mother liquor to prepare molecular sieve gel, which is then dried, crystallized, washed, filtered, and calcined to prepare SAPO-5 molecular sieve, achieving resource utilization and yielding a high-performance adsorbent. This method uses crystallization mother liquor as raw material and employs a gas-solid phase crystallization method to prepare SAPO-5 molecular sieve, avoiding the addition of water and template agents, thus significantly reducing wastewater treatment costs and molecular sieve production costs.
[0035] This invention utilizes SAPO-34 crystallization mother liquor to prepare SAPO-5 molecular sieves, achieving zero discharge of crystallization mother liquor, reducing production costs, increasing single-reactor yield, and is simple to operate and highly applicable. Attached Figure Description
[0036] Figure 1 This is a process flow diagram for the preparation of molecular sieves according to the present invention.
[0037] Figure 2 The XRD pattern of SAPO-5 prepared in Example 1 of this invention.
[0038] Figure 3 The XRD pattern of the product prepared in Comparative Example 2 of this invention is shown.
[0039] Figure 4 The image shows the XRD pattern of the product prepared in Comparative Example 3 of this invention. Detailed Implementation
[0040] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0041] The present invention will be described in detail below through examples. In the following examples, the water absorption rate is tested using the national standard GB 6287-86 "Determination of Static Water Adsorption by Molecular Sieves".
[0042] The test method for cyclohexane adsorption capacity is the same as that in GB 6287-86, "Determination of Static Water Adsorption by Molecular Sieves", except that the saturated sodium chloride solution in the desiccator is replaced with cyclohexane.
[0043] In the embodiment, the method for determining the weight loss of the precursor at 120°C is as follows: the precursor is dried at 120°C to constant weight (weight loss rate less than 0.02%), the mass of the precursor before drying is m0, the mass after drying is m1, and the weight loss at 120°C is (m0-m1) / m0*100%.
[0044] Example 1
[0045] The composition of the SAPO-34 molecular sieve crystallization mother liquor is: 11.8 wt% phosphorus (as P2O5), 0.9 wt% aluminum (as Al2O3), 1 wt% silicon (as SiO2), 16 wt% template agent (as triethylamine), and the balance being water.
[0046] Reference Figure 1 The preparation method is as follows:
[0047] (1) The crystallization mother liquor was mixed with phosphoric acid, boehmite and ethyl silicate to prepare a gel. The raw material ratio of the gel was crystallization mother liquor: phosphoric acid: boehmite: ethyl silicate = 49wt%: 25wt%: 21wt%: 5wt%.
[0048] (2) The gel was dried at 100°C for 9 hours to obtain the precursor.
[0049] (3) The dried precursor was crystallized. The precursor lost 13 wt% at 120℃, the crystallization temperature was 195℃, and the crystallization time was 20h.
[0050] (4) After crystallization, the molecular sieve is washed and filtered, then dried and calcined. The drying temperature is 80℃ and the drying time is 16h. The calcination temperature is 550℃ and the calcination time is 5h.
[0051] from Figure 2It can be seen that the prepared product has good crystallinity and the crystal structure is SAPO-5 molecular sieve. The test results are shown in Table 1.
[0052] Example 2
[0053] The composition of the SAPO-34 molecular sieve crystallization mother liquor is: 6.8 wt% phosphorus (as P2O5), 5.6 wt% aluminum (as Al2O3), 4.3 wt% silicon (as SiO2), 20 wt% template agent (as triethylamine), and the balance is water.
[0054] Reference Figure 1 The preparation method is as follows:
[0055] (1) The crystallization mother liquor was mixed with phosphoric acid, boehmite and silica sol to prepare a gel. The raw material ratio of the gel was crystallization mother liquor: phosphoric acid: boehmite: silica sol = 40wt%: 30wt%: 22wt%: 8wt%.
[0056] (2) The gel was dried at 90°C for 12 hours to obtain the precursor.
[0057] (3) The dried precursor was crystallized. The precursor lost 17% of its weight at 120°C, the crystallization temperature was 170°C, and the crystallization time was 48h.
[0058] (4) After the crystallized molecular sieve is washed and filtered, it is dried and calcined. The drying temperature is 90℃ and the drying time is 12h. The calcination temperature is 500℃ and the calcination time is 6h. A molecular sieve with a crystal structure of SAPO-5 is obtained. The test results are detailed in Table 1.
[0059] Example 3
[0060] The composition of SAPO-34 molecular sieve crystallization mother liquor is: phosphorus (as P2O5) 2.3wt%, aluminum (as Al2O3) 5.6wt%, silicon (as SiO2) 4.2wt%, template agent (as triethylamine) 15wt%, and the balance is water (no additional water was added here; all water came from SAPO-34 molecular sieve crystallization mother liquor).
[0061] Reference Figure 1 The preparation method is as follows:
[0062] (1) The crystallization mother liquor was mixed with phosphorus, aluminum and silicon sources to prepare a gel. The raw material ratio of the gel was crystallization mother liquor: phosphoric acid: aluminum hydroxide: silica = 50wt%: 35wt%: 13wt%: 3wt%.
[0063] (2) The gel was dried at 150°C for 5 hours to obtain the precursor.
[0064] (3) The dried precursor was crystallized. The precursor lost 6% of its weight at 120℃, the crystallization temperature was 210℃, and the crystallization time was 12h.
[0065] (4) After the crystallized molecular sieve is washed and filtered, it is dried and calcined. The drying temperature is 100℃ and the drying time is 10h. The calcination temperature is 600℃ and the calcination time is 3h. A molecular sieve with a crystal structure of SAPO-5 is obtained. The test results are detailed in Table 1.
[0066] Example 4
[0067] The composition of the SAPO-34 molecular sieve crystallization mother liquor is: 9.1 wt% phosphorus (as P2O5), 3.8 wt% aluminum (as Al2O3), 3.2 wt% silicon (as SiO2), 10 wt% template agent (as triethylamine), and the balance being water.
[0068] Reference Figure 1 The preparation method is as follows:
[0069] (1) The crystallization mother liquor was mixed with phosphorus, aluminum and silicon sources to prepare a gel. The raw material ratio of the gel was crystallization mother liquor: phosphoric acid: aluminum hydroxide: silica = 60wt%: 20wt%: 14wt%: 6wt%.
[0070] (2) The gel was dried at 120°C for 7 hours to obtain the precursor.
[0071] (3) The dried precursor was crystallized. The precursor lost 8% of its weight at 120°C. The crystallization temperature was 190°C and the crystallization time was 24h.
[0072] (4) After crystallization, the molecular sieve was washed and filtered, then dried and calcined. The drying temperature was 120℃ and the drying time was 8h. The calcination temperature was 580℃ and the calcination time was 4h. A molecular sieve with a crystal structure of SAPO-5 was obtained. The test results are detailed in Table 1.
[0073] Example 5
[0074] The composition of the SAPO-34 molecular sieve crystallization mother liquor is: phosphorus (as P2O5) 9.1wt%, aluminum (as Al2O3) 5.6wt%, silicon (as SiO2) 4.2wt%, template agent (as triethylamine) 20wt%, and the balance is water.
[0075] Reference Figure 1 The preparation method is as follows:
[0076] (1) The crystallization mother liquor was mixed with phosphorus, aluminum and silicon sources to prepare a gel. The raw material ratio of the gel was crystallization mother liquor: phosphoric acid: boehmite: silica sol = 40wt%: 30wt%: 20wt%: 10wt%.
[0077] (2) The gel was dried at 130°C for 6 hours to obtain the precursor.
[0078] (3) The dried precursor was crystallized. The precursor lost 9% of its weight at 120°C. The crystallization temperature was 180°C and the crystallization time was 36h.
[0079] (4) After the crystallized molecular sieve is washed and filtered, it is dried and calcined. The drying temperature is 130℃ and the drying time is 5h. The calcination temperature is 550℃ and the calcination time is 4h. A molecular sieve with a crystal structure of SAPO-5 is obtained. The test results are detailed in Table 1.
[0080] Example 6
[0081] Molecular sieves were prepared according to the method in Example 1, except that the crystallization temperature in step (3) was 190℃ and the crystallization time was 24h, resulting in a molecular sieve with a crystal structure of SAPO-5. The test results are detailed in Table 1.
[0082] Example 7
[0083] Molecular sieves were prepared according to the method in Example 2, except that the crystallization temperature in step (3) was 185℃ and the crystallization time was 32h, resulting in a molecular sieve with a crystal structure of SAPO-5. The test results are detailed in Table 1.
[0084] Example 8
[0085] Molecular sieves were prepared according to the method of Example 3, except that the crystallization temperature in step (3) was 200℃ and the crystallization time was 18h, resulting in a molecular sieve with a crystal structure of SAPO-5. The test results are detailed in Table 1.
[0086] Comparative Example 1
[0087] The molecular sieve was prepared according to the method of Example 1, except that step (3) was carried out by hydrothermal crystallization to obtain a molecular sieve with a crystal structure of SAPO-5. The test results are detailed in Table 1.
[0088] Comparative Example 2
[0089] Molecular sieves were prepared according to the method in Example 1, except that the drying conditions in step (2) were different. The drying temperature was 80°C and the time was 4 hours. In step (3), the precursor lost 25% of its weight at 120°C, resulting in a molecular sieve of 60% SAPO-5 and 40% SAPO-34. The test results are detailed in Table 1.
[0090] Comparative Example 3
[0091] Molecular sieves were prepared according to the method in Example 3, except that the drying conditions in step (2) were different. The drying temperature was 155℃ and the time was 12h. In step (3), the precursor lost 2% weight at 120℃, resulting in a molecular sieve of 80% SAPO-5 + 20% SAPO-34. The test results are detailed in Table 1.
[0092] Table 1
[0093]
Claims
1. An application of SAPO-5 molecular sieve as an adsorbent, characterized in that, Methods for preparing SAPO-5 molecular sieves include: A precursor is obtained by drying a mixture containing SAPO-34 molecular sieve crystallization mother liquor, phosphorus source, aluminum source, silicon source and water; The precursor is crystallized and calcined to obtain the SAPO-5 molecular sieve; the crystallization is a gas-solid phase crystallization. In the SAPO-34 molecular sieve crystallization mother liquor, the mass ratio of phosphorus (calculated as P2O5), aluminum (calculated as Al2O3), silicon (calculated as SiO2), and template agent (calculated as triethylamine) is 2.3~11.8: 0.9~5.6: 1~4.3: 10~20. The drying temperature is 90–150°C; the drying time is 5–12 hours; the weight loss of the precursor at 120°C is 3 wt%–21 wt%. The SAPO-5 molecular sieve has a cyclohexane adsorption capacity of 24%–27% and a water absorption rate of 24%–26%.
2. The application according to claim 1, characterized in that, The precursor loses 6 wt% to 17 wt% of its weight at 120°C.
3. The application according to claim 1, characterized in that, The crystallization temperature is 170~210℃, and the crystallization time is 12~48h.
4. The application according to claim 1, characterized in that, The roasting temperature is 500~600℃, the roasting time is 3~6h, and the roasting atmosphere is air.
5. The application according to any one of claims 1-4, characterized in that, In the mixture, the mass ratio of SAPO-34 molecular sieve crystallization mother liquor, phosphorus source, aluminum source, and silicon source is (40~60):(20~35):(14~22):(4~16); And / or, the phosphorus source is selected from at least one of phosphoric acid, polyphosphoric acid, and phosphate; And / or, the aluminum source is selected from at least one of boehmite, aluminum hydroxide, aluminum isopropoxide, aluminum oxide, and aluminum sol; And / or, the silicon source is selected from at least one of silica sol, ethyl silicate, propyl silicate, silica fume, silicic acid, and silica gel; And / or, the template agent is selected from at least one of triethylamine, diethylamine, quaternary ammonium base, and morpholine.
6. The application according to any one of claims 1-4, wherein the phosphorus source is selected from at least one of ammonium phosphate and ammonium dihydrogen phosphate.