A pseudo-boehmite and a method for preparing and using the same
By preparing pseudoboehmite to treat the mother liquor of SAPO-34 molecular sieve crystallization, the problem of organic amine treatment was solved, achieving green and efficient wastewater treatment and raw material reuse, and reducing energy consumption and costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGKE CATALYSIS NEW TECH (DALIAN) CO LTD
- Filing Date
- 2026-01-21
- Publication Date
- 2026-06-09
AI Technical Summary
Existing technologies are insufficient for efficiently treating organic amines in the mother liquor of SAPO-34 molecular sieve crystallization. Incineration is energy-intensive, costly, and prone to causing secondary pollution, while distillation is unsuitable. There is a lack of green and efficient treatment technologies.
Phobospore was synthesized by mechanically steam-compressing the production wastewater from methanol-to-olefins catalysts, adding sodium hydroxide to recover organic amines, and then centrifuging it to perform desilication, aluminum dissolution, and gelation steps, which served as the raw material for SAPO-34 molecular sieves.
The treatment of SAPO-34 molecular sieve crystallization mother liquor has been made green and pollution-free, which has significantly reduced costs and improved economic benefits.
Smart Images
Figure CN122166804A_ABST
Abstract
Description
Technical Field
[0001] This application relates to a pseudoboehmite, its preparation method, and its application, belonging to the field of coal chemical wastewater treatment technology. Background Technology
[0002] Methanol-to-olefins (MTO) is an important industrial chemical reaction that catalytically produces olefins from methanol and steam under high temperature and pressure. However, this process generates a large amount of water vapor in addition to the target product, forming wastewater. Therefore, how to efficiently treat this wastewater has become a crucial issue in the methanol-to-olefins process.
[0003] SAPO-34 molecular sieves, due to their suitable acidity, unique pore structure, and strong hydrothermal stability, exhibit excellent activity and low-carbon olefin selectivity in methanol-to-olefins (MTO) reactions, making them the preferred active component for MTO catalysts. Currently, industrially produced SAPO-34 molecular sieves are synthesized using a hydrothermal crystallization method. However, the organic amine template agent and crystallization raw materials cannot be 100% converted, resulting in a large amount of crystallization mother liquor containing organic amines and silicon-phosphorus-aluminum species. This mother liquor has high total nitrogen content and COD value of organic amines, making it difficult to degrade using conventional methods. Currently, direct incineration and distillation are commonly used methods. Incineration is energy-intensive and costly, and direct incineration wastes a large amount of organic amines, while the generated exhaust gases can easily cause secondary pollution. Distillation can theoretically separate organic amines from water in wastewater, but it is not suitable for SAPO-34 molecular sieve mother liquor systems because the organic amines are bound to the gel in the system and cannot be directly distilled off. Therefore, there is an urgent need to develop a green and efficient treatment technology for SAPO-34 molecular sieve crystallization mother liquor suitable for industrial production. Summary of the Invention
[0004] To address the aforementioned technical problems, this application provides a pseudoboehmite, its preparation method, and its applications. The components and their weight percentages in the pseudoboehmite are as follows: Al₂O₃: 98.415-99.169%; SiO₂: 0.260-0.936%; P₂O₅: 0.510-0.596%; the remainder is Na₂O. This application synthesizes pseudoboehmite by concentrating the production wastewater from a methanol-to-olefins catalyst (preferably SAPO-34 molecular sieve) using a mechanical vapor recompression device, adding a certain amount of sodium hydroxide, distilling and recovering the organic amine gas phase, centrifuging the liquid phase at high temperature, and then subjecting the centrifuged liquid to steps such as desilication, aluminum dissolution, gelation, washing, aging, and drying. The synthesized pseudoboehmite can also be used as a raw material for SAPO-34 molecular sieves. The synthesis route is green and pollution-free, with significant economic benefits.
[0005] According to a first aspect of this application, a pseudoboehmite is provided.
[0006] A pseudoboehmite, wherein the components and their weight percentages are as follows: Al2O3: 98.415-99.169%; SiO2: 0.260-0.936%; P2O5: 0.510-0.596%; The rest is Na2O.
[0007] Optionally, the pseudoboehmite has a colloidal index of 96.32-98.41%; The solid content of the pseudoboehmite is 78.18-79.28%.
[0008] Optionally, in the XRD diffraction pattern of the pseudoboehmite, characteristic diffraction peaks of the (020), (120), (031) and (200) crystal planes of pseudoboehmite are observed at 2θ angles of (14±0.5)°, (28±0.5)°, (38±0.5)°, and (49±0.5)°.
[0009] According to a second aspect of this application, a method for preparing the pseudoboehmite described above is provided.
[0010] A method for preparing the above-mentioned pseudoboehmite, the method comprising the following steps: S1. Concentrate the catalyst production wastewater, add alkali to obtain a gas phase and a liquid phase, separate the liquid phase to obtain a pseudoboehmite precursor, wherein the catalyst is selected from the methanol-to-olefins catalyst. S2. Desilication agent I and desilication agent II are added sequentially to the pseudoboehmite precursor and reacted separately, denoted as reaction I and reaction II. Then, an aluminum source is added to obtain a liquid after aluminum dissolution. S3. The liquid after aluminum dissolution is passed through carbon dioxide gas to form a gel, and the pH value is adjusted to obtain the pseudoboehmite.
[0011] Optionally, in S1, the catalyst is selected from SAPO-34 molecular sieve.
[0012] Optionally, in S1, the alkali is selected from sodium hydroxide, and the amount of sodium hydroxide used is 30-200% based on the mass of the concentrated production wastewater. Optionally, in S1, the gas phase is organic amine vapor, which is recovered by distillation or rectification.
[0013] After adding alkali, the concentrated production wastewater will immediately react to produce a large amount of organic amine vapor. After the reaction stabilizes, the organic amine vapor will be recovered by entering a distillation tower or rectification tower.
[0014] Optionally, in S1, the separation temperature is 70~90°C.
[0015] Optionally, in S1, the pseudoboehmite precursor is selected from the supernatant after separation.
[0016] Optionally, in S1, the separation is centrifugation.
[0017] Optionally, in S2, the temperature of reaction I is 100~300℃ and the time is 2~6h.
[0018] Optionally, in S2, the desilication agent I is sodium silicate.
[0019] Optionally, in step S2, after reaction I, the supernatant is taken and added to desilication agent II.
[0020] Optionally, in S2, the temperature of reaction II is 100~200℃ and the time is 2~6h.
[0021] Optionally, in S2, the desilication agent II is calcium oxide.
[0022] Optionally, in S2, after reaction II, the supernatant is taken and added to an aluminum source.
[0023] Optionally, in step S2, the temperature for melting aluminum is 90~150℃, and the time is 4~15h.
[0024] Optionally, in S2, the aluminum source is aluminum hydroxide.
[0025] Optionally, in step S3, the gelation temperature is 10~30°C.
[0026] Optionally, in step S3, the rate at which the carbon dioxide gas is introduced is 50-300 mL / min.
[0027] Optionally, in S3, the pH value is adjusted to ≤10.5.
[0028] Optionally, in step S3, the pseudoboehmite is sequentially subjected to washing, aging, and drying treatments.
[0029] Optionally, the washing temperature is 70~90℃ and the washing time is 10~60min / cycle; The aging temperature is 90~150℃, and the time is 4~15h; The drying temperature is 60~80℃, and the time is 4~12h.
[0030] Optionally, 1) Wastewater pretreatment: The production wastewater from the methanol-to-olefins catalyst is concentrated in a mechanical steam recompression device; 2) Organic amine recovery: Add 30-200% sodium hydroxide solid to the concentrated wastewater in one go. The wastewater will immediately release a large amount of organic amine vapor, which can be recovered by distillation or rectification. 3) Solid-liquid separation: The alkali-treated wastewater is centrifuged at 70~90℃ to obtain the centrifuged liquid phase, which is used as a precursor for the preparation of boehmite; 4) Desiliconization of centrifuged liquid: Add sodium silicate nonahydrate to the liquid obtained in step 3, react at 100~300℃ for 2~6h, take the supernatant, continue to add calcium oxide to the supernatant, react at 100~200℃ for 2~6h, and retain the supernatant. 5) Aluminum element conversion: Add 30-80% by mass of aluminum hydroxide to the liquid obtained above, and dissolve aluminum at 90-150℃ for 4-15 hours; 6) Synthesis of pseudoboehmite: The liquid after aluminum dissolution is gelled by passing carbon dioxide gas at 50-300 mL / min through it at 10~30℃ until the pH of the liquid drops below 10.5, resulting in a solid-liquid mixture. Then, it is processed by washing, aging, drying and other steps to obtain pseudoboehmite.
[0031] According to a third aspect of this application, the application of the pseudoboehmite described above or the pseudoboehmite prepared by the above preparation method in the synthesis of SAPO-34 molecular sieve is provided.
[0032] The beneficial effects that this application can produce include: This application involves concentrating the production wastewater from the methanol-to-olefins catalyst (preferably SAPO-34 molecular sieve) using a mechanical vapor recompression device, adding a certain amount of sodium hydroxide, distilling and recovering the organic amine gas phase, centrifuging the liquid phase at high temperature, and then subjecting the centrifuged liquid to steps such as desilication, aluminum dissolution, gelation, washing, aging, and drying to finally synthesize pseudoboehmite. The synthesized pseudoboehmite can also be used as a raw material for SAPO-34 molecular sieve. The synthesis route is green and pollution-free, with significant economic benefits. Attached Figure Description
[0033] Figure 1 The image shows the XRD diffraction pattern of the pseudoboehmite prepared in Example 1 of this application. Detailed Implementation
[0034] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0035] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0036] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0037] The methods for calculating the colloidal index and solid content of pseudoboehmite in the embodiments of this application are as follows: Weigh a certain mass of boehmite into a beaker, add an appropriate amount of deionized water to dilute it into a slurry containing 10% Al2O3, then add an appropriate amount of concentrated nitric acid for gelation, and stir for 10 min; take out a portion of the gelation slurry and centrifuge it, then draw the supernatant from the test tube into a constant-weight crucible, evaporate and dry it, then ignite it at 550℃ for 2 h, take it out and cool it to room temperature and weigh it (W1); take another portion of the same weight of gelation slurry into a constant-weight crucible, evaporate and dry it, then ignite it at 550℃ for 2 h, take it out and cool it to room temperature and weigh it (W2), gelation index = (W1 / W2)*100%.
[0038] Weigh a certain mass (W2) of boehmite into a crucible, ignite it at 800℃ for 2 hours, remove it, cool it to room temperature, and weigh it (W1). The solid content is (W1 / W2)*100%.
[0039] Example 1 Take 100g of waste liquid treated by a mechanical vapor recompression device, add 60g of sodium hydroxide, heat to 120℃, and recover organic amines by distillation. Centrifuge the alkali-treated waste liquid at 75℃ and 4000rpm for 15min to obtain a primary centrifuge. Add 8g of sodium silicate nonahydrate to the primary centrifuge and react at 200℃ for 6h. Centrifuge and collect the supernatant. Add 3g of calcium oxide to the supernatant and react at 120℃ for 6h. Centrifuge and collect the supernatant. Add 30g of aluminum hydroxide to the supernatant, heat to 145℃ and maintain the temperature for 13h. After the reaction, filter the liquid and dilute it with 300g of water. Place the diluted solution in an 18℃ water bath and react with pure carbon dioxide while stirring until the pH reaches about 10. Stop the aeration. Centrifuge the resulting mixture at 4000rpm for 5min and collect the lower solid layer. Wash the lower solid layer repeatedly with water at 75℃ until the conductivity of the washing wastewater drops to 750μs / cm, then stop washing. Add 250g of water to the washed solid, transfer it to a reaction vessel, heat to 95℃, and maintain the temperature for 13h. After the heat treatment, centrifuge to separate the solid, and place the solid in a 60℃ oven to dry for 8h to obtain boehmite. The parameters of boehmite are shown in Table 1.
[0040] Example 2 The preparation method of pseudoboehmite is the same as in Example 1, except that the reaction time for adding sodium silicate nonahydrate and calcium oxide is 2 hours to obtain pseudoboehmite. The parameters of pseudoboehmite are shown in Table 1.
[0041] Example 3 The preparation method of pseudoboehmite is the same as in Example 1, except that the reaction of sodium silicate nonahydrate and calcium oxide is not introduced. Pseudoboehmite is obtained directly by a single centrifugation. The parameters of pseudoboehmite are shown in Table 1.
[0042] Table 1
[0043] Characterization results Taking the pseudoboehmite prepared in Example 1 as an example: Figure 1 The XRD diffraction pattern of the pseudoboehmite prepared in Example 1 of this application shows the characteristic diffraction peaks of the (020), (120), (031) and (200) crystal planes of pseudoboehmite observed at 2θ angles of (14)°, (28)°, (38)° and (49)°.
[0044] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A pseudoboehmite, characterized in that, The components and their weight percentages in the pseudoboehmite are as follows: Al2O3: 98.415-99.169%; SiO2: 0.260-0.936%; P2O5: 0.510-0.596%; The rest is Na2O.
2. The pseudoboehmite according to claim 1, characterized in that, The gel solubility index of the pseudoboehmite is 96.32-98.41%; The solid content of the pseudoboehmite is 78.18-79.28%.
3. The pseudoboehmite according to claim 1, characterized in that, In the XRD diffraction pattern of the pseudoboehmite, characteristic diffraction peaks of the (020), (120), (031) and (200) crystal planes of pseudoboehmite were observed at 2θ angles of (14±0.5)°, (28±0.5)°, (38±0.5)°, and (49±0.5)°.
4. A method for preparing boehmite according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: S1. Concentrate the catalyst production wastewater, add alkali to obtain a gas phase and a liquid phase, separate the liquid phase to obtain a pseudoboehmite precursor, wherein the catalyst is selected from the methanol-to-olefins catalyst. S2. Desilication agent I and desilication agent II are added sequentially to the pseudoboehmite precursor and reacted separately, denoted as reaction I and reaction II. Then, an aluminum source is added to obtain a liquid after aluminum dissolution. S3. The liquid after aluminum dissolution is passed through carbon dioxide gas to form a gel, and the pH value is adjusted to obtain the pseudoboehmite.
5. The preparation method according to claim 4, characterized in that, In S1, the catalyst is selected from SAPO-34 molecular sieve; Preferably, in step S1, the alkali is selected from sodium hydroxide, and the amount of sodium hydroxide used is 30-200% based on the mass of the concentrated production wastewater. Preferably, in step S1, the separation temperature is 70~90°C; Preferably, in S1, the pseudoboehmite precursor is selected from the supernatant after separation; Preferably, in S1, the separation is centrifugation.
6. The preparation method according to claim 4, characterized in that, In S2, the temperature of reaction I is 100~300℃ and the time is 2~6h; Preferably, in S2, the desilication agent I is sodium silicate; Preferably, in step S2, after reaction I, the supernatant is taken and added to desilication agent II; Preferably, in S2, the temperature of reaction II is 100~200℃ and the time is 2~6h; Preferably, in S2, the desilication agent II is calcium oxide; Preferably, in step S2, after reaction II, the supernatant is taken and added to an aluminum source.
7. The preparation method according to claim 4, characterized in that, In step S2, the temperature for melting aluminum is 90~150℃, and the time is 4~15h; Preferably, in step S2, the aluminum source is aluminum hydroxide.
8. The preparation method according to claim 4, characterized in that, In step S3, the gelation temperature is 10~30℃; Preferably, in step S3, the rate at which the carbon dioxide gas is introduced is 50-300 mL / min; Preferably, in step S3, the pH value is adjusted to ≤10.
5.
9. The preparation method according to claim 4, characterized in that, In step S3, the pseudoboehmite is sequentially subjected to washing, aging, and drying processes. Preferably, the washing temperature is 70~90℃ and the washing time is 10~60min / cycle; The aging temperature is 90~150℃, and the time is 4~15h; The drying temperature is 60~80℃, and the time is 4~12h.
10. The use of the pseudoboehmite according to any one of claims 1 to 3 or the pseudoboehmite prepared by the preparation method according to any one of claims 4 to 9 in the synthesis of SAPO-34 molecular sieve.