A kind of sheet layered hierarchical pore HZSM-5 molecular sieve catalyst and its preparation method and application
Patent Information
- Application Number
- CN202211353224.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-11-01
- Publication Date
- 2026-09-25
- Estimated Expiration
- 2042-11-01
AI Technical Summary
甘油脱水制取丙烯醛具有严重的积碳问题，极易导致催化剂快速失活
[0078](1)本申请提供了一种用于制备片层状多级孔HZSM-5分子筛催化剂方法，该制备方法简单，能够制备片层状多级孔HZSM-5分子筛。
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Abstract
Description
Technical Field
[0001] This application belongs to the field of molecular sieve modification and catalysis, specifically relating to a layered hierarchical porous HZSM-5 molecular sieve catalyst, its preparation method, and its application. Background Technology
[0002] Molecular sieves are porous materials with regular and uniform pore structures, playing an important role in petroleum refining, petrochemicals, and fine chemicals. Conventional microporous molecular sieves, due to their narrow pore size, are prone to pore blockage during reactions, leading to restricted molecular diffusion and limiting the full potential of their catalytic activity. Therefore, the development of molecular sieve materials possessing both micro- and mesoporous characteristics, i.e., hierarchical porous molecular sieves, is necessary. The "top-down" method for preparing hierarchical porous molecular sieves, exemplified by alkali treatment, is simple to operate and has low cost.
[0003] Acrolein is an important fine chemical product, mainly used in the synthesis of fine chemicals such as acrylic acid and 1,3-propanediol. The production of acrolein from glycerol via dehydration suffers from severe carbon buildup, which easily leads to rapid catalyst deactivation. Therefore, there is an urgent need to develop highly efficient catalysts to mitigate catalyst deactivation and extend catalyst lifespan. Summary of the Invention
[0004] Therefore, the purpose of this application is to provide a method for preparing hierarchical porous molecular sieve catalysts by combining alkali treatment with aluminum salts. This method can prepare a layered hierarchical porous HZSM-5 molecular sieve. The catalyst has abundant micropores and mesopores. Its hierarchical pore structure can effectively improve mass transfer capacity, which is beneficial to the mass transfer of reactant and product molecules. The catalyst has excellent stability.
[0005] This application proposes a simple and effective method for preparing layered hierarchical porous HZSM-5 molecular sieve catalysts. The method is characterized by its ability to prepare layered hierarchical porous HZSM-5 molecular sieves and apply them to glycerol dehydration reactions, exhibiting excellent stability.
[0006] According to another aspect of this application, a layered hierarchical porous HZSM-5 molecular sieve catalyst is provided, wherein the layered hierarchical porous HZSM-5 molecular sieve catalyst has a layered structure;
[0007] The layered hierarchical porous HZSM-5 molecular sieve catalyst has micropores and mesopores;
[0008] The silica-alumina ratio of the layered hierarchical porous HZSM-5 molecular sieve catalyst is 20–200.
[0009] The pore volume of the micropores is 0.07–0.1 cm³. 3 / g;
[0010] The specific surface area of the micropores is 164–195 m². 2 / g;
[0011] The pore volume of the mesopore is 0.22–0.32 cm³. 3 / g;
[0012] The specific surface area of the mesopores is 189–225 m². 2 / g;
[0013] The pore size of the mesopore is 7–17 nm.
[0014] According to another aspect of this application, a method for preparing the above-mentioned layered hierarchical porous HZSM-5 molecular sieve catalyst is provided, comprising the following steps:
[0015] 1) HZSM-5 molecular sieve, aluminum isopropoxide and alkaline solution are mixed, dried (I) and calcined (I) to obtain catalyst precursor;
[0016] 2) The catalyst precursor obtained in 1) is subjected to ion exchange, drying (II), and calcination (II) to obtain the layered hierarchical porous HZSM-5 molecular sieve catalyst.
[0017] 1) In,
[0018] The silica-alumina ratio of the HZSM-5 molecular sieve is 20 to 200.
[0019] Optionally, the silica-alumina ratio of the HZSM-5 molecular sieve is 30 to 100;
[0020] Optionally, the silica-alumina ratio of the HZSM-5 molecular sieve is any value among 30, 40, 50, 60, 70, 80, 90, and 100, or a range between any two.
[0021] The mass ratio of aluminum in the HZSM-5 molecular sieve to aluminum in the aluminum isopropoxide is 20 to 0.1.
[0022] Optionally, the mass ratio of aluminum in the HZSM-5 molecular sieve to aluminum in the aluminum isopropoxide is 10 to 2.
[0023] Optionally, the mass ratio of aluminum in the HZSM-5 molecular sieve to aluminum in the aluminum isopropoxide is any value from 10, 9, 8, 7, 6, 5, 4, 3, 2 or any range between the two.
[0024] The alkaline solution is an aqueous solution selected from at least one of LiOH, NaOH, KOH, and CsOH.
[0025] The concentration of the alkaline solution is 0.05–2 mol / L;
[0026] Optionally, the concentration of the alkaline solution is 0.5 to 1 mol / L.
[0027] Optionally, the concentration of the alkaline solution is any value or a range between 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, and 1 mol / L.
[0028] The mixing temperature is 60–90°C;
[0029] Optionally, the mixing temperature is 65–80°C;
[0030] Optionally, the mixing temperature is any value among 65°C, 70°C, 75°C, and 80°C, or a range between any two.
[0031] Optionally, the mixing includes stirring;
[0032] The stirring time is 15–90 min;
[0033] Optionally, the stirring time is 30 to 60 minutes;
[0034] Optionally, the stirring time is any value among 30 min, 40 min, 50 min, and 60 min, or a range between any two.
[0035] The temperature of the drying process I is 100–120°C;
[0036] Optionally, the temperature of the drying process I is any value among 100°C, 110°C, and 120°C, or a range between any two.
[0037] The drying time for step I is 12–36 hours;
[0038] Optionally, the drying time I is any value among 12h, 18h, 24h, 30h, and 36h, or a range between any two.
[0039] The temperature of the calcination I is 350–550°C;
[0040] Optionally, the temperature of the calcination I is any value of 350°C, 400°C, 450°C, 500°C, or 550°C, or a range between any two.
[0041] The roasting time for the first stage is 1 to 6 hours.
[0042] Optionally, the roasting time I is any value among 1h, 2h, 3h, 4h, 5h, and 6h, or a range between any two.
[0043] Before drying, centrifuge and wash until neutral.
[0044] Drying I is carried out in an oven.
[0045] 2) In,
[0046] The ion exchange includes the following process:
[0047] The catalyst precursor obtained in step 1) is impregnated in an ion exchange solution;
[0048] The ion exchange solution is selected from at least one of NH4Cl solution, NH4NO3 solution, and (NH4)2SO4 solution;
[0049] The concentration of the ion exchange solution is 0.5–2 mol / L.
[0050] Optionally, the concentration of the ion exchange solution is any value or a range between any two of the following: 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, and 2 mol / L.
[0051] Ion exchange was performed three times.
[0052] The temperature of the drying II process is 100–120°C;
[0053] Optionally, the temperature of the drying II is any value among 100°C, 110°C, and 120°C, or a range between any two.
[0054] The drying time for step II is 12–36 hours;
[0055] Optionally, the drying time II is any value among 12h, 18h, 24h, 30h, and 36h, or a range between any two.
[0056] The temperature of the second calcination is 350–550°C;
[0057] Optionally, the temperature of the calcination II is any value among 350°C, 400°C, 450°C, 500°C, and 550°C, or a range between any two.
[0058] The roasting time for the second stage is 1 to 6 hours.
[0059] Optionally, the roasting time II is any value among 1h, 2h, 3h, 4h, 5h, and 6h, or a range between any two.
[0060] Before drying (II), centrifuge and wash until neutral.
[0061] Drying II is carried out in an oven.
[0062] According to another aspect of this application, a method for producing acrolein by dehydrating glycerol is provided, comprising the following steps:
[0063] In a reactor, a raw material containing glycerol is introduced and reacted with a catalyst to obtain a product containing acrolein.
[0064] The catalyst is selected from the above-mentioned layered hierarchical porous HZSM-5 molecular sieve catalyst or the layered hierarchical porous HZSM-5 molecular sieve catalyst prepared by the above-mentioned preparation method.
[0065] The content of glycerol in the raw materials is 5-60 wt%.
[0066] Optionally, the content of glycerol in the raw material is any value or a range between any two of 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, and 60wt%.
[0067] The mass hourly space velocity (MSV) of the raw material is 0.5–10 h⁻¹. -1 ;
[0068] Optionally, the mass hourly space velocity (MHSV) of the raw material is 1–5 h⁻¹. -1 .
[0069] Optionally, the mass hourly space velocity (MHSV) of the raw material is 1 h⁻¹. -1 2h -1 3h -1 4h -1 5h -1 Any value in the range or any value between the two.
[0070] The reaction temperature is 200–500°C;
[0071] Optionally, the reaction temperature is 300–350°C;
[0072] Optionally, the temperature of the reaction is any value of 300°C, 310°C, 320°C, 330°C, 340°C, or 350°C, or a range between any two.
[0073] The reaction pressure is 0.1–0.5 MPa;
[0074] Optionally, the reaction pressure is 0.1–0.25 MPa;
[0075] Optionally, the pressure of the reaction is any value among 0.1 MPa, 0.15 MPa, 0.2 MPa, and 0.25 MPa, or a range between any two.
[0076] Optionally, the reactor is a fixed-bed reactor.
[0077] The beneficial effects of this application include, but are not limited to:
[0078] (1) This application provides a method for preparing layered hierarchical porous HZSM-5 molecular sieve catalyst. The preparation method is simple and can prepare layered hierarchical porous HZSM-5 molecular sieve.
[0079] (2) The above-mentioned layered hierarchical porous HZSM-5 molecular sieve catalyst provided in this application can significantly improve the stability of the catalyst when applied to the glycerol dehydration reaction. Attached Figure Description
[0080] Figure 1 The image shows a scanning electron microscope (SEM) image of the Z5 molecular sieve in Comparative Example 1.
[0081] Figure 2 The image shows a scanning electron microscope (SEM) image of the hierarchical porous HZSM-5 molecular sieve obtained in Example 1.
[0082] Figure 3 The conversion curve of glycerol in test example 1. Detailed Implementation
[0083] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0084] Unless otherwise specified, all raw materials used in this application were purchased commercially and used directly without special treatment.
[0085] Specific surface area and pore size distribution of the molecular sieves were analyzed using a Micromeritics ASAP-2460 physical adsorption system. Scanning electron microscopy (SEM) was performed using a JEOL JM-7800F field emission scanning electron microscope. Product composition was analyzed using an Agilent 7890B gas chromatography system (FID detector, FFAP capillary column).
[0086] The conversion rate and selectivity calculations in this embodiment are as follows:
[0087]
[0088]
[0089] Example 1: Preparation of Hierarchical Porous HZSM-5 Molecular Sieves
[0090] Weigh 5.00 g of HZSM-5 molecular sieve (Si / Al = 35) and 0.12 g of aluminum isopropoxide, and add them simultaneously to 150 ml of 0.2 mol / L NaOH solution. Stir at 65 °C for 30 min, centrifuge and wash until neutral, dry at 120 °C for 12 h, and calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. Take 3.00 g of the calcined sample and add it to 60 ml of 0.8 mol / L NH4Cl solution. Perform ion exchange three times at 85 °C, centrifuge and wash, dry at 120 °C for 12 h, and finally calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. The resulting solid sample is the hierarchical porous molecular sieve, designated as sample 1#.
[0091] Example 2: Preparation of Hierarchical Porous HZSM-5 Molecular Sieves
[0092] Weigh 5.00 g of HZSM-5 molecular sieve (Si / Al = 35) and 0.47 g of aluminum isopropoxide, and add them simultaneously to 150 ml of 0.2 mol / L NaOH solution. Stir at 65 °C for 30 min, centrifuge and wash until neutral, dry at 120 °C for 12 h, and calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. Take 3.00 g of the calcined sample and add it to 60 ml of 0.8 mol / L NH4Cl solution. Perform ion exchange three times at 85 °C, centrifuge and wash, dry at 120 °C for 12 h, and finally calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. The resulting solid sample is the hierarchical porous molecular sieve, designated as sample 2#.
[0093] Example 3: Preparation of Hierarchical Porous HZSM-5 Molecular Sieves
[0094] Weigh 5.00 g of HZSM-5 molecular sieve (Si / Al = 35) and 0.59 g of aluminum isopropoxide, and add them simultaneously to 150 ml of 0.3 mol / L NaOH solution. Stir at 65 °C for 60 min, centrifuge and wash until neutral, dry at 120 °C for 12 h, and calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. Take 3.00 g of the calcined sample and add it to 60 ml of 0.8 mol / L NH4Cl solution. Perform ion exchange three times at 85 °C, centrifuge and wash, dry at 120 °C for 12 h, and finally calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. The resulting solid sample is the hierarchical porous molecular sieve, designated as sample 3#.
[0095] Example 4: Preparation of Hierarchical Porous HZSM-5 Molecular Sieves
[0096] Weigh 5.00 g of HZSM-5 molecular sieve (Si / Al = 35) and 0.95 g of aluminum isopropoxide, and add them simultaneously to 150 ml of 0.4 mol / L NaOH solution. Stir at 65 °C for 60 min, centrifuge and wash until neutral, dry at 120 °C for 12 h, and calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. Take 3.00 g of the calcined sample and add it to 60 ml of 0.8 mol / L NH4Cl solution. Perform ion exchange three times at 85 °C, centrifuge and wash, dry at 120 °C for 12 h, and finally calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. The resulting solid sample is the hierarchical porous molecular sieve, designated as sample 4#.
[0097] Example 5: Preparation of Hierarchical Porous HZSM-5 Molecular Sieves
[0098] Weigh 5.00 g of HZSM-5 molecular sieve (Si / Al = 35) and 0.95 g of aluminum isopropoxide, and add them simultaneously to 150 ml of 0.5 mol / L NaOH solution. Stir at 80 °C for 30 min, centrifuge and wash until neutral, dry at 120 °C for 12 h, and calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. Take 3.00 g of the calcined sample and add it to 60 ml of 0.8 mol / L NH4Cl solution. Perform ion exchange three times at 85 °C, centrifuge and wash, dry at 120 °C for 12 h, and finally calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. The resulting solid sample is the hierarchical porous molecular sieve, designated as sample 5#.
[0099] Example 6: Preparation of Hierarchical Porous HZSM-5 Molecular Sieves
[0100] 5.00 g of HZSM-5 molecular sieve (Si / Al = 35) and 1.90 g of aluminum isopropoxide were weighed and added to 150 ml of 0.6 mol / L NaOH solution. The mixture was stirred at 65 °C for 60 min, centrifuged and washed until neutral, dried at 120 °C for 12 h, and calcined in a muffle furnace at 550 °C for 3 h in air. 3.00 g of the calcined sample was added to 60 ml of 0.8 mol / L NH4Cl solution, and subjected to three ion exchanges at 85 °C. After centrifugation and washing, the sample was dried at 120 °C for 12 h and finally calcined in a muffle furnace at 550 °C for 3 h in air. The resulting solid sample was the hierarchical porous molecular sieve and was designated as sample 6#.
[0101] Example 7: Preparation of Hierarchical Porous HZSM-5 Molecular Sieves
[0102] Weigh 5.00 g of HZSM-5 molecular sieve (Si / Al = 35) and 1.90 g of aluminum isopropoxide, and add them simultaneously to 150 ml of 0.8 mol / L NaOH solution. Stir at 80 °C for 30 min, centrifuge and wash until neutral, dry at 120 °C for 12 h, and calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. Take 3.00 g of the calcined sample and add it to 60 ml of 0.8 mol / L NH4Cl solution. Perform ion exchange three times at 85 °C, centrifuge and wash, dry at 120 °C for 12 h, and finally calcine at 550 °C for 3 h in a muffle furnace under air atmosphere. The resulting solid sample is the hierarchical porous molecular sieve, designated as sample 7#.
[0103] Comparative Example 1
[0104] HZSM-5 molecular sieve (Si / Al = 35) was used as the catalyst, denoted as sample Z5.
[0105] Figure 1 The image shows a scanning electron microscope (SEM) image of the Z5 molecular sieve in Comparative Example 1. As can be seen from the image, it has a regular cubic morphology and a smooth surface.
[0106] Figure 2 The image shows a scanning electron microscope (SEM) image of the hierarchical porous HZSM-5 molecular sieve obtained in Example 1; the image shows that it has a multi-layered sheet-like structure.
[0107] Example 8: Characterization of Nitrogen Physical Adsorption
[0108] The multi-level porous molecular sieves Z5 and those prepared in Examples 1 to 7 of this application were characterized by nitrogen physical adsorption. The specific surface area of their micropores, the volume of their micropores, the specific surface area of their mesopores, the volume of their mesopores, and the diameter of their mesopores were calculated based on the nitrogen physical adsorption-desorption curves. The results are summarized in Table 1.
[0109] Table 1. Pore specific surface area, pore volume, and pore size distribution of the catalysts in Examples 1-7 and Comparative Example 1.
[0110]
[0111] Test Example 1: Application of Catalysts
[0112] Take 0.5g of sample 1#, which has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. First, pretreat it in nitrogen at 500℃ for 2h, then lower the temperature to 350℃ and introduce a 25wt% glycerol aqueous solution to start the reaction. The mass hourly space velocity (WHSV) is 2h. -1 The pressure was 0.1 MPa, the nitrogen flow rate was 20 mL / min, and the reaction was analyzed after 30 min. Catalyst #1 was replaced with catalysts #2–7, and the above process was repeated. The reaction results are shown in Table 2.
[0113] Table 2. Glycerol conversion and acrolein selectivity of catalysts in Examples 1-7
[0114] 1# 98.1 90.2 2# 98.2 90.0 3# 98.0 91.0 4# 98.3 90.4 5# 97.8 90.2 6# 98.1 90.5 7# 98.4 90.4
[0115] Z5 and samples 1#, 2# and 3# from Examples 1-3 of this application were applied to a glycerol dehydration reaction. The reaction process was the same, and the results were as follows: Figure 3 As shown. By Figure 3 It is evident that the glycerol conversion rate remained essentially unchanged after 30 hours of reaction.
[0116] 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 method for preparing a layered, hierarchical porous HZSM-5 molecular sieve catalyst, characterized in that, Includes the following steps: 1) HZSM-5 molecular sieve, aluminum isopropoxide and alkaline solution are mixed at 60~90℃, dried and calcined to obtain catalyst precursor; The alkaline solution is an aqueous solution selected from at least one of LiOH, NaOH, KOH, and CsOH. 2) The catalyst precursor obtained in 1) is subjected to ion exchange, drying (II), and calcination (II) to obtain the layered hierarchical porous HZSM-5 molecular sieve catalyst; wherein, the ion exchange includes the following process: the catalyst precursor obtained in 1) is impregnated in an ion exchange solution; the ion exchange solution is selected from at least one of NH4Cl solution, NH4NO3 solution, and (NH4)2SO4 solution; The layered hierarchical porous HZSM-5 molecular sieve catalyst has a layered structure; The layered hierarchical porous HZSM-5 molecular sieve catalyst has micropores and mesopores; The silica-alumina ratio of the layered hierarchical porous HZSM-5 molecular sieve catalyst is 20~200.
2. The preparation method according to claim 1, characterized in that, In step 1), The silica-alumina ratio of the HZSM-5 molecular sieve is 30~100; The mass ratio of aluminum in the HZSM-5 molecular sieve to aluminum in the aluminum isopropoxide is 20~0.1; The concentration of the alkaline solution is 0.05~2 mol / L.
3. The preparation method according to claim 1, characterized in that, In step 1), The mass ratio of aluminum in the HZSM-5 molecular sieve to aluminum isopropoxide is 10~2; The concentration of the alkaline solution is 0.5~1 mol / L.
4. The preparation method according to claim 1, characterized in that, In step 1), The mixing includes stirring; The stirring time is 15-90 minutes; The temperature of the drying process I is 100~120℃; The drying time for step I is 12-36 hours; The temperature of the calcination I is 350~550℃; The roasting time for the first stage is 1 to 6 hours.
5. The preparation method according to claim 4, characterized in that, In step 1), The mixing temperature is 65~80℃; The stirring time is 30-60 minutes.
6. The preparation method according to claim 1, characterized in that, 2) In, The concentration of the ion exchange solution is 0.5~2 mol / L.
7. The preparation method according to claim 3, characterized in that, 2) In, The temperature of the drying II process is 100~120℃; The drying time for step II is 12-36 hours; The temperature of calcination II is 350~550℃; The roasting time for the second stage is 1 to 6 hours.
8. A method for producing acrolein by dehydrating glycerol, characterized in that, Includes the following steps: In a reactor, a raw material containing glycerol is introduced and reacted with a catalyst to obtain a product containing acrolein. The catalyst is selected from the layered hierarchical porous HZSM-5 molecular sieve catalyst prepared by the preparation method according to any one of claims 1 to 7.
9. The method according to claim 8, characterized in that, The glycerol content in the raw material is 5-60 wt%. The mass hourly space velocity (MSV) of the raw material is 0.5–10 h⁻¹. -1 .
10. The method according to claim 8, characterized in that, The mass hourly space velocity of the raw material is 1-5 h. -1 .
11. The method according to claim 8, characterized in that, The reaction temperature is 200~500℃; The reaction pressure is 0.1~0.5 MPa; The reactor is a fixed-bed reactor.
12. The method according to claim 8, characterized in that, The reaction temperature is 300~350℃; The reaction pressure is 0.1~0.25 MPa.