High-temperature-resistant molecular sieve membrane and preparation method thereof

Abstract

The present disclosure provides a high-temperature-resistant molecular sieve membrane and a preparation method thereof, the high-temperature-resistant molecular sieve membrane comprising a molecular sieve and an inorganic binder; the molecular sieve is an inorganic small-pore molecular sieve, the pore size of the molecular sieve is not greater than 5 nm; the inorganic binder is a low-pore or non-pore binder, the melting temperature of the inorganic binder is greater than 400 DEG C; the content of the molecular sieve is 5-90 wt% and the content of the binder is 10-95 wt% based on the total mass of the high-temperature-resistant molecular sieve membrane. The high-temperature-resistant molecular sieve membrane of the present disclosure has good separation effect, and is particularly suitable for the separation and purification of specific molecular structures in oil products.

Description

Technical Field

[0001] This disclosure relates to the field of molecular sieves and carriers, and more specifically, to a high-temperature resistant molecular sieve membrane and its preparation method. Background Technology

[0002] Generally, crude oil rarely contains only one compound, but oils for specific applications often require pure compounds. The process of transforming crude oil into the target product typically involves two steps: a reaction process, where suitable reaction conditions are used to maximize the conversion of the crude oil components into the target product; and a separation process, where appropriate methods are used to separate and purify the target product to obtain the highest possible quality product. If the crude oil already contains the target product, then separation can be used to directly obtain it, avoiding the problem of non-ideal target products being passively converted into other products during the reaction process.

[0003] Common separation methods are based on differences in the properties of compounds, such as: (1) different boiling points, such as distillation and rectification techniques; (2) different adsorption characteristics on specific surfaces, such as pressure swing adsorption; (3) different solubility in specific solvents, such as crystallization and extraction; (4) different molecular sizes, such as membrane separation; (5) different diffusion coefficients, such as microfiltration, ultrafiltration, reverse osmosis, and electrodialysis.

[0004] Energy consumption is relatively high in chemical separation processes. For example, in crude oil processing, approximately 25-30% of the energy consumed in the distillation process is lost, with most of this energy being lost in the condenser at the top of the column. Other separation processes exhibit similar characteristics. Many processes require operation near room temperature, necessitating the cooling of reactants to suitable separation conditions before reheating for the next reaction step. This repeated process results in unnecessary energy consumption during heating and cooling. Maintaining the separation and reaction conditions as closely as possible is crucial for reducing separation energy consumption and improving separation efficiency.

[0005] Some existing separation processes are suitable for high temperatures and certain pressures. Membrane separation is one such process; however, due to the poor high-temperature resistance of most organic membranes, inorganic membranes are more commonly used. Inorganic membrane materials are divided into two types: ceramic membranes and molecular sieve membranes. The former has a larger pore size and a wider pore size distribution, making it suitable for the separation of large molecules; the latter, based on the pore size of the molecular sieve itself, has a narrower pore size distribution and a definite pore size, and can be used for the separation of molecules with fine size differences in different molecular structures. Among these, molecular sieve membranes are more valuable in practical applications due to their regular pore structure.

[0006] Several common methods exist for preparing molecular sieve membranes, including in-situ hydrothermal synthesis, secondary growth, microwave heating, vapor phase deposition, direct heating of the support, pulsed laser evaporation, pore-blocking, and electrophoretic deposition. In-situ hydrothermal synthesis is relatively simple and requires no special equipment; however, its simplicity makes it difficult to achieve precise control over the microstructure of the molecular sieve membrane. Vapor phase deposition and direct heating of the support do not offer significant advantages over other methods and are unlikely to see further development. Secondary growth combines in-situ hydrothermal synthesis with ex-situ dip-coating, separating the nucleation and growth of molecular sieve crystals. This allows for effective control over the size, orientation, and thickness of the molecular sieve crystals, and it is a simple and effective method that does not require special equipment. Microwave heating utilizes the microwave effect to produce molecular sieve membranes with high crystallinity and no impurities. It effectively controls the microstructure of the molecular sieve membrane and has the advantage of short crystallization time; however, the microwave generator is relatively expensive. Laser evaporation completely separates the preparation and film formation processes of the molecular sieve, thus simplifying the process. Other methods for synthesizing molecular sieve membranes often involve the simultaneous formation of sieve crystals and the membrane itself, complicating the process. During synthesis, suitable conditions must be selected to obtain the desired sieve crystals; simultaneously, suitable conditions must be chosen to link the crystals into a membrane. These two requirements are often difficult to balance, especially for molecular sieves with demanding synthesis conditions. Laser evaporation, however, eliminates the need for sieve synthesis; by controlling the laser evaporation conditions, excellent molecular sieve membranes can be obtained. Theoretically, any type of molecular sieve membrane can be synthesized, a feat unmatched by other methods. Its drawback lies in the requirement for a laser device, which is highly disadvantageous for industrial applications.

[0007] In existing technologies, most molecular sieve membranes need to be formed under specific conditions, and the synthesis is difficult and cannot meet the requirements for high temperature resistance. Summary of the Invention

[0008] The purpose of this disclosure is to provide a high-temperature resistant molecular sieve membrane with good separation performance.

[0009] To achieve the above objectives, this disclosure provides a high-temperature resistant molecular sieve membrane, comprising a molecular sieve and an inorganic binder; the molecular sieve is an inorganic small-pore molecular sieve with a pore size not greater than 5 nm; the inorganic binder is a low-porosity or non-porous binder with a melting temperature greater than 400 °C; based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve is 5-90% by weight, and the content of the inorganic binder is 10-95% by weight.

[0010] Optionally, the inorganic adhesive has a melting temperature greater than 450°C.

[0011] Optionally, the inorganic binder contains silicon oxide and metal oxide; optionally, the metal oxide is selected from one or more of barium oxide, zinc oxide, aluminum oxide, calcium oxide, sodium oxide and nickel oxide; preferably, based on the total weight of the inorganic binder, the content of silicon oxide is 25-40% by weight, the content of barium oxide is 5-30% by weight, the content of zinc oxide is 5-20% by weight, the content of aluminum oxide is 5-12% by weight, the content of calcium oxide is 3-25% by weight, the content of sodium oxide is 8-12% by weight, and the content of nickel oxide is 3-7% by weight.

[0012] Optionally, the pore size of the molecular sieve is no greater than 3 nm, preferably no greater than 1 nm.

[0013] Optionally, the molecular sieve is selected from at least one of ZSM-5 molecular sieve, 4A molecular sieve, 3A molecular sieve, 5A molecular sieve and Y-type molecular sieve, preferably a molecular sieve with a pore size of not more than 7.0 Å.

[0014] Optionally, based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve is 10-90% by weight, preferably 30-85% by weight, and more preferably 70-85% by weight; the content of the adhesive is 10-90% by weight, preferably 15-70% by weight, and more preferably 15-30% by weight.

[0015] Optionally, the high-temperature resistant molecular sieve membrane further includes an organic binder; optionally, based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the organic binder is 0.01-5% by weight, preferably 0.05-3% by weight. Optionally, the organic adhesive is selected from water-based adhesives, preferably at least one of carboxymethyl cellulose adhesives, polyvinyl alcohol adhesives, starch adhesives, acrylic latex adhesives, and vinyl acetate adhesives.

[0016] This disclosure also provides a method for preparing a high-temperature resistant molecular sieve membrane, the method comprising: S1. Mix molecular sieve and inorganic binder to obtain a first material, or mix molecular sieve, inorganic binder and organic binder to obtain a second material; S2. Add solvent to the first material or the second material and then crush and press it to obtain a mixture; S3. The mixture is dried and calcined.

[0017] Optionally, the weight ratio of the molecular sieve to the inorganic binder is 5-90:10-95; preferably 10-80:20-90; or the weight ratio of the molecular sieve to the inorganic binder is 5-90:10-95; preferably 10-80:20-90, and the ratio of the total weight of the molecular sieve and the inorganic binder to the organic binder is 1:0.01-5; preferably 1:0.05-3; the solvent is water, preferably one of deionized water, distilled water and purified water.

[0018] Optionally, in step S2, the diameter of the mixture is 5-100 mm and the thickness is 0.01-20 mm; in step S3, the drying includes air drying and oven drying; the air drying conditions include: temperature of 20-35℃ and time of 0.5-48 hours; the oven drying conditions include: temperature of 85-150℃ and time of 0.5-48 hours; the calcination conditions include: temperature of 450-900℃ and time of 0.1-10 hours.

[0019] The present disclosure provides a high-temperature resistant molecular sieve membrane, comprising a molecular sieve and an inorganic binder, wherein the molecular sieve is an inorganic small-pore molecular sieve, and the inorganic binder is a high-temperature resistant low-porosity or non-porous binder. The high-temperature resistant molecular sieve membrane provided by the present disclosure exhibits excellent separation performance and is particularly suitable for the separation and purification of specific molecular structures in oils.

[0020] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0021] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0022] This disclosure provides a high-temperature resistant molecular sieve membrane, comprising a molecular sieve and an inorganic binder; the molecular sieve is an inorganic small-pore molecular sieve with a pore size not greater than 5 nm; the inorganic binder is a low-porosity or non-porous binder with a melting temperature greater than 400 °C; based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve is 5-90% by weight, and the content of the inorganic binder is 10-95% by weight.

[0023] The high-temperature resistant molecular sieve membrane disclosed herein can withstand high-temperature treatment at 250°C for at least 3 hours in air without significant structural collapse. This high-temperature resistant molecular sieve membrane exhibits excellent separation performance and is particularly suitable for the separation and purification of specific molecular structures in oils.

[0024] According to this disclosure, the melting temperature of the inorganic adhesive is preferably greater than 450°C.

[0025] Particularly preferably, the inorganic binder used in this disclosure may contain silicon oxide and metal oxides, wherein the metal oxides may be selected from one or more of barium oxide, zinc oxide, aluminum oxide, calcium oxide, sodium oxide, and nickel oxide; wherein, based on the total weight of the inorganic binder, the content of silicon oxide may be 25-40% by weight, the content of barium oxide may be 5-30% by weight, the content of zinc oxide may be 5-20% by weight, the content of aluminum oxide may be 5-12% by weight, the content of calcium oxide may be 3-25% by weight, the content of sodium oxide may be 8-12% by weight, and the content of nickel oxide may be 3-7% by weight. In this preferred embodiment, the inorganic binder has strong adhesive force, does not damage the structure of the molecular sieve, and also enables the molecular sieve membrane to have excellent high-temperature resistance.

[0026] According to this disclosure, the pore size of the molecular sieve may be no greater than 3 nm, preferably no greater than 1 nm.

[0027] The molecular sieves used in this disclosure may be those known to those skilled in the art, for example, one or more of the molecular sieves listed in the Database of Zeolite Structures (iza-structure.org); optionally, the molecular sieve may be selected from at least one of ZSM-5 molecular sieve, 4A molecular sieve, 3A molecular sieve, 5A molecular sieve and Y-type molecular sieve, preferably a molecular sieve with a pore size not greater than 7.0 Å.

[0028] According to this disclosure, based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve can be 10-90% by weight, preferably 30-85% by weight, and more preferably 70-85% by weight; the content of the adhesive can be 10-90% by weight, preferably 15-70% by weight, and more preferably 15-30% by weight.

[0029] According to this disclosure, the high-temperature resistant molecular sieve membrane may further include an organic adhesive; optionally, based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the organic adhesive is 0.01-5% by weight, preferably 0.05-3% by weight; optionally, the organic adhesive is selected from water-based adhesives, preferably at least one of carboxymethyl cellulose adhesives, polyvinyl alcohol adhesives, starch adhesives, acrylic latex adhesives, and vinyl acetate adhesives.

[0030] This disclosure also provides a method for preparing a high-temperature resistant molecular sieve membrane, the method comprising: S1. Mix molecular sieve and inorganic binder to obtain a first material, or mix molecular sieve, inorganic binder and organic binder to obtain a second material; S2. Add solvent to the first material or the second material and then crush and press it to obtain a mixture; S3. The mixture is dried and calcined.

[0031] The high-temperature resistant molecular sieve membrane disclosed herein can be rolled and pressed into a mixture with a specific shape and size as needed. After drying and calcination, the mixture has a certain strength and can stand on its own or be combined with other components.

[0032] According to this disclosure, the weight ratio of the molecular sieve to the inorganic binder can be 5-90:10-95; preferably 10-80:20-90; or the weight ratio of the molecular sieve to the inorganic binder can be 5-90:10-95; preferably 10-80:20-90, and the ratio of the total weight of the molecular sieve and the inorganic binder to the organic binder is 1:0.01-5; preferably 1:0.05-3; the solvent can be water, preferably one of deionized water, distilled water and purified water.

[0033] According to this disclosure, in step S2, the diameter of the mixture can be 5-100 mm and the thickness can be 0.01-20 mm; in step S3, the drying can include air drying and oven drying; the air drying conditions can include: a temperature of 20-35℃ and a time of 0.5-48 hours; the oven drying conditions can include: a temperature of 85-150℃ and a time of 0.5-48 hours; the calcination conditions can include: a temperature of 450-900℃ and a time of 0.1-10 hours.

[0034] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0035] The inorganic binder T50 used in the examples or comparative examples was commercially available and had a melt temperature of 550°C. Analysis revealed that the inorganic binder T50 contained approximately 40% by weight of silicon dioxide, approximately 5% by weight of aluminum oxide, approximately 10% by weight of sodium oxide, approximately 25% by weight of calcium oxide, approximately 6% by weight of zinc oxide, approximately 6% by weight of barium oxide, approximately 2% by weight of magnesium oxide, and approximately 6% by weight of nickel oxide.

[0036] The organic binder used in the examples or comparative examples is carboxymethyl cellulose.

[0037] The ZSM-5 molecular sieve used in the examples or comparative examples has a pore size of 0.54-0.56 nm, and the 4A molecular sieve has a pore size of 0.4 nm.

[0038] Example 1 Take 16.0g of ZSM-5 molecular sieve (purchased from Zibo Qichuang New Material Technology Co., Ltd.), 0.1g of carboxymethyl cellulose (purchased from Qimao Catalyst Co., Ltd.), and 4.4g of T50 powder (commercially purchased inorganic binder, melting point 550℃). Mix them evenly, add 9g of deionized water, and repeatedly mix and press for 15 minutes. Then, place the material in a tablet press to press it into a sheet with a diameter of about 25mm and a thickness of about 1mm. After drying the sheet at room temperature, dry it at 105℃ for 6 hours, then put it into a calcination furnace and treat it at 720℃ for 2 hours. After cooling to room temperature, take it out to obtain molecular sieve membrane A.

[0039] Example 2 The preparation method of the molecular sieve membrane in this embodiment is the same as that in Example 1. The difference is that the amount of ZSM-5 molecular sieve and T50 powder (commercially purchased inorganic binder, melting point 550°C) added in this embodiment is 13.5g and 9.1g, respectively, to obtain molecular sieve membrane B.

[0040] Example 3 The preparation method of the molecular sieve membrane in this embodiment is the same as that in Example 1. The difference is that the amount of ZSM-5 molecular sieve and T50 powder (commercially purchased inorganic binder, melting point 550℃) added in this embodiment is 11.3g and 11.4g, respectively, to obtain molecular sieve membrane C.

[0041] Example 4 The preparation method of the molecular sieve membrane in this embodiment is the same as that in Example 1. The difference is that the amount of ZSM-5 molecular sieve and T50 powder (commercially purchased inorganic binder, melting point 550°C) added in this embodiment is 6.5g and 15.1g, respectively, to obtain molecular sieve membrane D.

[0042] Example 5 The preparation method of the molecular sieve membrane in this embodiment is the same as that in Example 1. The difference is that the amount of ZSM-5 molecular sieve and T50 powder (commercially purchased inorganic binder, melting point 550℃) added in this embodiment is 18.2g and 4.4g, respectively, to obtain molecular sieve membrane E.

[0043] Example 6 The preparation method of the molecular sieve membrane in this embodiment is the same as that in Example 1, except that the ZSM-5 molecular sieve in Example 1 is replaced with an equal amount of 4A molecular sieve to obtain molecular sieve membrane F.

[0044] Comparative Example 1 Take 21g of 4A molecular sieve and 0.1g of carboxymethyl cellulose (from Qimao Catalyst Co., Ltd.), mix them evenly, add 9g of deionized water, mix and press repeatedly for 15 minutes, then place the material in a tablet press to press it to obtain a sheet with a diameter of about 25mm and a thickness of about 1mm. After drying the sheet at room temperature, dry it at 105℃ for 6 hours, then put it into a calcination furnace and treat it at 750℃ for 2 hours. After cooling to room temperature, take it out to obtain molecular sieve membrane X1.

[0045] Test Example 1 The composition of the molecular sieve membranes in Examples 1-6 and Comparative Example 1 was calculated, and the specific results are shown in Table 1. The molecular sieve content and the inorganic binder content are respectively calculated based on the total weight of the molecular sieve and the inorganic binder, and the addition ratio of the organic binder is the ratio of the organic binder to the total weight of the molecular sieve and the inorganic binder.

[0046] Table 1

[0047] Test Example 2 The diffusion coefficients of n-hexane and cyclohexane at 250℃ were determined by the time delay method, and the ratio of the diffusion coefficients of the two molecules was calculated to determine the selective permeability of the molecular sieve membrane for molecules of different sizes. The results are shown in Table 2.

[0048] Table 2

[0049] The data in Table 2 show that the high-temperature resistant molecular sieve membrane disclosed herein has a high diffusion coefficient ratio of n-hexane to cyclohexane.

[0050] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0051] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0052] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A high-temperature resistant molecular sieve membrane, characterized in that, The high-temperature resistant molecular sieve membrane is a sheet comprising a molecular sieve and an inorganic binder; The molecular sieve is an inorganic small-pore molecular sieve, and the pore size of the molecular sieve is no greater than 5 nm. The inorganic adhesive is a low-porosity or non-porosity adhesive, and the melting temperature of the inorganic adhesive is greater than 400°C. Based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve is 5-90% by weight, and the content of the inorganic binder is 10-95% by weight. Based on the total weight of the inorganic binder, the content of silicon oxide is 25-45% by weight, the content of barium oxide is 5-30% by weight, the content of zinc oxide is 5-20% by weight, the content of aluminum oxide is 5-12% by weight, the content of calcium oxide is 3-25% by weight, the content of sodium oxide is 8-12% by weight, and the content of nickel oxide is 3-7% by weight.

2. The molecular sieve membrane according to claim 1, wherein, The inorganic adhesive has a melting temperature greater than 450°C.

3. The molecular sieve membrane according to claim 1, wherein, The pore size of the molecular sieve is no greater than 3 nm.

4. The molecular sieve membrane according to claim 3, wherein, The pore size of the molecular sieve is no greater than 1 nm.

5. The molecular sieve membrane according to claim 3, wherein, The molecular sieve is selected from at least one of ZSM-5 molecular sieve, 4A molecular sieve, 3A molecular sieve, 5A molecular sieve and Y-type molecular sieve.

6. The molecular sieve membrane according to claim 5, wherein, The molecular sieve is a molecular sieve with a pore size of no more than 7.0 Å.

7. The molecular sieve membrane according to claim 1, wherein, Based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve is 10-90% by weight; the content of the adhesive is 10-90% by weight.

8. The molecular sieve membrane according to claim 7, wherein, Based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve is 30-85% by weight; the content of the adhesive is 15-70% by weight.

9. The molecular sieve membrane according to claim 8, wherein, Based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the molecular sieve is 70-85% by weight; the content of the adhesive is 15-30% by weight.

10. The molecular sieve membrane according to claim 1, wherein, The high-temperature resistant molecular sieve membrane also includes an organic adhesive; Based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the organic binder is 0.01-5% by weight. The organic adhesive is selected from water-based adhesives.

11. The molecular sieve membrane according to claim 10, wherein, Based on the total mass of the high-temperature resistant molecular sieve membrane, the content of the organic binder is 0.05-3% by weight. The organic adhesive is selected from at least one of carboxymethyl cellulose adhesives, polyvinyl alcohol adhesives, starch adhesives, acrylic latex adhesives, and vinyl acetate adhesives.

12. A method for preparing the high-temperature resistant molecular sieve membrane according to any one of claims 1-11, characterized in that, The method includes: S1. Mix molecular sieve and inorganic binder to obtain a first material, or mix molecular sieve, inorganic binder and organic binder to obtain a second material; S2. Add solvent to the first material or the second material and then crush and press it to obtain a mixture; S3. The mixture is dried and calcined. In step S1, the weight ratio of the molecular sieve to the inorganic binder is 5-90:10-95, or the weight ratio of the molecular sieve to the inorganic binder is 5-90:10-95, and the ratio of the total weight of the molecular sieve and the inorganic binder to the organic binder is 1:0.01-5. The roasting conditions include: a temperature of 450-900℃ and a time of 0.1-10 hours.

13. The method according to claim 12, wherein, In step S1, the weight ratio of the molecular sieve to the inorganic binder is 10-80:20-90; or The weight ratio of the molecular sieve to the inorganic binder is 10-80:20-90, and the ratio of the total weight of the molecular sieve and the inorganic binder to the organic binder is 1:0.05-3. The solvent is water.

14. The method according to claim 13, wherein, In step S1, the solvent is one of deionized water, distilled water, and purified water.

15. The method according to claim 12 or 13, wherein, In step S2, the mixture has a diameter of 5-100 mm and a thickness of 0.01-20 mm; In step S3, the drying includes air drying and oven drying; The air-drying conditions include a temperature of 20-35℃ and a time of 0.5-48 hours; the drying conditions include a temperature of 85-150℃ and a time of 0.5-48 hours.

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