A silico-aluminum molecular sieve, a preparation method and application thereof

Abstract

The present application relates to a kind of silicon-aluminum molecular sieve and its preparation method and application, which comprises the following steps: S1, organic silicon source, aluminum source, alkaline template agent and aqueous solution containing carbon quantum dots are mixed to obtain first mixture;S2, first mixture is hydrothermally treated at 80-250 DEG C for 1-96h, to obtain second mixture;S3, second mixture is spray dried, to obtain first material and second material, first material is calcined, to obtain silicon-aluminum molecular sieve;Wherein, the average particle size of first material is 10-200 μm, the average particle size of second material is 1-50 μm;S4, second material is mixed with the second mixture obtained in step S2.The yield of the method of silicon-aluminum molecular sieve is high, and the particle size distribution of silicon-aluminum molecular sieve can be optimized, and the catalytic performance is relatively optimal.

Description

Technical Field

[0001] This invention relates to a silica-alumina molecular sieve, its preparation method, and its application. Background Technology

[0002] In modern chemical production, many processes, such as olefin hydration, utilize the acid catalytic properties of molecular sieves. Commonly used acid-catalyzing molecular sieves are silica-alumina molecular sieves, whose framework is entirely composed of silicon, aluminum, and oxygen. These were the earliest developed artificial zeolites and have broad application prospects in petroleum refining and petrochemicals. Various silica-alumina molecular sieves with structures such as X, Y, A, β, mordenite, and ZSM-5 are used in various petroleum refining and petrochemical applications. However, there is still room for improvement in the synthesis yield of existing silica-alumina molecular sieves, especially in terms of particle size distribution, and further enhancement of catalytic performance is needed for their application in certain reactions. Summary of the Invention

[0003] The purpose of this invention is to provide a silica-alumina molecular sieve, its preparation method, and its application. The method yields silica-alumina molecular sieves with optimized particle size distribution, which is particularly beneficial for molding and other processes. It also exhibits excellent catalytic performance and a long service life.

[0004] To achieve the above objectives, a first aspect of the present invention provides a method for preparing aluminosilicate molecular sieves, the method comprising:

[0005] S1. Mix the organosilicon source, aluminum source, alkaline template agent and aqueous solution containing carbon quantum dots to obtain the first mixture;

[0006] S2. The first mixture is subjected to hydrothermal treatment at 80-250℃ for 1-96 hours to obtain the second mixture;

[0007] S3. Spray dry the second mixture to obtain a first material and a second material. Calcine the first material to obtain a silica-alumina molecular sieve. The average particle size of the first material is 10-200 μm, and the average particle size of the second material is 1-50 μm.

[0008] S4. Mix the second material with the second mixture obtained in step S2, and then spray dry the resulting mixture again in step S3.

[0009] Optionally, in step S1, the weight ratio of the organosilicon source, the aluminum source, the alkaline template agent, and the aqueous solution containing carbon quantum dots is 100:(0.2-10):(1-20):(250-10000); and the concentration of carbon quantum dots in the aqueous solution containing carbon quantum dots is 0.01-1000ppm.

[0010] Optionally, in step S3, the spray drying conditions include: an inlet temperature of 200-380℃ and an outlet temperature of 120-200℃; preferably, the inlet temperature is 220-360℃ and the outlet temperature is 130-180℃.

[0011] Optionally, the method further includes preparing an aqueous solution containing carbon quantum dots by mixing organic matter with an oxygen content of 20-75% by weight with water and then carrying out a hydrothermal reaction at 200-400°C and autogenous pressure for 1-72 hours.

[0012] Optionally, in step S3, the calcination conditions include: a temperature of 300-800℃ and a time of 0.5-12h.

[0013] Optionally, in step S4, the weight ratio of the second material to the second mixture is 10:(30-250).

[0014] Optionally, the organosilicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate;

[0015] The aluminum source is an organic aluminum source and / or an inorganic aluminum source, wherein the inorganic aluminum source is selected from one or more of the following: dry adhesive powder, boehmite, sodium aluminate, aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum nitrate, and aluminum phosphate.

[0016] The alkaline template agent is an organic base and / or an inorganic base, wherein the organic base is selected from one or more of urea, quaternary ammonium compounds, fatty amine compounds and alcoholic amine compounds, and the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide and barium hydroxide.

[0017] The second aspect of the present invention provides a silica-alumina molecular sieve prepared by the method provided in the first aspect of the present invention.

[0018] Optionally, the average particle size of the silica-alumina molecular sieve is 20-90 μm, the relative crystallinity is 80-150%, the bulk ratio is 0.4-0.8 g / mL, and the particle size distribution uniformity deviation is 5-20%.

[0019] Preferably, the average particle size is 30-90 μm, the relative crystallinity is 0.5-0.7%, the bulk density is 0.5-0.7 g / mL, and the particle size distribution uniformity deviation is 5-15%.

[0020] The third aspect of the present invention provides an application of the silica-alumina molecular sieve provided in the second aspect of the present invention in the olefin hydration reaction.

[0021] Through the above technical solution, the method of the present invention uses carbon dot solution to prepare silicon-aluminum molecular sieves, which increases the mixing of materials and makes the particles have better sphericity and more uniform particle size distribution during spray molding. The prepared silicon-aluminum molecular sieves have better catalytic performance.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0023] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] The first aspect of the present invention provides a method for preparing aluminosilicate molecular sieves, the method comprising: S1, mixing an organosilicon source, an aluminum source, an alkaline template agent and an aqueous solution containing carbon quantum dots to obtain a first mixture; S2, subjecting the first mixture to hydrothermal treatment at 80-250°C for 1-96 hours to obtain a second mixture; S3, spray-drying the second mixture to obtain a first material and a second material, and calcining the first material to obtain aluminosilicate molecular sieves; wherein the average particle size of the first material is 10-200 μm, and the average particle size of the second material is 1-50 μm; S4, mixing the second material with the second mixture obtained in step S2, and subjecting the resulting mixed second mixture to spray-drying again as in step S3.

[0025] The method of this invention introduces an aqueous solution containing carbon quantum dots during the preparation of silicon-aluminum molecular sieves, which increases the uniformity of material mixing, effectively shortens the hydrothermal reaction time, and is beneficial to optimizing the sphericity and uniformity of catalyst particles during spray molding. Furthermore, returning a portion of the spray-dried material to the previous step improves the total yield of silicon-aluminum molecular sieve catalysts, thus enabling the preparation of silicon-aluminum molecular sieves with superior particle size distribution and excellent catalytic performance.

[0026] According to the present invention, in step S1, the weight ratio of the organosilicon source, the aluminum source, the alkaline template agent, and the aqueous solution containing carbon quantum dots can vary within a wide range, for example, it can be 100:(0.2-10):(1-20):(250-10000), preferably 100:(0.5-5):(5-15):(600-5000). The present invention does not limit the mixing method of the raw materials in step S1, as long as the raw materials can be mixed uniformly.

[0027] According to the present invention, the hydrothermal treatment in step S2 is well known to those skilled in the art. Preferably, the hydrothermal treatment is carried out under closed and stirred conditions, and the temperature of the hydrothermal treatment is 100-200°C and the time is 2-48h.

[0028] According to the present invention, in step S3, the spray drying is well known to those skilled in the art, and the spray drying conditions may include: an inlet temperature of 200-380℃, preferably 220-360℃, and an outlet temperature of 120-200℃, preferably 130-180℃. In a specific embodiment of the present invention, the material obtained from the main outlet is the first material, and the material obtained from the secondary outlet is the second material. Preferably, the average particle size of the first material is 20-100μm, and the average particle size of the second material is 1-20μm. In the present invention, the material from the secondary outlet is mixed with the second mixture obtained in step S2, which not only makes the material from the secondary outlet usable, but also increases the solid content in the newly obtained second mixture, thereby optimizing the particle size distribution of the silicon-aluminum molecular sieve catalyst, which is particularly beneficial to processes such as molding, and results in excellent catalytic performance.

[0029] In one specific embodiment of the present invention, the method may further include preparing an aqueous solution containing carbon quantum dots by the following steps: mixing an organic compound with an oxygen content of 20-75% by weight with water and then subjecting it to a hydrothermal reaction at 200-400°C and autogenous pressure for 1-72 hours. The organic compound with an oxygen content of 20-75% by weight may be selected from one or more of organic acids, cellulose, starch, and lignin. Examples of organic acids include citric acid, malic acid, tartaric acid, and ascorbic acid. The weight ratio of organic compound to water can vary within a wide range, for example, 10:(10-500), preferably 10:(50-200); the concentration of carbon quantum dots in the aqueous solution can vary within a wide range, preferably 0.01-1000 ppm, more preferably 0.1-100 ppm. The method of the present invention uses an aqueous solution containing carbon quantum dots with the above-mentioned concentration to prepare aluminosilicate molecular sieve, which can further improve the uniformity of material mixing, shorten the hydrothermal crystallization reaction time, improve the sphericity during spray molding, and is beneficial to further improve the uniformity of particle size distribution and catalytic performance of aluminosilicate molecular sieve.

[0030] In one specific embodiment of the present invention, in step S3, the calcination conditions may include: a temperature of 300-800℃ and a time of 0.5-12h, preferably, a temperature of 400-700℃ and a time of 1-6h. Calcination can be carried out in equipment conventionally used by those skilled in the art, such as a tube furnace or a muffle furnace. There are no specific limitations on the calcination atmosphere; it can be an inert atmosphere, an air atmosphere, etc.

[0031] In one specific embodiment of the present invention, in step S4, the weight ratio of the second material to the second mixture can vary within a wide range, for example, it can be 10:(30-250), preferably 10:(50-200). When the weight ratio of the second material to the second mixture is within the above range, the particle size distribution uniformity of the silicon-aluminum molecular sieve can be further improved.

[0032] According to the present invention, the organosilicon source can be any type known to those skilled in the art for synthesizing silica-alumina molecular sieves, and the organosilicon source can be of the general formula R. 4 The compound represented by 4SiO4, where R 4 The alkyl group is C1-C4, including straight-chain alkyl groups of C1-C4 and branched alkyl groups of C3-C4, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, or tert-butyl. In one embodiment of the invention, the organosilicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, tetra-n-propyl orthosilicate, and tetra-n-butyl orthosilicate.

[0033] According to the present invention, the aluminum source is an organic aluminum source and / or an inorganic aluminum source, wherein the inorganic aluminum source is selected from one or more of the following: dry adhesive powder, boehmite, sodium aluminate, aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum nitrate, and aluminum phosphate; the organic aluminum source may include, but is not limited to, aluminum isopropoxide.

[0034] According to the present invention, the alkaline template agent is an organic base and / or an inorganic base, wherein the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide and barium hydroxide, and the organic base is selected from one or more of urea, quaternary ammonium compounds, fatty amine compounds and alkanolamine compounds.

[0035] Among them, the general molecular formula of quaternary ammonium bases can be (R 1 )4NOH, where R 1 It may be selected from at least one of C1-C4 straight-chain alkyl and C3-C4 branched alkyl. Preferably, the quaternary ammonium base compound is selected from tetrabutylammonium hydroxide, tetrapropylammonium hydroxide or tetraethylammonium hydroxide, or a combination of two or three of them.

[0036] The general molecular formula of aliphatic amine compounds can be R 2 (NH2) n , where R 2 It can be a C1-C6 alkyl or alkylene group. Preferably, the aliphatic amine compound is selected from butanediamine, n-butylamine, ethylamine or hexanediamine, or a combination of two or three of them.

[0037] The general molecular formula for alcohol amines can be (HOR) 3 ) m NH(3-m) , where R 3 It can be a C1-C4 alkyl group, where m is an integer of 1, 2, or 3. Preferably, it is an alkanolamine compound, such as monoethanolamine, diethanolamine, or triethanolamine, or a combination of two or three of them.

[0038] The second aspect of the present invention provides a silica-alumina molecular sieve prepared by the method provided in the first aspect of the present invention.

[0039] In one specific embodiment of the present invention, the average particle size of the silica-alumina molecular sieve is 20-90 μm, the relative crystallinity is 80-150%, the bulk ratio is 0.4-0.8 g / mL, and the particle size distribution uniformity deviation is 5-20%. Preferably, the average particle size is 30-70 μm, the relative crystallinity is 100-140%, the bulk ratio is 0.5-0.7 g / mL, and the particle size distribution uniformity deviation is 5-15%. The particle size distribution uniformity deviation is expressed as the percentage of the difference between particle sizes D50 and D90 to D50; a larger value indicates poorer particle size distribution uniformity. The average particle size of the silica-alumina molecular sieve can be obtained using a particle size analyzer. The relative crystallinity is obtained using a Siemens D5005 X-ray diffractometer based on Comparative Example 1. The bulk ratio is measured and calculated using standard methods. The silica-alumina molecular sieve of the present invention has a superior particle size distribution and excellent catalytic performance.

[0040] The third aspect of the present invention provides an application of the silica-alumina molecular sieve provided in the second aspect of the present invention in the olefin hydration reaction.

[0041] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0042] Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available. The aqueous solutions containing carbon quantum dots used in Examples 1, 4, 5, 6, and 7 were prepared by mixing cellulose and deionized water at a weight ratio of 10:80 and then subjecting the mixture to a hydrothermal reaction at 320°C and autogenous pressure for 24 hours. The aqueous solution containing carbon quantum dots used in Example 2 was prepared by mixing cellulose and deionized water at a weight ratio of 10:40 and then subjecting the mixture to a hydrothermal reaction at 300°C and autogenous pressure for 20 hours. The aqueous solution containing carbon quantum dots used in Example 3 was prepared by mixing lignin and deionized water at a weight ratio of 10:100 and then subjecting the mixture to a hydrothermal reaction at 320°C and autogenous pressure for 18 hours.

[0043] In the examples and comparative examples, the particle size of the aluminosilicate molecular sieves was determined using a laser particle size analyzer, and the bulk density was measured according to standard methods well known to those skilled in the art. The X-ray diffraction (XRD) phase diagrams of the products were determined using a Siemens D5005 X-ray diffractometer, and the relative crystallinity was compared with the aluminosilicate molecular sieve sample of Comparative Example 1, i.e., the relative crystallinity of the aluminosilicate molecular sieve of Comparative Example 1 was 100%.

[0044] Example 1

[0045] S1. At room temperature (20°C), tetraethyl orthosilicate, aluminum isopropoxide, tetrapropylammonium hydroxide and an aqueous solution containing carbon quantum dots are mixed in a weight ratio of 100:2:10:1500 to obtain a first mixture; wherein the concentration of carbon quantum dots in the aqueous solution containing carbon quantum dots is 20 ppm.

[0046] S2. The first mixture is transferred to a stainless steel sealed reactor and subjected to hydrothermal treatment at 180°C and autogenous pressure for 48 hours to obtain the second mixture.

[0047] S3. The second mixture obtained after hydrothermal treatment is sent to a spray drying equipment and spray dried at an inlet temperature of 280℃ and an outlet temperature of 160℃. Then, the material from the main outlet of the spray drying (i.e. the first material with an average particle size of 45μm) is calcined at 550℃ for 3 hours to obtain a silicon-aluminum molecular sieve.

[0048] S4. The material from the secondary outlet of the spray dryer (i.e., the second material, with an average particle size of 6 μm) is mixed with the second mixture from step S2 at a weight ratio of 10:100 and then fed into the spray drying equipment of step S3 for molding. Its XRD phase diagram is consistent with that of Comparative Example 1, indicating that a silica-alumina molecular sieve with an MFI structure is obtained. Its relative crystallinity, particle size, bulk ratio, and yield are listed in Table 1.

[0049] Example 2

[0050] S1. At room temperature (20°C), tetramethyl orthosilicate, tetrapropyl aluminate, hexamethylenediamine and an aqueous solution containing carbon quantum dots are mixed in a weight ratio of 100:5:2:1000 to obtain a first mixture; wherein the concentration of carbon quantum dots in the aqueous solution containing carbon quantum dots is 2 ppm.

[0051] S2. The first mixture is transferred to a stainless steel sealed reactor and subjected to hydrothermal treatment at 120°C and autogenous pressure for 48 hours to obtain the second mixture.

[0052] S3. The second mixture obtained after hydrothermal treatment is sent to a spray drying equipment and spray dried at an inlet temperature of 360℃ and an outlet temperature of 180℃. Then, the material from the main outlet of the spray drying (i.e. the first material with an average particle size of 52μm) is calcined at 550℃ for 3 hours to obtain a silicon-aluminum molecular sieve.

[0053] S4. The material from the secondary outlet of the spray dryer (i.e., the second material, with an average particle size of 8 μm) is mixed with the second material from step S2 at a weight ratio of 10:40 and fed into the spray drying equipment of step S3 for molding. Its XRD phase diagram is consistent with that of Comparative Example 1, indicating that the obtained product is a silica-alumina molecular sieve with an MFI structure. Its relative crystallinity, particle size, bulk density, and yield are listed in Table 1.

[0054] Example 3

[0055] S1. At room temperature (20°C), tetrapropyl orthosilicate, aluminum nitrate, triethanolamine and an aqueous solution containing carbon quantum dots are mixed in a weight ratio of 100:0.2:20:250 to obtain a first mixture; wherein the concentration of carbon quantum dots in the aqueous solution containing carbon quantum dots is 25 ppm.

[0056] S2. The first mixture is transferred to a stainless steel sealed reactor and subjected to hydrothermal treatment at 250°C and autogenous pressure for 4 hours to obtain the second mixture.

[0057] S3. The second mixture obtained after hydrothermal treatment is sent to a spray drying equipment and spray dried at an inlet temperature of 220℃ and an outlet temperature of 130℃. Then, the material from the main outlet of the spray drying (i.e. the first material with an average particle size of 48μm) is calcined at 550℃ for 3 hours to obtain a silicon-aluminum molecular sieve.

[0058] S4. The material from the secondary outlet of the spray dryer (i.e., the second material, with an average particle size of 4 μm) is mixed with the second material from step S2 at a weight ratio of 10:100 and fed into the spray drying equipment of step S3 for molding. Its XRD phase diagram is consistent with that of Comparative Example 1, indicating that the obtained product is a silica-alumina molecular sieve with an MFI structure. Its relative crystallinity, particle size, bulk ratio, and yield are listed in Table 1.

[0059] Example 4

[0060] Aluminosilicate molecular sieves were prepared according to the method of Example 1, except that the spray drying conditions in step S3 were: inlet temperature 380°C, outlet temperature 200°C, average particle size of the material at the main discharge port of the spray dryer was 55 μm (i.e., the first material), and average particle size of the material at the secondary discharge port was 10 μm (i.e., the second material). The XRD phase diagram of the prepared aluminosilicate molecular sieve catalyst was consistent with that of Comparative Example 1, indicating that the obtained aluminosilicate molecular sieve had an MFI structure. Its relative crystallinity, particle size, bulk density, and yield are listed in Table 1.

[0061] Example 5

[0062] The silica-alumina molecular sieve was prepared according to the method of Example 1, except that the spray drying conditions in step S3 were: inlet temperature 200℃, outlet temperature 120℃, average particle size of the material at the main discharge port of the spray dryer was 37 μm (i.e., the first material), and average particle size of the material at the secondary discharge port was 4 μm (i.e., the second material). The XRD phase diagram of the prepared silica-alumina molecular sieve catalyst was consistent with that of Comparative Example 1, indicating that the obtained silica-alumina molecular sieve had an MFI structure. Its relative crystallinity, particle size, bulk density, and yield are listed in Table 1.

[0063] Example 6

[0064] The silica-aluminum molecular sieve was prepared according to the method of Example 1, except that in step S1, the weight ratio of tetraethyl orthosilicate, aluminum isopropoxide, tetrapropylammonium hydroxide, and the aqueous solution containing carbon quantum dots was 100:2:18:500. The concentration of carbon quantum dots in the aqueous solution was 20 ppm.

[0065] Example 7

[0066] The silica-alumina molecular sieve was prepared according to the method of Example 1, except that in step S3, the calcination temperature was 300°C and the calcination time was 6 hours.

[0067] Example 8

[0068] The silica-aluminum molecular sieve was prepared according to the method of Example 1, except that in step S4, the material from the secondary outlet of the spray dryer (i.e., the second material with an average particle size of 6 μm) and the second mixture in step S2 were mixed at a weight ratio of 10:40 and then fed into the spray drying equipment in step S3 for molding.

[0069] Comparative Example 1

[0070] This comparative example illustrates the process of preparing silica-alumina molecular sieve samples using conventional methods.

[0071] The preparation was carried out according to the method described in Zeolites, 1992, Vol. 12, pp. 943-950. Specifically, at room temperature (20°C), 22.5 g of tetraethyl orthosilicate was mixed with 7.0 g of tetrapropylammonium hydroxide as a template agent, and 59.8 g of distilled water was added. After stirring and mixing, the mixture was hydrolyzed at atmospheric pressure and 60°C for 1.0 h to obtain a hydrolysate solution of tetraethyl orthosilicate. Under vigorous stirring, a solution consisting of 1.1 g of aluminum isopropoxide and 5.0 g of anhydrous isopropanol was slowly added to the hydrolysate solution. The resulting mixture was stirred at 75°C for 3 h to obtain a clear, transparent colloid. This colloid was placed in a stainless steel sealed reactor and kept at a constant temperature of 170°C for 36 h to obtain a mixture of crystallized products. The mixture was filtered, and the collected solid was washed with water and dried at 110°C for 60 min. Then it was calcined at 500°C for 6 h to obtain aluminosilicate molecular sieve. Its X-ray diffraction pattern (XRD pattern) showed that it was an aluminosilicate molecular sieve with an MFI structure.

[0072] Comparative Example 2

[0073] Aluminosilicate molecular sieves were prepared according to the method of Example 1, except that step S4 was omitted. Their XRD phase diagrams were consistent with those of Comparative Example 1, indicating that the obtained aluminosilicate molecular sieve had an MFI structure. Their relative crystallinity, particle size, bulk density, and yield are listed in Table 1.

[0074] Comparative Example 3

[0075] Aluminosilicate molecular sieves were prepared according to the method of Example 1, except that the carbon quantum dot solution in step S1 was replaced with the same weight of water. Its XRD phase diagram was consistent with Comparative Example 1, indicating that aluminosilicate molecular sieve with an MFI structure was obtained. Its relative crystallinity, particle size, bulk density, and yield are listed in Table 1.

[0076] Table 1

[0077]

[0078]

[0079] As shown in Table 1, the particle size distribution of the silica-alumina molecular sieve prepared by the method of the present invention is optimized and the preparation yield is high.

[0080] Test Implementation Examples

[0081] These test examples illustrate the application of the silica-alumina molecular sieves prepared in Examples 1-8 and Comparative Examples 1-3 as catalysts in the catalytic hydration reaction of olefins.

[0082] The reaction was carried out in a fixed-bed microreactor. 2g of catalyst was loaded into the isothermal section of the fixed bed, and the reactants and products continuously entered and exited the reactor. The process parameters were as follows: the molar ratio of ethylene to water was 1:5, and the ethylene feed space velocity was 20 h⁻¹. -1 The reaction was carried out at a temperature of 140℃ and a pressure of 1.5 MPa for 1 hour. The results are listed in Table 2. The reaction products were analyzed by gas chromatography (GC: Agilent, 7890A) and gas chromatography-mass spectrometry (GC-MS: Thermo Fisher Trace ISQ).

[0083] The following formulas are used to calculate the conversion of ethylene and the selectivity of alcohols:

[0084] Ethylene conversion rate % = (molar amount of ethylene added before reaction - molar amount of ethylene remaining after reaction) / molar amount of ethylene added before reaction × 100%;

[0085] Selectivity of alcohol % = (molar amount of target product generated after reaction) / (molar amount of ethylene added before reaction - molar amount of ethylene remaining after reaction) × 100%.

[0086] Table 2

[0087]

[0088]

[0089] As shown in Table 2, the silica-alumina molecular sieve prepared by the method of this disclosure has excellent catalytic performance in olefin hydration reaction.

[0090] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0091] 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, the present invention will not describe the various possible combinations separately.

[0092] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. The application of silica-alumina molecular sieves in olefin hydration reactions, characterized in that, The method for preparing the silica-alumina molecular sieve includes: S1. Mix the organosilicon source, aluminum source, alkaline template agent and aqueous solution containing carbon quantum dots to obtain the first mixture; S2. The first mixture is subjected to hydrothermal treatment at 80-250℃ for 4-48 hours to obtain the second mixture; S3. The second mixture is spray-dried, and the material obtained from the main outlet is the first material, and the material obtained from the auxiliary outlet is the second material. The first material is calcined to obtain aluminosilicate molecular sieve; wherein the average particle size of the first material is 20-100μm, and the average particle size of the second material is 1-20μm; the average particle size of the first material is different from the average particle size of the second material. S4. Mix the second material with the second mixture obtained in step S2, and then perform the spray drying in step S3 on the resulting mixed second mixture again. The weight ratio of the second material to the second mixture is 10:(50-250); In step S1, the weight ratio of the organosilicon source, the aluminum source, the alkaline template agent, and the aqueous solution containing carbon quantum dots is 100:(0.2-10):(1-20):(250-10000); the concentration of carbon quantum dots in the aqueous solution containing carbon quantum dots is 2-25 ppm.

2. The application according to claim 1, wherein, In step S3, the conditions for spray drying include: an inlet temperature of 200-380℃ and an outlet temperature of 120-200℃.

3. The application according to claim 2, wherein, The inlet temperature is 220-360℃, and the outlet temperature is 130-180℃.

4. The application according to claim 1, wherein, The method for preparing the silica-alumina molecular sieve further includes preparing an aqueous solution containing carbon quantum dots by the following steps: mixing organic matter with an oxygen content of 20-75% by weight with water and then carrying out a hydrothermal reaction at 200-400°C and autogenous pressure for 1-72 hours.

5. The application according to claim 1, wherein, In step S3, the calcination conditions include: a temperature of 300-800℃ and a time of 0.5-12h.

6. The application according to claim 1, wherein, The organosilicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate; The aluminum source is an organic aluminum source and / or an inorganic aluminum source, wherein the inorganic aluminum source is selected from one or more of the following: dry adhesive powder, boehmite, sodium aluminate, aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum nitrate, and aluminum phosphate. The alkaline template agent is an organic base and / or an inorganic base, wherein the organic base is selected from one or more of urea, quaternary ammonium compounds, fatty amine compounds and alcoholic amine compounds, and the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide and barium hydroxide.

7. The application according to claim 1, wherein, The average particle size of the silica-alumina molecular sieve is 20-90 μm, the relative crystallinity is 80-150%, the bulk density is 0.4-0.8 g / mL, and the particle size distribution uniformity deviation is 5-20%.

8. The application according to claim 1, wherein, The average particle size of the silica-alumina molecular sieve is 30-90 μm, the relative crystallinity is 100-140%, the bulk density is 0.5-0.7 g / mL, and the particle size distribution uniformity deviation is 5-15%.

Images