SAPO-11 molecular sieve and its preparation method and alkane hydrogenation isomerization catalyst

Abstract

The present invention provides a kind of SAPO-11 molecular sieve and its preparation method and alkane hydroisomerization catalyst. The preparation method of the SAPO-11 molecular sieve includes mixing a phosphorus source, an aluminum source, a mesoporous template, an organic amine template, and a silicon source, aging, and forming a gel A; adding an amino acid and a gallium source to the gel A to form a gel B; the gel B is crystallized for the first time, the product of the first step crystallization is ultrasonicated, and then a chelating agent is added, and then the second step crystallization is performed; the product of the second step crystallization is dried and roasted to obtain the SAPO-11 molecular sieve. The present invention also provides a SAPO-11 molecular sieve obtained by the above-mentioned preparation method and an alkane hydroisomerization catalyst prepared by the SAPO-11 molecular sieve. The SAPO-11 molecular sieve has a small particle size and a multi-level pore structure, and has good catalytic performance for the hydroisomerization of long-chain alkanes.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieve porous materials, and in particular to a SAPO-11 molecular sieve and a preparation method thereof, and an alkane hydrogenation isomerization catalyst. Background Art

[0002] As the use of petroleum products in high-cold areas around the world increases year by year, the performance of oil products is required to meet the use standards under high-cold conditions, that is, to have a lower pour point and better low-temperature fluidity. The presence of a high content of long-chain normal alkanes leads to a higher pour point for diesel and poor low-temperature fluidity for lubricant base oils. In order to resolve this contradiction, traditional industry generally uses solvent dewaxing and catalytic dewaxing to reduce the content of long-chain normal alkanes in oil products. However, while solvent dewaxing and catalytic dewaxing can reduce the pour point of diesel and improve the low-temperature fluidity of lubricant base oils, they will also lead to a decrease in the yield of oil products. Isomerization dewaxing can not only reduce the pour point of diesel and improve the low-temperature fluidity of lubricant base oils, but also ensure a high yield of oil products.

[0003] In the hydroisomerization process, the isomerization catalyst carrier plays a core role. SAPO-11 molecular sieve is composed of three tetrahedral units SiO 2 、AlO 2 - and PO 2 + The microporous crystals formed by alternating tetrahedrons have an AEL (International Zeolite Association designated code) structure and a one-dimensional ten-membered ring channel with a pore size of 0.39nm×0.64nm. SAPO-11 molecular sieve has been widely used in petrochemical fields such as normal alkane skeleton isomerization, alkylation, gasoline isomerization octane recovery, diesel pour point reduction and lubricating oil isomerization dewaxing due to its suitable acidity and unique one-dimensional channel structure.

[0004] The pore structure and moderate acidity of SAPO-11 molecular sieve are very suitable for the isomerization reaction of normal alkanes, but its own micropores are not conducive to the diffusion of long-chain normal alkane molecules and long-chain isoalkane molecules, which can easily lead to further cracking of alkane molecules under the action of acidic centers, thereby reducing the isomerization selectivity. Therefore, it is necessary to introduce mesopores into SAPO-11 molecular sieves to reduce diffusion resistance; secondly, when the size of SAPO-11 molecular sieve is large, the diffusion path of long-chain alkane molecules in its pores increases, which can easily further crack on the acidic centers in the pores, reducing the isomerization selectivity. However, the existing multi-level pore SAPO-11 cannot have both large pore volume and small grains, and the mesoporous structure is also less.

[0005] In summary, the synthesis of SAPO-11 molecular sieves with small crystals and multi-level pores has become a key issue that needs to be urgently solved in the field of long-chain alkane hydroisomerization. Summary of the invention

[0006] In order to solve the above problems, the present invention aims to provide a SAPO-11 molecular sieve and a preparation method thereof and an alkane hydroisomerization catalyst. The SAPO-11 molecular sieve has a small particle size and a multi-level pore structure, and has good catalytic performance for the hydroisomerization of long-chain alkanes.

[0007] In order to achieve the above object, the present invention provides a method for preparing SAPO-11 molecular sieve, the preparation method comprising:

[0008] A phosphorus source, an aluminum source, a mesoporous template, an organic amine template, and a silicon source are mixed and aged to form a gel A; amino acids and a gallium source are added to the gel A to form a gel B;

[0009] Performing a first step crystallization on the gel B, ultrasonicating the product of the first step crystallization, then adding a chelating agent, and then performing a second step crystallization;

[0010] Drying and calcining the product of the second step crystallization to obtain the SAPO-11 molecular sieve;

[0011] The molar amount of the aluminum source is expressed as Al 2 O 3 In terms of molar amount, the molar ratio of the aluminum source to the amino acid in the gel A is 1.0:0.04-0.5;

[0012] The molar amount of the aluminum source is expressed as Al 2 O 3 The molar amount of gallium source is Ga 2 O 3 The molar ratio of the aluminum source to the gallium source in gel A is 1.0:0.1-0.4;

[0013] The molar amount of the gallium source is Ga 2 O 3 Based on the molar amount, the molar ratio of the chelating agent to the gallium source can be 2.0-5.0:1.0.

[0014] In a specific embodiment of the present invention, the preparation method uses gel A (mesoporous silicoaluminophosphate gel) as a precursor and amino acids as growth inhibitors, and utilizes the chelating synergistic effect between metal gallium and the chelating agent to inhibit the aggregation between SAPO-11 grains, and synthesizes SAPO-11 molecular sieves with small grains and a multi-level pore structure through a semi-continuous step-by-step crystallization method and an ultrasound-assisted method.

[0015] In the above preparation method, the aging temperature is generally controlled to be 10-50° C. For example, the aging temperature may be 20-40° C.; and the aging time is generally controlled to be 2-10 h.

[0016] In the above preparation method, the temperature of the first crystallization step is generally controlled to be 50-150° C. For example, the temperature of the first crystallization step may be 80-130° C. Accordingly, the time of the first crystallization step may be controlled to be 1-12 hours, for example, 4-8 hours.

[0017] In a specific embodiment of the present invention, the ultrasonic treatment can make the crystal nuclei formed during the first step of crystallization dispersed evenly, reduce the aggregation of crystal nuclei, and prevent the formation of large grains. Specifically, the power of the ultrasound is generally controlled to be 200-400W, the frequency of the ultrasound is generally controlled to be 30-60kHz, and the time of the ultrasound is generally controlled to be 0.5-3h, for example, 0.5-2h.

[0018] In the above preparation method, the temperature of the second step crystallization is generally controlled to be 150-250° C., for example, the temperature of the second step crystallization can be 170-200° C. Correspondingly, the time of the second step crystallization is generally controlled to be 12-48 hours, for example, the time of the second step crystallization can be 24-36 hours.

[0019] In a specific embodiment of the present invention, the first step crystallization and the second step crystallization can be carried out in a crystallization device such as a stainless steel reactor or a polytetrafluoroethylene reactor.

[0020] In the above preparation method, the phosphorus source may include one or a combination of two or more of phosphoric acid, phosphorous acid, hypophosphorous acid, ammonium phosphate, ammonium monohydrogen phosphate and ammonium dihydrogen phosphate, preferably phosphoric acid. In some specific embodiments, the phosphoric acid may be phosphoric acid with a mass concentration of 85%.

[0021] In the above preparation method, the aluminum source may include one or a combination of two or more of pseudo-boehmite, aluminum isopropoxide, activated alumina and aluminum sulfate. Preferably, the aluminum source includes a combination of pseudo-boehmite and aluminum isopropoxide. In some specific embodiments, the pseudo-boehmite may be selected from a material with a specific surface area of ​​200-400 m 2 / g, pore volume is 0.6-1.3cm 3 / g of pseudo-boehmite.

[0022] In the above preparation method, the mesoporous template agent can be selected from long-chain alkyl ammonium bromide, and the carbon number of the long-chain alkyl ammonium bromide is generally above 15. Specifically, the mesoporous template agent can include one or more of dodecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium bromide. Preferably, the mesoporous template agent includes dodecyl trimethyl ammonium bromide or hexadecyl trimethyl ammonium bromide.

[0023] In the above preparation method, the organic amine template is generally a small molecule organic amine template, specifically an alkylamine with a carbon number less than or equal to 6. Preferably, the organic amine template includes one or a combination of two or more of dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, triethylamine and n-butylamine. More preferably, the organic amine template includes a combination of di-n-propylamine and diisopropylamine; wherein the molar ratio of di-n-propylamine to diisopropylamine is preferably 4:6, and the mass ratio of the two can be controlled to be 1:1.

[0024] In the above preparation method, the silicon source may include one or a combination of two or more of silicon dioxide, white carbon black, water glass, tetraethyl orthosilicate, propyl orthosilicate and butyl orthosilicate. The silicon source preferably includes silicon dioxide or tetraethyl orthosilicate. The silicon dioxide may be added in the form of silica sol, specifically acidic silica sol. The mass concentration of the acidic silica sol may be 30%.

[0025] In a specific embodiment of the present invention, by doping element gallium into the synthesis system of the molecular sieve, due to the similar electronic properties of the main group elements, after the first stage of crystallization is completed, gallium can enter the framework of the SAPO-11 crystal grains and a portion of gallium can be distributed on the surface of the SAPO-11 crystal grains. Specifically, the gallium source can include one or a combination of two or more of gallium nitrate, gallium perchlorate and gallium sulfate.

[0026] In a specific embodiment of the present invention, the amino acid can inhibit the growth of crystals by adsorbing on the surface of SAPO-11 crystals, thereby controlling the size of SAPO-11 molecular sieve crystals. Specifically, the amino acid can include one or a combination of two or more of L-lysine, D-lysine, L-proline, D-proline and glycine. In some specific embodiments, the molar amount of the aluminum source is expressed as Al 2 O 3 Based on the molar amount, the molar ratio of the aluminum source to the amino acid in the gel A can be controlled to be 1.0:0.04-0.2.

[0027] Furthermore, by adding a chelating agent after the ultrasonic treatment, the chelating agent can chelate with the gallium element distributed on the surface of the SAPO-11 grains, thereby utilizing the steric hindrance effect of the chelating agent to inhibit the aggregation of the SAPO-11 grains during the second step of crystallization, thereby further controlling the size of the SAPO-11 grains. Specifically, the chelating agent can include one or a combination of two or more of ethylenediaminetetraacetic acid, polyacrylic acid, citric acid, diethylenetriaminepentaacetic acid and hydrolyzed polymaleic anhydride.

[0028] According to a specific embodiment of the present invention, the molar amount of the aluminum source in the gel A is expressed as Al 2 O 3The molar amount of gallium source is Ga 2 O 3 Based on the molar amount, the molar ratio of the aluminum source to the gallium source in gel A can be controlled to be 1.0:0.2-0.4.

[0029] In a specific embodiment of the present invention, the phosphorus source is P 2 O 5 The aluminum source is Al 2 O 3 The silicon source is SiO 2 The molar ratio of the phosphorus source, aluminum source, mesoporous template, organic amine template and silicon source is generally controlled to be 0.4-2.0:1.0:0.02-0.2:0.2-2.0:0.2-3, and can be further controlled to be 0.5-2.0:1.0:0.02-0.2:0.2-2.0:0.2-3, and can be further controlled to be 0.5-1.0:1.0:0.03-0.1:0.8-1.5:0.3-0.8.

[0030] In the above preparation method, the gel A can be obtained by mixing a phosphorus source, an aluminum source, a mesoporous template, an organic amine template, and a silicon source in a solvent and aging. The solvent generally includes water and / or alcohol. The alcohol can include one or a combination of two or more of ethanol, propanol, n-butanol, ethylene glycol, and isopropanol. Preferably, the solvent includes a combination of water and n-butanol, and the molar ratio of water to n-butanol can be controlled to be 4:1.

[0031] In the above preparation method, the molar ratio of the solvent to the aluminum source is generally controlled to be 20-200:1.0, for example, 30-100:1.0.

[0032] According to a specific embodiment of the present invention, the mass ratio of the aluminum source to the phosphorus source can be controlled to be 11-20:8-11; and the phosphorus source is P 2 O 5 The silicon source is SiO 2 The molar ratio of the phosphorus source, the mesoporous template, the organic amine template, and the silicon source is 0.4-2.0: 0.02-0.2: 0.2-2.0: 0.2-3. Specifically, the mass ratio of the aluminum source to the phosphorus source can be 11-20: 8, 11-20: 9, 11-20: 10, 11-20: 11, etc.

[0033] According to a specific embodiment of the present invention, the mass ratio of the aluminum source to the amino acid can be controlled to be 11-20:0.5-0.7. Specifically, in parts by mass, the mass ratio of the aluminum source to the amino acid can be 11-20:0.5, 11-20:0.55, 11-20:0.6, 11-20:0.65, 11-20:0.7, etc.

[0034] According to a specific embodiment of the present invention, the mass ratio of the aluminum source to the gallium source can be controlled to be 11-20:4-5. Specifically, in parts by mass, the mass ratio of the aluminum source to the amino acid can be 11-20:4, 11-20:4.5, 11-20:5, etc.

[0035] In the above preparation method, the drying temperature is generally controlled to be 50-150° C., and the drying time can be controlled to be 3-24 hours.

[0036] In the above preparation method, the calcination process can remove the mesoporous template and the organic amine template, thereby obtaining a SAPO-11 molecular sieve without an organic template. In some specific embodiments, the calcination temperature is generally controlled to be 350-650°C; for example, the calcination temperature can be 550-650°C. Accordingly, the calcination time is generally controlled to be 2-12h; for example, the calcination time can be 5-12h.

[0037] According to an embodiment of the present invention, the above preparation method may specifically include the following steps:

[0038] 1. Mix the phosphorus source, aluminum source, mesoporous template and solvent, then add the organic amine template, and then slowly add the silicon source, stir evenly, and age at 10-50°C to obtain gel A;

[0039] 2. Add amino acids and gallium source to gel A and stir evenly to form gel B;

[0040] 3. Perform the first step crystallization of gel B at 50-150°C for 1-12h, perform ultrasonic treatment on the product of the first step crystallization at room temperature for 0.5-3h, the ultrasonic conditions are 200-400W, 30-60kHz, add a chelating agent, and perform the second step crystallization at 150-250°C for 12-48h;

[0041] 4. Take out the product of the second step crystallization, separate the solid product, wash it, dry it at 50-150°C for 3-24h, and then calcine it at 350-650°C for 2-12h to remove the organic template to obtain SAPO-11 molecular sieve.

[0042] The present invention also provides a SAPO-11 molecular sieve, which is prepared by the above preparation method. The SAPO-11 molecular sieve has an AEL structure confirmed by the International Molecular Sieve Association.

[0043] According to a specific embodiment of the present invention, the particle size of the SAPO-11 molecular sieve is 80-200 nm, and the specific surface area of ​​the SAPO-11 molecular sieve is 200-350 m 2 / g, and the mesopore volume of the SAPO-11 molecular sieve is 0.25-0.5cm 3 / g.

[0044] The present invention also provides an alkane hydroisomerization catalyst, which is prepared from the above-mentioned SAPO-11 molecular sieve. The alkane includes n-hexadecane, that is, the alkane hydroisomerization catalyst can be a n-hexadecane hydroisomerization catalyst, etc. For example, the SAPO-11 molecular sieve is applied to the n-hexadecane hydroisomerization, and the isomer selectivity of n-hexadecane can reach a maximum of 89.8%.

[0045] The beneficial effects of the present invention are:

[0046] 1. The preparation method provided by the present invention can reduce the grain size and particle size of SAPO-11 molecular sieve, shorten the diffusion path of alkane molecules in the molecular sieve, and the molecular sieve with small grains has a large specific surface area and more exposed pores, which can improve the catalytic activity of the molecular sieve.

[0047] 2. The SAPO-11 molecular sieve provided by the present invention not only has an AEL structure and a high degree of crystallinity, but also has a small grain size and particle diameter, a rich mesoporous structure, a large specific surface area and excellent acidity. The molecular sieve is loaded with a certain amount of metal components to prepare a catalyst for the hydrogenation isomerization of long-chain alkanes, which has a high isomerization selectivity and exhibits excellent isomerization performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the XRD spectrum of the SAPO-11 molecular sieve prepared in Example 1.

[0049] Figure 2 This is the SEM image of the SAPO-11 molecular sieve prepared in Example 1.

[0050] Figure 3 N is the SAPO-11 molecular sieve prepared in Example 1 2 Adsorption-desorption isotherms.

[0051] Figure 4 This is the SEM image of the SAPO-11 molecular sieve prepared in Example 4.

[0052] Figure 5 This is the TEM image of the SAPO-11 molecular sieve prepared in Example 5.

[0053] Figure 6 This is the XRD spectrum of the SAPO-11 molecular sieve prepared in Comparative Example 1.

[0054] Figure 7 This is the SEM image of the SAPO-11 molecular sieve prepared in Comparative Example 1.

[0055] Figure 8 N is the N of the SAPO-11 molecular sieve prepared in Comparative Example 1 2 Adsorption-desorption isotherms.

[0056] Fig. 9 NH 3 -TPD curve. DETAILED DESCRIPTION

[0057] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0058] Example 1

[0059] This embodiment provides a method for preparing SAPO-11 molecular sieve, which comprises:

[0060] 1. Stir and mix 8.647g phosphoric acid (AR, 85%) and 30.5g deionized water, then add 11.143g pseudo-boehmite (AR, 70%) and stir evenly; then add a mixed solution of 0.701g dodecyltrimethylammonium bromide (AR, 99%) and 5g deionized water, add 5.163g of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as an organic amine template under stirring, and stir for 2h; then slowly add 4.506g acidic silica sol (30% SiO 2 ), stirred evenly. Aged at 30°C for 2h to obtain gel A;

[0061] 2. Add a mixed solution of 0.597 g of L-lysine (AR, 98%) and 5 g of deionized water to gel A, then add 4.5 g of gallium nitrate, and stir evenly to form gel B;

[0062] 3. Place gel B in a polytetrafluoroethylene reactor and perform the first step crystallization at 90°C for 6 hours. Take out the mixture in the reactor and treat it with ultrasound (50kHz, 350W) at room temperature for 1 hour. Add 8.0g of ethylenediaminetetraacetic acid and continue to place it in the polytetrafluoroethylene reactor and perform the second step crystallization at 190°C for 24 hours.

[0063] 4. The crystallization product of the second step is taken out, the solid product is separated, washed, dried at 110° C. for 6 h, and then calcined at 600° C. for 6 h to remove the organic template, thereby obtaining a small-grain multi-level porous SAPO-11 molecular sieve.

[0064] Example 2

[0065] This embodiment provides a method for preparing SAPO-11 molecular sieve, which comprises:

[0066] 1. Stir and mix 8.647g phosphoric acid (AR, 85%) and 30.5g deionized water, then add 11.143g pseudo-boehmite (AR, 70%) and stir evenly; then add a mixed solution of 0.821g hexadecyltrimethylammonium bromide (AR, 99%) and 5g deionized water, add 5.163g of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as an organic amine template under stirring, and stir for 2h; then slowly add 4.506g acidic silica sol (30% SiO 2 ), stirred evenly. Aged at 30°C for 2h to obtain gel A;

[0067] 2. Add a mixed solution of 0.597 g of L-lysine (AR, 98%) and 5 g of deionized water to gel A, then add 4.5 g of gallium nitrate, and stir evenly to form gel B.

[0068] 3. Place gel B in a polytetrafluoroethylene reactor and perform the first step crystallization at 100°C for 10 hours. Take out the mixture in the reactor, ultrasonically treat it at room temperature (50kHz, 350W) for 0.5 hours, add 7.0g of citric acid, continue to place it in the polytetrafluoroethylene reactor, and perform the second step crystallization at 190°C for 24 hours.

[0069] 4. The crystallization product of the second step is taken out, the solid product is separated, washed, dried at 110° C. for 6 h, and calcined at 600° C. for 6 h to remove the organic template to obtain a small-grain multi-level porous SAPO-11 molecular sieve.

[0070] Example 3

[0071] This embodiment provides a method for preparing SAPO-11 molecular sieve, which comprises:

[0072] 1. Stir and mix 10.524g phosphoric acid (AR, 85%) and 30.5g deionized water, then add 11.143g pseudo-boehmite (AR, 70%) and stir evenly; then add a mixed solution of 0.931g hexadecyltrimethylammonium bromide (AR, 99%) and 5g deionized water, add an equal mass of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as an organic amine template under stirring conditions, totaling 5.163g, and stir for 2h; then slowly add 4.768g of tetraethyl orthosilicate (GC, >99%) and stir evenly; age at 30°C for 2h to obtain gel A;

[0073] 2. Add a mixed solution of 0.597 g of D-lysine (AR, 98%) and 5 g of deionized water to gel A, then add 4.5 g of gallium nitrate, and stir evenly to form gel B;

[0074] 3. Place gel B in a polytetrafluoroethylene reactor and perform the first step crystallization at 90°C for 6 hours. Take out the mixture in the reactor, ultrasonically treat it (50kHz, 350W) at room temperature for 1 hour, add 7.0g of citric acid, continue to place it in the polytetrafluoroethylene reactor, and perform the second step crystallization at 200°C for 24 hours.

[0075] 4. The crystallization product of the second step is taken out, the solid product is separated, washed, dried at 110° C. for 12 h, and calcined at 600° C. for 6 h to remove the organic template to obtain a small-grain multi-level porous SAPO-11 molecular sieve.

[0076] Example 4

[0077] This embodiment provides a method for preparing SAPO-11 molecular sieve, which comprises:

[0078] 1. Stir and mix 8.647g phosphoric acid (AR, 85%) and 30.5g deionized water, then add 11.143g pseudo-boehmite (AR, 70%) and stir evenly; then add a mixed solution of 0.701g dodecyltrimethylammonium bromide (AR, 99%) and 5g deionized water, add 5.163g of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as an organic amine template under stirring, stir for 2h, and slowly add 4.506g acidic silica sol (30% SiO 2 ), stirred evenly; aged at 30°C for 2h to obtain gel A;

[0079] 2. Add a mixed solution of 0.597 g of L-lysine (AR, 98%) and 5 g of deionized water to gel A, then add 5.0 g of gallium sulfate, and stir evenly to form gel B;

[0080] 3. Place gel B in a polytetrafluoroethylene reactor and perform the first step crystallization at 90°C for 6 hours. Take out the mixture in the reactor and treat it with ultrasound (50kHz, 350W) at room temperature for 1 hour. Add 8.0g of ethylenediaminetetraacetic acid and continue to place it in the polytetrafluoroethylene reactor and perform the second step crystallization at 190°C for 24 hours.

[0081] 4. The crystallization product of the second step is taken out, the solid product is separated, washed, dried at 110°C for 6 hours, and calcined at 600°C for 6 hours to remove the organic template to obtain a small-grain multi-level porous SAPO-11 molecular sieve.

[0082] Example 5

[0083] This embodiment provides a method for preparing SAPO-11 molecular sieve, which comprises:

[0084] 1. Stir and mix 8.647g phosphoric acid (AR, 85%), 25g deionized water, and 29.g n-butanol (CP, 98%); then add 20.4g aluminum isopropoxide (CP, 98%) and stir evenly; then add a mixed solution of 0.701g dodecyltrimethylammonium bromide (AR, 99%) and 5g deionized water, add an equal mass of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as an organic amine template under stirring, and slowly add 4.506g acidic silica sol (30% SiO 2 ), stirred evenly, and aged at 30°C for 2h to obtain gel A;

[0085] 2. Add a mixed solution of 0.597 g of L-lysine (AR, 98%) and 5 g of deionized water to gel A, then add 5.0 g of gallium sulfate, and stir evenly to form gel B;

[0086] 3. Place gel B in a polytetrafluoroethylene reactor and perform the first step crystallization at 90°C for 6 hours. Take out the mixture in the reactor and treat it with ultrasound (50kHz, 350W) at room temperature for 1 hour. Add 8.0g of ethylenediaminetetraacetic acid and continue to place it in the polytetrafluoroethylene reactor and perform the second step crystallization at 190°C for 24 hours.

[0087] 4. The crystallization product of the second step was taken out, the solid product was separated, washed, dried at 110° C. for 6 h, and calcined at 600° C. for 6 h to remove the organic template, thereby obtaining a small-grain multi-level porous SAPO-11 molecular sieve.

[0088] Example 6

[0089] This embodiment provides a method for preparing SAPO-11 molecular sieve, which comprises:

[0090] 1. Stir and mix a mixture of 8.647 g phosphoric acid (AR, 85%), 25 g deionized water and 29. g n-butanol (CP, 98%), then add 11.143 g pseudo-boehmite (AR, 70%) and stir evenly; then add a mixed solution of 0.701 g dodecyltrimethylammonium bromide (AR, 99%) and 5 g deionized water, add an equal mass of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as an organic amine template under stirring, and slowly add 4.768 g of tetraethyl orthosilicate (GC, >99%) after stirring for 2 h, and stir evenly; age at 20°C for 2 h to obtain gel A;

[0091] 2. Add a mixed solution of 0.556 g of L-proline (AR, 98%) and 5 g of deionized water to gel A, then add 5.0 g of gallium sulfate, stir evenly to form gel B, place gel B in a polytetrafluoroethylene reactor, perform the first step crystallization at 90° C. for 10 h, take out the mixture in the reactor, ultrasonically treat (50 kHz, 350 W) at room temperature for 1 h, then add 8.0 g of ethylenediaminetetraacetic acid, continue to place in the polytetrafluoroethylene reactor, and perform the second step crystallization at 190° C. for 24 h;

[0092] 3. The crystallization product of the second step is taken out, the solid product is separated, washed, dried at 110° C. for 6 h, and calcined at 600° C. for 6 h to remove the organic template, thereby obtaining a small-grain multi-level porous SAPO-11 molecular sieve.

[0093] Example 7

[0094] This embodiment provides a method for preparing SAPO-11 molecular sieve, which comprises:

[0095] 1. Stir and mix a mixture of 8.647g phosphoric acid (AR, 85%), 25g deionized water and 29.g n-butanol (CP, 98%), then add 11.143g pseudo-boehmite (AR, 70%) and stir evenly; then add a mixed solution of 0.824g tetradecyltrimethylammonium bromide (AR, 99%) and 5g deionized water, add an equal mass of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as an organic amine template under stirring, and slowly add 4.506g acidic silica sol (30% SiO 2 ), stirred evenly, and aged at 30°C for 2 h to obtain gel A.

[0096] 2. Add a mixed solution of 0.607 g of glycine (AR, 98%) and 5 g of deionized water to gel A, then add 5.0 g of gallium sulfate, and stir evenly to form gel B.

[0097] 3. Place gel B in a polytetrafluoroethylene reactor and perform the first step crystallization at 90°C for 6 hours. Take out the mixture in the reactor, treat it ultrasonically (55kHz, 300W) at room temperature for 2 hours, add 8.0g of ethylenediaminetetraacetic acid, continue to place it in the polytetrafluoroethylene reactor, and perform the second step crystallization at 210°C for 24 hours.

[0098] 4. The crystallization product of the second step is taken out, the solid product is separated, washed, dried at 100°C for 6 hours, and calcined at 550°C for 10 hours to remove the organic template to obtain a small-grain multi-level porous SAPO-11 molecular sieve.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing a SAPO-11 molecular sieve, which comprises:

[0101] 1. Stir and mix 8.647g phosphoric acid (AR, 85%) and 40.5g deionized water, then add 11.143g pseudo-boehmite (AR, 70%) and stir evenly; add 5.163g of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as organic amine templates under stirring, stir for 2h, then slowly add 4.506g acidic silica sol (30% SiO 2 ), stirring evenly; aging at 30°C for 2h, stirring evenly to form gel A;

[0102] 2. Place the gel obtained in step 1 in a polytetrafluoroethylene reactor and perform the first step of crystallization at 190° C. for 36 hours; take out the crystallized product, separate the solid product, wash it, dry it at 110° C. for 6 hours, and calcine it at 600° C. for 6 hours to remove the organic template, thereby obtaining SAPO-11 molecular sieve.

[0103] Compared with the preparation methods of Examples 1 to 7, the preparation method provided in this comparative example does not add amino acids, gallium sources and chelating agents, does not perform ultrasonic treatment, and only undergoes one crystallization.

[0104] Comparative Example 2

[0105] This comparative example provides a method for preparing a SAPO-11 molecular sieve, which comprises:

[0106] 1. Stir and mix 8.647g phosphoric acid (AR, 85%) and 40.5g deionized water, then add 11.143g pseudo-boehmite (AR, 70%) and stir evenly; add 5.163g of di-n-propylamine (CP, 98%) and diisopropylamine (CP, 98%) as organic amine templates under stirring, stir for 2h, then slowly add 4.506g acidic silica sol (30% SiO 2 ), stirring evenly; aging at 30°C for 2h, stirring evenly to form gel A;

[0107] 2. Add 5.0 g of gallium sulfate to gel A and stir evenly to form gel B.

[0108] 3. Place gel B in a polytetrafluoroethylene reactor and perform the first step crystallization at 90°C for 6 hours. Take out the mixture in the reactor, add 8.0 g of ethylenediaminetetraacetic acid, continue to place it in the polytetrafluoroethylene reactor, and perform the second step crystallization at 210°C for 24 hours.

[0109] 4. The crystallization product of the second step was taken out, the solid product was separated, washed, dried at 100° C. for 6 h, and calcined at 550° C. for 10 h to remove the organic template to obtain SAPO-11 molecular sieve.

[0110] Test Example 1

[0111] This test example provides a structural characterization test of the SAPO-11 molecular sieves prepared in Examples 1 to 7 and Comparative Examples 1 and 2.

[0112] Figure 1 , Figure 2 , Figure 3 The XRD spectrum, SEM image and N 2 Adsorption-desorption isotherm curve. Figure 1 It can be seen that the SAPO-11 molecular sieve prepared in Example 1 has the AEL structure confirmed by the International Molecular Sieve Association. Figure 2 It can be seen that the particle size of the SAPO-11 molecular sieve prepared in Example 1 is 80-200 nm. Figure 3 It can be seen that the adsorption-desorption isotherm curve of the SAPO-11 molecular sieve prepared in Example 1 is a type IV curve, which proves that the molecular sieve has a mesoporous structure.

[0113] Figure 4 This is the SEM image of the SAPO-11 molecular sieve prepared in Example 4. Figure 5 This is a TEM image of the SAPO-11 molecular sieve prepared in Example 5. Figure 4 , Figure 5 It can also be seen that the particle sizes of the SAPO-11 molecular sieves prepared in Example 4 and Example 5 are both 80-200 nm.

[0114] Figure 6 , Figure 7 , Figure 8 The XRD spectrum, SEM image and N 2 Adsorption-desorption isotherm curve. Figure 6 It can be seen that the product prepared in Comparative Example 1 has the characteristic peaks of SAPO-11 molecular sieve; Figure 7 It can be seen that the particle size of the SAPO-11 molecular sieve prepared in Comparative Example 1 is 8-10 μm; Figure 8 It is not possible to see that the SAPO-11 molecular sieve prepared in Comparative Example 1 has an obvious mesoporous structure. Figure 8 After analysis, it was found that the mesopore volume of the SAPO-11 molecular sieve prepared in Comparative Example 1 was only 0.104 cm 3 / g.

[0115] The particle size of the molecular sieves of each embodiment and comparative example was measured by scanning electron microscopy and transmission electron microscopy, and the specific surface area and mesopore volume of the molecular sieves of each embodiment and comparative example were measured by nitrogen adsorption test. The results are shown in Table 1.

[0116] Table 1

[0117]

[0118]

[0119] It can be seen from the above measurement data that compared with Comparative Examples 1 and 2, the SAPO-11 molecular sieves prepared in Examples 1 to 7 have smaller particle sizes, and larger specific surface areas and mesopore volumes, indicating that the preparation method of the present invention can obtain SAPO-11 molecular sieves with small particle sizes and high mesopore content by adding amino acids, gallium sources and chelating agents, performing ultrasound and step-by-step crystallization.

[0120] Test Example 2

[0121] This test example provides a hydroisomerization catalytic performance test of the SAPO-11 molecular sieves of Examples 1 to 7, Comparative Examples 1 and 2.

[0122] The SAPO-11 molecular sieves of the above embodiments and comparative examples were used as samples to be tested. Each sample was subjected to ammonium ion exchange, washed, dried, and calcined at 500° C. for 6 h to obtain H-type SAPO-11 molecular sieves corresponding to each embodiment and comparative example.

[0123] The H-type SAPO-11 molecular sieve obtained above was tableted, sieved, and 20-40 mesh H-type SAPO-11 molecular sieve was used as a carrier. The equal volume impregnation method was used to load 0.5 wt% Pt (based on the mass of the catalyst) to obtain a Pt / SAPO-11 catalyst.

[0124] The isomerization performance of the prepared Pt / SAPO-11 catalyst was evaluated using n-hexadecane as a model compound. The reaction conditions were: 340°C, 4.5MPa, WASV=1.5h -1 、nH 2 : nC16 = 15. The results of the catalytic performance evaluation of the Pt / SAPO-11 catalyst for the hydroisomerization reaction of n-hexadecane are summarized in Table 2.

[0125] The conversion rate is calculated as follows: conversion rate = (mass of n-hexadecane in the raw material - mass of n-hexadecane in the reaction product) / mass of n-hexadecane in the raw material × 100%;

[0126] The calculation method of isomerization selectivity is: isomerization selectivity = mass of isohexadecane / mass of all products × 100%;

[0127] The calculation method of isomerization yield is: isomerization yield = n-hexadecane conversion rate × iso-hexadecane selectivity.

[0128] Table 2

[0129]

[0130]

[0131] It can be seen from the data in Table 2 that, under the condition of loading the same amount of Pt, the isomerization catalysts with small-grain SAPO-11 molecular sieves with a multi-level pore structure prepared in each embodiment as a carrier have significantly higher conversion rate, isomerization selectivity and isomerization yield for n-hexadecane than the SAPO-11 molecular sieves prepared in Comparative Example 1.

[0132] Fig. 9 NH 3 -TPD curve. The specific test steps are to load a small amount of sample into the middle of a U-shaped quartz tube, heat it to 600℃ in an argon atmosphere and keep it for 0.5h, wait for the temperature to drop to 70℃, introduce ammonia for adsorption for 15min, then purge with argon for 1h until the baseline is stable, heat it from 70℃ to 800℃ at a heating rate of 10℃ / min, and record the signal with a thermal conductivity detector (TCD). Fig. 9 It can be seen that the reduction in grain size significantly increases the weak acid content and medium-strong acid content of SAPO-11 molecular sieve; this is because the reduction in grain size is conducive to more acid sites being exposed and detected.

[0133] The above results indicate that the small-grain multi-level pore SAPO-11 molecular sieve provided by the present invention has more excellent acid properties and improves the conversion rate of n-hexadecane. It also has more mesopores, smaller grain size and larger specific surface area, which is beneficial to reduce the diffusion resistance and diffusion path of alkane molecules in the molecular sieve pores, thereby improving the selectivity and yield of isoalkanes.

[0134] The above content is a further detailed description of the technical solution of the present invention in combination with a specific preferred implementation method, and should not be understood as a limitation on the applicable scope of the present invention. For ordinary technicians in the field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the present invention, which should be deemed to fall within the scope of patent protection determined by the claims submitted for the present invention.

Claims

1. A method for preparing SAPO-11 molecular sieve, the method comprising: A phosphorus source, an aluminum source, a mesoporous template, an organic amine template, and a silicon source are mixed and aged to form a gel A; adding amino acids and a gallium source to the gel A to form gel B; The gel B is subjected to a first crystallization step, the product of the first crystallization step is subjected to ultrasonic treatment, a chelating agent is added, and then a second crystallization step is performed; Drying and calcining the product of the second step crystallization to obtain the SAPO-11 molecular sieve; The aluminum source is calculated as Al2O3, and the molar ratio of the aluminum source to the amino acid is 1.0:0.04-0.5; The aluminum source is calculated as Al2O3, the gallium source is calculated as Ga2O3, and the molar ratio of the aluminum source to the gallium source is 1.0:0.1-0.4; The gallium source is calculated as Ga2O3, and the molar ratio of the chelating agent to the gallium source is 2.0-5.0:1.

0.

2. The preparation method according to claim 1, wherein The aging temperature is 10-50° C., and the aging time is 2-10 h.

3. The preparation method according to claim 2, wherein The aging temperature is 20-40°C.

4. The preparation method according to claim 1, wherein The temperature of the first step of crystallization is 50-150°C; The first step of crystallization takes 1-12 hours.

5. The preparation method according to claim 4, wherein The temperature of the first step crystallization is 80-130°C.

6. The preparation method according to claim 4, wherein The first step of crystallization takes 4-8 hours.

7. The preparation method according to claim 1, wherein The power of the ultrasound is 200-400W, the frequency of the ultrasound is 30-60kHz, and the time of the ultrasound is 0.5-3h.

8. The preparation method according to claim 7, wherein: The ultrasonic time is 0.5-2h.

9. The preparation method according to claim 1, wherein: The temperature of the second step crystallization is 150-250°C; The second step of crystallization takes 12-48 hours.

10. The preparation method according to claim 9, wherein The temperature of the second step crystallization is 170-200°C.

11. The preparation method according to claim 9, wherein The second step of crystallization takes 24-36 hours.

12. The preparation method according to claim 1, wherein: The phosphorus source includes one or a combination of two or more of phosphoric acid, phosphorous acid, hypophosphorous acid, ammonium phosphate, monoammonium hydrogen phosphate and diammonium hydrogen phosphate; And / or, the aluminum source includes one or a combination of two or more of pseudo-boehmite, aluminum isopropoxide, activated alumina and aluminum sulfate; And / or, the mesoporous template agent comprises a long-chain alkyl ammonium bromide having a carbon number greater than or equal to 15; And / or, the organic amine template is an alkylamine having a carbon number less than or equal to 6; And / or, the silicon source includes one or a combination of two or more of silicon dioxide, white carbon black, water glass, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate; And / or, the gallium source includes one or a combination of two or more of gallium nitrate, gallium perchlorate and gallium sulfate; and / or, the amino acids include one or a combination of two or more of L-lysine, D-lysine, L-proline, D-proline and glycine; And / or, the chelating agent includes one or a combination of two or more of ethylenediaminetetraacetic acid, polyacrylic acid, citric acid, diethylenetriaminepentaacetic acid and hydrolyzed polymaleic anhydride.

13. The preparation method according to claim 12, wherein: The mesoporous template agent includes one or more of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide and octadecyltrimethylammonium bromide.

14. The preparation method according to claim 12, wherein: The organic amine template agent includes one or a combination of two or more of dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, triethylamine and n-butylamine.

15. The preparation method according to claim 12, wherein: The organic amine template comprises a combination of di-n-propylamine and diisopropylamine.

16. The preparation method according to claim 12, wherein: The silicon dioxide includes silica sol.

17. The preparation method according to claim 1 or 12, wherein: The phosphorus source is calculated as P2O5, the aluminum source is calculated as Al2O3, and the silicon source is calculated as SiO2. The molar ratio of the phosphorus source, the aluminum source, the mesoporous template, the organic amine template, and the silicon source is 0.4-2.0:1.0:0.02-0.2:0.2-2.0:0.2-3.

18. The preparation method according to claim 17, wherein: The aluminum source is calculated as Al2O3, the gallium source is calculated as Ga2O3, and the molar ratio of the aluminum source to the gallium source is 1.0:0.2-0.

4.

19. The preparation method according to claim 17, wherein: The aluminum source is calculated as Al2O3, and the molar ratio of the aluminum source to the amino acid is 1.0:0.04-0.

2.

20. The preparation method according to claim 17, wherein: The phosphorus source is calculated as P2O5, the aluminum source is calculated as Al2O3, and the silicon source is calculated as SiO2. The molar ratio of the phosphorus source, the aluminum source, the mesoporous template, the organic amine template, and the silicon source is 0.5-2.0:1.0:0.02-0.2:0.2-2.0:0.2-3.

21. The preparation method according to claim 17, wherein: The phosphorus source is calculated as P2O5, the aluminum source is calculated as Al2O3, and the silicon source is calculated as SiO2. The molar ratio of the phosphorus source, the aluminum source, the mesoporous template, the organic amine template, and the silicon source is 0.5-1.0: 1.0: 0.03-0.1: 0.8-1.5: 0.3-0.

8.

22. The preparation method according to claim 1, wherein: The calcination temperature is 350-650°C; The calcination time is 2-12 hours.

23. The preparation method according to claim 22, wherein: The calcination temperature is 550-650°C.

24. The preparation method according to claim 22, wherein: The calcination time is 5-12 hours.

25. A SAPO-11 molecular sieve prepared by the preparation method according to any one of claims 1 to 24.

26. The SAPO-11 molecular sieve according to claim 25, wherein The particle size of the SAPO-11 molecular sieve is 80-200 nm, and the specific surface area of ​​the SAPO-11 molecular sieve is 200-350 m 2 / g, and the mesopore volume of the SAPO-11 molecular sieve is 0.25-0.5cm 3 / g.

27. An alkane hydroisomerization catalyst prepared from the SAPO-11 molecular sieve according to claim 25 or 26.

28. The alkane hydroisomerization catalyst according to claim 27, wherein The alkane hydroisomerization catalyst includes a n-hexadecane hydroisomerization catalyst.

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