Hierarchical pore SAPO-11 molecular sieve as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a hierarchical pore SAPO-11 molecular sieve as well as a preparation method and application thereof. The average particle size of the hierarchical porous SAPO-11 molecular sieve is 100-1000 nm, and the external specific surface area of the hierarchical porous SAPO-11 molecular sieve is 80.0-150.0 m < 2 > / g; the pore volume of mesopores is 0.100 to 0.200 cm < 3 > / g; the specific average particle size of the molecular sieve enables the molecular sieve to diffuse quickly in a catalytic reaction, so that the catalytic efficiency and isomerization selectivity of the molecular sieve are improved; more acidic sites outside the molecular sieve are exposed due to the specific external specific surface area, and the contact area of reactants and the catalyst is increased, so that the reaction activity of hydroisomerization of the molecular sieve is improved; the molecular sieve has mesopores, grease molecules can enter internal pore channels of the molecular sieve to generate catalytic reaction, and specific pore volume of the mesopores can provide more active sites, enhance mass transfer speed and improve reaction efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a hierarchical pore SAPO-11 molecular sieve, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of technology, it is imperative to vigorously develop renewable energy fuels - bio-aviation kerosene. At present, using oils and fats as raw materials for hydrodeoxygenation to prepare bio-aviation fuel is one of the relatively mature technologies. This method mainly uses natural oils and fats (fatty acids, triglycerides) and waste oils, such as peanut oil, soybean oil, jatropha oil, camelina oil, waste cooking oil, etc. as raw materials to remove oxygen from the raw materials through decarboxylation-decarbonylation method, and prepare straight-chain alkanes with carbon atoms in the range of 14-22. Then, selective cracking and isomerization reactions are carried out to isomerize n-alkanes into short-chain isoparaffins, and different fractions C8-C 16 A bio-aviation fuel product composed of aliphatic hydrocarbons (n-alkanes, isoparaffins) and cyclic hydrocarbons meets the requirements of aviation fuel. Among them, the proportion of isoparaffins in aviation fuel components is 40-85%. Therefore, it is of great significance to efficiently convert oils and fats into short-chain isoparaffins by hydrogenation.

[0003] At present, the main key problem in improving the hydroisomerization reaction of oils and fats lies in the research and development of efficient catalysts. The hydroisomerization catalyst for oils and fats is mainly a bifunctional catalyst composed of a metal center and an acidic support. The metal centers are noble metals such as Pt and Pb and non-noble metals such as Ni and Co. The molecular sieve support not only has Bronsted acid sites and a large specific surface area, but also a specific pore structure can simultaneously perform molecular shape selection on reactants, intermediate products, and final products during the catalytic process. Among them, the SAPO-11 molecular sieve with a one-dimensional ten-membered ring structure is an excellent hydroisomerization catalyst because of its good shape selectivity and medium acidity. However, the SAPO-11 molecular sieve synthesized by the traditional hydrothermal method has the disadvantages of too large crystal size, slow diffusion rate in the oil hydrogenation reaction, low isomer selectivity, serious secondary cracking and side reactions. The SAPO-11 molecular sieve prepared by the traditional method has a microporous structure. When applied to the hydroisomerization catalytic process of oils and fats, because the oil molecules are relatively large (larger than 2 nm), the large molecule oils are difficult to enter the pores of the SAPO-11 molecular sieve, which hinders the diffusion of oil molecules in the catalyst and makes it difficult for them to reach the active metal center. Therefore, the role of the SAPO-11 molecular sieve in catalyzing the hydrogenation of oils and fats to prepare bio-aviation kerosene is greatly limited.

[0004] Developing a hierarchical pore SAPO-11 molecular sieve with cheap raw materials, environmental friendliness and excellent mass transfer efficiency to support metal for catalytic hydroisomerization has important research significance in the research of preparing isoparaffin components of bio-aviation kerosene. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of low efficiency of the existing SAPO-11 molecular sieve in the mass transfer process, so as to provide a hierarchical pore SAPO-11 molecular sieve, a preparation method thereof and an application thereof.

[0006] For this reason, the present invention provides the following technical solutions:

[0007] In the first aspect, the present invention protects a hierarchical pore SAPO-11 molecular sieve, wherein the average particle size of the hierarchical pore SAPO-11 molecular sieve is 100-1000 nm, the external specific surface area is 80.0-150.0 m 2 / g, and the mesoporous pore volume is 0.100-0.200 cm 3 / g.

[0008] According to the present invention, the specific surface area of the hierarchical pore SAPO-11 molecular sieve is 200.0-300.0 m 2 / g.

[0009] According to the present invention, the average pore size of the hierarchical pore SAPO-11 molecular sieve is 3.5-10.0 nm.

[0010] According to the present invention, the microporous pore volume of the hierarchical pore SAPO-11 molecular sieve is 0.050-0.100 cm 3 / g, the total pore volume is 0.200-0.300 cm 3 / g, and the ratio of the microporous pore volume to the mesoporous pore volume is 0.30-0.85:1.

[0011] In the second aspect, the present invention protects a preparation method of a hierarchical pore SAPO-11 molecular sieve, which includes the following steps:

[0012] S1. Perform a first mixing on a first aluminum source, a silicon source, and a phosphorus source, add a second aluminum source and water, add a template agent to obtain a gel, and pre-crystallize the gel to obtain in-situ seeds;

[0013] S2. Perform a second mixing on the in-situ seeds and an alcohol reagent, perform a first drying to obtain a dry gel, crystallize the dry gel, perform a second drying, and calcine to obtain a hierarchical pore SAPO-11 molecular sieve.

[0014] In the present invention, in step S1, after adding water, stirring is performed, and after adding the template agent, stirring is performed to make the dispersion more uniform; adding the "first aluminum source, silicon source, phosphorus source", "second aluminum source", "water" and "template agent" step by step can avoid too high local concentration of reactants during the reaction, forming crystal impurities, ensuring the formation of a stable gel system, and being beneficial to the stability and uniformity of the molecular sieve synthesis system.

[0015] In the present invention, the first mixing is carried out under a water bath condition.

[0016] In the present invention, the water is deionized water, ultrapure water or other conventional laboratory water in the art.

[0017] In the present invention, it also includes first removing the surface moisture of the in-situ seed, and then adding an alcohol reagent. The method of first removing the surface moisture of the in-situ seed is to evaporate the moisture to dryness; the step of drying after the second mixing specifically includes: stirring and evaporating the product after the second mixing at 30-120 °C for the first drying to obtain a xerogel; after the xerogel is crystallized, it also includes the steps of washing with water and drying, which are all conventional operations in the art.

[0018] In the present invention, the crystallization is carried out in a crystallization kettle, and specifically includes the following steps: putting the xerogel into a small crucible (such as a crucible with a specification of 20 mL), putting the crucible into a reaction kettle (such as a crystallization kettle with a specification of 100 mL), adding water between the crucible and the reaction kettle for crystallization. Adding water can regulate the reaction progress, promote the growth and uniform distribution of crystals. After crystallization, a crystal structure has been formed. After calcination, the template agent can be removed and the specific surface area and the stability of the molecular sieve framework can be improved.

[0019] According to the present invention, the molar ratio of aluminum element, silicon element and phosphorus element in the gel is 1:(0.05-0.4):(0.4-2).

[0020] According to the present invention, the molar ratio of water, template agent to aluminum element in the gel is (25-80):(0.1-1):1.

[0021] According to the present invention, the first aluminum source includes at least one of aluminosilicate and pseudoboehmite; optionally, it includes at least one of kaolin, montmorillonite and pseudoboehmite.

[0022] According to the present invention, the silicon source includes layered silicate; optionally, it includes at least one of kaolin and montmorillonite.

[0023] In the present invention, when adding aluminosilicate, it is equivalent to adding aluminum source and silicon source to the system at the same time. According to the actual calculation of the content of each element in the final product, the second aluminum source is supplemented.

[0024] According to the present invention, the first aluminum source and / or the silicon source are also subjected to thermal activation treatment. The thermal activation treatment can improve the reaction activity of the layered silicate. After the layered silicate is activated, the reaction conditions can be further relaxed in the subsequent reaction, and the reaction can be more complete.

[0025] According to the present invention, the temperature of the thermal activation is 700-1000 °C, and the time is 2-8 h.

[0026] According to the present invention, the phosphorus source includes at least one of phosphoric acid, phosphorous acid and hypophosphorous acid.

[0027] According to the present invention, the second aluminum source includes at least one of organoaluminum salts and aluminum-containing oxides; optionally, it includes at least one of aluminum isopropoxide and pseudo-boehmite.

[0028] According to the present invention, the template agent includes an organic amine template agent; optionally, the organic amine template agent includes at least one of triethylamine, diethylamine, di-n-propylamine, and diisopropylamine.

[0029] According to the present invention, the temperature of the first mixing is 30 - 80 °C and the time is 4 - 12 h.

[0030] According to the present invention, the temperature of the precrystallization is 100 - 160 °C and the time is 10 - 16 h; optionally, the temperature of the precrystallization is 130 - 160 °C and the time is 12 - 16 h.

[0031] According to the present invention, the alcohol reagent includes at least one of ethanol, butanol, and isopropanol.

[0032] According to the present invention, the molar ratio of aluminum element in the gel to the alcohol reagent is 1:5 - 10, and can be 1:5 - 7.5.

[0033] According to the present invention, the temperature of the second mixing is 30 - 120 °C and the time is 4 - 10 h; optionally, the temperature of the second mixing is 60 - 120 °C and the time is 6 - 8 h.

[0034] According to the present invention, the temperature of the first drying is 100 - 120 °C and the time is 24 - 48 h.

[0035] According to the present invention, the temperature of the crystallization is 160 - 200 °C and the time is 12 - 48 h; optionally, the temperature of the crystallization is 160 - 180 °C and the time is 16 - 24 h.

[0036] According to the present invention, the temperature of the second drying is 100 - 120 °C and the time is 24 - 48 h.

[0037] According to the present invention, the temperature of the calcination is 550 - 650 °C and the time is 8 - 12 h.

[0038] The third aspect of the present invention protects the application of the aforementioned hierarchical pore SAPO-11 molecular sieve or the hierarchical pore SAPO-11 molecular sieve prepared by the aforementioned preparation method in the catalytic hydrogenation of oil and fat.

[0039] In the present invention, generally, the hierarchical pore SAPO-11 molecular sieve is loaded with nickel to prepare a bifunctional catalyst for use during specific applications.

[0040] The technical solution of the present invention has the following advantages:

[0041] 1. The present invention provides a hierarchical pore SAPO-11 molecular sieve, wherein the average particle size of the hierarchical pore SAPO-11 molecular sieve is 100-1000 nm, the external specific surface area is 80.0-150.0 m 2 / g, and the mesoporous pore volume is 0.100-0.200 cm 3 / g; in the present invention, the specific average particle size of the SAPO-11 molecular sieve enables the molecular sieve to have fast diffusion in the oil hydrogenation catalytic reaction, shortens the diffusion path of the reactants, improves the effective diffusion rate, and thus improves the catalytic efficiency and isomerization selectivity of the molecular sieve; the specific external specific surface area exposes more acidic sites on the outside of the molecular sieve, enhances the contact area between the reactants and the catalyst, and thus improves the reaction activity of the molecular sieve for hydroisomerization; and since the molecular sieve has mesopores, oil molecules can enter the internal pore channels of the molecular sieve to carry out catalytic reactions, and the specific mesoporous pore volume can provide more active sites, enhance the mass transfer rate, and improve the reaction efficiency.

[0042] 2. The specific preparation method of the molecular sieve of the present invention includes the following steps: S1, mixing a first aluminum source, a silicon source, and a phosphorus source for the first time, adding a second aluminum source and water, and adding a template agent to obtain a gel, and pre-crystallizing the gel to obtain in-situ seeds; S2, mixing the in-situ seeds with an alcohol reagent for the second time, performing the first drying to obtain a dry gel, crystallizing the dry gel, performing the second drying, and calcining to obtain a hierarchical pore SAPO-11 molecular sieve; wherein, first, mixing the first aluminum source, the silicon source, and the phosphorus source for the first time, then adding the second aluminum source and water, and then adding the template agent. Adding step by step can avoid too high local concentration of reactants during the reaction process to form crystal impurities, and adding step by step can form a stable gel system, which is beneficial to the stability and uniformity of the system, thereby controlling the initial crystal particle size; mixing the obtained in-situ seeds with the alcohol reagent for the second time, and the alcohol reagent weakens the convection of the in-situ seed system and the diffusion rate of reaction particles, and can regulate the crystal growth rate, thereby forming a molecular sieve with a specific crystal size and a specific mesoporous pore volume.

[0043] 3. In the present invention, when the first aluminum source and the silicon source are aluminum-containing layered silicates, compared with directly using pseudo-boehmite and aluminum isopropoxide as the aluminum source and compared with directly using tetraethyl orthosilicate as the silicon source, it can reduce the raw material cost, reduce the use of chemical reagents, save costs, and can increase the specific surface area and expand the pore channels in the crystal structure, thereby affecting the pore size distribution and the ratio of the microporous pore volume to the mesoporous pore volume.

[0044] 4. The specific pre-crystallization conditions of the present invention can further slow down the crystal nucleus growth rate and help control the crystal size.

[0045] 5. The specific molar ratio of aluminum element to alcohol reagent in the gel of the present invention can better control the crystal formation rate during the formation of molecular sieve, thereby affecting the structure of the finally formed molecular sieve.

[0046] 6. The specific conditions of the second mixing in the present invention can further slow down the formation rate of molecular sieve, making the crystals of molecular sieve more perfect.

[0047] 7. The specific conditions of crystallization in the present invention can further regulate the average particle size of crystals, so that more acidic sites are exposed on the outside of the molecular sieve, improving the mass transfer efficiency, and further improving the activity of isoparaffin.

[0048] 8. In the present invention, the in-situ seed is mixed with the alcohol reagent and subjected to the first drying to obtain a dry gel, and the dry gel is crystallized. The water content in the dry gel is low, the chemical environment around the seed is stable, and there is less impurity interference. The nucleation and growth environment during crystallization is relatively orderly; after the second drying and then calcination, the second drying prevents the internal stress caused by water evaporation, and finally crystals with a specific particle size, external specific surface area and mesopore volume are formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0050] Figure 1 is the XRD pattern of the hierarchical pore SAPO-11 molecular sieve in Example 1;

[0051] Figure 2 is the pore size distribution diagram of the hierarchical pore SAPO-11 molecular sieve in Example 1;

[0052] Figure 3 is the TEM pattern of the hierarchical pore SAPO-11 molecular sieve in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] The following embodiments are provided to better further understand the present invention. They are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features that is the same as or similar to the present invention falls within the protection scope of the present invention.

[0054] For those examples where specific experimental procedures or conditions are not specified, the operations or conditions of the conventional experimental procedures described in the literature in this field can be followed. For reagents or instruments whose manufacturers are not specified, they are all conventional reagent products that can be obtained through commercial purchases.

[0055] Kaolin: The main components are: the content of SiO2 is 53.7 wt%, the content of A12O3 is 43.5 wt%, and the other components are impurities, which are MgO, Fe2O3, TiO2, etc., and the content is negligible;

[0056] Montmorillonite: The main components are: the content of SiO2 is 55.8 wt%, the content of A12O3 is 23.2 wt%, the content of MgO is 4.65 wt%, the content of Fe2O3 is 2.7 wt%, and the other components are impurities, which are K2O, Na2O, etc., and the content is negligible;

[0057] The concentration of the orthophosphoric acid solution is 85 wt%;

[0058] Pseudoboehmite: The content of Al2O3 is 70 wt%, the content of H2O is 28.8 wt%, and the other components are impurities, mainly SiO2, Fe2O3, Na2O, etc., and the content is negligible.

[0059] Example 1

[0060] This example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0061] S1, subject the kaolin to thermal activation treatment, the activation temperature is 800 °C, and the time is 6 h; under the water bath condition, 11.50 g of the orthophosphoric acid solution is mixed with 1.68 g of the activated kaolin, stirred in a water bath at 80 °C for 4 h, then cooled to 30 °C, 17.56 g of aluminum isopropoxide and 45 g of deionized water are added, mechanically stirred for 6 h, 10.12 g of di-n-propylamine is added, and stirring is continued for 2 h to form a gel. The molar ratio of aluminum element, silicon element, and phosphorus element in the gel is 1:0.15:1; the molar ratio of water, template agent to aluminum element in the gel is 25:1:1. The gel is placed in a crystallization kettle and precrystallized at 140 °C for 16 h to obtain SAPO-11 in-situ seeds;

[0062] S2. Evaporate the water of the in-situ seed of SAPO-11 at 100 °C to dryness, then add ethanol. The molar ratio of aluminum element in the gel to ethanol is 1:6. Then stir at 80 °C for 8 h, and then dry at 100 °C for 24 h to evaporate the solvent in the gel, obtaining a dry gel. Put the dry gel into a 20 mL crucible, place the crucible in a 100 mL crystallization kettle, add 20 mL of deionized water between the crucible and the crystallization kettle, crystallize at 180 °C for 24 h, wash with water, dry at 110 °C for 24 h, and calcine at 600 °C for 10 h to obtain hierarchical pore SAPO-11 molecular sieve. Test the hierarchical pore SAPO-11 molecular sieve, and the obtained XRD pattern is as Figure 1 shown. It can be seen from Figure 1 that the product prepared by this method is a crystalline phase SAPO-11 molecular sieve; the obtained pore size distribution diagram is as Figure 2 shown. It can be seen from Figure 2 that there are micropore and mesopore structures, and the most probable pore diameters in the mesopore distribution are 3.7 nm and 7.5 nm respectively; the obtained TEM image is as Figure 3 shown. It can be seen from Figure 3 that the SAPO-11 molecular sieve is a crystal structure formed by stacking nanosheets with a length of about 600 nm and a width of about 200 nm.

[0063] Example 2

[0064] This example provides a hierarchical pore SAPO-11 molecular sieve. The specific preparation method includes:

[0065] S1. Perform thermal activation treatment on montmorillonite. The activation temperature is 800 °C and the time is 6 h. Under water bath conditions, mix 11.50 g of orthophosphoric acid solution with 2.16 g of activated montmorillonite. After stirring in a water bath at 80 °C for 4 h, cool down to 30 °C, add 8.20 g of aluminum isopropoxide and 72.00 g of deionized water, stir mechanically for 6 h, add 2.53 g of di-n-propylamine, and continue to stir for 2 h to form a gel. The molar ratio of aluminum element, silicon element, and phosphorus element in the gel is 1:0.4:2; the molar ratio of water, template agent to aluminum element in the gel is 80:0.5:1. Place the gel in a crystallization kettle and pre-crystallize at 130 °C for 16 h to obtain the in-situ seed of SAPO-11.

[0066] S2. Evaporate the water of the in-situ seed of SAPO-11 at 100 °C to dryness, then add butanol. The molar ratio of aluminum element in the gel to butanol is 1:5. Then stir at 120 °C for 8 h, and then dry at 120 °C for 24 h to evaporate the solvent in the gel, obtaining a dry gel. Put the dry gel into a 20 mL crucible, place the crucible in a 100 mL crystallization kettle, add 20 mL of deionized water between the crucible and the crystallization kettle, crystallize at 180 °C for 24 h, wash with water, dry at 110 °C for 24 h, and calcine at 600 °C for 10 h to obtain the hierarchical pore SAPO-11 molecular sieve.

[0067] Example 3

[0068] This example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0069] In the same manner as in Example 1, the difference is that in step S2, the molar ratio of aluminum element to ethanol in the gel is 1:10.

[0070] Example 4

[0071] This example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0072] In the same manner as in Example 1, the difference is that in step S2, “stir at 80 °C for 8 h” is changed to “stir at 50 °C for 10 h”.

[0073] Example 5

[0074] This example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0075] In the same manner as in Example 1, the difference is that in step S1, “pre-crystallize at 140 °C for 16 h” is changed to “pre-crystallize at 100 °C for 12 h”.

[0076] Example 6

[0077] This example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0078] In the same manner as in Example 1, the difference is that in step S2, “crystallize at 180 °C for 24 h” is changed to “crystallize at 200 °C for 12 h”.

[0079] Example 7

[0080] This example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0081] S1, Dissolve 7.30 g of pseudo-boehmite in 45 g of deionized water and stir for 2 h, then add 11.50 g of orthophosphoric acid solution. After stirring in a water bath at 30 °C for 4 h, slowly add 10.12 g of di-n-propylamine and 3.12 g of tetraethyl orthosilicate, and continue to stir for 6 h to form a gel. The molar ratio of aluminum element, silicon element, and phosphorus element in the gel is 1:0.15:1; the molar ratio of water, template agent to aluminum element in the gel is 25:1:1. Place the gel in a crystallization kettle and pre-crystallize at 140 °C for 16 h to obtain SAPO-11 in-situ seeds;

[0082] S2. In-situ seed SAPO-11 is dried at 100 °C to remove moisture, and then ethanol is added. The molar ratio of aluminum element in the gel to ethanol is 1:6. Then it is stirred at 80 °C for 8 h, and then dried at 100 °C for 24 h to evaporate the solvent in the gel, obtaining a dry gel. The dry gel is placed in a 20 mL crucible, and the crucible is placed in a 100 mL crystallization kettle. 20 mL of deionized water is added between the crucible and the crystallization kettle. It is crystallized at 180 °C for 24 h, washed with water, dried at 110 °C for 24 h, and calcined at 600 °C for 10 h to obtain hierarchical pore SAPO-11 molecular sieve.

[0083] Comparative Example 1

[0084] This comparative example provides a hierarchical pore SAPO-11 molecular sieve. The specific preparation method includes:

[0085] In the same way as in Example 1, the difference is that in step S2, in-situ seed SAPO-11 is directly dried at 100 °C to remove moisture to obtain a dry gel. The dry gel is placed in a 20 mL crucible, and the crucible is placed in a 100 mL crystallization kettle. 20 mL of deionized water is added between the crucible and the crystallization kettle. It is crystallized at 180 °C for 24 h, washed with water, dried at 110 °C for 24 h, and calcined at 600 °C for 10 h to obtain hierarchical pore SAPO-11 molecular sieve.

[0086] Comparative Example 2

[0087] This comparative example provides a hierarchical pore SAPO-11 molecular sieve. The specific preparation method includes:

[0088] In the same way as in Example 1, the difference is that kaolin is subjected to thermal activation treatment. The activation temperature is 800 °C and the time is 6 h. Under water bath conditions, 11.50 g of orthophosphoric acid solution is mixed with 1.68 g of activated kaolin. After stirring in a water bath at 80 °C for 4 h, the temperature is lowered to 30 °C. 17.56 g of aluminum isopropoxide and 45 g of deionized water are added, and mechanically stirred for 6 h. 10.12 g of di-n-propylamine is added and stirring is continued for 2 h to form a gel. The molar ratio of aluminum element, silicon element, and phosphorus element in the gel is 1:0.15:1. The molar ratio of water, template agent to aluminum element in the gel is 25:1:1. Then ethanol is added. The molar ratio of aluminum element in the gel to ethanol is 1:6. Then it is stirred at 80 °C for 8 h, and then dried at 100 °C for 24 h to evaporate the solvent in the gel, obtaining a dry gel. The dry gel is placed in a 20 mL crucible, and the crucible is placed in a 100 mL crystallization kettle. 20 mL of deionized water is added between the crucible and the crystallization kettle. It is crystallized at 180 °C for 24 h, washed with water, dried at 110 °C for 24 h, and calcined at 600 °C for 10 h to obtain hierarchical pore SAPO-11 molecular sieve.

[0089] Comparative Example 3

[0090] This comparative example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0091] S1, perform according to step S1 of Example 1;

[0092] S2, evaporate the water of the SAPO-11 in-situ seed at 100 °C, then add ethanol, and the molar ratio of aluminum element to ethanol in the gel is 1:6, then stir at 80 °C for 8 h; put the mixed gel into a 20 mL crucible, put the crucible into a 100 mL crystallization kettle, add 20 mL of deionized water between the crucible and the crystallization kettle, crystallize at 180 °C for 24 h, wash with water, dry at 110 °C for 24 h, and calcine at 600 °C for 10 h to obtain the hierarchical pore SAPO-11 molecular sieve.

[0093] Comparative Example 4

[0094] This comparative example provides a hierarchical pore SAPO-11 molecular sieve, and the specific preparation method includes:

[0095] In the same manner as in Example 1, the difference is that at a water bath temperature of 80 °C, 11.50 g of orthophosphoric acid solution, 1.68 g of activated kaolin, 17.56 g of aluminum isopropoxide, 45 g of deionized water, and 10.12 g of di-n-propylamine are mixed and stirred for 12 hours to form a gel. The molar ratio of aluminum element, silicon element, and phosphorus element in the gel is 1:0.15:1; the molar ratio of water, template agent to aluminum element in the gel is 25:1:1. The gel is placed in a crystallization kettle and pre-crystallized at 140 °C for 16 h to obtain the SAPO-11 in-situ seed;

[0096] S2, evaporate the water of the SAPO-11 in-situ seed at 100 °C, then add ethanol, and the molar ratio of aluminum element to ethanol in the gel is 1:6, then stir at 80 °C for 8 h, and then dry at 100 °C for 24 h to evaporate the solvent in the gel to obtain a dry gel; put the dry gel into a 20 mL crucible, put the crucible into a 100 mL crystallization kettle, add 20 mL of deionized water between the crucible and the crystallization kettle, crystallize at 180 °C for 24 h, wash with water, dry at 110 °C for 24 h, and calcine at 600 °C for 10 h to obtain the hierarchical pore SAPO-11 molecular sieve.

[0097] Test Example

[0098] (1) Test the crystal structure of the SAPO-11 molecular sieve by a Dutch PANalytical (X’Pert Pro MPD) X-ray diffractometer (XRD). The scanning range is 2θ = 10~80°, the scanning step is 0.02°, the sampling time is 0.2 s, the tube voltage is 40 kV, the tube current is 40 mA, and the characteristic ray is the Cu target radiation light source;

[0099] (2) The microscopic morphology and particle size of the SAPO-11 sample were tested using a JEM-2100F field emission electron microscope (TEM). The specific test results are shown in Table 1.

[0100] Table 1

[0101] Average particle size (nm) Example 1 500 Example 2 670 Example 3 780 Example 4 820 Example 5 960 Example 6 890 Example 7 850 Comparative Example 1 3450 Comparative Example 2 2680 Comparative Example 3 2890 Comparative Example 4 3800

[0102] (3) Test method for specific surface area and pore structure of SAPO-11 molecular sieve: It was carried out on a Micromeritics ASAP 2020 automatic physical sorption analyzer. The method is as follows: Before adsorption analysis, the sample was placed in the measuring tube, heated to 300 °C in the degassing station and maintained at this temperature for 10 h to remove moisture and impurity gases in the sample. When liquid nitrogen reached -196 °C, the specific surface area and pore structure of the SAPO-11 molecular sieve were tested. The BET method was used to calculate the specific surface area of the sample, the t-Plot method was used to test the external specific surface area of the catalyst, and the BJH method was used to test the pore structure of the catalyst. The specific test results are shown in Table 2.

[0103] Table 2

[0104]

[0105] (4) The hierarchical pore SAPO-11 molecular sieve prepared in the examples and comparative examples was used as a carrier to prepare a bifunctional catalyst. The preparation method is as follows: After mixing the hierarchical pore SAPO-11 molecular sieve with nickel nitrate, it was calcined at 600 °C for 3 h, and then placed in a mixed gas of hydrogen and nitrogen (the volume ratio of hydrogen to nitrogen is 1:9) and reduced at 500 °C for 2 h to obtain a bifunctional catalyst. Based on the total mass of the catalyst, 6 wt% of nickel was loaded; among them, oleic acid was added for the hydrogenation reaction. Based on the mass of oleic acid, the mass of the catalyst was 5 wt%. The catalytic reaction was carried out under a hydrogen pressure of 4 MPa, the reaction temperature was 360 °C, and the time was 4 h;

[0106] The mass of the reacted oleic acid was tested by gas chromatography. The mass of the reacted oleic acid = (raw material - mass of oleic acid after reaction); The conversion rate calculation formula is: conversion rate = (mass of the reacted oleic acid / mass of raw material oleic acid) × 100%;

[0107] The amount of substance of isoparaffin in the product was tested by gas chromatography. The calculation formula for the selectivity of isoparaffin is: selectivity of isoparaffin = (amount of substance of isoparaffin in the product / total amount of substance of the product) × 100%;

[0108] The specific test results are shown in Table 3.

[0109] Table 3

[0110] Conversion rate (wt%) Isoparaffin selectivity (wt%) Example 1 99.7 71.2 Example 2 99.5 65.3 Example 3 99.2 57.8 Example 4 99.1 61.2 Example 5 98.7 53.8 Example 6 98.3 56.3 Example 7 97.5 51.3 Comparative Example 1 96.7 39.6 Comparative Example 2 95.8 48.5 Comparative Example 3 91.7 35.4 Comparative Example 4 89.5 16.7

[0111] In the present invention, the specific average particle size of the SAPO-11 molecular sieve enables fast diffusion of the molecular sieve in the oil hydrogenation catalytic reaction, shortens the diffusion path of reactants and products, increases the effective diffusion rate, and improves the catalytic efficiency of the molecular sieve; the specific external specific surface area can expose more acidic sites on the outside of the molecular sieve, enhance the contact area between reactants and the catalyst, and thus improve the reaction activity of the molecular sieve for hydroisomerization; and the specific pore size distribution and the ratio of micropore volume to mesopore volume can enable some reactants to enter the internal pore channels, provide more active sites, enhance the mass transfer rate, and improve the reaction efficiency.

[0112] Comparing Example 1 with Comparative Example 1, it can be seen that adding an alcohol reagent can weaken the convection of the in-situ seed system and the diffusion rate of reaction particles, thereby affecting the crystal formation rate and forming a molecular sieve with a specific crystal size.

[0113] Comparing Example 1 with Comparative Example 2, it can be seen that by performing two processes of precrystallization and crystallization, compared with only performing one-step crystallization, a molecular sieve with smaller crystal particles is formed.

[0114] Comparing Example 1 with Comparative Example 3, it can be seen that in step S2, a dry gel is formed through the synergistic effect of the first drying and the second drying, making the nucleation and growth environment relatively orderly during the crystallization of the dry gel, and finally generating crystals with a specific particle size, external specific surface area, and mesopore volume.

[0115] Comparing Example 1 with Comparative Example 4, it can be seen that in step S1, adding reactants step by step can form a stable gel system, which is beneficial to the stability and uniformity of the system and controls the initial crystal particle size.

[0116] Comparing Example 1 with Example 3, it can be seen that a specific molar ratio of aluminum element to alcohol reagent in the gel can better control the crystal formation rate during the formation of the molecular sieve, thereby affecting the structure of the finally generated molecular sieve.

[0117] Comparing Example 1 with Example 4, it can be seen that specific conditions of the second mixing can further slow down the formation rate of the molecular sieve, form a nano-sized SAPO-11 molecular sieve, and affect the structure of the molecular sieve.

[0118] Comparing Example 1 with Example 5, it can be seen that specific conditions of precrystallization can further slow down the growth rate of crystal nuclei, contribute to controlling the crystal size, and contribute to forming a nano-SAPO-11 molecular sieve structure.

[0119] Comparing Example 1 with Example 6 shows that, under specific crystallization conditions, the average crystal particle size can be further regulated, thereby increasing the external specific surface area of the molecular sieve, exposing more acidic sites on the outside of the molecular sieve, improving the mass transfer efficiency, and further enhancing the catalytic activity and isoparaffin selectivity.

[0120] Comparing Example 1 with Example 7 shows that when the first aluminum source and silicon source are layered silicates, the raw material cost can be reduced, the use of chemical reagents can be decreased, cost can be saved, and the specific surface area can be increased, expanding the pores in the crystal structure, thereby affecting the pore size distribution and the ratio of micropore volume to mesopore volume.

[0121] Obviously, the above examples are merely illustrations for clear explanation and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or alterations derived therefrom still fall within the protection scope of the present invention.

Claims

1. A hierarchical pore SAPO-11 molecular sieve, characterized in that, The average particle size of the hierarchical pore SAPO-11 molecular sieve is 100-1000 nm, the external specific surface area is 80.0-150.0 m 2 / g, and the mesopore volume is 0.100-0.200 cm 3 / g.

2. The hierarchical pore SAPO-11 molecular sieve according to claim 1, wherein The specific surface area of the hierarchical pore SAPO-11 molecular sieve is 200.0 - 300.0 m 2 / g; And / or, the average pore size of the hierarchical pore SAPO-11 molecular sieve is 3.5 - 10.0 nm; and / or, the micropore volume of the hierarchical pore SAPO-11 molecular sieve is 0.050 - 0.100 cm 3 / g, the total pore volume is 0.200 - 0.300 cm 3 / g, and the ratio of the micropore volume to the mesopore volume is 0.30 - 0.85:

1.

3. A preparation method of hierarchical pore SAPO-11 molecular sieve, characterized in that, Comprising the following steps: S1, perform a first mixing on a first aluminum source, a silicon source, and a phosphorus source, add a second aluminum source and water, add a template agent, to obtain a gel, and pre-crystallize the gel to obtain in-situ seeds; S2, perform a second mixing on the in-situ seeds and an alcohol reagent, perform a first drying to obtain a dry gel, crystallize the dry gel, perform a second drying, and calcine to obtain a hierarchical pore SAPO-11 molecular sieve.

4. The preparation method according to claim 3, characterized in that, The molar ratio of aluminum element, silicon element, and phosphorus element in the gel is 1:(0.05 - 0.4):(0.4 - 2); And / or, the molar ratio of water, the template agent to the aluminum element in the gel is (25 - 80):(0.1 - 1):

1.

5. The preparation method according to claim 3 or 4, characterized in that, The first aluminum source includes at least one of aluminous layered silicate and pseudo-boehmite; And / or, the silicon source includes layered silicate; And / or, perform a thermal activation treatment on the first aluminum source and / or the silicon source; And / or, the phosphorus source includes at least one of phosphoric acid, phosphorous acid, and hypophosphorous acid; And / or, the second aluminum source includes at least one of organic aluminum salts and aluminum-containing oxides; And / or, the template agent includes an organic amine template agent.

6. The preparation method according to claim 5, characterized in that, The first aluminum source includes at least one of kaolin, montmorillonite, and pseudo-boehmite; And / or, the silicon source includes at least one of kaolin and montmorillonite; And / or, the temperature of the thermal activation is 700 - 1000 °C, and the time is 2 - 8 h; And / or, the second aluminum source includes at least one of aluminum isopropoxide and pseudo-boehmite; And / or, the organic amine template agent includes at least one of triethylamine, diethylamine, di-n-propylamine, and diisopropylamine.

7. The preparation method according to any one of claims 3-6, characterized in that, The temperature of the first mixing is 30 - 80 °C, and the time is 4 - 12 h; And / or, the temperature of the pre-crystallization is 100 - 160 °C, and the time is 10 - 16 h; optionally, the temperature of the pre-crystallization is 130 - 160 °C, and the time is 12 - 16 h.

8. The preparation method according to any one of claims 3-7, characterized in that, The alcohol reagent includes at least one of ethanol, butanol, and isopropanol; And / or, the molar ratio of the aluminum element in the gel to the alcohol reagent is 1:5 - 10, and can be 1:5 - 7.

5.

9. The preparation method according to any one of claims 3-8, characterized in that, The temperature of the second mixing is 30 - 120 °C, and the time is 4 - 10 h; optionally, the temperature of the second mixing is 60 - 120 °C, and the time is 6 - 8 h; And / or, the temperature of the first drying is 100 - 120 °C, and the time is 24 - 48 h; And / or, the temperature of the crystallization is 160 - 200 °C, and the time is 12 - 48 h; optionally, the temperature of the crystallization is 160 - 180 °C, and the time is 16 - 24 h; And / or, the temperature of the second drying is 100 - 120 °C, and the time is 24 - 48 h; And / or, the temperature of the calcination is 550 - 650 °C, and the time is 8 - 12 h.

10. Application of the hierarchical pore SAPO-11 molecular sieve according to claim 1 or 2 or the hierarchical pore SAPO-11 molecular sieve prepared by the preparation method according to any one of claims 3 - 9 in catalytic hydrogenation of oils and fats.

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