Lamellar AEL molecular sieve as well as preparation method and application thereof

Abstract

The invention discloses a lamellar aluminum phosphate-based AEL molecular sieve and a preparation method and application thereof, belongs to the technical field of molecular sieve porous materials, and particularly relates to a preparation method of a lamellar aluminum phosphate-based AEL molecular sieve, which comprises the following steps: stirring ethylene glycol and organic amine hydrochloride for the first time to obtain a premixed solution; respectively adding a phosphoric acid solution and an aluminum source into the premixed solution, and stirring for the second time to obtain an aluminum phosphate solution; adding heteroatoms, and stirring for the third time to obtain a heteroatom aluminum phosphate solution; dropwise adding an organic amine solution, and stirring for the fourth time to obtain a heteroatom aluminum phosphate precursor solution; and performing crystallization, ultrasonic treatment, washing, drying and roasting treatment on the heteroatom aluminum phosphate precursor solution to obtain the lamellar AEL molecular sieve. According to the method, the low-temperature eutectic mixture is adopted as a reaction medium, a mesoporous template agent and a growth inhibitor are not added, the steps are simple, and the prepared lamellar molecular sieve is large in specific surface area, has hierarchical pore characteristics and appropriate acidity and has a wide prospect in the aspect of isomerization reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve porous materials, and in particular relates to a lamellar AEL molecular sieve and a preparation method and application thereof. Background Art

[0002] Alkane isomerization is one of the important reactions in the petroleum refining process, and is mainly used in the production of high-quality fuel oil and high-grade lubricating oil. Alkane isomerization catalysts are usually bifunctional catalysts with shape-selective functions, including acidic functions and hydrogenation / dehydrogenation functions. The acidic carrier provides acidic sites for isomerization / cracking, and the metal sites provide hydrogenation / dehydrogenation functions.

[0003] Zeolite molecular sieves, as an inorganic porous material, have a regular and uniform pore structure. Due to the unique size and shape of its internal pores, only molecules smaller than the crystal pores can enter the pores for catalytic reactions or adsorption processes, which has shape selectivity. At the same time, the introduction of heteroatoms into the molecular sieve framework to replace A1 atoms or P atoms can achieve acidic modulation of the molecular sieve, so zeolite molecular sieves are often used as acidic carriers for the preparation of bifunctional catalysts to achieve control of specific chemical reactions. Studies have shown that when using AEL structure molecular sieves to catalyze isomerization reactions, single-branched skeleton isomers can be generated in their pores through the pores, while double-branched skeleton isomers are mainly generated at the pores and outer surface of the acidic carrier due to steric hindrance effects. Therefore, to improve the selectivity of the catalyst for the isomerization reaction, we should start with increasing the number of pores and the external surface area.

[0004] As a member of aluminum phosphate molecular sieves, AlPO-11 has an AEL topological structure. The elliptical non-intersecting ten-membered ring channel is composed of ( http: / / www.iza-structure.org / databases / ). The unique and ordered pore structure enables it to have shape-selective function, which can selectively catalyze according to the size and shape of reactant and product molecules. At the same time, heteroatoms (Co, Cu, Fe, Mg, Ni, Si or Zn) are doped into the aluminum phosphate molecular sieve to produce acid centers. Due to its unique pore structure and suitable medium-strong acid centers, it exhibits excellent catalytic performance in isomerization reactions and is often used as an acid carrier for preparing catalysts for isomerization reactions.

[0005] Under normal circumstances, molecular sieves with AEL topological structure can be synthesized by traditional hydrothermal method, which is mainly divided into two steps: preparation of seed crystals and synthesis of molecular sieves. For example, first, preparation of seed crystals: using a uniform mixed slurry composed of deionized water, phosphoric acid, and pseudo-boehmite, tetraethyl orthosilicate (TEOS) is added dropwise, and after stirring evenly, the template agent di-n-propylamine (DPA) is quickly added. The resulting seed crystal precursor slurry is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, statically crystallized at 200°C for 48h, washed, dried, and calcined to obtain seed crystals. Second, synthesis of molecular sieves: pseudo-boehmite and DPA are added to a dilute phosphoric acid solution, TEOS and heterogeneous seed crystals are added to the obtained gel, stirred evenly, and then loaded into a polytetrafluoroethylene-lined autoclave, crystallized at 200°C for 12h, washed, filtered, dried at 120°C for 3h, and calcined at 600°C for 4h to obtain AEL molecular sieve powder. The silicoaluminophosphate AEL molecular sieve synthesized under traditional hydrothermal conditions is a spherical aggregate formed by the accumulation of relatively regular block crystals. Compared with the present invention, the traditional hydrothermal method has complex steps, high cost, and high energy consumption. In addition, the molecular sieve grows rapidly in the c-axis direction to form larger and thicker block crystals with a small specific surface area and fewer exposed active sites, which is not conducive to the catalytic reaction. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a lamellar AEL molecular sieve and a preparation method and application thereof, using ethylene glycol and organic amine hydrochloride as low-temperature eutectic, without adding mesoporous template agent and growth inhibitor. The prepared lamellar AEL molecular sieve is aggregated into a flower shape by lamellar layers, has a large specific surface area, a regular pore structure, good hydrothermal stability, and has broad prospects in isomerization reactions.

[0007] To achieve the above object, the present invention provides a method for preparing a lamellar AEL molecular sieve, comprising the following steps:

[0008] (1) Add ethylene glycol solution and organic amine hydrochloride to a beaker in sequence and stir for the first time to obtain a premixed solution;

[0009] (2) adding a phosphoric acid solution and an aluminum source to the premixed solution of step (1) in sequence, and stirring for a second time to obtain an aluminum phosphate solution;

[0010] (3) adding heteroatoms to the aluminum phosphate solution of step (2), and stirring for the third time to obtain a heteroatom aluminum phosphate solution;

[0011] (4) adding an organic amine dropwise to the heteroatom aluminum phosphate solution of step (3), stirring for a fourth time, and obtaining a heteroatom aluminum phosphate precursor solution;

[0012] (5) The heteroatom aluminum phosphate precursor solution in step (4) is subjected to crystallization, ultrasonication, water washing, drying and calcination in sequence to obtain the lamellar AEL molecular sieve.

[0013] Furthermore, in step (1), the ethylene glycol solution uses water as a solvent, and the concentration of the ethylene glycol solution is 35 to 99 wt %; the organic amine hydrochloride is one of diethylamine hydrochloride, triethylamine hydrochloride, di-n-propylamine hydrochloride or di-n-butylamine hydrochloride.

[0014] Furthermore, in step (1), the temperature of the first stirring is 25 to 90° C., the time is 0.1 to 2 h, and the rotation speed is 50 to 600 r / min.

[0015] Furthermore, in step (2), the phosphoric acid solution uses water as a solvent, and the concentration of the phosphoric acid solution is 25 to 99 wt %; the aluminum source is one of crystalline aluminum chloride, pseudo-boehmite, aluminum hydroxide or aluminum isopropoxide.

[0016] Furthermore, in step (2), the temperature of the second stirring is 30 to 90° C., the time is 0.1 to 4 h, and the rotation speed is 50 to 600 r / min.

[0017] Furthermore, in step (3), the heteroatom is one of Co, Cu, Fe, Mg, Ni, Si or Zn; the temperature of the third stirring is 40-90° C., the time is 0.5-4 h, and the rotation speed is 50-600 r / min.

[0018] Furthermore, the organic amine in step (4) is one of imidazole, 1-methylimidazole or 1-ethylimidazole; the rate of adding the organic amine is 1 to 60 drops / min; the temperature of the fourth stirring is 40 to 90°C, the time is 0.1 to 6 hours, and the speed is 50 to 600 r / min; the heteroatom aluminum phosphate precursor solution has M:Al 2 O 3 :P 2 O 5 The molar ratio of EG is 0.001-2.0:0.01-10.0:0.01-30.0:0.6-1500, wherein M represents one of the heteroatoms Co, Cu, Fe, Mg, Ni, Si or Zn.

[0019] Furthermore, in step (5), the crystallization temperature is 100-250°C, and the time is 0.5-360h; the ultrasonic power is 50-300W, and the time is 5-35min; the drying temperature is 80-160°C, and the time is 1-24h; the calcination temperature is 400-600°C, and the time is 4-20h.

[0020] The present invention also provides a lamellar AEL molecular sieve prepared by the preparation method.

[0021] The present invention also provides an application of the lamellar AEL molecular sieve in an isomerization reaction.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] 1) The present invention provides an aluminum phosphate-based AEL molecular sieve having a flower-like morphology formed by the aggregation of lamellar structures by using a low-temperature eutectic as a reaction medium. In the prior art, the conventional hydrothermal method often adopts a method of first preparing seed crystals and then synthesizing the molecular sieve, and the obtained aluminum phosphate-based AEL molecular sieve presents a spherical aggregate morphology formed by the accumulation of blocky crystals, and the c-axis corresponding to the (002) crystal plane is long, the specific surface area is small, and the synthesis steps are complicated, and the cost and energy consumption are high. The AEL molecular sieve synthesized by the present invention has a short c-axis corresponding to the (002) crystal plane, a large specific surface area, and the synthesis process does not require seed crystals, and does not require the addition of mesoporous templates and growth inhibitors, thereby reducing the cost of synthesizing aluminum phosphate-based AEL molecular sieves by the conventional hydrothermal method.

[0024] 2) The lamellar aluminum phosphate-based AEL molecular sieve prepared by the present invention introduces heteroatoms into the AEL molecular sieve framework, giving the molecular sieve new active sites, which can adjust the acidity of the molecular sieve and optimize the performance of the AEL molecular sieve, forming a special lamellar morphology with a large specific surface area and a multi-level pore structure. It can be used as an acidic carrier to load metals to prepare catalysts, improve the problems of low product yield and poor selectivity in isomerization reactions, and can improve the activity and selectivity in isomerization reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 XRD spectra of the flaky aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention and the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method, wherein (a) is the flaky aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention, and (b) is the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method;

[0027] Figure 2 The SEM images of the flaky aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention and the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method are shown in Figure 1, wherein (a) is the flaky aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention, and (b) is the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method, and the scales are 2 μm and 10 μm, respectively;

[0028] Figure 3 The figure is a relationship diagram between the conversion rate of n-C16 and the temperature of the flaky aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention and the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method, wherein (a) is the flaky aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention, and (b) is the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method;

[0029] Figure 4 The isomer yield and temperature diagram of the lamellar aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention and the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method, wherein (a) is the lamellar aluminum phosphate-based AEL molecular sieve synthesized in Example 1 of the present invention, and (b) is the aluminum phosphate-based AEL molecular sieve synthesized by the traditional hydrothermal method. DETAILED DESCRIPTION

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0032] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0033] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0034] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0035] The present invention provides a method for preparing a lamellar aluminum phosphate-based AEL molecular sieve, comprising the following steps:

[0036] (1) Adding ethylene glycol (EG, 35-99 wt%) and organic amine hydrochloride in a beaker in sequence, stirring at 25-90° C. and 50-600 r / min for 0.1-2 h to obtain a premixed solution; wherein the organic amine hydrochloride is one of diethylamine hydrochloride, triethylamine hydrochloride, di-n-propylamine hydrochloride or di-n-butylamine hydrochloride;

[0037] (2) Add phosphoric acid aqueous solution (H 3 PO 4 , 25 to 99 wt%), then adding an aluminum source, stirring at 30 to 90° C. at 50 to 600 r / min for 0.1 to 4 h to obtain an aluminum phosphate solution; wherein the aluminum source is one of crystalline aluminum chloride, pseudo-boehmite, aluminum hydroxide or aluminum isopropoxide;

[0038] (3) adding heteroatoms to the aluminum phosphate solution, stirring at 40 to 90° C. and 50 to 600 r / min for 0.5 to 4 h to obtain a heteroatom aluminum phosphate solution; wherein the heteroatom is one of Co, Cu, Fe, Mg, Ni, Si or Zn;

[0039] (4) adding an organic amine to the heteroatom aluminum phosphate solution at a rate of 1 to 60 drops / min, stirring at a rate of 50 to 600 r / min at a temperature of 40 to 90° C. for 0.1 to 6 hours to obtain a heteroatom aluminum phosphate precursor solution; wherein the organic amine is one of imidazole, 1-methylimidazole or 1-ethylimidazole; and M in the heteroatom aluminum phosphate precursor solution is Al 2 O 3 :P 2 O 5 The molar ratio of EG is 0.001-2.0:0.01-10.0:0.01-30.0:0.6-1500, and M represents one of the heteroatoms Co, Cu, Fe, Mg, Ni, Si or Zn.

[0040] (5) The heteroatom aluminum phosphate precursor solution is charged into a stainless steel reactor, crystallized at 100-250° C. for 0.5-360 h, ultrasonicated in an ultrasonic cleaning machine with a power of 50-300 W for 5-35 min, washed with water three times, dried at 80-160° C. for 1-24 h, ground and calcined at 400-600° C. in an air atmosphere for 4-20 h to obtain an aluminum phosphate-based AEL molecular sieve.

[0041] The present invention will be further described in detail below in conjunction with specific embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0042] Example 1

[0043] Embodiment 1 of the present invention provides a method for preparing a lamellar silicoaluminophosphate AEL molecular sieve, comprising the following steps:

[0044] (1) In a 50 mL beaker, 12.4 g of ethylene glycol (EG, 99 wt%) and 5.5 g of triethylamine hydrochloride were added in sequence, and the mixture was stirred at 200 r / min for 0.1 h at 25° C. to obtain a premixed solution;

[0045] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 0.24g of crystalline aluminum chloride, and stir for a second time at 200r / min at 35°C for 0.5h to obtain an aluminum phosphate solution;

[0046] (3) Add 0.042 g of tetraethyl orthosilicate (TEOS) to the aluminum phosphate solution, and stir for 1 h at 200 r / min at 45 °C to obtain a silicon aluminum phosphate solution. 2 :Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.01:0.1:2:10;

[0047] (4) adding 2 g of imidazole to the silicoaluminophosphate solution at a rate of 10 drops / min, and stirring at 200 r / min for 1 h at 45° C. to obtain a silicoaluminophosphate precursor solution;

[0048] (5) The aluminum silicophosphate precursor solution was placed in a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 110° C. for 36 h, ultrasonicated in a 150 W ultrasonic cleaner for 10 min, washed with water three times, dried at 90° C. for 12 h, ground, and calcined at 400° C. in an air atmosphere for 4 h to obtain an aluminum silicophosphate AEL molecular sieve.

[0049] Example 2

[0050] Embodiment 2 of the present invention provides a method for preparing a lamellar silicoaluminophosphate AEL molecular sieve, comprising the following steps:

[0051] (1) In a 50 mL beaker, 20.8 g of ethylene glycol (EG, 99 wt%) and 5.5 g of di-n-propylamine hydrochloride were added in sequence, and the mixture was stirred at 80° C. and 350 r / min for 0.2 h to obtain a premixed solution;

[0052] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4, 85wt%), then add 1.61g of crystalline aluminum chloride, stir for a second time at 80°C and 350r / min for 0.5h to obtain an aluminum phosphate solution;

[0053] (3) Add 0.07 g of tetraethyl orthosilicate (TEOS) to the aluminum phosphate solution, and stir for 1 h at 80 °C and 350 r / min to obtain an aluminum phosphate solution. 2 :Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.05:1:6:50;

[0054] (4) adding 5.77 g of 1-ethylimidazole to the silicoaluminophosphate solution at a rate of 20 drops / min, and stirring at 350 r / min for 1 h at 80° C. to obtain a silicoaluminophosphate precursor solution;

[0055] (5) The aluminum silicophosphate precursor solution was placed in a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 200° C. for 8 h, ultrasonicated in a 300 W ultrasonic cleaner for 25 min, washed with water 3 times, dried at 120° C. for 1.5 h, ground, and calcined at 550° C. in an air atmosphere for 7 h to obtain an aluminum silicophosphate AEL molecular sieve.

[0056] Example 3

[0057] Embodiment 3 of the present invention provides a method for preparing a lamellar silicoaluminophosphate AEL molecular sieve, comprising the following steps:

[0058] (1) In a 50 mL beaker, 18.62 g of ethylene glycol (EG, 99 wt%) and 9.64 g of di-n-propylamine hydrochloride were added in sequence, and the mixture was stirred at 90° C. and 250 r / min for 0.2 h to obtain a premixed solution;

[0059] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 0.6g of crystalline aluminum chloride, stir for a second time at 90°C and 200r / min for 0.5h to obtain an aluminum phosphate solution;

[0060] (3) Add 0.05 g of tetraethyl orthosilicate (TEOS) to the aluminum phosphate solution, and stir for 1 h at 90 °C and 200 r / min to obtain a silicon aluminum phosphate solution. 2 :Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.05:1:8:60;

[0061] (4) adding 5.75 g of 1-methylimidazole to the silicoaluminophosphate solution at a rate of 30 drops / min, and stirring at 200 r / min for 2 h at 90° C. to obtain a silicoaluminophosphate precursor solution;

[0062] (5) The aluminum silicophosphate precursor solution was placed in a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 200° C. for 120 h, ultrasonicated in a 300 W ultrasonic cleaner for 25 min, washed with water three times, dried at 90° C. for 12 h, ground, and calcined at 570° C. in an air atmosphere for 10 h to obtain an aluminum silicophosphate AEL molecular sieve.

[0063] Example 4

[0064] Embodiment 4 of the present invention provides a method for preparing a lamellar zinc aluminum phosphate AEL molecular sieve, comprising the following steps:

[0065] (1) In a 50 mL beaker, 7.76 g of ethylene glycol (EG, 99 wt%) and 6.63 g of di-n-butylamine hydrochloride were added in sequence, and the mixture was stirred at 60° C. and 300 r / min for 0.1 h to obtain a premixed solution;

[0066] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 0.6g of crystalline aluminum chloride, stir for a second time at 60°C and 300r / min for 0.5h to obtain an aluminum phosphate solution;

[0067] (3) Add 0.015 g zinc nitrate hexahydrate (Zn(NO 3 ) 2 6H 2 O), stirred at 60°C and 300r / min for 2h to obtain a zinc aluminum phosphate solution. 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.01:1:8:25;

[0068] (4) adding 4.11 g of 1-methylimidazole to the zinc aluminum phosphate solution at a rate of 40 drops / min, and stirring at 300 r / min for 1 h at 60° C. to obtain a zinc aluminum phosphate precursor solution;

[0069] (5) The zinc aluminum phosphate precursor solution was placed in a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 160° C. for 96 h, ultrasonicated in an ultrasonic cleaner with a power of 200 W for 10 min, washed with water 3 times, dried at 100° C. for 2 h, ground, and calcined at 600° C. in an air atmosphere for 6 h to obtain a zinc aluminum phosphate AEL molecular sieve.

[0070] Example 5

[0071] Embodiment 5 of the present invention provides a method for preparing a lamellar nickel aluminum phosphate AEL molecular sieve, comprising the following steps:

[0072] (1) In a 50 mL beaker, 19.86 g of ethylene glycol (EG, 99 wt%) and 5.5 g of triethylamine hydrochloride were added in sequence, and the mixture was stirred at 70° C. and 400 r / min for 0.1 h to obtain a premixed solution;

[0073] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 0.817g of aluminum isopropoxide, and stir for a second time at 70°C and 400r / min for 0.5h to obtain an aluminum phosphate solution;

[0074] (3) Add 0.08 g of nickel acetate (NiC 4 H 6 O 4 ·4H 2 O), stirred at 70°C and 400r / min for 1h to obtain a nickel aluminum phosphate solution. 2 O 3 :Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.08:1:5:40;

[0075] (4) adding 3.4 g of imidazole to the nickel aluminum phosphate solution at a rate of 20 drops / min, and stirring at 400 r / min for 2 h at 70° C. to obtain a nickel aluminum phosphate precursor solution;

[0076] (5) The nickel aluminum phosphate precursor solution was placed in a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 180° C. for 120 h, ultrasonicated in a 300 W ultrasonic cleaning machine for 16 min, washed with water three times, dried at 110° C. for 3 h, ground, and calcined at 400° C. in an air atmosphere for 10 h to obtain a nickel aluminum phosphate AEL molecular sieve.

[0077] Example 6

[0078] Embodiment 6 of the present invention provides a method for preparing a lamellar magnesium aluminum phosphate AEL molecular sieve, comprising the following steps:

[0079] (1) In a 50 mL beaker, 12.4 g of ethylene glycol (EG, 99 wt%) and 5.5 g of di-n-propylamine hydrochloride were added in sequence, and the mixture was stirred at 300 r / min for 0.2 h at 30° C. to obtain a premixed solution;

[0080] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 0.24g of crystalline aluminum chloride, and stir for a second time at 300r / min at 40°C for 1h to obtain an aluminum phosphate solution;

[0081] (3) Add 0.04 g of magnesium chloride hexahydrate (MgCl 2 6H 2 O), stirred at 50°C and 300r / min for 3h to obtain a magnesium aluminum phosphate solution. The magnesium aluminum phosphate solution has a ratio of MgO:Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.01:0.1:2:10;

[0082] (4) adding 2 g of imidazole to the magnesium aluminum phosphate solution at a rate of 10 drops / min, stirring at 300 r / min for 1 h at 50° C. to obtain a magnesium aluminum phosphate precursor solution;

[0083] (5) The magnesium aluminum phosphate precursor solution was charged into a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 120° C. for 36 h, ultrasonically cleaned in an ultrasonic cleaner with a power of 150 W for 10 min, washed with water three times, dried at 100° C. for 2 h, ground, and calcined at 550° C. in an air atmosphere for 10 h to obtain a magnesium aluminum phosphate AEL molecular sieve.

[0084] Example 7

[0085] Embodiment 7 of the present invention provides a method for preparing a lamellar magnesium aluminum phosphate AEL molecular sieve, comprising the following steps:

[0086] (1) In a 50 mL beaker, 7.5 g of ethylene glycol (EG, 99 wt%) and 6.88 g of triethylamine hydrochloride were added in sequence, and the mixture was stirred at 80° C. and 300 r / min for 0.1 h to obtain a premixed solution;

[0087] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 0.61g of aluminum isopropoxide, and stir for a second time at 80°C and 300r / min for 0.5h to obtain an aluminum phosphate solution;

[0088] (3) Add 0.05 g of magnesium acetate (C 4 H 6 MgO 4 ·4H 2O), stirred at 80°C and 300r / min for 1h to obtain a magnesium aluminum phosphate solution. The magnesium aluminum phosphate solution has a ratio of MgO:Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.04:1:7:20;

[0089] (4) adding 4.08 g of imidazole to the magnesium aluminum phosphate solution at a rate of 20 drops / min, and stirring at 300 r / min for 1 h at 80° C. to obtain a magnesium aluminum phosphate precursor solution;

[0090] (5) The magnesium aluminum phosphate precursor solution was charged into a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 180° C. for 168 h, ultrasonicated in an ultrasonic cleaner with a power of 200 W for 25 min, washed with water three times, dried at 100° C. for 2 h, ground, and calcined at 550° C. in an air atmosphere for 10 h to obtain a magnesium aluminum phosphate AEL molecular sieve.

[0091] Example 8

[0092] Embodiment 8 of the present invention provides a method for preparing a lamellar cobalt aluminum phosphate AEL molecular sieve, comprising the following steps:

[0093] (1) In a 50 mL beaker, 12.4 g of ethylene glycol (EG, 99 wt%) and 2.2 g of diethylamine hydrochloride were added in sequence, and the mixture was stirred at 400 r / min at 50° C. for 0.1 h to obtain a premixed solution;

[0094] (2) Add 1.15 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 1.02g of aluminum isopropoxide, and stir for a second time at 400r / min at 50°C for 0.5h to obtain an aluminum phosphate solution;

[0095] (3) Add 0.05 g of cobalt chloride hexahydrate (CoCl 2 6H 2 O), stirred at 50°C and 300r / min for 2h to obtain a cobalt aluminum phosphate solution. 2 O 3 :Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.02:1:2:20;

[0096] (4) adding 4.8 g of 1-ethylimidazole to the cobalt aluminum phosphate solution at a rate of 20 drops / min, and stirring at 300 r / min for 2 h at 50° C. to obtain a cobalt aluminum phosphate precursor solution;

[0097] (5) The cobalt aluminum phosphate precursor solution was placed in a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 150° C. for 72 h, ultrasonicated in an ultrasonic cleaner with a power of 150 W for 10 min, washed with water 3 times, dried at 110° C. for 4 h, ground, and calcined at 550° C. in an air atmosphere for 10 h to obtain the cobalt aluminum phosphate AEL molecular sieve.

[0098] Example 9

[0099] Embodiment 9 of the present invention provides a method for preparing a lamellar cobalt aluminum phosphate AEL molecular sieve, comprising the following steps:

[0100] (1) In a 50 mL beaker, 19.86 g of ethylene glycol (EG, 99 wt%) and 2.8 g of triethylamine hydrochloride were added in sequence, and the mixture was stirred at 60° C. and 300 r / min for 0.1 h to obtain a premixed solution;

[0101] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 0.49g of crystalline aluminum chloride, and stir for a second time at 60°C and 300r / min for 1h to obtain an aluminum phosphate solution;

[0102] (3) Add 0.05 g of cobalt chloride hexahydrate (CoCl 2 6H 2 O), stirred at 60°C and 300r / min for 1h to obtain a cobalt aluminum phosphate solution. 2 O 3 :Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.1:1:10:80;

[0103] (4) adding 4.08 g of imidazole to the cobalt aluminum phosphate solution at a rate of 40 drops / min, and stirring at 300 r / min for 1 h at 60° C. to obtain a cobalt aluminum phosphate precursor solution;

[0104] (5) The cobalt aluminum phosphate precursor solution was charged into a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 160° C. for 144 h, ultrasonicated in a 300 W ultrasonic cleaning machine for 30 min, washed with water three times, dried at 110° C. for 10 h, ground, and calcined at 600° C. in an air atmosphere for 8 h to obtain the cobalt aluminum phosphate AEL molecular sieve.

[0105] Example 10

[0106] Embodiment 10 of the present invention provides a method for preparing a lamellar nickel aluminum phosphate AEL molecular sieve, comprising the following steps:

[0107] (1) In a 50 mL beaker, 10 g of ethylene glycol (EG, 99 wt%) and 2.8 g of triethylamine hydrochloride were added in sequence, and the mixture was stirred at 50 ° C and 200 r / min for 0.5 h to obtain a premixed solution;

[0108] (2) Add 2.4 g of phosphoric acid aqueous solution (H 3 PO 4 , 85wt%), then add 1.23g of aluminum isopropoxide, and stir for a second time at 200r / min at 50°C for 0.5h to obtain an aluminum phosphate solution;

[0109] (3) Add 0.005 g of nickel acetate (NiC 4 H 6 O 4 ·4H 2 O), stirred at 50°C and 200r / min for 0.5h to obtain a nickel aluminum phosphate solution. 2 O 3 :Al 2 O 3 :P 2 O 5 : The molar ratio of EG is 0.01:3:10:40;

[0110] (4) adding 6.73 g of 1-ethylimidazole to the nickel aluminum phosphate solution at a rate of 20 drops / min, and stirring the mixture at 200 r / min for 0.5 h at 50° C. to obtain a nickel aluminum phosphate precursor solution;

[0111] (5) The nickel aluminum phosphate precursor solution was placed in a 30 mL polytetrafluoroethylene-lined stainless steel reactor, crystallized at 180° C. for 120 h, ultrasonicated in a 250 W ultrasonic cleaner for 25 min, washed with water three times, dried at 90° C. for 12 h, ground, and calcined at 500° C. in an air atmosphere for 10 h to obtain a nickel aluminum phosphate AEL molecular sieve.

[0112] Comparative Example 1

[0113] Traditional hydrothermal preparation of AEL structure silicoaluminophosphate molecular sieve:

[0114] 4.08g of aluminum isopropoxide, 2.30g of phosphoric acid with a mass concentration of 85%, and 0.08g of magnesium chloride were added to 10.0g of deionized water in sequence, stirred for 2h, and then 1.60g of di-n-propylamine was added. After stirring at room temperature for 2h, a molecular sieve precursor was obtained. The above precursor was added to a reactor and reacted at 200°C for 48h. The product was filtered, washed, and dried, and then calcined in an air atmosphere at 600°C for 5h to obtain a Mg-doped AEL structured silicoaluminophosphate molecular sieve prepared by a traditional hydrothermal method. The AEL molecular sieve synthesized by the open system prepared in Example 1 and the AEL structured silicoaluminophosphate molecular sieve prepared by traditional hydrothermal method in Comparative Example 1 were used to catalyze the isomerization reaction of long-chain alkanes:

[0115] Take 2.0g of calcined molecular sieve as the catalyst carrier and impregnate 0.5wt% H 2 PtCl 6 After drying at 120℃ for 4h, the isomerization catalyst was obtained by calcining at 500℃ for 4h in a muffle furnace and then reducing at 400℃ for 4h in a hydrogen atmosphere. 2 / nC 16 =10, the pressure is 2.0 MPa, and the catalytic performance of the molecular sieves of Example 1 and Comparative Example 1 is evaluated in the range of 240-360°C.

[0116] The lamellar aluminum phosphate AEL molecular sieve prepared in Example 1 and the aluminum phosphate AEL molecular sieve synthesized by traditional hydrothermal method were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the structure and morphology information of the molecular sieves were obtained. At the same time, the lamellar aluminum phosphate AEL molecular sieve was loaded with metal to prepare a catalyst, and the catalytic performance of the molecular sieve was evaluated by comparing with the catalyst prepared by aluminum phosphate AEL molecular sieve synthesized by traditional hydrothermal method. The isomerization reaction of n-hexadecane was carried out in a continuous flow fixed bed reactor, and the product was analyzed by gas chromatograph.

[0117] The results are as follows, Figure 1The XRD spectra of the lamellar aluminum phosphate AEL molecular sieve prepared in Example 1 of the present invention and the aluminum phosphate AEL molecular sieve synthesized by the traditional hydrothermal method show that the lamellar aluminum phosphate AEL molecular sieve (a) prepared by the present invention and the aluminum phosphate AEL molecular sieve (b) synthesized by the traditional hydrothermal method have strong characteristic diffraction peaks of aluminum phosphate AEL molecular sieve at 2θ=8.09°, 9.43°, 13.12°, and 21.12°, corresponding to their (110), (020), (200), and (002) crystal planes, respectively. By comparison, it can be obtained that the diffraction peak of the lamellar aluminum phosphate AEL molecular sieve prepared by the present invention corresponding to the (002) crystal plane at 21.12° is shorter than that of the traditional hydrothermal method at the corresponding position, indicating that the growth of the lamellar aluminum phosphate AEL molecular sieve in the c-axis direction is inhibited, and finally a special lamellar aggregate is formed. This is consistent with the morphology presented in the SEM image.

[0118] Figure 2 The following are SEM images of the lamellar aluminum phosphate AEL molecular sieve synthesized in Example 1 of the present invention and the aluminum phosphate AEL molecular sieve synthesized by the traditional hydrothermal method. Figure 2 As shown in (a), the lamellar aluminum phosphate AEL molecular sieve synthesized in Example 1 of the present invention is composed of regular thin lamellar aggregates; Figure 2 As shown in (b), the aluminum phosphate AEL molecular sieve synthesized by the traditional hydrothermal method appears as spherical aggregates formed by the accumulation of irregular blocky grains.

[0119] Figure 3 The flaky aluminum phosphate AEL molecular sieve (a) synthesized in Example 1 of the present invention and the aluminum phosphate AEL molecular sieve (b) synthesized by the conventional hydrothermal method are used to react with n-hexadecane nC 16 The relationship between the conversion rate and temperature. As shown in the figure, as the reaction temperature increases, nC 16 The conversion rates of the AEL molecular sieves synthesized by the traditional hydrothermal method and the AEL molecular sieves synthesized by the lamellar aluminum phosphate both showed an increasing trend. In comparison, to achieve the same conversion rate as the catalyst prepared by the AEL molecular sieve synthesized by the traditional hydrothermal method (Pt / C-SAPO-11), the catalyst (Pt / N-SAPO-11) with the AEL molecular sieves as the carrier only needs a lower reaction temperature.

[0120] Figure 4The relationship between the yield of isomers of the lamellar aluminum phosphate AEL molecular sieve (a) synthesized in Example 1 of the present invention and the aluminum phosphate AEL molecular sieve (b) synthesized by the traditional hydrothermal method and temperature. As can be seen from the figure, as the reaction temperature increases, the isomer yields of the two catalysts show a trend of first increasing and then decreasing. The isomerization yield of Pt / N-SAPO-11 can reach nearly 90%, while the isomerization yield on Pt / C-SAPO-11 is up to 70%. This shows that the performance of the lamellar aluminum phosphate AEL molecular sieve is more conducive to the conduct of heterogeneous catalysis, which can effectively improve the catalyst activity and selectivity.

[0121] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a lamellar AEL molecular sieve, characterized in that: The following steps are involved: (1) Add ethylene glycol solution and organic amine hydrochloride to a beaker in sequence and stir for the first time to obtain a premixed solution; (2) adding a phosphoric acid solution and an aluminum source to the premixed solution of step (1) in sequence, and stirring for a second time to obtain an aluminum phosphate solution; (3) adding heteroatoms to the aluminum phosphate solution of step (2), and stirring for the third time to obtain a heteroatom aluminum phosphate solution; (4) adding an organic amine dropwise to the heteroatom aluminum phosphate solution of step (3), stirring for a fourth time, and obtaining a heteroatom aluminum phosphate precursor solution; (5) The heteroatom aluminum phosphate precursor solution in step (4) is subjected to crystallization, ultrasonication, water washing, drying and calcination in sequence to obtain the lamellar AEL molecular sieve.

2. The preparation method according to claim 1, characterized in that: In step (1), the ethylene glycol solution uses water as solvent, and the concentration of the ethylene glycol solution is 35-99wt%; the organic amine hydrochloride is one of diethylamine hydrochloride, triethylamine hydrochloride, di-n-propylamine hydrochloride or di-n-butylamine hydrochloride.

3. The preparation method according to claim 1, characterized in that: In step (1), the temperature of the first stirring is 25 to 90° C., the time is 0.1 to 2 h, and the rotation speed is 50 to 600 r / min.

4. The preparation method according to claim 1, characterized in that: In step (2), the phosphoric acid solution uses water as solvent, and the concentration of the phosphoric acid solution is 25-99 wt %; the aluminum source is one of crystalline aluminum chloride, pseudo-boehmite, aluminum hydroxide or aluminum isopropoxide.

5. The preparation method according to claim 1, characterized in that: In step (2), the second stirring is carried out at a temperature of 30 to 90° C., for a time of 0.1 to 4 h, and at a rotation speed of 50 to 600 r / min.

6. The preparation method according to claim 1, characterized in that: In step (3), the heteroatom is one of Co, Cu, Fe, Mg, Ni, Si or Zn; the temperature of the third stirring is 40-90° C., the time is 0.5-4 h, and the rotation speed is 50-600 r / min.

7. The preparation method according to claim 1, characterized in that: The organic amine in step (4) is one of imidazole, 1-methylimidazole or 1-ethylimidazole; the rate of adding the organic amine is 1 to 60 drops / min; the temperature of the fourth stirring is 40 to 90°C, the time is 0.1 to 6 hours, and the rotation speed is 50 to 600 r / min; the molar ratio of M:Al2O3:P2O5:EG in the heteroatom aluminum phosphate precursor solution is 0.001 to 2.0:0.01 to 10.0:0.01 to 30.0:0.6 to 1500, wherein M represents one of the heteroatoms Co, Cu, Fe, Mg, Ni, Si or Zn.

8. The preparation method according to claim 1, characterized in that: In step (5), the crystallization temperature is 100-250° C. and the time is 0.5-360 h; the ultrasonic power is 50-300 W and the time is 5-35 min; the drying temperature is 80-160° C. and the time is 1-24 h; the calcination temperature is 400-600° C. and the time is 4-20 h.

9. The lamellar AEL molecular sieve prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the lamellar AEL molecular sieve as claimed in claim 9 in isomerization reaction.

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