CN108328623B - Preparation method of high-activity SAPO-34 molecular sieve - Google Patents

Preparation method of high-activity SAPO-34 molecular sieve Download PDF

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CN108328623B
CN108328623B CN201810222941.8A CN201810222941A CN108328623B CN 108328623 B CN108328623 B CN 108328623B CN 201810222941 A CN201810222941 A CN 201810222941A CN 108328623 B CN108328623 B CN 108328623B
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梁光华
狄春雨
李志宏
窦涛
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Shenzhen Keguan Huatai New Material Technology Co ltd
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Abstract

A preparation method of a high-activity SAPO-34 molecular sieve comprises the steps of adding a cationic surfactant into deionized water, stirring, adding a template agent I, stirring for 0.5-1.0 h, adding a silicon source, and stirring to form a solution A; firstly, adding an aluminum source into a template agent II, stirring, adding a phosphorus source, stirring, finally adding an anionic surfactant, and stirring to form a solution B; respectively crystallizing the solution A and the solution B, mixing and stirring the crystallized solution A and the crystallized solution B to form a solution C, crystallizing, centrifuging, washing, drying and roasting to obtain the SAPO-34 molecular sieve. The invention has the advantages of low acidity, good diffusion and prolonged service life.

Description

Preparation method of high-activity SAPO-34 molecular sieve
Technical Field
The invention relates to a preparation method of a high-activity SAPO-34 molecular sieve.
Background
In 1984, silicoaluminophosphate series SAPO-34 molecular sieves (USP4440871) were developed by United states Union carbonization (UCC). The molecular sieve is a kind of crystalline silicoaluminophosphate, and the three-dimensional framework structure of the molecular sieve is PO2 +、AlO2 -And SiO2Tetrahedron formation. The SAPO-34 molecular sieve is of a chabazite-like structure, a main pore channel is formed by eight circular rings, and the pore opening is 0.38nm multiplied by 0.38nm, so that the SAPO-34 molecular sieve has an excellent catalytic performance in a reaction of preparing low-carbon olefin (MTO) from methanol due to the proper acidity and pore channel structure, and is of great interest.
Through research and development for more than thirty years, people gradually improve the understanding of the reaction catalysis mechanism of the methanol-to-low carbon olefin, and indicate a road for the subsequent optimization direction of the SAPO-34 molecular sieve: reducing acidity and improving diffusion effects. With respect to reducing acidity, the current research direction is mainly to reduce the silica-alumina ratio in molecular sieves and to optimize the distribution of silicon atoms in the molecular sieve framework. For example, the patent US7547812B2 discloses a method for synthesizing a low silicon SAPO-34 molecular sieve, the core idea of which is to prepare a high silicon SAPO-34 seed crystal solution, then add it into a low silicon crystalline gel, stir it evenly, and crystallize it to obtain a low silicon-aluminum ratio SAPO-34 molecular sieve; patent CN101121528A discloses a SAPO-34 molecular sieve synthesis method with a framework rich in Si (4Al), which adopts a mode of adding fluoride into initial gel for synthesis and controlling Si to enter a molecular sieve framework, thereby reducing the formation of coordination structures of Si (0Al), Si (1Al), Si (2Al) and Si (3Al), promoting Si to enter the molecular sieve framework in a coordination form of Si (4Al), and effectively realizing the dispersion of silicon atoms in the molecular sieve framework. With respect to the improved diffusion effect of molecular sieves, the current research direction is mainly focused on reducing the crystal size of molecular sieves and synthesizing molecular sieves with special crystal morphology. For example, WO2003/048042 reports a method for obtaining small-particle SAPO-34 molecular sieve by using tetraethoxysilane as a silicon source; patent CN 104192860a prepares SAPO-34 molecular sieve with lamellar morphology by adding double-headed amine cationic surfactant in the synthesis system. At present, the research on the SAPO-34 molecular sieve only optimizes one aspect of the acidity or diffusion effect of the SAPO-34 molecular sieve from a large direction.
Si/Si-Al type M41S series mesoporous materials are prepared by Beck and Kresge et Al of Mobil corporation in the nineties of the twentieth century by adopting hydrothermal synthesis, and the use of a surfactant serving as a template is paid more and more attention by researchers. In patent CN1188689A, cetyl trimethyl ammonium bromide is used as a cationic surfactant, alkyl carboxylic acid sodium salt is used as an anionic surfactant, and the mixture of the two is used as a template agent to prepare the MCM-48 mesoporous molecular sieve with good performance. Patent CN101456562A adopts a cationic surfactant as a template agent to synthesize a mesoporous titanium silicalite molecular sieve, which is applied to catalyzing olefin oxidation and alcohol oxidation, and shows good selectivity and conversion rate. In patent CN102826569A, bifunctional triammonium quaternary ammonium salt cationic surfactant is used as a template agent to prepare the ZSM-5 molecular sieve with a mesopore/micropore multiple pore structure, so that the defect of a single pore structure is effectively avoided, and the mass transfer efficiency is improved. Patent CN104986780A adopts triethylamine and Cetyl Trimethyl Ammonium Bromide (CTAB) as double templates to synthesize a nanoscale sheet SAPO-34 molecular sieve, which is applied to the reaction of preparing low carbon olefin (MTO) from methanol, the molecular diffusion path is obviously shortened, and the catalytic life is greatly prolonged. The current use of surfactants is mainly focused on silico-aluminous molecular sieves; the phosphorus-aluminum molecular sieve is less in use and only adopts a single surfactant, and is mainly used for synthesizing molecular sieves with special shapes and small particle sizes. By adopting the synthesis method, the pore-forming capability of the anionic and cationic surfactants is fully exerted, and the research on the preparation of the SAPO-34 molecular sieve with consideration of lower acidity and excellent diffusion effect is not reported in documents.
Disclosure of Invention
The invention aims to provide a preparation method of a high-activity SAPO-34 molecular sieve with low acidity, good diffusion and long service life and application thereof in preparation of low-carbon olefin from methanol.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a preparation method of a high-activity SAPO-34 molecular sieve for preparing low-carbon olefins from methanol comprises the following steps:
(1) adding a cationic surfactant into deionized water, and stirring for 0.5-1.0 h; then adding a template agent I, and stirring for 0.5-1.0 h; finally, adding a silicon source, and stirring for 1.0-2.0 h to form a solution A;
(2) firstly, adding an aluminum source into a template agent II, and stirring for 0.5-1.0 h; then adding a phosphorus source, and stirring for 0.5-1.0 h; finally, adding an anionic surfactant, and stirring for 1.0-2.0 h to form a solution B;
(3) respectively putting the solution A and the solution B into a high-temperature crystallization kettle, and pre-crystallizing for 24-36 hours at 120-140 ℃;
(4) after the pre-crystallization is finished, mixing and stirring the solution A and the solution B for 2-4 hours to form a solution C, and finally, putting the solution C into a high-temperature crystallization kettle for crystallization at 160-180 ℃ for 36-48 hours;
(5) centrifuging, washing and drying after crystallization is finished to obtain SAPO-34 molecular sieve raw powder; roasting the raw powder at 550-580 ℃ for 5-8 h to obtain the high-activity SAPO-34 molecular sieve;
wherein R1 is template agent I, R2 is template agent II, S+Is a cationic surfactant, S-Being an anionic surfactant, Al2O3Is an aluminum source, P2O5As a source of phosphorus, SiO2The silicon source is prepared from the following raw materials in a molar ratio: al (Al)2O3：P2O5：SiO2：R1：R2：S+：S-：H2O＝1.0：(0.9～1.1)：(0.08～0.16)：(0～3.0)：(0.5～2.0)：(0.001～0.01)：(0.001～0.01)：(30～60)。
The cationic surfactant in the step (1) is dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide or octadecyl trimethyl ammonium bromide; the template agent I is at least one of triethylamine and diethylamine; the silicon source is silica sol or ethyl orthosilicate.
The anionic surfactant in the step (2) is Sodium Dodecyl Sulfate (SDS), Sodium Dodecyl Carboxylate (SDC) or hexadecyl methionine; the template agent II is at least one of tetraethyl ammonium hydroxide, triethylamine or diethylamine; the aluminum source is pseudo-boehmite or aluminum isopropoxide; the phosphorus source is orthophosphoric acid.
When the method is used for the reaction of preparing low-carbon olefin (MTO) from methanol, the reaction conditions are as follows: the reaction temperature is 450-500 ℃; pressure: 0 to 0.2 MPa; the weight space velocity is 1.5-3.0 h-1The mass percent of methanol in the methanol raw material is as follows: 40-95%.
Compared with the prior art, the invention has the following advantages:
1. the method carries out long-time pre-crystallization on the cationic surfactant and the silicon species under the alkalescent condition, realizes the assembly and adsorption of the silicon species and the surfactant after full depolymerization, and similarly realizes the assembly and adsorption of the anionic surfactant and the phosphorus-aluminum species, wherein the anionic surfactant and the phosphorus-aluminum species are fully dispersed before mixing, thereby being beneficial to improving the utilization rate of each atom and reducing the silicon-aluminum ratio of the synthesized molecular sieve and the uniform placement of silicon atoms in a molecular sieve framework.
2. According to the invention, the anionic and cationic surfactants are adopted, and compared with a synthesis system without the surfactants, the strong electrostatic action between the anionic and cationic surfactant compound systems greatly improves the surface activity of the anionic and cationic surfactant compound systems, and is beneficial to synthesizing the SAPO-34 molecular sieve with rich mesopores; the effect of reducing the particle size of the molecular sieve by the surfactant is enhanced, and the particle size is reduced from 2.0-2.5 mu m to 0.5-0.8 mu m; the specific surface area of the molecular sieve is remarkably increased and is 550m2Increasing the/g to 700-710 m2/g。
3. The method adopts special preparation process conditions, well considers the acidity and diffusion effects of the SAPO-34 molecular sieve, is applied to the reaction of preparing low-carbon olefin from methanol, and compared with a conventional preparation process sample, the method has the advantages that the catalytic life is prolonged by 20-50%, and the selectivity of ethylene and propylene is improved by 1.2-5.6%.
4. The introduction of the anionic and cationic surfactants greatly improves the utilization rate of various raw materials and the yield; meanwhile, the phosphorus-aluminum colloid in the crystallization liquid is obviously reduced, the separation is easy, and the method has great industrial application value.
Drawings
FIG. 1 shows XRD spectra of S-1 to S-5 samples.
It can be seen from the figure that pure phase SAPO-34 molecular sieve is synthesized, which shows that the method of the present invention does not affect the crystalline phase of the final product.
FIG. 2 is SEM photographs of samples of example S-4 and comparative example S-5, in which A is example sample S-4 and B is comparative example sample S-5.
The crystal morphology of the sample of example S-4 changed dramatically compared to comparative example S-5: the particle size is reduced by one order of magnitude; the crystal surface is rougher.
FIG. 3 is N of a sample of example S-42Adsorption/desorption isotherm schematic and N of comparative example S-5 sample2Adsorption/desorption isotherms are compared.
Calculated from the adsorption isotherm, comparative example S-5 BET specific surface area of sample 550m2In g, the sample of example S-4 had a BET specific surface area of 702m2(ii) in terms of/g. The adsorption isotherm of the sample of example S-4 was classified as a class IV isotherm, compared to the sample of comparative example S-5, indicating that mesopores were present in the sample of example S-4.
FIG. 4 is a graph showing the pore size distribution curve of the sample of example S-4 in comparison with that of the sample of comparative example S-5 (BJH method).
According to the pore size distribution curve calculated by the BJH model, the comparative example S-5 is a standard micropore pore size distribution diagram, and the average pore size is 0.69 nm; the sample of example S-4 showed a relatively pronounced mesoporous size distribution with an average pore size of 3.12 nm.
Detailed Description
The present invention will be described in detail below by way of examples.
Example 1
1.0 mol% Al2O3：1.0P2O5：0.08SiO2：3.0TEA：0.005S+：0.005S-：30H2O, 0.10g of cetyltrimethylammonium bromide (S)+Mass fraction is more than or equal to 99.5 percent) is added into 23.07g of deionized water and stirred for 0.5 h; then adding 3.26g of triethylamine (TEA mass fraction is more than or equal to 99 percent), and stirring for 1.0 h; finally, 1.10g of silica Sol (SiO) was added225 percent of mass percent) and stirring for 1.8 hours to form a solution A; then 9.00g of pseudo-boehmite (Al)2O365 percent of the mass fraction) is added into 13.03g of triethylamine (TEA mass fraction is more than or equal to 99 percent), and the mixture is stirred for 0.5 hour; then 13.22g phosphoric acid (P) was added2O561.6 percent of mass percent) and stirring for 1.0 h; finally, 0.10g of sodium dodecyl sulfate (S) was added-75 percent of mass percent) and stirring for 1.5 hours to form a solution B; respectively transferring the prepared solution A and solution B to a stainless steel crystallization kettle, pre-crystallizing for 24 hours at 140 ℃ and autogenous pressure, cooling the high-pressure crystallization kettle to room temperature, adding the pre-crystallized solution A into the solution B, mixing and stirring for 4 hours to form solution C, finally filling the solution C into the stainless steel crystallization kettle, and crystallizing for 40 hours at 170 ℃. And centrifuging, washing and drying after crystallization to obtain SAPO-34 molecular sieve raw powder with the sample number of S-1.XRD representation is carried out on the sample raw powder, the result shows that the sample raw powder is a pure-phase SAPO-34 molecular sieve, and the SEM result shows that the particle size is 0.8 mu m, and the crystal surface is rough; the sample is calcined at 550 ℃ for 8h by introducing air, and the BET result is 700m2/g，N2The adsorption/desorption isotherm shows that mesopores appear, and the average pore diameter of the sample is calculated to be 3.10nm according to a pore diameter distribution curve comparison graph (BJH method).
Example 2
1.0 mol% Al2O3：0.9P2O5：0.16SiO2：2.0TEAOH：0.5TEA：0.001S+：0.001S-：60H2O, 0.02g of octadecyl trimethyl ammonium bromide (S)+Mass fraction is more than or equal to 98 percent) is added into 24.04g of deionized water and stirred for 0.6 h; then adding 1.90g of triethylamine (TEA mass fraction is more than or equal to 99 percent), and stirring for 0.8 h; finally, 1.97g of ethyl orthosilicate (SiO) was added228 percent of mass percent) and stirring for 2.0 hours to form a solution A; then 9.00g of pseudo-boehmite (Al)2O365 percent of the weight fraction) is added into a mixture of 48.17g of tetraethyl ammonium hydroxide (TEAOH weight fraction is 35 percent) and 1.00g of triethylamine (TEA weight fraction is more than or equal to 99 percent), and the mixture is stirred for 0.8 h; then 11.90g phosphoric acid (P) was added2O561.6 percent of mass fraction), and stirring for 0.6 h; finally, 0.018g of sarcosyl (S) was added-95.5 percent of mass percent) and stirring for 1.0 hour to form a solution B; transferring the prepared solution A and solution B to a stainless steel crystallization kettle, pre-crystallizing for 36 hours at 120 ℃ and autogenous pressure, cooling the high-pressure crystallization kettle to room temperature, adding the pre-crystallized solution A into the solution B, mixing and stirring for 3.5 hours to form solution C, finally filling the solution C into the stainless steel crystallization kettle, and crystallizing for 36 hours at 180 ℃. And centrifuging, washing and drying after crystallization to obtain SAPO-34 molecular sieve raw powder with the sample number of S-2. XRD representation is carried out on the sample raw powder, the result shows that the sample raw powder is a pure-phase SAPO-34 molecular sieve, and the SEM result shows that the particle size is 0.5 mu m, and the crystal surface is rough; the sample is calcined at 560 ℃ for 7h by introducing air, and the BET result is 710m2/g，N2The adsorption/desorption isotherm shows that mesopores appear, and the average pore diameter of the sample is calculated to be 3.15nm according to a pore diameter distribution curve comparison graph (BJH method).
Example 3
1.0 mol% Al2O3：1.1P2O5：0.12SiO2：1.5TEAOH：0.5DEA：0.01S+：0.01S-：45H2O, 0.18g of dodecyltrimethylammonium bromide (S)+99 percent by mass) of the mixture is added into 16.40g of deionized water and stirred for 0.8 h; then 2.09g of diethylamine (DEA mass fraction is more than or equal to 99%) is added, and the mixture is stirred for 0.6 h; finally, 1.65g of silica Sol (SiO) was added225 percent of mass percent) and stirring for 1.0 hour to form a solution A; then 9.00g of pseudo-boehmite (Al)2O365 percent of the weight percentage) is added into 36.13g of tetraethyl ammonium hydroxide (TEAOH weight percentage is 35 percent) and stirred for 0.6 h; then 14.54g phosphoric acid (P) was added2O561.6 percent of mass fraction), and stirring for 0.8 h; finally, 0.18g of sodium lauryl sulfate (S) was added-91 percent of mass percent) and stirring for 1.8 hours to form a solution B; transferring the prepared solution A and solution B to a stainless steel crystallization kettle, pre-crystallizing for 30 hours at 130 ℃ and autogenous pressure, cooling the high-pressure crystallization kettle to room temperature, adding the pre-crystallized solution A into the solution B, mixing and stirring for 2 hours to form solution C, finally filling the solution C into the stainless steel crystallization kettle, and crystallizing for 48 hours at 160 ℃. And centrifuging, washing and drying after crystallization to obtain SAPO-34 molecular sieve raw powder with the sample number of S-3. XRD representation is carried out on the sample raw powder, the result shows that the sample raw powder is a pure-phase SAPO-34 molecular sieve, and the SEM result shows that the particle size is 0.6 mu m, and the crystal surface is rough; the sample is calcined at 570 ℃ for 6h by introducing air, and the BET result is 708m2/g，N2The adsorption/desorption isotherm shows that mesopores appear, and the average pore diameter of the sample is calculated to be 3.14nm according to a pore diameter distribution curve comparison graph (BJH method).
Example 4
1.0 mol% Al2O3：1.0P2O5：0.10SiO2：2.0DEA：1.0TEA：0.008S+：0.004S-：40H2O, 0.17g of cetyltrimethylammonium bromide (S)+Mass fraction is more than or equal to 99.5 percent) is added into 35.27g of deionized water and stirred for 1.0 h; then adding a mixture of 5.79g of triethylamine (TEA mass fraction is more than or equal to 99%) and 1.37g of diethylamine (DEA mass fraction is more than or equal to 99%), and stirring for 0.5 h; finally, the1.23g of tetraethoxysilane (SiO) was added228 percent of mass percent) and stirring for 1.5 hours to form a solution A; then 9.00g of pseudo-boehmite (Al)2O365 percent of the mass fraction) is added into 7.00g of diethylamine (the DEA mass fraction is more than or equal to 99 percent), and the mixture is stirred for 1.0 hour; then 13.22g phosphoric acid (P) was added2O561.6 percent of mass fraction), and stirring for 0.5 h; finally, 0.07g of sarcosyl (S) was added-95.5 percent of mass percent) and stirring for 2.0 hours to form a solution B; transferring the prepared solution A and solution B to a stainless steel crystallization kettle, pre-crystallizing for 30 hours at 125 ℃ and autogenous pressure, cooling the high-pressure crystallization kettle to room temperature, adding the pre-crystallized solution A into the solution B, mixing and stirring for 3 hours to form solution C, finally filling the solution C into the stainless steel crystallization kettle, and crystallizing for 43 hours at 165 ℃. And centrifuging, washing and drying after crystallization to obtain SAPO-34 molecular sieve raw powder with the sample number of S-4. XRD representation is carried out on the sample raw powder, the result shows that the sample raw powder is a pure-phase SAPO-34 molecular sieve, and the SEM result shows that the particle size is 0.8 mu m, and the crystal surface is rough; the sample is calcined at 580 ℃ for 5h by introducing air, and the BET result is 702m2/g，N2The adsorption/desorption isotherm shows that mesopores appear, and the average pore diameter of the sample is calculated to be 3.12nm according to a pore diameter distribution curve comparison graph (BJH method).
Comparative example 1
1.0 mol% Al2O3：1.0P2O5：0.10SiO2：2.0DEA：1.0TEA：40H2O, firstly, adding 5.79g of triethylamine (TEA mass fraction is more than or equal to 99%) into 35.27g of deionized water, and stirring for 0.5 h; then 1.23g of tetraethoxysilane (SiO) were added228 percent of mass percent) and stirring for 1.5 hours to form a solution A; then 9.00g of pseudo-boehmite (Al)2O365 percent of the mass fraction) is added into 8.37g of diethylamine (the DEA mass fraction is more than or equal to 99 percent), and the mixture is stirred for 1.0 hour; then 13.22g phosphoric acid (P) was added2O561.6 percent of mass percent) and stirring for 0.5h to form a solution B; transferring the prepared solution A and solution B to a stainless steel crystallization kettle, pre-crystallizing at 125 ℃ under autogenous pressure for 30h, cooling the high-pressure crystallization kettle to room temperature, adding the pre-crystallized solution A into the solution B, mixing and stirring for 3h to form solution C, finally filling the solution C into the stainless steel crystallization kettle, and putting the solution C into the stainless steel crystallization kettleCrystallizing at 165 deg.C for 43 h. And centrifuging, washing and drying after crystallization to obtain SAPO-34 molecular sieve raw powder with the sample number of S-5. XRD representation is carried out on the sample raw powder, the result shows that the sample raw powder is a pure-phase SAPO-34 molecular sieve, and the SEM result shows that the grain size is 2.2 mu m, and the surface of a crystal is smooth; the sample is calcined at 580 ℃ for 5h by introducing air, and the BET result is 550m2/g，N2The adsorption/desorption isotherm shows that no mesopores appear, and the average pore diameter of the sample is calculated to be 0.69nm according to a pore diameter distribution curve comparison graph (BJH method).
Example 6
NH of five SAPO-34 molecular sieve products obtained in examples 1, 2, 3 and 4 and comparative example 13TPD analysis was performed on a model TL 5000.II multipurpose adsorption apparatus from Tianjin Xianchao corporation, the samples after activation were pulse-adsorbed with ammonia at 120 ℃ until saturation, then the temperature was raised to 550 ℃ at a rate of 10 ℃/min, TCD detected the amount of ammonia desorbed, and the results of acid amount and acid strength of each sample were obtained by calculation, see Table 1.
NH of the samples of Table 13-TPD characterization results
Figure BDA0001600463540000071
As can be seen from the characterization results in Table 1, the SAPO-34 molecular sieve sample synthesized by the preparation method provided by the invention has the advantages that the strong acid strength is greatly reduced on the premise that the weak acid strength and the weak acid amount are approximately equivalent, and the specific expression is that the strong acid desorption temperature is reduced by 48-75 ℃; the acid amount of the strong acid is greatly reduced, and the specific expression is that the acid amount of the strong acid is reduced by 54-57%.
Example 7
Five SAPO-34 molecular sieves obtained in examples 1, 2, 3 and 4 and comparative example 1 were tabletted and crushed to 20-40 mesh. Weighing 0.5g of sample, loading the sample into a fixed bed reactor, and carrying out the reaction evaluation of preparing low carbon olefin (MTO) from methanol. The reaction temperature is 450 ℃, the mass percent is 40wt percent of methanol feeding, and the weight space velocity is 3.0h-1At normal pressure, the reaction product is analyzed by on-line gas chromatography; catalyst life is defined as the time at which 100% conversion of methanol occurs and no dimethyl ether is present. Reaction concreteThe results are shown in Table 2.
Table 2 reaction results of methanol to light olefins
Figure BDA0001600463540000081
Maximum (ethylene + propylene) selectivity at 100% methanol conversion
As can be seen from Table 2, the SAPO-34 molecular sieve synthesized by the preparation method disclosed by the invention has the advantages that the catalytic life is prolonged by 20-55%, and the selectivity of low-carbon olefin is improved by 3.2-4.6%.
The above-described embodiments of the present invention are intended to be illustrative of the present invention and not to limit the present invention, and therefore, any changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (9)

1. A preparation method of a high-activity SAPO-34 molecular sieve is characterized by comprising the following steps:
(1) adding a cationic surfactant into deionized water, and stirring for 0.5-1.0 h; then adding a template agent I, and stirring for 0.5-1.0 h; finally, adding a silicon source, and stirring for 1.0-2.0 h to form a solution A;
(2) firstly, adding an aluminum source into a template agent II, and stirring for 0.5-1.0 h; then adding a phosphorus source, and stirring for 0.5-1.0 h; finally, adding an anionic surfactant, and stirring for 1.0-2.0 h to form a solution B;
(3) respectively putting the solution A and the solution B into a high-temperature crystallization kettle, and pre-crystallizing for 24-36 hours at 120-140 ℃;
(4) after the pre-crystallization is finished, mixing and stirring the solution A and the solution B for 2-4 hours to form a solution C, and finally, putting the solution C into a high-temperature crystallization kettle for crystallization at 160-180 ℃ for 36-48 hours;
(5) centrifuging, washing and drying after crystallization is finished to obtain SAPO-34 molecular sieve raw powder; roasting the raw powder at 550-580 ℃ for 5-8 h to obtain the high-activity SAPO-34 molecular sieve;
wherein R1 is template agent I, R2 is template agent II, S+As a cation watchSurfactants, S-Being an anionic surfactant, Al2O3Is an aluminum source, P2O5As a source of phosphorus, SiO2The silicon source is prepared from the following raw materials in a molar ratio: al (Al)2O3 ：P2O5：SiO2：R1：R2：S+：S-：H2O=1.0：（0.9～1.1）：（0.08～0.16）：（0～3.0）：（0.5～2.0）：（ 0.001～0.01）：（ 0.001～0.01）：（30～60）。
2. The method for preparing a high activity SAPO-34 molecular sieve according to claim 1, wherein the cationic surfactant in step (1) is dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide or octadecyl trimethyl ammonium bromide.
3. The method for preparing a high activity SAPO-34 molecular sieve according to claim 1, wherein the template I in step (1) is at least one of triethylamine and diethylamine.
4. The method for preparing a high activity SAPO-34 molecular sieve according to claim 1, wherein the silicon source in step (1) is silica sol or tetraethoxysilane.
5. The method for preparing a high activity SAPO-34 molecular sieve according to claim 1, wherein the anionic surfactant in step (2) is sodium dodecyl sulfate, sodium dodecyl carboxylate or hexadecyl methionine.
6. The method for preparing a high activity SAPO-34 molecular sieve according to claim 1, wherein the template II in step (2) is at least one of tetraethylammonium hydroxide, triethylamine or diethylamine.
7. The method for preparing a high activity SAPO-34 molecular sieve according to claim 1, wherein the aluminum source in step (2) is pseudoboehmite or aluminum isopropoxide.
8. The method for preparing a high activity SAPO-34 molecular sieve according to claim 1, wherein the phosphorus source in step (2) is orthophosphoric acid.
9. A high activity SAPO-34 molecular sieve prepared according to any one of claims 1 to 8, characterized in being prepared by a method for its preparation.
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