A phosphorus-containing ssz-13 molecular sieve and a synthesis method and application thereof

Abstract

A kind of phosphorus-containing SSZ-13 molecular sieve, after the molecular sieve of 800 ℃, 100% water vapor treatment 17h, the ratio of the content of four-coordinated framework aluminum and five-coordinated non-framework aluminum in the aluminum coordination state of the molecular sieve is 0.8-2.The in-situ synthesis method of the molecular sieve is characterized in that it comprises: mixing a phosphorus source, water and an additive, then sequentially adding a template agent R and an aluminum source, and mixing uniformly to obtain a mixture I;adding a silicon source to the mixture I, and mixing uniformly to obtain a mixture II;the mixture II is hydrothermally crystallized, and the product is recovered to obtain an SSZ-13 molecular sieve.

Description

TECHNICAL FIELD

[0001] The present invention relates to a molecular sieve and a method for synthesizing the same, and more particularly, the present invention relates to a phosphorus-containing SSZ-13 molecular sieve and a method for synthesizing the same. BACKGROUND

[0002] Molecular sieves are a class of commercially important crystalline materials that have strong acidity, large specific surface area, special pore structure and stable physicochemical properties. These characteristics make molecular sieves be used as heterogeneous catalysts in many industrial processes. SSZ-13 molecular sieve is a molecular sieve belonging to CHA topology, and its structure is connected by aluminum-oxygen tetrahedron and silicon-oxygen tetrahedron through the oxygen atoms at the vertices to form ellipsoidal cages with eight-membered ring structure (0.73 x 1.2 nm) and three-dimensional cross-pore structure, and the pore size is 0.38 x 0.38 nm, which belongs to small-pore molecular sieves. Due to its small pore, SSZ-13 molecular sieve is widely used in gas separation and shape-selective catalysis.

[0003] The synthesis method of SSZ-13 molecular sieve was first disclosed in US4544538. In this method, N,N,N-trimethyl-1-adamantylammonium hydroxide is used as a template agent, the template agent, a silicon source, an aluminum source, an alkali metal salt and water are uniformly mixed, and then hydrothermal crystallization is performed at 100-235°C for more than 3 days to obtain SSZ-13 molecular sieve. On the basis of this method, new synthesis methods of SSZ-13 molecular sieve are constantly disclosed.

[0004] CN101973562A provides a method for synthesizing SSZ-13 molecular sieve using copper amine complex as a template agent. In this method, gibbsite is first dissolved in deionized water, a divalent copper salt is added, and then an organic amine is added dropwise after stirring; after sufficient stirring, sodium hydroxide solid is added and stirred; then silica sol is added to the solution, stirred for 2-3 hours, and then loaded into a reaction kettle, and crystallized at a temperature of 140-180°C for 3-20 days; after filtration, drying and calcination, the final product is obtained. Although this method does not use organic ammonium salt as a template agent, the ion exchange performance of the obtained SSZ-13 molecular sieve is poor, which is not conducive to subsequent modification treatment, and the Cu-SSZ-13 molecular sieve obtained by this method is mainly used for removing NO x from vehicle exhaust.

[0005] CN106824261A provides a preparation method of Ni-SSZ-13 molecular sieve. In this method, a nickel salt, a chelating agent or a nickel amine chelate is used as a template agent, and then mixed with a silicon source, an aluminum source and water, and then crystallized at 100-200°C for 5h-10 days, and then the crystallization product is washed with water, dried and calcined to obtain the final product, Ni-SSZ-13 molecular sieve.

[0006] CN111592008A provides a method for synthesizing Fe-SSZ-13 molecular sieve by one-step method using iron salt, chelating agent or iron ammine complex as template agent.

[0007] Although there are reports on the synthesis of heteroatom SSZ-13 molecular sieve by introducing other elements during in-situ synthesis, the existing technology of phosphorus-containing SSZ-13 molecular sieve is obtained by subsequent phosphorus modification of the synthesized molecular sieve using equal volume impregnation method. SUMMARY

[0008] One of the purposes of the present application is to provide a phosphorus-containing SSZ-13 molecular sieve different from the prior art, the second purpose is to provide an in-situ synthesis method of the molecular sieve, and the third purpose is to further provide the application of the molecular sieve in light hydrocarbon catalytic cracking reaction.

[0009] In order to achieve one of the above purposes, the present application provides a phosphorus-containing SSZ-13 molecular sieve, characterized in that the ratio of the content of four-coordinated framework aluminum to the content of five-coordinated non-framework aluminum in the aluminum coordination state of the molecular sieve after being treated by 800℃, 100% water vapor for 17h is 0.8-2, and the aluminum coordination state of the molecular sieve is measured by solid magic angle spinning nuclear magnetic resonance method.

[0010] The ratio of the content of four-coordinated framework aluminum to the content of five-coordinated non-framework aluminum in the aluminum coordination state of the molecular sieve after being treated by 800℃, 100% water vapor for 17h is 0.8-2, and the aluminum coordination state of the molecular sieve is measured by solid magic angle spinning nuclear magnetic resonance method. 27 In the Al MAS NMR nuclear magnetic resonance spectrum, the integral area of the peak near 60ppm corresponds to the content of four-coordinated framework aluminum, the integral area of the peak near 30ppm corresponds to the content of five-coordinated non-framework aluminum, and the aluminum coordination state of the peak near 0ppm is six-coordinated non-framework aluminum. The ratio of the content of four-coordinated framework aluminum to the content of five-coordinated framework aluminum is the ratio of the integral area of the peak near 60ppm in the nuclear magnetic resonance spectrum to the integral area of the peak near 30ppm in the nuclear magnetic resonance spectrum. After being treated by 800℃, 100% water vapor for 17h, the ratio of the content of four-coordinated framework aluminum to the content of five-coordinated non-framework aluminum of the phosphorus-containing SSZ-13 molecular sieve is preferably 0.9-1.5.

[0011] The phosphorus-containing SSZ-13 molecular sieve provided by the present application has a molar ratio of silicon oxide to aluminum oxide of 5-50, and preferably a molar ratio of silicon oxide to aluminum oxide of 10-35; in terms of P2O5 and based on the dry weight of the molecular sieve, the phosphorus content in the phosphorus-containing SSZ-13 molecular sieve is 0.1wt%-3wt%, and preferably the phosphorus content is 0.8wt%-2wt%.

[0012] To achieve the second of the above purposes, the application also provides an in-situ synthesis method of the above-mentioned phosphorus-containing SSZ-13 molecular sieve, characterized in that it comprises: mixing a phosphorus source, water and an additive, then sequentially adding a template agent R and an aluminum source, and mixing uniformly to obtain a mixture I; adding a silicon source to the mixture I and mixing uniformly to obtain a mixture II; subjecting the mixture II to hydrothermal crystallization and recovering a product to obtain the SSZ-13 molecular sieve; wherein the phosphorus source is calculated as P2O5, the aluminum source is calculated as Al2O3, the additive is at least one of ammonia, diethylamine and triethylamine, and the molar ratio of the components in the mixture II is P2O5: additive: template agent R: Al2O3: SiO2: H2O = 0.1-3: 0-5: 0.4-10: 1: 5-50: 50-1000.

[0013] In the synthesis method, the phosphorus source can be at least one of phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and diphosphorus pentoxide. The additive can be at least one of ammonia, diethylamine and triethylamine (when the phosphorus source is phosphoric acid). The aluminum source can be at least one of SB powder, aluminum alcoholate, aluminum oxide, aluminum hydroxide, aluminum sulfate and gibbsite. The template agent can be N,N,N-trimethyl-1-adamantylammonium hydroxide, which is added to the synthesis system in the form of an aqueous solution. In the aqueous solution of N,N,N-trimethyl-1-adamantylammonium hydroxide, the mass fraction of N,N,N-trimethyl-1-adamantylammonium hydroxide is 15-30%. The silicon source can be at least one of silica sol, silicon dioxide, white carbon black, silicate and solid silica gel. The crystallization conditions can be conventional crystallization conditions for synthesizing SSZ-13 molecular sieves in the art. The temperature of the crystallization reaction can be 140-200°C, and the time of the crystallization reaction can be 18-168h. The recovery of the product is a process of filtering, water washing, drying and calcining the crystallization product to obtain the product molecular sieve, which are all known to those skilled in the art. The calcination conditions include: an air atmosphere and / or a water vapor atmosphere, a calcination temperature of 400-800°C, and a calcination time of 0.5-8h.

[0014] The in-situ synthesis method of the phosphorus-containing SSZ-13 molecular sieve provided by the application avoids the complex post-modification treatment step of phosphorus, has fewer treatment steps than the post-modification molecular sieve treatment step commonly used at present, shortens the time and cost of the synthesis process, and avoids the reduction of the crystallinity of the molecular sieve in the post-treatment process. Moreover, since the in-situ synthesis method omits the alkali metal ion exchange process in the prior art, there is no ammonia-nitrogen wastewater discharge.

[0015] To achieve the third object of the present application, the phosphorus-containing SSZ-13 molecular sieve provided by the present application can be applied in catalytic cracking and catalytic cracking processes as an active component of a catalyst or an aid, has the characteristics of strong cracking ability, good shape selection performance, high conversion rate of reactants, and high propylene yield and selectivity. The more suitable phosphorus-containing SSZ-13 molecular sieve for catalytic cracking and catalytic cracking is a molecular sieve whose ratio of four-coordinated framework aluminum to five-coordinated non-framework aluminum in the aluminum coordination state of the molecular sieve after being treated by 800°C, 100% steam for 17h is 0.9-1.5, the phosphorus content is 0.8wt%-2wt%, and the molar ratio of silicon oxide to aluminum oxide is 10-35. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is an X-ray diffraction spectrum of the SSZ-13 molecular sieve sample A prepared in Example 1.

[0017] Figure 2 is a scanning electron microscope photograph of the SSZ-13 molecular sieve sample A prepared in Example 1.

[0018] Figure 3 is an Al MAS NMR spectrum of the SSZ-13 molecular sieve samples A and D1, D2 prepared in Example 1 and Comparative Examples 1 and 2. 27 Al MAS NMR spectrum. DETAILED DESCRIPTION

[0019] The present application is further illustrated by the following examples without limiting the present application.

[0020] The instruments and reagents used in the examples of the present application are all commonly used by those skilled in the art, unless otherwise specified.

[0021] The elemental chemical composition of the molecular sieve is determined by X-ray fluorescence method, and the standard method in GB / T 30905-2014 is used.

[0022] The relative crystallinity is expressed in percentage by the ratio of the sum of the peak areas of the four characteristic diffraction peaks near 13.0°, 16.1°, 17.9°, and 20.8° in the X-ray diffraction (XRD) spectrum of the obtained product and the SSZ-13 molecular sieve standard sample. The SSZ-13 molecular sieve synthesized by the method in Example 1 of US4544538 is used as the standard sample, and its crystallinity is defined as 100%. The X-ray diffraction spectrum is determined on a Japan Rigaku TTR-3 powder X-ray diffractometer, and the instrument parameters are: copper target (tube voltage 40kV, tube current 250mA), scintillation counter, step width 0.02°, scanning rate 0.4° / min.

[0023] Nitrogen adsorption-desorption curves were measured on an AS-3, AS-6 static nitrogen adsorption instrument produced by Quantachrome Instrument Co. The instrument parameters were as follows: the sample was placed in a sample treatment system, vacuumized at 300 ℃ to 1.33 x 10 -2 Pa, and kept for 4 h, and the sample was purified. The adsorption and desorption amounts of the purified sample at different P / P0 were tested at a liquid nitrogen temperature of -196 ℃, and N2 adsorption-desorption isotherm curves were obtained, and then the specific surface area was calculated by using a two-parameter BET formula.

[0024] Solid-state nuclear magnetic resonance tests were performed on a Bruker AVANCE III 600 WB nuclear magnetic resonance spectrometer, and the test conditions were as follows: 27 The detection nuclear magnetic resonance frequency of Al was 78.155 MHz, the magic angle rotation speed was 5000 Hz, the pulse width was 1.6 μs, the cycle delay time was 1 s, the number of scans was 8000 times, and the test temperature was about 25 ℃. The signal peak near the chemical shift of 60 ppm corresponds to four-coordinated framework aluminum, and the integral peak area S1. The signal peak near the chemical shift of 30 ppm corresponds to five-coordinated non-framework aluminum, and the integral peak area S2. S1 / S2 represents the ratio of the contents of four-coordinated framework aluminum and five-coordinated non-framework aluminum.

[0025] The phosphorus-containing SSZ molecular sieve was evaluated by using a light hydrocarbon catalytic cracking probe reaction. The reaction was performed in a fixed bed reactor, the raw oil was 1-octene, the carrier gas was nitrogen, the flow rate was 30 mL / min, the reaction temperature was 550 ℃, the regeneration temperature was 600 ℃, the weight hourly space velocity was 20.06 hr -1 After the molecular sieve was pressed, it was sieved into 20-40 mesh particles, the loading amount was 2.0 g, the catalyst / oil ratio was 1.28, the oil feeding time was 140 s, and the nitrogen purging time was 900 s, and then the sample was analyzed and the material balance was calculated.

[0026] Example 1

[0027] To 39.9 g of deionized water, 1.79 g of phosphoric acid aqueous solution (mass fraction of 85%) was added, 2.35 g of triethylamine solution (mass fraction of 99%) was added dropwise and stirred for 15 min, 45.22 g of N,N,N-trimethyl-1-adamantylammonium hydroxide aqueous solution (mass fraction of 19.49%) and 1.59 g of aluminum oxide were added to the solution and stirred for 30 min, 35 g of solid silica gel (containing SiO2 mass fraction of 77.4%) was added, and the sol was stirred for dispersion at room temperature for 3 h, the sol was transferred to an autoclave, and crystallization was performed at 160 ℃ for 60 h, filtration, washing to pH = 7-8, drying at 120 ℃ for 12 h, and then calcination at 600 ℃ for 6 h to obtain sample A. The sample A was subjected to light hydrocarbon catalytic cracking reaction after hydrothermal aging at 800 ℃ for 17 h by using 100% water vapor.

[0028] The XRD spectrum of sample A is shown in Figure 1, having characteristic peaks at 9.5°, 13.0°, 16.1°, 17.9°, 20.8°, which proves that it is SSZ-13 molecular sieve. Figure 1 The SEM picture of sample A is shown in Figure 2.

[0029] The SEM picture of sample A is shown in Figure 2. Figure 2

[0030] The XRD spectrum of sample A after hydrothermal aging for 17h at 800℃ under 100% steam is shown in Figure 1. 27 The Al MAS NMR spectrum of sample A is shown in Figure 3, curve A. Figure 3

[0031] The physicochemical properties, conversion rate, propylene yield and other data of sample A are listed in Table 1.

[0032] Comparative Example 1

[0033] This comparative example illustrates the direct synthesis of phosphorus-free SSZ-13 molecular sieve and its physicochemical properties.

[0034] To 34.99g of deionized water, 1.26g of sodium hydroxide, 25.22g of N,N,N-trimethyl-1-adamantylammonium hydroxide solution (mass fraction of 19.49%) and 1.55g of sodium aluminate were added and stirred for 30min, then 20g of solid silica gel (containing SiO2 mass fraction of 77.4%) was added, and the sol was dispersed at room temperature for 3h, then the sol was transferred to a hydrothermal kettle, and crystallized at 160℃ for 60h, filtered, washed to pH=7-8, dried at 120℃ for 12h, then calcined at 600℃ for 6h, and then exchanged with soluble ammonium salt at 80℃ for 2h to obtain sample D1, which was subjected to light hydrocarbon catalytic cracking reaction after hydrothermal aging for 17h at 800℃ under 100% steam.

[0035] The XRD spectrum of sample D1 has characteristics of Figure 1 The SEM picture of sample D1 has characteristics of Figure 2

[0036] The XRD spectrum of sample D1 after hydrothermal aging for 17h at 800℃ under 100% steam is shown in Figure 1. 27 The Al MAS NMR spectrum of sample D1 is shown in Figure 3, curve D1. Figure 3

[0037] The physicochemical properties, conversion rate, propylene yield and other data of sample D1 are listed in Table 1.

[0038] Comparative Example 2

[0039] This comparative example illustrates the preparation of phosphorus-containing SSZ-13 molecular sieve modified by diammonium hydrogen phosphate and its physicochemical properties.

[0040] ​​​​The sample from Comparative Example 1, which was ion-exchanged with soluble ammonium salts and then dried and calcined, was used as the parent molecular sieve. 15g of the above molecular sieve (85.1wt% on a dry basis) was added to 20g of deionized water and ground into a paste. 0.25g of diammonium hydrogen phosphate was added, mixed evenly, and dried to obtain sample D2. Sample D2 was subjected to hydrothermal aging at 800℃ with 100% steam for 17h and then subjected to light hydrocarbon catalytic cracking reaction.

[0041] The XRD pattern of sample D2 has Figure 1 The characteristics of the scanning electron microscope images are: Figure 2 Its characteristics.

[0042] Sample D2 was subjected to hydrothermal aging at 800°C with 100% water vapor for 17 hours. 27 The Al MAS NMR spectrum is shown below. Figure 3 The D2 curve.

[0043] The physicochemical properties, microreactor evaluation conversion rate, propylene yield, and other data of sample D2 are listed in Table 1.

[0044] pass Figure 3 Medium sample A, control samples D1 and D2 27 A comparison of Al MAS NMR spectra reveals that four-coordinated framework aluminum was retained in all three samples after hydrothermal aging. Sample A's spectrum shows a stronger peak near 60 ppm, indicating more four-coordinated framework aluminum. Compared to sample D1, it exhibits a traditional "volcano" shape. Compared to sample D2, the aluminum coordination state is predominantly distorted four-coordinated aluminum. Figure 3 Based on the data in Table 1, it can be seen that the relative content of four-coordinated framework aluminum in the three samples is as follows: A>D1>D2. This indicates that the phosphorus-containing SSZ-13 molecular sieve synthesized in this invention has a higher proportion of four-coordinated framework aluminum content after hydrothermal treatment.

[0045] Example 2

[0046] Add 2.95g of diammonium hydrogen phosphate (mass fraction 85%) to 27.5g of deionized water and stir for 15min. Add 44.93g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide aqueous solution (mass fraction 19.49%) and 1.68g of gibbsite and stir for 30min. Then add 28.5g of solid silica gel (containing SiO2 mass fraction 77.4%) and stir to disperse at room temperature for 1h. Transfer the sol to a hydrothermal reactor and crystallize at 160℃ for 60h. Filter, wash to pH=7-8, dry at 120℃ for 12h, and then calcine at 600℃ for 6h to obtain sample B. After hydrothermal aging of sample B at 100% steam and 800℃ for 17h, carry out light hydrocarbon catalytic cracking reaction.

[0047] The XRD pattern of sample B has the characteristics of Figure 1 The SEM picture has the characteristics of Figure 2 .

[0048] The Al MAS NMR spectrum of sample B after hydrothermal aging at 800℃ for 17h under 100% steam has the characteristics of 27 the A curve in Figure 3 .

[0049] The physicochemical properties, micro-reaction evaluation conversion rate, propylene yield, etc. of sample B are listed in Table 1.

[0050] Example 3

[0051] To 47.6g of deionized water, 4.22g of aqueous phosphoric acid (mass fraction of 85%) was added, 2.85g of triethylamine solution (mass fraction of 99%) was added dropwise and stirred for 15min, 30.27g of N,N,N-trimethyl-1-adamantylammonium hydroxide aqueous solution (mass fraction of 19.49%) and 1.91g of aluminum oxide were added to the solution and stirred for 30min, then 24g of solid silica gel (containing SiO2 mass fraction of 77.4%) was added, and the sol was transferred to a hydrothermal kettle and crystallized at 160℃ for 60h, filtered, washed to pH = 7-8, dried at 120℃ for 12h, and then calcined at 600℃ for 6h to obtain sample C, which was subjected to light hydrocarbon catalytic cracking reaction after hydrothermal aging at 800℃ for 17h under 100% steam.

[0052] The XRD pattern of sample C has the characteristics of Figure 1 The SEM picture has the characteristics of Figure 2 .

[0053] The Al MAS NMR spectrum of sample C after hydrothermal aging at 800℃ for 17h under 100% steam has the characteristics of 27 the A curve in Figure 3 .

[0054] The physicochemical properties, micro-reaction evaluation conversion rate, propylene yield, etc. of sample C are listed in Table 1.

[0055] Example 4

[0056] To 24.08 g of deionized water, 4.75 g of diammonium hydrogen phosphate (85% by mass) was added and stirred for 15 min, to the solution, 39.41 g of N,N,N-trimethyl-1-adamantylammonium hydroxide aqueous solution (19.49% by mass) and 2.85 g of aluminum sulfate were added and stirred for 30 min, and then 25 g of solid silica gel (containing SiO2 at 77.4% by mass) was added and dispersed at room temperature for 1 h, the sol was transferred to an autoclave, and crystallization was performed at 160°C for 60 h, filtered, washed to pH = 7-8, dried at 120°C for 12 h, and then calcined at 600°C for 6 h to obtain sample D, which was subjected to light hydrocarbon catalytic cracking reaction after hydrothermal aging at 100% water vapor, 800°C for 17 h.

[0057] The XRD pattern of sample D had characteristics of Figure 1 , and the scanning electron microscope picture had characteristics of Figure 2 .

[0058] The Al MAS NMR spectrum of sample D after hydrothermal aging at 100% water vapor, 800°C for 17 h had characteristics of 27 . Figure 3 .

[0059] The physicochemical properties, micro-reaction evaluation conversion rate, propylene yield, and the like of sample D are shown in Table 1.

[0060] Comparative Example 3

[0061] This comparative example illustrates the preparation of a phosphorus-modified SSZ-13 molecular sieve and its physicochemical properties.

[0062] To 33.47 g of deionized water, 0.89 g of sodium hydroxide, 15.13 g of N,N,N-trimethyl-1-adamantylammonium hydroxide solution (19.49% by mass), and 0.66 g of sodium aluminate were added and stirred for 30 min, and then 12 g of solid silica gel (containing SiO2 at 77.4% by mass) was added and dispersed at room temperature for 3 h, the sol was transferred to an autoclave, and crystallization was performed at 160°C for 72 h, filtered, washed to pH = 7-8, dried at 120°C for 12 h, and then calcined at 600°C for 6 h, and then exchanged with a soluble ammonium salt at 80°C for 2 h to obtain a H-type molecular sieve sample. 10 g of the H-type molecular sieve (molecular sieve dry basis 83.5 wt%) was added to 12 g of deionized water, ground to a paste, 0.28 g of diammonium hydrogen phosphate was added, and mixed uniformly, and after drying, sample D3 was obtained, which was subjected to light hydrocarbon catalytic cracking reaction after hydrothermal aging at 100% water vapor, 800°C for 17 h.

[0063] The XRD pattern of sample D3 had characteristics of Figure 1 , and the scanning electron microscope picture had characteristics of Figure 2 .

[0064] Sample D3 after hydrothermal aging at 100% steam, 800°C for 17h 27 The Al MAS NMR spectrum has characteristics of Figure 3 the curve of D2.

[0065] The physicochemical properties, micro-reaction evaluation conversion, propylene yield, etc. of sample D3 are listed in Table 1.

[0066] Example 5

[0067] To 66.06 g of deionized water, 7.51 g of aqueous phosphoric acid (mass fraction 85%) was added, 3.91 g of ammonia water (mass fraction 25%) was added dropwise and stirred for 15 min, 44.10 g of N,N,N-trimethyl-1-adamantylammonium hydroxide aqueous solution (mass fraction 19.49%) and 4.88 g of SB powder (containing Al2O3 mass fraction 70.6%) were added to the solution and stirred for 30 min, then 30 g of white carbon black (containing SiO2 mass fraction 81.5%) was added, and the dispersion was stirred at room temperature for 3 h, the sol was transferred to a hydrothermal kettle, and crystallization was carried out at 160°C for 60 h, filtered, washed to pH = 7-8, dried at 120°C for 12 h, and then calcined at 600°C for 6 h to obtain sample E. Sample E after hydrothermal aging at 100% steam, 800°C for 17h was subjected to light hydrocarbon catalytic cracking reaction.

[0068] The XRD spectrum of sample E has characteristics of Figure 1 The scanning electron microscope picture has characteristics of Figure 2 .

[0069] Sample E after hydrothermal aging at 100% steam, 800°C for 17h 27 The Al MAS NMR spectrum has characteristics of Figure 3 the curve of A.

[0070] The physicochemical properties, micro-reaction evaluation conversion, propylene yield, etc. of sample E are listed in Table 1.

[0071] Comparative Example 4

[0072] This comparative example illustrates the preparation of phosphorus-modified SSZ-13 molecular sieve and its physicochemical properties.

[0073] Add 0.12g sodium hydroxide, 18.92g N,N,N-trimethyl-1-adamantyl ammonium hydroxide solution (mass fraction 19.49%), and 2.68g sodium aluminate to 30.05g deionized water and stir for 30min. Then add 15g solid silica gel (containing 77.4% SiO2 by mass) and stir to disperse at room temperature for 3h. Transfer the sol to a hydrothermal reactor and crystallize at 165℃ for 72h. Filter, wash to pH=7-8, dry at 120℃ for 12h, then calcine at 600℃ for 6h, and then exchange with soluble ammonium salt at 80℃ for 2h to obtain H-type molecular sieve sample. Take 10g of H-type molecular sieve (88.3wt% on dry basis) and add 12g of deionized water. Grind into a paste, add 0.21g of diammonium hydrogen phosphate, mix evenly, and dry to obtain sample D4. After hydrothermal aging at 800℃ with 100% steam for 17h, sample D4 is subjected to light hydrocarbon catalytic cracking reaction.

[0074] The XRD pattern of sample D4 has Figure 1 The characteristics of the scanning electron microscope images are: Figure 2 Its characteristics.

[0075] Sample D4 after hydrothermal aging at 800°C with 100% water vapor for 17 hours 27 Al MAS NMR spectrum has Figure 3 Characteristics of the D2 curve.

[0076] The physicochemical properties, microreactor evaluation conversion rate, propylene yield, and other data for sample D4 are listed in Table 1.

[0077] Example 6

[0078] Add 1.81g of ammonium dihydrogen phosphate (85% by mass) to 56.83g of deionized water and stir for 15min. Add 36.75g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide aqueous solution (19.49% by mass) and 1.21g of SB powder (containing 70.6% Al2O3 by mass) to the solution and stir for 30min. Then add 28.5g of silica (containing 81.5% SiO2 by mass) and stir to disperse at room temperature for 3h. Transfer the sol to a hydrothermal reactor and crystallize at 160℃ for 60h. Filter, wash to pH=7-8, dry at 120℃ for 12h, and then calcine at 600℃ for 6h to obtain sample F. After hydrothermal aging at 800℃ with 100% steam for 17h, sample F is subjected to light hydrocarbon catalytic cracking reaction.

[0079] The XRD pattern of sample F has Figure 1 The characteristics of the scanning electron microscope images are: Figure 2 Its characteristics.

[0080] Sample F after hydrothermal aging at 100% steam, 800°C for 17h 27 The Al MAS NMR spectrum has Figure 3 The characteristic of curve B.

[0081] The physicochemical properties, micro-reaction evaluation conversion rate, propylene yield, etc. of sample F are listed in Table 1.

[0082] Table 1

[0083] Molecular sieve number A D1 D2 B C D D3 E D4 F Crystallinity / % 85 86 82 91 85 80 83 81 79 81 n(Si02) / n(Al203) 25 25 25 30 15 35 35 10 10 42 P2O5 content / wt% 1.02 0 1.02 1.25 1.42 1.63 1.63 1.18 1.18 1.52 S BET (m 2 / g)]]> 631 588 484 633 590 509 471 572 492 579 S1 / S2 1.08 0.79 0.45 0.91 1.07 1.18 0.58 1.48 0.51 1.21 Micro-reversion / % 89 70 79 92 85 82 76 98 83 80 Ethylene yield / % 2.8 0.9 0.7 2.8 2.4 2.6 0.7 2.7 1.0 2.5 Propylene yield / % 20.0 15.1 18.0 21.5 19.6 18.9 17.8 24.1 18.5 18.0 Butene yield / % 27.3 20.2 23.5 29.4 26.7 25.4 22.5 31.3 23.8 24.5 Total light olefin yield / % 50.1 36.2 42.2 53.7 48.7 46.9 41.0 58.1 43.3 45.0

[0084] As can be seen from the data in Table 1, the ratio of the content of four-coordinated framework aluminum to the content of five-coordinated non-framework aluminum of the phosphorus-containing SSZ-13 molecular sieve synthesized in the application is higher than that of the comparative samples D1-D4. In the probe reaction of catalytic cracking of 1-octene, the phosphorus-containing SSZ-13 molecular sieve (A) synthesized in situ in the application exhibits excellent reaction conversion rate and propylene and low-carbon olefin yield performance, while the reaction conversion rate and low-carbon olefin yield of the SSZ-13 molecular sieve (D1) without phosphorus are significantly lower, and the reaction conversion rate of the SSZ-13 molecular sieve (D2, D3, D4) without phosphorus synthesized and modified by phosphorus is slightly improved, but the propylene and low-carbon olefin yield is still low.

Claims

1. A phosphorus-containing SSZ-13 molecular sieve, characterized in that, The ratio of tetracoordinated framework aluminum to pentacoordinated non-framework aluminum in the aluminum coordination state of the molecular sieve after treatment with 100% steam at 800℃ for 17 hours is 0.8 to 2. The aluminum coordination state of the molecular sieve is measured by solid magic angle rotating nuclear magnetic resonance method.

2. The molecular sieve according to claim 1, wherein, The phosphorus content is 0.1 wt% to 3 wt%, calculated as P2O5 and based on the dry weight of the molecular sieve.

3. The molecular sieve according to claim 1, wherein, The phosphorus content is 0.8 wt% to 2 wt%, calculated as P2O5 and based on the dry weight of the molecular sieve.

4. The molecular sieve according to claim 1, wherein the molar ratio of silicon oxide to aluminum oxide is 5 to 50.

5. The molecular sieve according to claim 1, wherein the molar ratio of silicon oxide to aluminum oxide is 10 to 35.

6. The molecular sieve according to claim 1, after being treated at 800°C and 100% steam for 17 hours, has a ratio of 0.9 to 1.5 of the content of the four-coordinated framework aluminum to the content of the five-coordinated non-framework aluminum.

7. The in-situ synthesis method of the phosphorus-containing SSZ-13 molecular sieve according to claim 1, characterized in that... include: After mixing phosphorus source, water, and additives, template agent R and aluminum source are added sequentially and mixed evenly to obtain mixture I; silicon source is added to mixture I and mixed evenly to obtain mixture II; mixture II is subjected to hydrothermal crystallization and the product is recovered to obtain SSZ-13 molecular sieve; wherein, the phosphorus source is calculated as P2O5, the aluminum source is calculated as Al2O3, and the additive is at least one of ammonia, diethylamine, and triethylamine; the molar ratio of each component in mixture II is P2O5: additive: template agent R: Al2O3: SiO2: H2O = 0.1~3: 0~5: 0.4~10: 1: 5~50: 50~1000.

8. The synthesis method according to claim 7, wherein, The phosphorus source is at least one of phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and phosphorus pentoxide; and when the phosphorus source is phosphoric acid, an additive needs to be added, the additive being at least one of ammonia, diethylamine, and triethylamine.

9. The synthesis method according to claim 7, wherein, The aluminum source is selected from at least one of SB powder, aluminum alkoxide, aluminum oxide, aluminum hydroxide, aluminum sulfate, and gibbsite.

10. The synthesis method according to claim 7, wherein, The template agent is N,N,N-trimethyl-1-adamantyl ammonium hydroxide, and is an aqueous solution with a mass fraction of 15-30%.

11. The synthesis method according to claim 7, wherein, The silicon source is selected from at least one of silica sol, silicon dioxide, silicate, and solid silica gel.

12. The synthesis method according to claim 7, wherein, The hydrothermal crystallization conditions are crystallization at 140℃~200℃ for 18h~168h.

13. The application of the phosphorus-containing SSZ-13 molecular sieve of claim 1 as an active component in catalytic cracking and catalytic pyrolysis as a catalyst or auxiliary.

14. The application according to claim 13, wherein, The phosphorus-containing SSZ-13 molecular sieve, after being treated with 100% steam at 800℃ for 17 hours, has an aluminum coordination state in which the ratio of tetracoordinated framework aluminum to pentacoordinated non-framework aluminum is 0.9–1.5, the phosphorus content is 0.8 wt%–2 wt%, and the molar ratio of silicon oxide to aluminum oxide is 10–35.

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