An insitu synthesis method of a microsphere catalyst used for converting oxygen compound to olefine

Method for in situ synthesis of oxygenate conversion to olefin microsphere catalyst

FIELD

The invention relates to a preparation method of a microsphere catalyst containing a SAPO molecular sieve.

The invention further relates to the catalytic use of the above catalysts in the conversion of oxygenates to light olefins. Background technique

Ethylene and propylene in light olefins are the basic organic raw materials in the modern chemical industry, and their demand will increase. The traditional route for the production of ethylene and propylene is produced by cracking naphtha. The disadvantage of this route is that it is overly dependent on oil. For oil, there is a problem of rising prices and unstable supply in a short period of time; in the long run, there are limited reserves of resources, which leads to the problem of "oil crisis". The production of low-carbon olefins such as ethylene or propylene from natural gas or coal via methanol is the most promising alternative to the naphtha route to olefins. Natural gas (or coal) Single-series, large-scale industrialization technology for the production of methanol is very mature, so the research on the production of olefins from methanol has become a key technology for the production of low-carbon olefins from non-oil routes.

In 1984, the United States Carbide Corporation (UCC) issued a new series of silicoaluminophosphate molecular sieves (SAPO-n) (USP 4440871), a class of crystalline silicoaluminophosphates, by P0₄+, A10₄"> and Si0₄The tetrahedron constitutes a three-dimensional skeleton structure. With the advent of silicoaluminophosphate series molecular sieves, such small pores and moderately acidic molecular sieves have been used for MTO reactions such as SAPO-17, SAPO-18, SAPO-34, SAPO-44, etc. (US 4,499,327). Their pore size is about 0.43 nm, which is a good type of shape-selective catalyst. Among them, SAPO-34 molecular sieve has become a hot spot in current research because of its excellent acidity and pore structure and excellent catalytic performance in MTO reaction. Using SAPO-34 molecular sieve as catalyst, in 1995 UOP Company of Norway and Norsk Hydro Company of Norway completed the MTO fluidized bed pilot test for 0.5 t / d methanol. In the same year, the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences completed the synthesis gas. Pilot test for the preparation of light olefins via dimethyl ether.

The MTO process using a fluidized bed mode of operation requires that the catalyst be a microsphere with a suitable particle size distribution and high attrition. So far, it has been reported in the literature that MTO fluidized bed catalysts are prepared by spray drying. The preparation method comprises the steps of: mixing the active component SAPO-34 molecular sieve with a binder such as clay, silica alumina sol or the like to form a uniform slurry, followed by spray drying. The elemental composition of these catalysts was analyzed and consisted essentially of silica, alumina and phosphorous oxide. A method for spray drying a slurry of SAPO-34 molecular sieve, kaolin and silica sol is reported, for example, in USP 5,248,647; USP 6,153,552 discloses a method for preparing a microsphere catalyst comprising a SAPO molecular sieve, which is a SAPO molecular sieve, an inorganic oxide sol, And phosphorus-containing compound mixing and spray drying; USP6787501 reports that SAPO-34 molecular sieve, binder and matrix material are spray-dried to prepare catalyst for methanol conversion; CN01 132533A reports preparation of wear-resistant catalyst for methanol conversion It is an effect of increasing catalyst wear by reducing the mass content of the molecular sieve in the catalyst. So far, no SAPO molecular sieves have been synthesized directly on the silicon phosphorus aluminum microspheres 5, and they have been reported for the MTO process. Summary of the invention

It is an object of the present invention to provide a process for the direct synthesis of an oxygenate-converted olefin microsphere catalyst. In order to achieve the above object, the technical solution of the present invention is to provide a method for in situ synthesis of an oxygen-containing compound to be converted into a 10 olefin microsphere catalyst, which is characterized in that first, a silicon-containing phosphorus-aluminum oxide-containing microparticle is prepared by a spray drying method. The ball is then hydrothermally synthesized to grow the SAPO molecular sieve in situ on the surface and in the body of the microsphere.

The method described is as follows:

a mixing silicon, aluminum and phosphorus raw materials, through a colloid mill for grinding, using a spray drying method to obtain silicon phosphorus aluminum oxide microspheres;

\ 5b The silicon phosphorus aluminum oxide microspheres are calcined, mixed with the templating agent and water, sealed and heated to the crystallization temperature, and subjected to constant temperature crystallization under autogenous pressure; after the crystallization is completed, the solid product is separated and washed to the middle. Sex, and dry;

c The sample obtained in step b is calcined in air at 500-700 ° C for 3-8 hours to obtain a microsphere catalyst containing a SAPO molecular sieve.

The more specific preparation process of the method is as follows:

Ch mixing silicon, aluminum and phosphorus raw materials, colloid grinding, and grinding, preparing silicon phosphorus aluminum oxide microspheres by spray drying;

b The silicon phosphorus aluminum oxide microspheres are calcined, mixed with the metered templating agent and water, and placed in a stainless steel synthetic kettle lined with polytetrafluoroethylene, sealed and heated to the crystallization temperature, and subjected to autothermal pressure. After the crystallization is completed, the solid product is separated by centrifugation, washed with deionized water to neutrality, and air-dried at 12 CTC;

5c The sample obtained in step b is calcined in air at 500-700 ° C for 3-8 hours to obtain a microsphere catalyst containing a SAPO molecular sieve.

In the method, the amorphous silicon phosphorus aluminum oxide microsphere prepared by the spray drying method has a molar ratio of oxides of each component:

Si0₂/Al₂0₃ = 0.1-10.0;

0 Ρ₂Ο₅/ Α1₂Ο₃ = 0.2~ 2·0. In the method, in the step a, the silicon source is a mixture of one or more of silica sol, active silica, orthosilicate or kaolin; the aluminum source is aluminum salt, activated alumina, a mixture of one or more of aluminum oxyhydroxide, pseudo-boehmite, pseudoboehmite or kaolin; phosphorus source is orthophosphoric acid, ammonium hydrogen phosphate, dihydrogen phosphate, organic phosphide or phosphorus oxide a mixture of one or several.

In the method, in the step b, the baking temperature of the silicon phosphorus aluminum oxide microspheres before crystallization is 300-

700 ° C o

In the method described, in the step b, the templating agent used is all organic nitrogen compounds for hydrothermal synthesis of SAPO molecular sieves: diethylamine, triethylamine, n-propylamine, isopropylamine, tri-n-propylamine, three Isopropylamine, di-n-propylamine, diisopropylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, 1,6-hexanediamine, cyclohexylamine, morpholine, ethanolamine, two A mixture of one or more of ethanolamine, triethanolamine, or N, N, N, N-tetramethyl-1,6-hexanediamine.

In the method, in the step b, the template dosage according to the volume ratio is: templating agent/silicon phosphorus aluminum oxide microspheres of 0.3 to 3.

In the method described, in the step b, the amount of water used is in a volume ratio: water/template agent=0~2. In the method, in the step b, the crystallization temperature is ΙδΟ ΖδΟ^, and the crystallization time is 2~150h. In the method, the SAPO molecular sieve in the microsphere catalyst synthesized is SAPO-5, -11, -17, -18, -31, -34, -35, -37, -40, -41, -42 , -44, -56.

In the method, the synthesized microsphere catalyst containing SAPO molecular sieve has a multi-stage pore structure.

In the method described, the synthesized SAPO molecular sieve-containing microsphere catalyst is used for the conversion of an oxygenate to an olefin.

In the method of the invention, since the molecular sieve is grown in situ on the surface and in the body of the microsphere, the synthesis method simplifies the preparation process of the catalyst and reduces the production cost of the catalyst. DRAWINGS

Figure 1 : SEM photograph of a sample of Examples 1, 2, 3, 4 of the present invention;

Figure 2: XRD spectra of samples of Examples 1, 2, and 3 of the present invention;

Figure 3: XRD spectrum of a sample of Example 4 of the present invention;

Figure 4: Nitrogen adsorption isotherm of a sample of Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION The method of the present invention is characterized in that microspheres of silicon phosphorus aluminum oxide are first prepared by spray drying, and then SAPO molecular sieves are grown on the surface and in vivo of the microspheres by in situ hydrothermal synthesis.

The method of the invention is characterized in that the amorphous silicon phosphorus aluminum oxide microspheres used have a molar ratio of each component oxide - Si0₂/AI₂0₃ = 0.1-10.0;

Ρ₂Ο₅/ Α1₂Ο₃ = 0·2~ 2.0.

The preparation process of the direct synthesis oxygenate-converting olefin microsphere catalyst provided by the method of the invention is as follows: a mixing raw materials containing silicon, aluminum and phosphorus, grinding by colloid mill, and preparing silicon phosphorus aluminum oxide by spray drying method Microspheres;

The silicon phosphorus aluminum oxide microspheres are calcined at 300-700 ° C, and mixed with the metering template and water (volume ratio: templating agent / silicon phosphorus aluminum oxide microspheres = 0.3 to 3; water / templating agent = 0~ 2), placed in a stainless steel synthetic kettle lined with polytetrafluoroethylene, sealed and heated to the crystallization temperature (150~250^QC), under constant pressure, perform constant temperature crystallization (2~150h). After the crystallization is completed, the solid product is centrifuged, washed with deionized water to neutrality, and air dried at 120 ° C; c The sample obtained in step b is calcined in air at 500-700 ° C for 3-8 hours. A microsphere catalyst containing a SAPO molecular sieve was obtained.

In the above process, the silicon source is a mixture of one or more of silica sol, active silica, orthosilicate or kaolin; the aluminum source is aluminum salt, activated alumina, aluminum oxyhydroxide, pseudo-boehmite, a mixture of one or more of pseudoboehmite or kaolin; the phosphorus source is a mixture of one or more of orthophosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, organic phosphide or phosphorus oxide; The agent may be any organic nitrogen-containing compound for hydrothermal synthesis of SAPO molecular sieves, such as diethylamine, triethylamine, n-propylamine, isopropylamine, tri-n-propylamine, triisopropylamine, di-n-propylamine, diisopropylamine, tetramethyl Ammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, 1,6-hexanediamine, cyclohexylamine, morpholine, ethanolamine, diethanolamine, triethanolamine, or N', N, N , a mixture of one or more of N_tetramethyl-1,6-hexanediamine, and the like.

The SAPO molecular sieve in the SAPO molecular sieve-containing microsphere catalyst prepared by the method provided by the invention may be SAPO-5, -11, -17, -18, -31, -34, -35, -37, -40, -41 , -42, -44, -56.

The invention is described in detail below by way of examples.

Example 1

The solid content of the oxide is 30% by weight, and the molar ratio of each raw material is Si. _: Al : P = 0.3: l : l calculation, will measure the phosphoric acid (H₃P0₄Content 85wt%), pseudo-boehmite (A1₂0₃Content 70wt%) and silica sol (Si0₂The content of 30% by weight) was added to deionized water in sequence. After stirring for 30 min, the colloid mill was subjected to rubber grinding so that the solid particle diameter in the finally obtained slurry was 70% less than 5 μm. Spray drying was carried out to obtain a silicon phosphorus aluminum oxide microsphere, which was designated as MS-1. Example 2

The microsphere obtained in Example 1 was passed through 400.^QAfter calcination, it was placed in a stainless steel synthesis vessel lined with polytetrafluoroethylene, and then triethylamine and deionized water were added in a volume ratio of water/triethylamine/microsphere = 0.5/1/1. The synthesis kettle was sealed and placed in an oven for crystallization at 453 for 12 hours. After the crystallization was completed, it was separated, washed, and dried to obtain a synthetic sample, which was designated as MS34-1. The sample was calcined at 600 ° for 4 h to obtain a microsphere catalyst. Sample SEM photographs and XRD spectra are shown in Figures 1 and 2, respectively. It can be seen that tetragonal small crystal grains are grown on the surface of the microspheres and in the body, which is a typical crystal appearance of SAPO-34. The XRD spectrum is 9.6 at 2theta^GThere is a weak diffraction peak on the left and right, which is the characteristic diffraction peak of SAPO-34. Example 3

The microsphere obtained in Example 1 was passed through 600.^QAfter calcination, it was placed in a stainless steel synthesis vessel lined with polytetrafluoroethylene, and then cyclohexylamine and deionized water were added in a volume ratio of water/cyclohexylamine/microsphere = 1/1.5/1. The synthesis kettle was sealed and placed in an oven for crystallization at 453 for 12 hours. After the crystallization was completed, it was separated, washed, and dried to obtain a synthetic sample, which was designated as MS 17-1. Sample via 600^QA microsphere catalyst was obtained after C was calcined for 4 hours. Sample SEM photographs and XRD spectra are shown in Figures 1 and 2, respectively. It can be seen that the XRD spectrum is 7.7 at 2theta^QThere is a weak diffraction peak on the left and right, which is the characteristic diffraction peak of SAPO-17. Example 4

The solid content of the oxide is 30% by weight, and the molar ratio of each raw material is Si. _: Al : P=4_:l : l calculation, will measure the phosphoric acid (H₃P0₄Content 85wt%), pseudo-boehmite (A1₂0₃Content 70wt%) and silica sol (Si0₂The content of 30 wt%) was added to deionized water in sequence. After stirring for 30 min, the colloid mill was subjected to rubber grinding so that the solid particles in the resulting slurry had a diameter of 70% less than 5 μm. Spray drying was carried out to obtain silicon phosphorus aluminum oxide microspheres, which were designated as MS-2. Microspheres through 500^QAfter calcination, the mixture was placed in a stainless steel synthesis vessel lined with a polytetrafluoroethylene liner, and a templating agent, diethylamine, was added in a volume ratio of microspheres/template ice = 1/1/0.5. The synthesis kettle was sealed and placed in an oven for crystallization at 453 K for 12 hours. After the crystallization was completed, the mixture was separated, washed, and dried to obtain a synthetic sample, which was designated as MS34-2. Sample via 600^DA microsphere catalyst was obtained after C was calcined for 4 hours. Sample SEM photographs and XRD spectra are shown in Figures 1 and 3, respectively. As you can see, the XRD spectrum is 9.6 at 2theta.^QThere is a weak diffraction peak on the left and right, which is the characteristic diffraction peak of SAPO-34. Example 5

The MS34-1 sample obtained in Example 2 was subjected to EDX characterization to determine the elemental composition of the SAPO-34 molecular sieve in the microsphere catalyst, and the result was Al: Si: P = 1.0 : 0.23 : 1.51 (molar ratio). Will be 400^QSamples of C-fired MS-1 and MS34-1 were subjected to nitrogen physical adsorption experiments, and the results are shown in Table 1 and Figure 4. The adsorption isotherm of MS34-1 shows that after in-situ crystallization, the mesoporous structure also appears in the microspheres, indicating that the synthesized microsphere catalyst containing SAPO-34 molecular sieve has a multi-stage pore structure.

Table 1 Specific surface area of ​​the sample

Sample BET specific surface area

MS-1 3.49 m²/g

MS34-1 68.8 m²/g

Example 6

The MS34-1 sample obtained in Example 2 was subjected to methanol conversion to olefin reaction, and 2.5 g of a sample of 20-40 mesh particle catalyst was separately taken, charged into a fixed bed reactor, activated by nitrogen at 550 Torr for 1 hour, and then cooled to The reaction was carried out at 450 °C. Using a micro pump feed, 40% methanol aqueous solution, methanol weight space velocity 2.01 ^. The composition of the reaction product was analyzed by on-line gas chromatography, and the results are shown in Table 2. It can be seen that the selectivity of ethylene plus propylene in the reaction product can be as high as 89%.

Table 2 Methanol conversion of MS34-1 sample to olefin reaction result reaction time (min)

Product distribution

4 40 75 110 145 180

CH₄ 1.01 1.27 1.37 1.4 1.42 1.51

C2H4 41.23 46.29 47.5 49.7 50.49 50.95

C₂H6 0.36 0.57 0.58 0.47 0.42 0.41

C3H6 39.12 38.99 38.9 38.64 38.93 38.9

C₃H₈ 2.31 1.4 1.07 1.1 0.95 0.91

C₄+ 12.43 9.06 8.35 6.59 6.04 5.65 c₅+ 2.96 2.42 2.21 2.1 1.75 1.67 c₆+ 0.59 0 0.04 0 0 0 Conversion rate (%) 100 100 100 100 100 98.7

∑c₂⁼-c₃= 80.35 85.28 86.4 88.34 89.42 89.85