CN1456502A - Preparation of silicon aluminum phosphoric molecular sieves and preparation thereof - Google Patents

Abstract

The invention relates to a preparation method of aluminophosphosilicate molecular sieve catalyst, specifically a method for synthesizing SAPO-41 silicon aluminophosphate molecular sieve. Synthetic colloid is made, the temperature of gelation is 10-50 DEG C, and then the synthetic colloid is hydrothermally crystallized under the condition of 160-230 DEG C and hydrothermal crystallization under self-generated pressure for 15-300 hours, and the product is recovered. The method of the invention uses reactants with general purity as raw materials, uses relatively low content of conventional templates, and uses short crystallization time to synthesize pure-phase SAPO-41 silicoaluminophosphate molecular sieve with high crystallinity.

Description

Preparation method of silicoaluminophosphate molecular sieve

Technical field

The technical solution claimed in the present invention relates to the preparation method of aluminophosphosilicate (SAPO compound) molecular sieve catalyst, specifically the synthesis method of silicoaluminophosphate molecular sieve SAPO-41.

Background technique

The framework of silicoaluminophosphate molecular sieve SAPO-41 is composed of Si, P, Al and O elements, and the International Zeolite Society named it AFO. The silicoaluminophosphate molecular sieve SAPO-41 has a one-dimensional ten-membered ring channel system, the channel is elliptical, the free diameter is 0.70×0.43 nm, and it belongs to the orthorhombic crystal system, and the unit cell size is a=0.97, b=2.55, c=0.84 nm . Due to the existence of Si-O-Al links in the framework structure of SAPO-41, the molecular sieve is acidic. SAPO-41 showed good catalytic activity and selectivity for the alkylation of aromatic hydrocarbons. At the same time, because the size and geometric configuration of the SAPO-41 pore structure are very favorable for the formation of single-branched alkane isomers, the Pt-Pd/SAPO-41 silicoaluminophosphate molecular sieve catalyst loaded with platinum and palladium metal can be used in the formation of long-chain alkane It shows excellent catalytic performance in isomerization reaction.

US.4440871 reported the synthesis method of SAPO-41 silicoaluminophosphate molecular sieve, using pseudoboehmite as the aluminum source, phosphoric acid as the phosphorus source, white carbon black as the silicon source, and the template used for synthesis is tetrabutylammonium hydroxide -- -tetra-n-butylammoniumhydroxide(TBAOH) and di-n-propylamine---di-n-propylammine(DPA). Because molecular sieves such as SAPO-11 with AEL structure, SAPO-31 with ATO structure, SAPO-39 with ATN structure, and SAPO-43 with GIS structure can be synthesized by di-n-propylamine (DPA) as a template, they are extremely Easy symbiosis, therefore, the main problem encountered in the method used in US.4440871 is that SAPO-41 is difficult to synthesize, especially difficult to obtain a pure phase. Literature "Silicoaluminophosphate molecular sieve SAPO-11.SAPO-31 and SAPO-41: synthesis and characterization and alkylation of toluene with methanol" (Microporous Materials: 1996, 6, 89) and "Multinuclear MAS NMR study on the microporous aluminophosphate1 AlPO ₄ -4 andSAPO-41" (J.Chem.Soc.Faraday Trans., 1998, 94 (5), 723) reported the synthesis of SAPO-41 by adding seed crystals in the crystallization mixture. The main deficiency of this method is that the template agent The demand for n-propylamine is large, and the molar ratio is about 3.0 to 4.0; the article "Synthesis and characterization of SAPO-41: effect of the silicon content and the crystalsize on the hydroisomerization of n-octane over Pt-Pd/SAPO-41" (Microporous and MesoporousMater.1998, 26, 161) reported the use of high-purity reactants as raw materials, especially extremely high requirements for the purity of the template agent di-n-propylamine, and the high-purity raw materials have a high cost and cannot be mass-produced. In addition, the crystallization time of the above method is generally more than 2 days.

The technical problem to be solved by the present invention is to provide a pure phase SAPO-41 silicophosphoric acid with high crystallinity synthesized with a reactant of general purity as a raw material, with a lower content of a conventional template, and with a shorter crystallization time. Aluminum molecular sieve method.

The technical scheme adopted by the present invention to solve the technical problem is: the steps of the preparation method of the silicon aluminum phosphate molecular sieve of the present invention are: firstly mix the silicon source, the aluminum source, the phosphorus source, the organic templating agent and water to uniformly make a synthetic colloid, and form a synthetic colloid. The temperature during the gelation is 10-50 DEG C, and then the synthetic colloid is hydrothermally crystallized under the condition of 160-230 DEG C and autogenous pressure for 15-300 hours, and the product is recovered.

In the method of the present invention, wherein said phosphorus source is the compound of phosphorous acid, trivalent phosphorus and the compound of phosphoric acid, pentavalent phosphorus or uses phosphorous acid-phosphoric acid as dual phosphorus source; Aluminum source is pseudoboehmite, isopropyl Aluminum alcohol, aluminum hydroxide, aluminum oxide and aluminum salts; silicon source is silica gel, silica sol, silicon aerogel (fume silica) white carbon black or tetraethyl silicate; organic template is di-n-propylamine, Diisopropylamine, di-n-butylamine, diethylamine, formyldipropylamine, or tetrabutylammonium hydroxide.

In the method of the present invention, it is preferable to use phosphorous acid as the phosphorus source or phosphorous acid-phosphoric acid as the dual phosphorus source, pseudo-boehmite as the aluminum source, silica sol as the silicon source, and di-n-propylamine or tetrabutylammonium hydroxide as the template.

In the method of the present invention, the organic template is preferably di-n-propylamine.

In the method of the present invention,

I. When phosphorous acid is used as the phosphorus source, silicon source --- SiO ₂ , aluminum source --- Al ₂ O ₃ , phosphorus source --- P ₂ O ₃ , organic template agent ---R and water --- -H ₂ O synthesizes colloids according to the following molar ratio, SiO ₂ : Al ₂ O ₃ : P ₂ O _{3 :} R: H ₂ O=(0.05～0.30):(0.5～1.2):(0.75～1.5):( 1.0 to 5.0): (25 to 190.8), preferably SiO ₂ : Al ₂ O ₃ : P ₂ O ₃ : R: _{H 2} O = (0.10 to 0.20): (0.75 to 1.20): (1.00 to 1.25): ( 1.5～4.0): (50～143.8);

II. When using phosphorous acid-phosphoric acid as the dual phosphorus source, the silicon source --- SiO ₂ , the aluminum source --- Al ₂ O ₃ , the phosphorus source --- P ₂ O ₃ , the organic template --- R and Water---H ₂ O synthesizes colloids according to the following molar ratio, SiO ₂ : _{Al 2} O ₃ : P ₂ O ₃ : P ₂ O ₅ : R: _{H 2} O=(0.05～0.30):(0.5～1.2) :(0.25～1.25):(1.5～0.25):(1.0～5.0):(25～190.8), preferably SiO ₂ :Al ₂ O ₃ : _{P 2} O ₃ :P ₂ O ₅ :R:H ₂ O= (0.10～0.20):(0.75～1.20):(0.35～1.00):(1.00～0.35):(1.5～4.0):(50～95.4);

In the method of the present invention, the addition order of said phosphorus source, aluminum source, silicon source and organic template is according to the order of aluminum source, phosphorus source, silicon source, organic template, or aluminum source, organic template, phosphorus source , the order of the silicon source, or the order of the phosphorus source, the organic template agent, the aluminum source, and the silicon source.

In the method of the present invention, it is preferred to perform hydrothermal crystallization at 190-200° C. and autogenous pressure for 19-72 hours and recover the product.

In the method of the present invention, it is preferred that the temperature during gel formation is 20-35°C.

The beneficial effect of the present invention is: the silicon source that adopts in the synthetic method of SAPO-41 molecular sieve provided by the present invention, aluminum source, phosphorus source and organic templating agent are all determined according to existing technical specification, and the present invention to its There are no special restrictions, so the cost of raw materials is low, and a pure-phase SAPO-41 molecular sieve product with high crystallinity can be synthesized in a short period of time (19 hours) with a relatively low content of template agent (the minimum molar ratio is about 1.0-1.5).

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the scanning electron micrograph of the product SAPO-41 gained in embodiment 1 of the present invention

Fig. 2 is the scanning electron micrograph of the product SAPO-41 obtained in embodiment 6 of the present invention

Fig. 3 is the powder X-ray diffractogram (XRD) of product SAPO-41 obtained in embodiment 1 of the present invention

Fig. 4 is the powder X-ray diffraction pattern (XRD) of product SAPO-41 obtained in Example 2 of the present invention

Fig. 5 is the powder X-ray diffraction pattern (XRD) of product SAPO-41 obtained in embodiment 3 of the present invention

Detailed ways

The following examples will further illustrate the present invention.

Example 1

At 25°C, dissolve 1.91 g of phosphorous acid in 10 ml of water, pour the phosphorous acid aqueous solution into 1.55 g of pseudo-boehmite solid powder and stir rapidly, then add 0.395 ml of silica sol (5.9MSiO ₂ ), and stir 6.38 ml of DPA (di-n-propylamine) was added, stirred until uniform, then transferred to a 30 ml stainless steel reactor for crystallization at 200°C for 216 hours. The generated product detection results are shown in the scanning electron microscope photo of the product SAPO-41 obtained in Fig. 1 and the powder X-ray diffraction pattern (XRD) of the product SAPO-41 obtained in Fig. 3 .

Example 2

At 25°C, dissolve 1.91 g of phosphorous acid in 10 ml of water, pour the phosphorous acid aqueous solution into 1.55 g of pseudo-boehmite solid powder and stir rapidly, then add 0.198 ml of silica sol (5.9MSiO ₂ ), and stir Add 4.78 ml of DPA (di-n-propylamine), stir until uniform, then transfer to a 30 ml stainless steel reaction kettle for crystallization at 180°C for 168 hours. The generated product testing results are shown in Figure 4 for the powder X-ray diffraction pattern (XRD) of the product SAPO-41 obtained.

Example 3

At 25°C, dissolve 0.96 grams of phosphorous acid in 10 milliliters of water, pour this phosphorous acid aqueous solution into 1.82 grams of pseudo-boehmite solid powder and stir rapidly, add 0.86 milliliters of phosphoric acid (85wt%) dropwise, and then add 0.20 milliliters of silicon Sol (5.9MSiO ₂ ), 6.38ml of DPA (di-n-propylamine) was added while stirring, stirred until uniform, then transferred into a 30ml stainless steel reactor for crystallization at 160°C for 96 hours. The generated product test results are shown in Figure 5 for the powder X-ray diffraction pattern (XRD) of the product SAPO-41 obtained.

Example 4

At 25°C, dissolve 1.91 grams of phosphorous acid with 10 milliliters of water, pour this phosphorous acid aqueous solution into 1.82 grams of pseudo-boehmite solid powder and stir rapidly, add 0.43 milliliters of phosphoric acid (85wt%) dropwise, and then add 0.395 milliliters of silicon Sol (5.9MSiO ₂ ), 6.38ml of DPA (di-n-propylamine) was added while stirring, stirred until uniform, then transferred into a 30ml stainless steel reactor for crystallization at 200°C for 72 hours.

Example 5

At 40°C, dissolve 1.83 grams of phosphorous acid with 10 milliliters of water, pour this phosphorous acid aqueous solution into 3.47 grams of pseudo-boehmite solid powder and stir rapidly, add 1.64 milliliters of phosphoric acid (85wt%) dropwise, and then add 0.395 milliliters of silicon Sol (5.9MSiO ₂ ), 13ml of DPA (di-n-propylamine) was added while stirring, stirred until uniform, then transferred into a 30ml stainless steel reaction kettle for crystallization at 190°C for 20 hours.

Example 6

At 15°C, dissolve 1.83 grams of phosphorous acid (Tianjin Yuehua Chemical Factory) with 10 ml of water, pour the phosphorous acid aqueous solution into 3.47 grams of pseudo-boehmite solid powder (Shandong Aluminum Group) and stir quickly, drop into _1.64 milliliters of phosphoric acid (85wt%) (Tianjin Chemical Reagent No. United Chemical Plant), stirred until uniform, then transferred to a 30 ml stainless steel reactor for crystallization at 200°C for 20 hours. Generate the product test result and see the scanning electron microscope photo of the product SAPO-41 obtained in Figure 2

Example 7

At 25°C, dissolve 1.83 grams of phosphorous acid with 10 milliliters of water, pour this phosphorous acid aqueous solution into 5.20 grams of pseudo-boehmite solid powder and stir rapidly, add 1.64 milliliters of phosphoric acid (85wt%) dropwise, and then add 0.395 milliliters of silicon Sol (5.9MSiO ₂ ), 8.13ml of DPA (di-n-propylamine) was added while stirring, stirred until uniform, then transferred into a 30ml stainless steel reactor for crystallization at 200°C for 19 hours.

Claims (9)

1. the preparation method of aluminium silicophosphate molecular sieve, it is characterized in that: the step of the inventive method is, earlier silicon source, aluminium source, phosphorus source, organic formwork agent and water are mixed and make synthetic colloid, temperature when becoming glue is 10～50 ℃, should synthesize colloid hydrothermal crystallizing 15～300 hours under hydrothermal crystallizing and autogenous pressure under 160～230 ℃ of conditions then, and reclaim product.

2. the preparation method of aluminium silicophosphate molecular sieve according to claim 1, it is characterized in that: in the inventive method, said phosphorus source is phosphorous acid, phosphorous compound and phosphoric acid, phosphoric compound or uses phosphorous acid-phosphoric acid as two phosphorus sources; The aluminium source is the salt of pseudo-boehmite, aluminum isopropylate, aluminium hydroxide, aluminum oxide and aluminium; The silicon source is aerogel, white carbon black or the tetraethoxy of silica gel, silicon sol, silicon; Organic formwork agent is di-n-propylamine, Diisopropylamine, Di-n-Butyl Amine, diethylamine, formyl dipropyl amine or TBAH.

3. the preparation method of aluminium silicophosphate molecular sieve according to claim 1, it is characterized in that: in the inventive method, adopting phosphorous acid is that phosphorus source or phosphorous acid-phosphoric acid are that aluminium source, silicon sol are that silicon source, di-n-propylamine or TBAH are template as two phosphorus sources, pseudo-boehmite.

4. the preparation method of aluminium silicophosphate molecular sieve according to claim 1, it is characterized in that: organic formwork agent is a di-n-propylamine.

5. according to the preparation method of claim 1 or 3 described aluminium silicophosphate molecular sieves, it is characterized in that:

When I. adopting phosphorous acid to be the phosphorus source, with silicon source---SiO ₂, aluminium source---Al ₂O ₃, phosphorus source---P ₂O ₃, organic formwork agent--R and water---H ₂O is according to the synthetic colloid of following mole proportioning, SiO ₂: Al ₂O ₃: P ₂O ₃: R: H ₂O=(0.05～0.30): (0.5～1.2): (0.75～1.5): (1.0～5.0): (25～190.8);

When II. adopting phosphorous acid-phosphoric acid, with silicon source---SiO as two phosphorus source ₂, aluminium source---Al ₂O ₃, phosphorus source---P ₂O ₃, organic formwork agent--R and water---H ₂O is according to the synthetic colloid of following mole proportioning, SiO ₂: Al ₂O ₃: P ₂O ₃: P ₂O ₅: R:H ₂O=(0.05～0.30): (0.5～1.2): (0.25～1.25): (1.5～0.25): (1.0～5.0): (25～190.8).

6. according to the preparation method of claim 1 or 3 described aluminium silicophosphate molecular sieves, it is characterized in that:

When I. adopting phosphorous acid to be the phosphorus source, with silicon source---SiO ₂, aluminium source---Al ₂O ₃, phosphorus source---P ₂O ₃, organic formwork agent--R and water---H ₂O is according to the synthetic colloid of following mole proportioning, SiO ₂: Al ₂O ₃: P ₂O ₃: R: H ₂O=(0.10～0.20): (0.75～1.20): (1.00～1.25): (1.5～4.0): (50～143.8);

When II. adopting phosphorous acid-phosphoric acid, with silicon source---SiO as two phosphorus source ₂, aluminium source---Al ₂O ₃, phosphorus source---P ₂O ₃, organic formwork agent--R and water---H ₂O is according to the synthetic colloid of following mole proportioning, SiO ₂: Al ₂O ₃: P ₂O ₃: P ₂O ₅: R: H ₂O=(0.10～0.20): (0.75～1.20): (0.35～1.00): (1.00～0.35): (1.5～4.0): (50～95.4).

7. the preparation method of aluminium silicophosphate molecular sieve according to claim 1, it is characterized in that: in the inventive method, the addition sequence of said phosphorus source, aluminium source, silicon source and organic formwork agent is that the order according to the order in the order of aluminium source, phosphorus source, silicon source, organic formwork agent or aluminium source, organic formwork agent, phosphorus source, silicon source or phosphorus source, organic formwork agent, aluminium source, silicon source adds.

8. the preparation method of aluminium silicophosphate molecular sieve according to claim 1 is characterized in that: in the inventive method, be hydrothermal crystallizing 19～72 hours and reclaim product under hydrothermal crystallizing and autogenous pressure under 190～200 ℃ of conditions.

9. the preparation method of aluminium silicophosphate molecular sieve according to claim 1 is characterized in that: in the inventive method, the temperature when becoming glue is 20～35 ℃.

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