WO2008022532A1

WO2008022532A1 - A method for rapidly synthesizing a silicoaluminophosphate sapo-34 molecular sieve

Info

Publication number: WO2008022532A1
Application number: PCT/CN2007/002375
Authority: WO
Inventors: Zhongmin Liu; Lei Xu; Peng Tian; Yue Yang; Lixin Yang; Changqing He; Zhihui Lv; Shuanghe Meng; Gongwei Wang; Xinde Sun; Hongyi Yang; Xiangao Wang; Cuiyu Yuan; Minzhi Li; Yingxu Wei; Yue Qi; Shukui Zhu; Jinling Zhang; Xiao Lu; Hua Wang
Original assignee: Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences
Priority date: 2006-08-08
Filing date: 2007-08-08
Publication date: 2008-02-28
Also published as: CN101121529A; CN100584758C

Abstract

Provided is a method for rapidly synthesizing a silicoaluminophosphate SAPO-34 molecular sieve, wherein triethylamine and/or diethylamine are/is used as templating agents, an organic amine accelerator is added to the initial gel for synthesis at the same time, and the gel mixture is optionally subjected to aging treatment. The method could give SAPO-34 molecular sieves with high crystallization degree in a relative short crystallization period. The SAPO-34 molecular sieve catalysts synthesized by the method can be used in the MTO or DTO reaction, the selectivity of C2~C3 olefins in the product could be up to about 90%.

Description

Rapid synthesis method of phosphorus silicon aluminum SAPO-34 molecular sieve

Technical field

The invention relates to a rapid synthesis method of a phosphorous silicon aluminum SAPO-34 molecular sieve.合成This synthesis method can synthesize high crystallinity SAPO-34 molecular sieves in a shorter crystallization time. Background technique

The phosphosilicate aluminum SAPO-34 molecular sieve is a molecular sieve having a chabazite-like structure composed of phosphorus, silicon, aluminum and oxygen. Its structural unit is composed of P0 ₂ ⁺ , Si0 ₂ and Α10 ₂ · tetrahedron. The anhydrous chemical composition can be expressed as: mM- (Si _x -Al _y -P _z ) 0 ₂ , where M is present in the molecular sieve crystal The templating agent in the micropores, m is the number of moles of M, x, y, z are the molar fractions of iJ Si, Al, P, and satisfy x + y + z = l. European Patent EP 0 103 117 discloses a hydrothermal synthesis process for SAPO-34 molecular sieves using tetraethylammonium hydroxide, isopropylamine or a mixture of tetraethylammonium hydroxide and di-n-propylamine as a templating agent. In 1984, the United States Carbide Corporation (UCC) issued a series of new silica-alumina series molecular sieves (SAPO-n) (USP 4,440,871), using the same templating agent in the synthesis of SAPO-34. With the advent of the silicoaluminophosphate series of molecular sieves, it has begun to use such small pores of moderately acidic molecular sieves for MTO reactions such as SAPO-17, SAPO-18, SAPO-34, SAPO-44, etc. Their pore sizes are approximately 0.43 nm is a good type of shape-selective catalyst. Among them, SAPO-34 molecular sieve exhibits excellent catalytic performance in MTO reaction due to its suitable acidity and pore structure. In 1988, Chinese researchers reported for the first time that SAPO-34 molecular sieves have excellent performance in the conversion of methanol to ethylene and propylene (Applied Catalysis, Vol. 40, No 1-2, 1988, p316).

Due to the high price of tetraethylammonium hydroxide, the high cost of synthesizing SAPO-34 molecular sieve is not conducive to industrial production. Chinese Patent ZL93112230 discloses a method for synthesizing SAPO-34 using triethylamine as a template, which is relatively inexpensive and can reduce the synthesis cost of SAPO-34 molecular sieve. Since then, Chinese patents ZL93112015 and ZL94110059 have respectively disclosed a method of synthesizing SAPO-34 molecular sieve with diethylamine as a template or a combination of triethylamine and diethylamine to reduce the synthesis cost. However, in these patents, the templating agent is used in a large amount and has a long crystallization time and a large energy consumption. Summary of the invention

The object of the present invention is to provide a rapid synthesis method of a phosphosilicate aluminum SAPO-34 molecular sieve, which adopts three The amine and/or diethylamine is used as a templating agent, and an organic amine promoter is added to the initial gel, and the gel mixture is optionally subjected to aging treatment, followed by crystallization, which can be synthesized in a shorter crystallization time. High crystallinity SAPO-34 molecular sieve.

In order to achieve the above object, the present invention provides a rapid synthesis method of a phosphosilicate aluminum SAPO-34 molecular sieve, which comprises mixing a phosphorus source, a silicon source, an aluminum source, a water and an organic amine template into a gel, and then adding an organic amine promoter. , to improve the solubility of the organic amine template in the gel, can prepare a uniform SAPO-34 molecular sieve to synthesize the initial gel mixture, optionally aging the gel mixture, and then crystallization, in the 180~250 crystallization conditions The crystallization time can be shortened to 0.5 to 12 hours, and a high crystallinity SAPO-34 molecular sieve can be synthesized.

Wherein, the molar ratio of each oxide in the initial gel mixture is:

SiO2/Al ₂ O ₃ = 0.1~2.0;

Ρ ₂ Ο ₅ / Α1 ₂ Ο ₃ = 0.5~15;

H ₂ 0/ A1 ₂ 0 ₃ = 10- 100;

Mj/ A1 ₂ 0 ₃ = 1~5, Mj is a template agent;

M ₂ / A1 ₂ 0 ₃ = 0.01 〜 1, M ₂ is an organic amine promoter.

In the above synthesis method, the crystallization time is 1 to 6 hours.

In the above synthesis method, the templating agent is one or a mixture of two of triethylamine and diethylamine. In the above synthesis method, the silicon source is at least one selected from the group consisting of silica sol, silicone gel, water glass, active silica or orthosilicate; the aluminum source is selected from the group consisting of aluminum salts and alumina acids. At least one of a salt, an activated alumina, an aluminum alkoxide, a pseudo-boehmite or a pseudoboehmite; the phosphorus source being at least one selected from the group consisting of orthophosphoric acid, phosphate, organic phosphide or phosphorus oxide One. '

In the above synthesis method, the organic amine promoter is a quaternary ammonium salt, and its structural formula is:

Wherein R], R _2, R ₃ is alkyl with the ~C _5, R 'is C _{5 ~C} ₂₄ alkyl group; X is Cl, Br or I. In the above synthesis method, the aging treatment temperature is room temperature to 180 ° C, and the aging time is 1 to 12 hours. The SAPO-34 molecular sieve prepared by the above synthesis method can be used as a catalyst for the reaction of methanol or dimethyl ether to produce a low-carbon olefin.

In the process of the invention, the templating agent triethylamine and/or diethylamine can be promoted by the addition of an organic amine promoter. The dissolution in the gel reduces the amount of the templating agent used on the one hand, and on the other hand, it can effectively shorten the crystallization time and reduce the energy consumption.

In the process of the invention, the synthetic gel mixture is optionally subjected to an aging treatment followed by crystallization. The SAPO-34 molecular sieve catalyst synthesized by the present invention can be used for the reaction of methanol and dimethyl ether to produce a low-carbon olefin, which can effectively improve the selectivity of ethylene and propylene. detailed description

The invention provides a rapid synthesis method of a phosphosilicate aluminum SAPO-34 molecular sieve, the method comprising: a) mixing an organic amine template, a phosphorus source, an aluminum source, a silicon source and water to provide an initial gel mixture; b) adding an organic amine promoter to the initial gel mixture obtained in step a) to obtain a uniform initial gel mixture;

c) optionally aging the homogeneous initial gel mixture obtained in step b);

d) crystallization is carried out to obtain a molecular sieve product.

The molar ratio of each oxide in the initial gel mixture in the method of the invention is - SiO ₂ /Al ₂ O ₃ = 0.1~2.0;

P ₂ 0 ₅ / A1 ₂ 0 ₃ = 0.5-15;

H ₂ 0/ A1 ₂ 0 ₃ = 10~ 100;

Μ!/ Α1 ₂ 0 ₃ = 1~5, Mi is a template;

Μ ₂ / Α1 ₂ Ο ₃ = 0.01~1, M ₂ is an organic amine promoter.

The templating agent used in the present invention is a mixture of one or both of triethylamine and diethylamine, and the silicon source used is selected from the group consisting of silica sol, silicone gel, water glass, active silica or orthosilicate. At least one of the esters; the aluminum source is at least one selected from the group consisting of aluminum salts, aluminates, activated aluminas, aluminum alkoxides, pseudoboehmite or pseudoboehmite; It is at least one selected from the group consisting of orthophosphoric acid, phosphate, organic phosphide or phosphorus oxide.

The organic amine promoter used in the present invention is a quaternary ammonium salt, and its structural formula is:

Wherein Ri, R ₂ is an alkyl group of 〜3⁄4, R' is a C ₅ -C ₂₄ alkyl group; and X is Cl, Br or I. According to a preferred embodiment, the method for rapidly synthesizing a phosphosilica SAPO-34 molecular sieve of the present invention comprises: a) prototyping a mold, a phosphorus source, an aluminum source, a silicon source and water into an initial gel of a SAPO-34 molecular sieve Mixture

b) adding a metered organic amine promoter to the initial gel mixture obtained in step a), stirring to obtain a homogenous initial gel mixture;

C) The uniform initial gel mixture obtained in the step b) is placed in a stainless steel synthetic kettle lined with polytetrafluoroethylene, sealed, and aged at room temperature to 180 ° C, and the aging time is 1 to 12 hours;

d) further heating the aged mixture obtained in the step c) to a crystallization temperature, and performing isothermal crystallization under autogenous pressure, the crystallization temperature is 180 to 250 Å, and the crystallization time is 0.5 to 12 hours, preferably the crystallization time. For 1 to 6 hours;

e) centrifuging the solid product obtained from step d), washing it to neutral with deionized water, and drying in 120 Torr of air to obtain a raw powder of SAPO-34 molecular sieve;

)) The SAPO-34 molecular sieve raw powder obtained in the step e) is calcined in air at 500-600 ° C for 3 to 8 hours to obtain a SAPO-34 molecular sieve catalyst.

The SAPO-34 molecular sieve catalyst synthesized by the invention can be used for the reaction of methanol or dimethyl ether to produce a low-carbon olefin, the reaction temperature is 300-600 ° C, the preferred reaction temperature is 400-500 ° C, and the weight of the raw material methanol or dimethyl ether is empty. The rate is from 1 to 40 h- ^] , and the selectivity of the C ₂ -C ₃ low-carbon olefin in the product is about 90%. The invention is described in detail below by way of examples. Example 1 (SAPO-34 molecular sieve synthesis)

Mixing the metering materials with an initial gel ratio of 3.0 TEA: 0.6 SiO ₂ : P ₂ 0 ₅ : A1 ₂ 0 ₃ : 50H ₂ O (TEA is a triethylamine templating agent) on a molar basis, and fully stirring into a gel. After aging at 80 ° C for 5 hours, it was placed in a stainless steel autoclave lined with polytetrafluoroethylene, sealed and heated to 200 ° C, and crystallized at autogenous pressure for 5 hours. The solid product was centrifuged, washed with deionized water to neutrality, and dried in air at 120 ° C. The XRD analysis was as shown in Table 1, and the synthesized product was a SAPO-34 molecular sieve raw powder. Table 1 X-ray diffraction analysis results of the synthesized sample of Example 1

2Θ D(A) IOQXI/IQ

9.43 9.37 100

12.78 6.92 15

15.96 .55 44 07 002375

20.52 4.32 59

21.07 4.21 12

25.17 3.55 11

25.81 3.45 16

30.49 2.93 18

31.07 2.88 18 Example 2 (Synthesis of SAPO-34 molecular sieve)

On a molar basis, the initial gel ratio is 2.5 TEA: 0.6 SiO ₂ : P ₂ 0 ₅ : A1 ₂ 0 ₃ : 50H ₂ O: 0.1 CTAB (TEA is a triethylamine template, CTAB is cetyltrimethyl The metering raw materials of ammonium bromide were mixed, fully stirred into a gel, aged under 100 Torr for 8 hours, and then placed in a stainless steel autoclave lined with polytetrafluoroethylene, and sealed to I8 (TC, at autogenous pressure). The crystal was separated by constant temperature for 2 hours. The solid product was separated by centrifugation, washed with deionized water until neutral, and dried in 120 Torr air. The XRD analysis was as shown in Table 2, and the synthesized product was the original powder of SAPO-34 molecular sieve. Example 2 X-ray diffraction analysis results of synthetic samples

2Θ D(A) ΙΟΟχΙ/Ιο

9.40 9.40 100

12.76 6.93 17

13.90 6.37 9

15.92 5.56 45

17.71 5.00 12

20.48 4.33 74

24.84 3.58 16

25.77 3.45 20

30.45 2.93 26

31.01 2.88 18 Example 3 (Synthesis of SAPO-34 molecular sieve)

The initial gel ratio is 2.0 DEA on a molar basis: 0.2 SiO ₂ : P ₂ 0 ₅ : A1 ₂ 0 ₃ : 50H ₂ O: 0.05CTAB (DEA is a diethylamine template, CTAB is cetyltrimethylammonium bromide), the metering materials are mixed, fully stirred into a gel, aged at 100 ° C for 4 hours, and then placed in the liner In a stainless steel autoclave made of polytetrafluoroethylene, it was hermetically heated to 220 Torr and crystallized at autogenous pressure for 2 hours. The solid product was centrifuged, washed with deionized water to neutrality, and dried in air at 120 ° C. The XRD analysis was as shown in Table 3, and the synthesized product was a raw powder of SAPO-34 molecular sieve. Table 3 X-ray diffraction analysis results of the synthesized sample of Example 3

9.42 9.38 100

12.75 6.94 20

15.93 5.56 50

17.87 4.96 12

20.48 4.33 73

21.18 4.19 14

25.12 3.54 16

25.78 3.45 21

30.48 2.93 24

31.04 2.88 20 Example 4 (Synthesis of SAPO-34 molecular sieve)

The initial gel ratio is 1.0 TEA on a molar basis: 1.0 DEA: 0.2 SiO ₂ : P ₂ 0 ₅ : A1 ₂ 0 ₃ : 503⁄40:

Mixing 0.02CTAB (TEA is a triethylamine template, DEA is a diethylamine template, CTAB is hexadecanoyltrimethylammonium bromide), fully stirred into a gel, aged at 120 ° C After 5 hours, it was placed in a stainless steel autoclave lined with polytetrafluoroethylene, sealed to 200 Torr, and crystallized at autogenous pressure for 2 hours. The solid product was centrifuged, washed with deionized water until neutral, and dried in 120 Torr air. The XRD analysis was as shown in Table 4, and the synthesized product was a SAPO-34 molecular sieve original powder. Table 4 X-ray diffraction analysis results of the synthesized sample of Example 4

2Θ D(A) 100xI/Io

9.46 9.34 100

12.80 6.91 20

15.96 5.55 51

17.91 4.95 13

20.53 4.32 80

23.06 3.85 11

25.15 3.54 19

25.81, 3.45 21

30.51 2.93 26

31.19 2.87 21 Example 5 (Preparation of SAPO-34 molecular sieve catalyst)

The four SAPO-34 molecular sieve raw powders obtained in Examples 1, 2, 3, and 4 were calcined at 350 ° C for 2 hours, 45 (TC calcined for 1 hour, and 55 CTC was calcined for 4 hours to obtain four SAPO-34 molecular sieve catalysts. The numbers are SP-01, SP-02, SP-03 and SP-04. Example 6 (catalytic reaction experiment)

The four SAPO-34 molecular sieve catalysts obtained in Example 5 were separately tableted and sieved. 0.6 g of 20-40 mesh granule catalyst samples were respectively charged into the reactor for methanol olefin catalytic reaction. Each was activated by a nitrogen gas at 550 ° C for 1 hour, and then cooled to 450 ° C to carry out a reaction. The raw material methanol was carried with nitrogen as a diluent gas, the nitrogen flow rate was 40 ml/min, and the methanol weight space velocity Ζ.ΟΙιΛ reaction product composition was analyzed by on-line gas chromatography, and the results are shown in Table 5. Table 5 Results of methanol conversion reaction of synthetic molecular sieve catalyst

No. SP-01 SP-02 SP-03 SP-04

CH ₄ 1.34 1.75 1.66 1.48

C ₂ H ₄ 50.67 55.29 54.98 55.80

C ₂ H ₆ 0.09 0.08 0.05 0.06

C ₃ H ₆ 36.85 34.98 35.44 34.77

C ₃ H ₈ 1.72 1.37 0.45 0.41

C ₄ ⁺ 7.02 5.61 6.21 6.09

C ₅ + 2.31 0.92 1.21 1.39

∑C ₂ ⁼ -C ₃ ⁼ 87.53 90.28 90.42 90.58 Example 7 (catalytic reaction experiment)

The four SAPO-34 molecular sieve catalysts obtained in Example 5 were separately tableted and sieved. 0.6 g of 20-40 mesh particle catalyst samples were respectively charged into the reactor for dimethylene to olefin catalytic reaction. Each was activated by a nitrogen gas at 550 ° C for 1 hour, and then cooled to 45 CTC for reaction. Nitrogen was used as the diluent gas, and the dimethyl ether gas was fed. The weight of the dimethyl ether was 2.0 h. The composition of the reaction product was analyzed by on-line gas chromatography. The results are shown in Table 6. Table 6 Results of dimethyl ether conversion reaction of synthetic molecular sieve catalyst No. SP-01 SP-02 SP-03 SP-04

CH ₄ 1.15 1.40 1.32 1.33

C2H4 50.24 55.08 55.52 55.33

C ₂ H ₆ 0.11 0.05 0.05

C3H6 35.79 35.51 35.43 35.89

C ₄ ⁺ 8.35 6.15 5.97 5.86

C ₅ ⁺ 2.20 1.51 1.40 1.28

∑C ₂ ⁼ -C ₃ ⁼ 86.04 90.60 90.95 91.22

Claims

Rights request

1. A rapid synthesis method of a phosphorous silicon aluminum SAPO-34 molecular sieve, the method comprising:

a) mixing an organic amine templating agent, a phosphorus source, an aluminum source, a silicon source, and water to provide an initial gel mixture;

b) adding an organic amine promoter to the initial gel mixture obtained in step a) to obtain a uniform initial gel mixture;

c) optionally aging the homogeneous initial gel mixture obtained in step b);

d) performing crystallization to obtain a molecular sieve product,

Wherein the molar ratio of each oxide in the initial gel mixture in step a) is:

Si0 ₂ /Al ₂ 0 ₃ = 0.1 -2.0;

Ρ ₂ θ5/ Α1 ₂ θ3 = 0.5~15;

Η ₂ Ο / Α _{1 2} Ο ₃ = 10 ～100;

M^ Al.Os ^ l 〜5, Mi is an organic amine template;

Μ ₂ / Α1 ₂ Ο ₃ = 0.01~1, M ₂ is an organic amine promoter.

The rapid synthesis method according to claim 1, wherein the crystallization temperature is 180 to 250 ° C and the crystallization time is 0.5 to 12 hours.

3. The rapid synthesis method according to claim 2, wherein said crystallization time is from 1 to 6 hours.

4. The rapid synthesis method according to claim 1, wherein the organic amine templating agent is one or a mixture of two of triethylamine and diethylamine.

5. The rapid synthesis method according to claim 1, wherein the organic amine promoter is a quaternary ammonium salt, and the structural formula is:

Wherein R ₂ and R ₃ are a fluorenyl group of Cr^Cs, and R' is a fluorenyl group of C ₅ to C ₂₄ ; and X is Cl, Br or I.

6. The rapid synthesis method according to claim 1, wherein the aging treatment temperature is room temperature 180. C, the aging time is 1 to 12 hours.

7. The rapid synthesis method according to claim 1, wherein the silicon source is at least one selected from the group consisting of silica sol, silicone gel, water glass, active silica or orthosilicate; Is at least one selected from the group consisting of aluminum salts, aluminates, activated aluminas, aluminum alkoxides, pseudo-boehmite or pseudoboehmite; the phosphorus source is selected from the group consisting of orthophosphoric acid, phosphate, and organic phosphorus. At least one of a compound or a phosphorus oxide.

A rapid synthesis method according to any one of claims 1 to 7, wherein the synthesized SAPO-34 molecular sieve is used in a reaction of methanol or dimethyl ether to produce a low-carbon olefin after calcination.