Preparation method and application of SAPO-34 molecular sieve

Abstract

The invention provides a preparation method and application of an SAPO-34 molecular sieve. The preparation method of the SAPO-34 molecular sieve provided by the invention comprises the following steps: S1, activating a used methanol-to-olefin catalyst; s2, mixing the activated catalyst with an acid solution to obtain a first mixture; s3, carrying out solid-liquid separation on the first mixture to obtain a liquid phase and a solid phase; and S4, mixing the liquid phase with an aluminum source, a phosphorus source, a silicon source and a template agent to obtain a second mixture, and carrying out crystallization treatment on the second mixture. The SAPO-34 molecular sieve prepared by the invention can be used in a methanol-to-olefin reaction, and can show excellent low-carbon olefin selectivity and relatively long catalyst life.

Description

Technical Field

[0001] The invention belongs to the field of catalysts, and specifically relates to a preparation method and application of a SAPO-34 molecular sieve. Background Art

[0002] SAPO molecular sieve is a crystal network structure composed of AlO4, SiO4 and PO4 tetrahedrons. 4+ Replace P 5+ or Al 3+ The acidity generated by the reaction or the acidity generated by metal substitution. Among the SAPO series of molecular sieves, SAPO-34 molecular sieve is widely used in the modern petroleum processing industry because of its good thermal stability and hydrothermal stability, moderate acidity, high specific surface area and highly ordered micropore channels. The most eye-catching is that this molecular sieve is used as an active component in the methanol to olefins (MTO) reaction, which can almost completely convert methanol, with the selectivity of ethylene and propylene exceeding 80%, and C5 + The content of the components is relatively small and almost no aromatics are produced.

[0003] Generally speaking, in addition to conventional chemical reagents such as silicon, aluminum, and phosphorus sources, a template agent needs to be added during the synthesis of SAPO-34 molecular sieves. Commonly used template agents are organic amine species such as morpholine, triethylamine, and tetraethylammonium hydroxide. Organic amines not only act as templates during the synthesis of molecular sieves, but also provide a suitable environment for the system. Therefore, broadening the source of raw materials for molecular sieve synthesis can broaden the scope of utilization of chemical raw materials, and at the same time can reduce the synthesis cost of molecular sieves to a certain extent. In addition, for the utilization of methanol to olefins catalysts after service, CN201410575041.3 uses waste SAPO-34 molecular sieve catalysts to adsorb and remove methanol, and CN201410573567.8 uses waste catalysts containing molecular sieves to prepare adsorbents and remove methanol. It is proposed that SAPO-34 waste catalysts are prepared into adsorbents by rolling balls, tableting or extruding, and used for olefin raw materials to remove oxygenated compounds such as methanol. However, such methods still have the problem of low utilization of MTO catalysts after service, and they can no longer be recycled as catalysts. CN201811433062.6 adopts secondary calcination to obtain alumina and silicon-phosphorus-nitrogen compound fertilizer by aluminum ammonium sulfate decomposition method and acid decomposition aging method. This method has high energy consumption and the added value of the obtained product is low.

[0004] In summary, how to broaden the range of raw materials for molecular sieve synthesis and fully utilize the methanol-to-olefin catalysts after service has always been a hot topic for scientific researchers. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a novel method for preparing SAPO-34 molecular sieve and a method for resource utilization of the catalyst after use in methanol to olefins. The method provided by the present invention can realize resource utilization of the MTO catalyst after service, and solve the problem of utilization of the MTO catalyst after service in an efficient and green way. At the same time, the prepared SAPO-34 molecular sieve can still maintain high catalytic performance when applied to the methanol to olefins reaction.

[0006] In a first aspect, the present invention provides a method for preparing a SAPO-34 molecular sieve comprising:

[0007] S1: activating the used methanol to olefins catalyst;

[0008] S2: mixing the activated catalyst with an acid solution to obtain a first mixture;

[0009] S3: performing solid-liquid separation on the first mixture to obtain a liquid phase and a solid phase;

[0010] S4: mixing the liquid phase with an aluminum source, a phosphorus source, a silicon source and a template to obtain a second mixture, and performing a crystallization treatment on the second mixture.

[0011] In some embodiments, in S2, the mass ratio of the catalyst to the acid solution is 1: (2-10), for example, 1: 2.5, 1: 3, 1: 3.5, 1: 4, 1: 4.5, 1: 5, 1: 5.5, 1: 6, 1: 6.5, 1: 7, 1: 7.5, 1: 8, 1: 8.5, 1: 9, 1: 9.5 or any value therebetween. In some embodiments, in S2, the mass ratio of the catalyst to the acid solution is 1: (3-8). In some embodiments, the mass ratio of the catalyst to the acid solution is 1: (4-6). After the catalyst after activation treatment is treated with an acid of an appropriate content, a molecular sieve with high crystallinity can be synthesized, which is beneficial to the improvement of its catalytic performance.

[0012] In some embodiments, in S2, the mixing temperature is 100°C-180°C, for example, 110°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or any value therebetween. In some embodiments, in S2, the mixing temperature is 120°C-150°C.

[0013] In some embodiments, in S2, the mixing time is 2h-24h, for example, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h. In some embodiments, in S2, the mixing time is 5h-20h.

[0014] In some embodiments, in S2, the acid solution is selected from one or more of inorganic acid solutions. In some embodiments, the inorganic acid solution is an aqueous solution of an inorganic acid. In some embodiments, in S2, the acid solution is selected from one or more of phosphoric acid, sulfuric acid and hydrochloric acid.

[0015] In some embodiments, the concentration of the acid solution is 0.5mol / L-7mol / L, for example, 1mol / L, 1.5mol / L, 2mol / L, 2.5mol / L, 3mol / L, 3.5mol / L, 4mol / L, 4.5mol / L, 5mol / L, 5.5mol / L, 6mol / L or 6.5mol / L. In some embodiments, the concentration of the acid solution is 2mol / L-6mol / L.

[0016] In some embodiments, the used methanol-to-olefins catalyst is selected from a used methanol-to-olefins catalyst.

[0017] In some embodiments, the methanol-to-olefins catalyst after service is selected from the fine powder obtained from the cyclone separator of the industrial methanol-to-olefins device or the catalyst obtained from the settling tank.

[0018] In some embodiments, the used methanol to olefins catalyst comprises SAPO-34 molecular sieve.

[0019] In some embodiments, in S1, the activation treatment comprises calcining the used methanol-to-olefins catalyst in an air atmosphere. In some embodiments, the calcination temperature is 600° C.-800° C. In some embodiments, the calcination time is 2 h-6 h.

[0020] In some embodiments, in S3, the solid-liquid separation includes filtration or centrifugation.

[0021] In some embodiments, in S4, the liquid phase is first mixed with the aluminum source and the phosphorus source, and then mixed with the silicon source and the template to obtain the second mixture.

[0022] In some embodiments, in S4, the temperature of the crystallization treatment is 150° C.-250° C., for example, 170° C., 200° C. or 220° C. In some embodiments, in S4, the time of the crystallization treatment is 10 h-60 h.

[0023] In some embodiments, in S4, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the phosphorus source is calculated as P2O5. In the second mixture, the molar ratio of aluminum source: silicon source: phosphorus source: template: water is 1: (0-1.5): (0.01-2.0): (0.05-3.0): (10-120).

[0024] In some embodiments, in S4, the molar ratio of the aluminum source: the silicon source is 1:0.1, 1:0.3, 1:0.5, 1:0.7, 1:1 or 1:1.3.

[0025] In some embodiments, in S4, the molar ratio of aluminum source:phosphorus source is 1:0.1, 1:0.3, 1:0.5, 1:0.7, 1:1, 1:1.3, 1:1.5 or 1:1.7.

[0026] In some embodiments, in S4, the molar ratio of aluminum source:template is 1:0.1, 1:0.3, 1:0.5, 1:0.7, 1:1, 1:1.3, 1:1.5, 1:1.7, 1:2, 1:2.3, 1:2.5 or 1:2.7.

[0027] In some embodiments, in S4, the molar ratio of aluminum source:water is 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100 or 1:110.

[0028] In some embodiments, the aluminum source is selected from one or more of alumina, pseudo-boehmite, aluminum isopropoxide, aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0029] In some embodiments, the phosphorus source is selected from one or more of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium hydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, potassium hydrogen phosphate, sodium phosphate, disodium hydrogen phosphate and sodium hydrogen phosphate.

[0030] In some embodiments, the silicon source is selected from one or more of silica sol, white carbon and tetraethyl orthosilicate.

[0031] In some embodiments, the template agent is selected from one or more of morpholine, triethylamine and tetraethylammonium hydroxide.

[0032] In some embodiments, conventional post-processing steps such as separation, washing and drying may be used after crystallization, wherein the separation, washing and drying processes may be carried out by conventional methods, such as separation may be carried out by centrifugal separation, washing may be carried out by deionized water, and drying may be carried out in an oven. For example, the drying conditions are: drying at 30° C.-120° C. for 2 h-20 h.

[0033] In some embodiments, the preparation method of the SAPO-34 molecular sieve of the present invention includes the following specific steps: first activating the used methanol to olefins catalyst at high temperature, and then adding it to an acidic solution for treatment; then separating the solid and liquid by centrifugation or filtration to obtain a supernatant; adding a supplementary aluminum source and a phosphorus source to the above-mentioned supernatant to form an initial gel I; finally, adding a silicon source and a template to the initial gel I to prepare an initial gel II, and then preparing the SAPO-34 molecular sieve under conventional hydrothermal conditions.

[0034] In a second aspect, the present invention provides a SAPO-34 molecular sieve prepared by the preparation method described in the first aspect.

[0035] In a third aspect, the present invention provides the use of the SAPO-34 molecular sieve prepared by the preparation method described in the first aspect in a methanol to olefin reaction.

[0036] In some embodiments, the reaction conditions of the methanol to olefins reaction are: reaction pressure of 0.1 MPa-1.0 MPa, reaction temperature of 400°C-700°C, methanol feed weight space velocity of 1 h -1 -10h -1 .

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. Broadened the range of raw materials for molecular sieve synthesis.

[0039] 2. Effectively solve the disposal problem of used methanol to olefins catalysts.

[0040] 3. The prepared molecular sieve has good crystallization performance and is applied in the methanol to olefin reaction, showing good catalytic performance. The yield of dienes (ethylene + propylene) is comparable to or better than that of the existing technology, achieving good technical results. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0042] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0043] The present invention will be further described below in conjunction with examples, but the examples do not limit the protection scope of the present invention.

[0044] The catalyst after service in the present invention is selected from the waste catalyst collected from the cyclone separator or the slurry tank of the methanol to olefins industrial device, and the composition of the catalyst is 45% (by weight) SAPO-34 molecular sieve: 45% (by weight) kaolin: 10% (by weight) binder. The composition of SAPO-34 molecular sieve is Al2O3: SiO2: P2O5 = 60: 20: 20.

[0045] Example 1

[0046] Step 1) Activation treatment:

[0047] The catalyst after service was placed in a muffle furnace and air was introduced at an air flow rate of 30 mL / min. The temperature was raised to 600°C and treated for 4 hours.

[0048] Step 2) Treatment of the activated catalyst:

[0049] 15g of the activated catalyst was added to 85g of phosphoric acid solution, wherein the phosphoric acid concentration was 4mol / L, the treatment temperature was 120°C, and the treatment time was 12 hours. After the treatment, the solid and liquid were separated by a centrifuge, and the supernatant was used for the subsequent synthesis of molecular sieves.

[0050] Step 3) Preparation of SAPO-34 molecular sieve:

[0051] Silica sol (30 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as supplementary silicon source, aluminum source and phosphorus source, and a mixture of tetraethylammonium hydroxide and triethylamine is added as a template to the clear solution of step 2), and a mixture gel is prepared according to the ratio of Al2O3: SiO2: P2O5: template: H2O = 1: 0.3: 0.8: 2.4: 50, wherein the mass ratio of triethylamine: tetraethylammonium hydroxide is 3: 1, and the mixture gel is crystallized at 200°C for 48h. After the crystallization is completed, the crystallized product is cooled, filtered, washed and dried, and calcined at 550°C for 5 hours to obtain SAPO-34 molecular sieve.

[0052] Example 2

[0053] Step 1) Activation treatment:

[0054] The catalyst after service was placed in a muffle furnace and air was introduced at an air flow rate of 30 mL / min. The temperature was raised to 600°C and treated for 4 hours.

[0055] Step 2) Treatment of the activated catalyst:

[0056] 15g of the activated catalyst was added to 75g of hydrochloric acid solution, wherein the hydrochloric acid concentration was 6mol / L, the treatment temperature was 150°C, and the treatment time was 8 hours. After the treatment, the solid and liquid were separated by a centrifuge, and the supernatant was used for the subsequent synthesis of molecular sieves.

[0057] Step 3) Preparation of SAPO-34 molecular sieve:

[0058] Silica sol (30 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as supplementary silicon source, aluminum source and phosphorus source, and a mixture of tetraethylammonium hydroxide and triethylamine is added as a template to the clear solution of step 2), and a mixture gel is prepared according to the ratio of Al2O3: SiO2: P2O5: template: H2O = 1: 0.3: 0.8: 2.4: 50, wherein the mass ratio of triethylamine: tetraethylammonium hydroxide is 3: 1, and the mixture gel is crystallized at 200°C for 48h. After the crystallization is completed, the crystallized product is cooled, filtered, washed and dried, and calcined at 550°C for 5 hours to obtain SAPO-34 molecular sieve.

[0059] Example 3

[0060] Step 1) Activation treatment:

[0061] The catalyst after service was placed in a muffle furnace and air was introduced at an air flow rate of 30 mL / min. The temperature was raised to 600°C and treated for 4 hours.

[0062] Step 2) Treatment of the activated catalyst:

[0063] 15g of the activated catalyst was added to 100g of sulfuric acid solution, wherein the sulfuric acid concentration was 2mol / L, the treatment temperature was 100°C, and the treatment time was 20 hours. After the treatment, the solid and liquid were separated by a centrifuge, and the supernatant was used for the subsequent synthesis of molecular sieves.

[0064] Step 3) Preparation of SAPO-34 molecular sieve:

[0065] Silica sol (30 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as supplementary silicon source, aluminum source and phosphorus source, and a mixture of tetraethylammonium hydroxide and triethylamine is added as a template to the clear solution of step 2), and a mixture gel is prepared according to the ratio of Al2O3: SiO2: P2O5: template: H2O = 1: 0.3: 0.8: 2.4: 50, wherein the mass ratio of triethylamine: tetraethylammonium hydroxide is 3: 1, and the mixture gel is crystallized at 200°C for 48h. After the crystallization is completed, the crystallized product is cooled, filtered, washed and dried, and calcined at 550°C for 5 hours to obtain SAPO-34 molecular sieve.

[0066] Example 4

[0067] The only difference between Example 4 and Example 2 is that in step 2), 15 g of the activated catalyst is added to 45 g of hydrochloric acid solution.

[0068] Example 5

[0069] The only difference between Example 5 and Example 2 is that in step 2), 15 g of the activated catalyst is added to 120 g of hydrochloric acid solution.

[0070] Example 6

[0071] The only difference between Example 6 and Example 2 is that: the acid solution treatment temperature in step 2) is 120°C.

[0072] Example 7

[0073] The difference between Example 7 and Example 2 is that the acid solution treatment temperature in step 2 is 160°C.

[0074] Example 8

[0075] The only difference between Example 8 and Example 2 is that in step 3), pseudo-boehmite and phosphoric acid are first added to the clear solution of step 2) to obtain a first gel, and then silica sol, triethylamine and tetraethylammonium hydroxide are added to the first gel to obtain a mixed gel.

[0076] Comparative Example 1

[0077] Preparation of SAPO-34 molecular sieve:

[0078] Silica sol (30 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as silicon source, aluminum source and phosphorus source, triethylamine and tetraethylammonium hydroxide are used as mixed templates, wherein the mass ratio of triethylamine:tetraethylammonium hydroxide is 3:1, and the mixture is mixed according to the molar ratio of Al2O3:SiO2:P2O5:template:H2O=1:0.3:0.8:2.4:50 to obtain a mixed gel, and the mixture is crystallized at 200°C for 48 hours. After the crystallization is completed, the crystallized product is cooled, filtered, washed and dried, and calcined at 550°C for 5 hours to obtain SAPO-34 molecular sieve.

[0079] Comparative Example 2

[0080] Step 1) Activation treatment:

[0081] The catalyst after service was placed in a muffle furnace and air was introduced at an air flow rate of 30 mL / min. The temperature was raised to 600°C and treated for 4 hours.

[0082] Step 2) Preparation of SAPO-34 molecular sieve:

[0083] The activated catalyst was added to deionized water and stirred, pseudo-boehmite was added as a supplementary aluminum source, phosphoric acid was added as a supplementary phosphorus source, triethylamine and tetraethylammonium hydroxide were used as mixed templates, wherein the mass ratio of triethylamine:tetraethylammonium hydroxide was 3:1, and the mixture was mixed according to the molar ratio of Al2O3:SiO2:P2O5:template:H2O=1:0.3:0.8:2.4:50 to obtain a mixed gel, and the mixture was crystallized at 200°C for 48 hours. After the crystallization, the crystallized product was cooled, filtered, washed and dried, and calcined at 550°C for 5 hours to obtain SAPO-34 molecular sieve.

[0084] Test Case

[0085] The molecular sieves obtained in the above examples and comparative examples were prepared into fluidized bed catalysts for methanol to olefins reaction. A fixed fluidized bed catalytic reaction device was used, the reactor was a stainless steel tube, and the process conditions used in the investigation were: catalyst loading 40.0 g, reaction temperature 480 ° C, weight space velocity 6 h -1 , pressure 0.1 MPa, the evaluation results are shown in Table 1. In the present invention, the yield of each product is based on mass.

[0086] The diene yield is the sum of the ethylene yield and the propylene yield, and both the ethylene yield and the propylene yield are calculated by gas chromatography.

[0087] The life of the catalyst refers to the time when the diene selectivity reaches the highest level.

[0088] Table 1

[0089]

[0090] From the data in Table 1, it can be seen that the catalyst prepared using the treated supernatant of the post-service methanol-to-olefins catalyst as raw material can significantly improve the diene yield in the methanol-to-olefins reaction, and the catalyst has good stability.

[0091] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing SAPO-34 molecular sieve, comprising: S1: activating the used methanol to olefins catalyst; S2: mixing the activated catalyst with an acid solution to obtain a first mixture; S3: performing solid-liquid separation on the first mixture to obtain a liquid phase and a solid phase; S4: mixing the liquid phase with an aluminum source, a phosphorus source, a silicon source and a template to obtain a second mixture, and performing a crystallization treatment on the second mixture.

2. The preparation method according to claim 1, characterized in that: In S2, the mass ratio of the catalyst to the acid solution is 1:(2-10), preferably 1:(3-8), and more preferably 1:(4-6).

3. The preparation method according to claim 1 or 2, characterized in that: In S2, the mixing temperature is 100°C-180°C, preferably 120°C-150°C; and / or The mixing time is 2h-24h, preferably 5h-20h.

4. The preparation method according to any one of claims 1 to 3, characterized in that In S2, the acid solution is selected from one or more inorganic acid solutions, preferably one or more selected from phosphoric acid, sulfuric acid and hydrochloric acid; and / or The concentration of the acid solution is 0.5 mol / L-7 mol / L, preferably 2 mol / L-6 mol / L.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The used methanol to olefins catalyst is selected from a used methanol to olefins catalyst, and preferably the used methanol to olefins catalyst is selected from a fine powder obtained from a cyclone separator or a catalyst obtained from a settling tank of an industrial methanol to olefins device; and / or The used methanol to olefins catalyst comprises SAPO-34 molecular sieve.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In S1, the activation treatment comprises calcining the used methanol-to-olefins catalyst in an air atmosphere, preferably, the calcination temperature is 600° C.-800° C., and the calcination time is 2 h-6 h; and / or In S3, the solid-liquid separation includes filtration or centrifugation.

7. The preparation method according to any one of claims 1 to 6, characterized in that: In S4, the liquid phase is first mixed with the aluminum source and the phosphorus source, and then mixed with the silicon source and the template to obtain the second mixture; and / or In S4, the temperature of the crystallization treatment is 150° C.-250° C., and the time of the crystallization treatment is 10 h-60 h.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the phosphorus source is calculated as P2O5, and in the second mixture, the molar ratio of the aluminum source: the silicon source: the phosphorus source: the template: the water is 1: (0-1.5): (0.01-2.0): (0.05-3.0): 10-120; and / or The aluminum source is selected from one or more of aluminum oxide, pseudo-boehmite, aluminum isopropoxide, aluminum nitrate, aluminum chloride and aluminum sulfate; and / or The phosphorus source is selected from one or more of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium hydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, potassium hydrogen phosphate, sodium phosphate, disodium hydrogen phosphate and sodium hydrogen phosphate; and / or The silicon source is selected from one or more of silica sol, white carbon black and tetraethyl orthosilicate; and / or The template agent is selected from one or more of morpholine, triethylamine and tetraethylammonium hydroxide.

9. Use of the SAPO-34 molecular sieve prepared by the preparation method according to any one of claims 1 to 8 in methanol to olefins reaction.

10. The use according to claim 9, characterized in that: The reaction conditions of the methanol to olefins reaction are: reaction pressure of 0.1MPa-1.0MPa, reaction temperature of 400°C-700°C, methanol feed weight space velocity of 1h -1 -10h -1 .

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