A C4 alkylation aluminum-rich molecular sieve catalyst coupling metal modification and hierarchical pore nanostructure, its preparation method and application

Abstract

The present invention discloses a C4 alkylation aluminum-rich molecular sieve catalyst coupling metal modification and hierarchical pore nanostructure, and its preparation method and application, belonging to the technical field of alkylation catalyst preparation. In the present invention, a crystal is obtained by crystallization through the cooperation of a template agent, a structure directing agent, an alkali reagent, an aluminum source, a silicon source and a seed crystal, and the C4 alkylation aluminum-rich molecular sieve catalyst is obtained through two exchange reactions of the crystal; the first exchange reaction is carried out in an ammonium salt solution, and the second exchange reaction is carried out in a metal salt solution. The C4 alkylation aluminum-rich molecular sieve catalyst has a hierarchical pore-rich aluminum-rich nanozeolite structure, which can accelerate the diffusion rate of products and reactants, significantly improve the catalytic activity and extend the service life; the C4 alkylation aluminum-rich molecular sieve catalyst exhibits good catalytic activity and catalytic life in the process of catalytically generating alkylated oil from C4 alkylation.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of alkylation catalysts, and more specifically relates to an aluminum-rich molecular sieve catalyst for C4 alkylation with coupled metal modification and hierarchical pore nanostructure, and a preparation method and application thereof. Background Art

[0002] As a gasoline blending component with the highest comprehensive performance, alkylate oil has the advantages of high octane number, no nitrogen and sulfur components, low vapor pressure, etc., and has the reputation of "liquid gold". Alkylate oil is produced from low-carbon olefins (generally butene) and isoparaffins (generally isobutane) as raw materials under strong acid conditions, and its research octane number (RON) can reach 94.5. Compared with C5 / C6 isomerized oil (87.5) and straight-run light gasoline (68.0), the octane number is 7.0 and 26.5 units higher respectively, showing significant advantages. The mainstream alkylation process is mainly the concentrated sulfuric acid process represented by DuPont Stratco. Although this technology has mature applications and high product quality, the sulfuric acid alkylation process has problems such as high acid consumption and serious equipment corrosion. In order to avoid the harm to the environment and production operators, it is an inevitable trend to use a safe and reliable solid acid alkylation catalyst to replace the liquid acid, and new solid acid catalysts and alkylation oil synthesis processes have been receiving much attention.

[0003] Due to the characteristics of easy separation of products and no corrosion, solid acids are considered the most potential liquid acid substitutes, such as solid acid catalysts like supported metal halides, solid superacids, acidic organic polymers, and molecular sieves. Among them, molecular sieves have been widely studied due to their stable structure, adjustable acidity, and diverse pore channels. However, solid acid catalysts face the problem of rapid deactivation and have not been industrially applied on a large scale so far. Therefore, it is urgent to develop a solid acid catalyst with a long catalytic life and high catalytic activity. Summary of the Invention

[0004] The purpose of the present invention is to provide an aluminum-rich molecular sieve catalyst for C4 alkylation with coupled metal modification and hierarchical pore nanostructure, and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art and effectively improve the life of the catalyst and the selectivity to the target product.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: provides a preparation method of an aluminum-rich molecular sieve catalyst for C4 alkylation with coupled metal modification and hierarchical pore nanostructure, including the following steps:

[0007] (1) Mix a template agent, a structure-directing agent, an alkali reagent, a silicon-aluminum source, seed crystals, and water to form a gel; subject the gel to static standing, crystallization, and first calcination in sequence to obtain a crystallized product;

[0008] (2) The crystallized product is subjected to a first ion-exchange reaction in an ammonium salt solution and then subjected to a second calcination to obtain a first ion-exchanged product;

[0009] (3) The first ion-exchanged product is subjected to a second ion-exchange reaction in a metal salt solution and then subjected to a third calcination to obtain the C4 alkylation dealuminized zeolite catalyst;

[0010] The template agent is one of the following structural formulas:

[0011]

[0012] The structure-directing agent is an organic compound containing nitrogen and / or oxygen;

[0013] The silicon-aluminum source includes seed crystals, a silicon source, and an aluminum source, and the seed crystals are dealuminized zeolites.

[0014] In the present invention, Beta zeolite crystals are obtained by crystallization through the cooperation of a template agent, a structure-directing agent, an alkali reagent, an aluminum source, a silicon source, and seed crystals. This type of zeolite has good catalytic effects in the C4 alkylation reaction. The Beta zeolite crystals are subjected to two ion-exchange reactions to obtain the C4 alkylation dealuminized zeolite catalyst. Among them, dealuminized zeolite is selected as the seed crystal. The dealuminized zeolite has a hierarchical pore structure. While retaining the microporous framework structure, a relatively large mesoporous structure / macroporous structure is introduced, which can not only improve the diffusion and mass transfer rate of reactant molecules during the preparation of alkylated oil, but also slow down the formation of carbon deposition and pore blockage phenomena, extend the catalytic life, and improve the catalytic activity. By introducing metal components through ion exchange in the dealuminized zeolite, the number of acid centers can be increased, the hydrogen transfer reaction can be promoted, and the selectivity for the products obtained from the preparation of alkylated oil can be improved. Among them, the structure-directing agent coordinates with the silicon source and the aluminum source to restrict the growth of zeolite during the synthesis process, and a zeolite with a nano-hierarchical pore structure is obtained. The zeolite with a nano-hierarchical pore structure enhances the diffusion of the products obtained from the preparation of alkylated oil and extends the catalytic life of the catalyst. In the present invention, the obtained Beta zeolite crystals are first ion-exchanged in an ammonium salt solution to obtain an ammonium-type zeolite, ion-exchanged in a metal salt solution to load metal components, and converted into a hydrogen-type zeolite through a third calcination, which is the C4 alkylation dealuminized zeolite catalyst. This catalyst has a dealuminized nano-zeolite structure rich in hierarchical pores.

[0015] The C4 alkylation aluminosilicate molecular sieve catalyst with a hierarchical pore-rich aluminous nanometer zeolite structure prepared by the present invention can accelerate the diffusion rates of products and reactants, significantly improve the catalytic activity, extend the service life, and solve the problem of rapid deactivation faced by existing solid acid catalysts. Among them, the improvement of the aluminous nanometer zeolite structure on the catalyst performance is mainly reflected in the following aspects: (1) Improving the activity and selectivity of the catalyst: The aluminous nanometer zeolite structure has highly dispersed nanocrystals and mesoporous structures, and these characteristics can effectively increase the mass transfer efficiency of the reaction, thereby improving the activity and selectivity of the catalyst. (2) Extending the service life of the catalyst: The aluminous nanometer zeolite has relatively high structural stability, which can reduce the carbon deposition phenomenon during the use of the catalyst, thereby extending the service life of the catalyst. (3) Reducing energy consumption: The aluminous nanometer zeolite catalyst does not require harsh use conditions, solving the problems of harsh conditions and high energy consumption required for traditional catalysts. The hierarchical pore structure introduces larger mesoporous structures / macroporous structures while retaining the microporous framework structure, which can not only improve the diffusion and mass transfer rates of reactant molecules, but also slow down the formation of carbon deposition and pore blockage phenomena, extend the catalytic life, and improve the catalytic activity.

[0016] Preferably, in the gel, the alkali reagent is Na 2 O, the aluminum source is Al 2 O 3 by mass, the silicon source is SiO 2 by mass, and the molar ratio of the template agent, structure-directing agent, alkali reagent, aluminum source, silicon source, seed crystal and water is 5 - 30:0.1 - 10:20 - 30:2 - 3:50 - 200:5000 - 7500; the mass of the seed crystal is 3 - 10% of the total mass of the silicon source.

[0017] Preferably, the nitrogen- and / or oxygen-containing organic compound includes one or more of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, ethylene glycol, ethylenediamine, lysine, oxalic acid and glycine; the alkali reagent includes one or more of sodium hydroxide, potassium hydroxide and ammonia water; the aluminum source includes sodium aluminate and / or aluminum hydroxide; the silicon source includes one or more of diatomite, silica gel and tetraethyl orthosilicate.

[0018] Preferably, the standing time is 20 - 100 min; the crystallization is carried out under stirring conditions, the crystallization temperature is 100 - 200 °C, the crystallization time is 10 - 40 h, and the stirring speed for crystallization is 20 - 60 r / min.

[0019] Preferably, the concentration of the ammonium salt solution in the first ion exchange reaction is 0.1 - 1 mol / L.

[0020] Preferably, in the second exchange reaction, the concentration of the metal salt solution is 0.1 - 1 mol / L, and the metals in the metal salt solution include copper, lanthanum, zinc, cobalt, cerium or iron.

[0021] Preferably, the temperatures of the first exchange reaction and the second exchange reaction are independently 50 - 100 °C, and the times of the first exchange reaction and the second exchange reaction are independently 1 - 10 h; the temperatures of the first calcination, the second calcination and the third calcination are independently 500 - 600 °C, and the times of the first calcination, the second calcination and the third calcination are independently 1 - 10 h.

[0022] Preferably, before the first calcination, the second calcination and the third calcination, there are also steps of washing and drying in sequence.

[0023] Technical solution two of the present invention: Provide a C4 alkylation aluminosilicate molecular sieve catalyst prepared by the preparation method of the C4 alkylation aluminosilicate molecular sieve catalyst coupling metal modification and hierarchical pore nanostructure.

[0024] Technical solution three of the present invention: Provide the application of the C4 alkylation aluminosilicate molecular sieve catalyst in the field of petrochemical industry.

[0025] Preferably, the petrochemical field includes the preparation of alkylated oil; the conditions for the preparation of alkylated oil are: the molar ratio of alkane to alkene is 10 - 1000:1, the mass space velocity of the alkene is 0.1 - 0.5 h -1 , the pressure is 0.5 - 5 MPa, and the temperature is 50 - 150 °C.

[0026] The present invention discloses the following technical effects:

[0027] 1. The C4 alkylation aluminosilicate molecular sieve catalyst prepared by the present invention has a hierarchical pore-rich aluminosilicate nanozeolite structure, which can accelerate the diffusion rate of products and reactants, significantly improve the catalytic activity, extend the service life, and solve the problem of rapid deactivation faced by existing solid acid catalysts.

[0028] 2. The C4 alkylation aluminosilicate molecular sieve catalyst prepared by the present invention can be directly applied in the field of petrochemical industry, and good application effects are obtained for the catalytic activity and catalytic life of the C4 alkylation aluminosilicate molecular sieve catalyst in the process of catalytically generating alkylated oil from C4 alkylation. Specific embodiments

[0029] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention.

[0030] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0032] Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0033] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0034] In the following examples and comparative examples, drying was carried out according to conventional methods unless otherwise specified; the raw materials used were commercially available unless otherwise specified.

[0035] Example 1

[0036] The template agent Sodium ethylenediaminetetraacetate, sodium hydroxide, sodium aluminate, diatomaceous earth, silica gel, and dealuminized zeolite (purchased from the Catalyst Factory of Nankai University, with a molar ratio of silicon atoms to aluminum atoms of 12.5:1) were dissolved in water and mixed to obtain a gel (in the gel, sodium hydroxide was calculated as Na 2 O, sodium aluminate was calculated as Al 2 O 3 Calculated, the silicon source composed of diatomaceous earth and silica gel was SiO 2Calculation: The molar ratio of the template agent, disodium ethylenediaminetetraacetate, sodium hydroxide, sodium aluminate, silicon source, aluminum-rich molecular sieve and water is 10:5:21:2:100:5000), where the aluminum-rich molecular sieve accounts for 5% of the total mass of the silicon source. First, let it stand for 50 min, and then crystallize at 140 °C and 30 r / min for 40 h; wash the obtained solid product with water until neutral and dry it, and then calcine it at 500 °C for 5 h; place the obtained solid product in a 0.5 mol / L ammonium chloride solution and treat it at 50 °C for 2 h to exchange it into an ammonium-type catalyst; wash the obtained ammonium-type catalyst with water until neutral and dry it, and then calcine it at 500 °C for 4 h; place the obtained solid product in a 1 mol / L copper sulfate solution and treat it at 55 °C for 2.5 h to exchange it into a copper-type catalyst; wash the obtained copper-type catalyst with water until neutral and dry it, and then calcine it at 500 °C for 3 h to obtain a C4 alkylation aluminum-rich molecular sieve catalyst.

[0037] Example 2

[0038] The difference from Example 1 is that "copper sulfate solution" is replaced with "lanthanum nitrate solution", and the others are the same as in Example 1.

[0039] Example 3

[0040] The difference from Example 1 is that "copper sulfate solution" is replaced with "zinc chloride solution", and the others are the same as in Example 1.

[0041] Example 4

[0042] The difference from Example 1 is that "copper sulfate solution" is replaced with "iron nitrate solution", and the others are the same as in Example 1.

[0043] Example 5

[0044] The difference from Example 1 is that "copper sulfate solution" is replaced with "cobalt sulfate solution", and the others are the same as in Example 1.

[0045] Example 6

[0046] The difference from Example 1 is that "copper sulfate solution" is replaced with "cerium chloride solution", and the others are the same as in Example 1.

[0047] Example 7

[0048] The difference from Example 1 is that the "template agent " is replaced with "tetraethylammonium hydroxide ", and the others are the same as in Example 1.

[0049] Example 8

[0050] The difference from Example 1 is that "disodium ethylenediaminetetraacetate" is replaced with "lysine", and the others are the same as in Example 1.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that the steps of the second exchange reaction and the third calcination are omitted, and the others are the same as in Example 1.

[0053] Comparative Example 2

[0054] According to the step of "exchanging to a copper-type catalyst" in Example 1, a commercially available Hβ catalyst (purchased from the Catalyst Factory of Nankai University, with a molar ratio of silicon atoms to chlorine atoms of 12.5:1) was exchanged to a copper type, washed with water until neutral and dried, and then calcined at 500 °C for 3 h to obtain a catalyst.

[0055] Comparative Example 3

[0056] A commercially available Hβ catalyst (purchased from the Catalyst Factory of Nankai University, with a molar ratio of silicon atoms to chlorine atoms of 12.5:1) was washed with water until neutral and dried, and then calcined at 500 °C for 3 h to obtain a catalyst.

[0057] Comparative Example 4

[0058] The difference from Example 1 is that in the synthesis process, no dealuminized zeolite is added as a seed crystal, and the others are the same as in Example 1.

[0059] The performance tests were carried out on the catalysts obtained from the above examples and comparative examples, and the test methods and results are as follows:

[0060] Test method:

[0061] The product composition was measured by a gas chromatograph; the catalytic life was determined according to the duration when the olefin conversion rate was not less than 99.5%; the octane number measured was the research octane number, that is, the octane number of the alkylate oil measured by the research method. The test results are shown in Table 1.

[0062] Table 1 Test results of catalytic life and octane number

[0063] Catalyst Catalytic life (min) Octane number Example 1 400 95.1 Example 2 380 95.3 Example 3 380 94.9 Example 4 400 95.5 Example 5 360 94.2 Example 6 380 95.2 Example 7 400 94.8 Example 8 380 95.0 Comparative Example 1 300 89.5 Comparative Example 2 260 92.8 Comparative Example 3 220 87.3 Comparative Example 4 230 86.6

[0064] As can be seen from Table 1, the octane number of the reaction product of the alkylation molecular sieve catalyst without metal modification (Comparative Example 1) is relatively low. This is because the strong Brønsted acid sites are insufficient, the hydrogen transfer reaction is inhibited, and the selectivity of C8 products is reduced. The catalytic life of the catalyst without nano-mesoporous structure (Comparative Example 2) is relatively short. This is because the product molecules cannot diffuse out of the pores in time, resulting in product polymerization or polyalkylation, causing the catalyst to deactivate due to carbon deposition. The catalyst without mesoporous structure and without metal modification (Comparative Example 3) has a short catalytic life and a relatively low octane number of the reaction product. The catalyst without adding seeded dealuminized zeolite (Comparative Example 4) has a short catalytic life and a relatively low octane number of the reactants. Compared with the catalysts without introducing mesoporous structure and metal components and the catalysts without adding seeds, the C4 alkylation dealuminized zeolite catalyst obtained in the examples significantly has a longer catalytic life, and the octane number of the product is also very high, indicating a high selectivity for the product.

[0065] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0066] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Application of a metal-modified and multi-level porous nanostructure coupled C4 alkylation aluminum-rich molecular sieve catalyst in the preparation of alkylation oil, characterized in that: The preparation method of the metal-modified and multi-level porous nanostructure coupled C4 alkylated aluminum-rich molecular sieve catalyst comprises the following steps: (1) mixing a template, a structure directing agent, an alkali agent, a silicon-aluminum source and water to form a gel; sequentially subjecting the gel to standing, crystallization and a first calcination to obtain a crystallized product; (2) subjecting the crystallized product to a first exchange reaction in an ammonium salt solution, and then subjecting the crystallized product to a second calcination to obtain a first exchange product; (3) subjecting the first exchange product to a second exchange reaction in a metal salt solution, and then subjecting the product to a third calcination to obtain the C4 alkylated aluminum-rich molecular sieve catalyst; The template is one of the following structural formulas: The structure directing agent is an organic substance containing nitrogen and / or oxygen; The silicon-aluminum source comprises a seed crystal, a silicon source and an aluminum source, the seed crystal is an aluminum-rich molecular sieve; the molar ratio of silicon atoms to aluminum atoms in the aluminum-rich molecular sieve is 12.5:1; The standing time is 20 to 100 minutes; the crystallization is carried out under stirring conditions, the crystallization temperature is 100 to 200° C., the crystallization time is 10 to 40 hours, and the crystallization stirring speed is 20 to 60 r / min.

2. The use according to claim 1, characterized in that: In the gel, the alkali reagent is calculated as Na2O, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, the molar ratio of the template agent, the structure directing agent, the alkali reagent, the aluminum source, the silicon source and water is 5-30:0.1-10:20-30:2-3:50-200:5000-7500; the mass of the seed crystal is 3-10% of the total mass of the silicon source.

3. The use according to claim 1, characterized in that: The nitrogen and / or oxygen-containing organic matter includes one or more of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, ethylene glycol, ethylenediamine, lysine, oxalic acid and glycine; the alkaline reagent includes one or more of sodium hydroxide, potassium hydroxide and ammonia water; the aluminum source includes sodium aluminate and / or aluminum hydroxide; the silicon source includes one or more of diatomaceous earth, silica gel and tetraethyl orthosilicate.

4. The use according to claim 1, characterized in that: The concentration of the ammonium salt solution in the first exchange reaction is 0.1-1 mol / L.

5. The use according to claim 1, characterized in that: In the second exchange reaction, the concentration of the metal salt solution is 0.1-1 mol / L; the metal in the metal salt solution includes copper, lanthanum, zinc, cobalt, cerium or iron.

6. The use according to claim 1, characterized in that: The temperatures of the first exchange reaction and the second exchange reaction are independently 50-100°C, and the times of the first exchange reaction and the second exchange reaction are independently 1-10h; the temperatures of the first calcination, the second calcination and the third calcination are independently 500-600°C, and the times of the first calcination, the second calcination and the third calcination are independently 1-10h.

7. The use according to claim 1, characterized in that: The first calcination, the second calcination and the third calcination further include washing and drying steps performed in sequence.

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