C4 alkylated aluminum-rich molecular sieve catalyst coupled with metal modification and hierarchical pore nanostructure as well as preparation method and application of C4 alkylated aluminum-rich molecular sieve catalyst

Abstract

The invention discloses a C4 alkylated aluminum-rich molecular sieve catalyst coupled with metal modification and a hierarchical pore nanostructure as well as a preparation method and application of the C4 alkylated aluminum-rich molecular sieve catalyst, and belongs to the technical field of preparation of alkylated catalysts. A template agent, a structure-directing agent, an alkali reagent, an aluminum source, a silicon source and a seed crystal are matched and crystallized to obtain crystals, and the crystals are subjected to two exchange reactions to obtain the C4 alkylated aluminum-rich molecular sieve catalyst. 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 alkylated aluminum-rich molecular sieve catalyst has an aluminum-rich nano zeolite structure rich in hierarchical pores, the diffusion rate of products and reactants can be increased, the catalytic activity is remarkably improved, and the service life is prolonged; the C4 alkylation aluminum-rich molecular sieve catalyst shows good catalytic activity and long catalytic life in the process of generating alkylated oil through C4 alkylation catalysis.

Description

Technical Field

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

[0002] As the gasoline blending component with the highest comprehensive performance, alkylate oil has the advantages of high octane number, no nitrogen and sulfur components, and low vapor pressure, and is known as "liquid gold". Alkylate oil is produced under strong acid conditions using low-carbon olefins (generally butene) and isoparaffins (generally isobutane) as raw materials, and its 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, which has significant advantages. The mainstream alkylation process is mainly concentrated sulfuric acid process represented by DuPont Stratco. Although the technology is mature and the product quality is high, the sulfuric acid alkylation process has problems such as high acid consumption and severe equipment corrosion. In order to avoid harm to the environment and production operators, it is an inevitable trend to use safe and reliable solid acid alkylation catalysts to replace liquid acids. New solid acid catalysts and alkylate oil synthesis processes have always attracted much attention.

[0003] Solid acids are considered to be the most promising alternatives to liquid acids due to their easy separation and non-corrosive properties. Solid acid catalysts include 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 pores. However, solid acid catalysts face the problem of rapid deactivation and have not yet been applied on a large scale in industry. Therefore, it is urgent to develop a solid acid catalyst with long catalytic life and high catalytic activity. Summary of the invention

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

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

[0006] One of the technical solutions of the present invention is to provide a method for preparing a C4 alkylated aluminum-rich molecular sieve catalyst coupled with metal modification and multi-level porous nanostructure, comprising the following steps:

[0007] (1) mixing a template, a structure directing agent, an alkali agent, a silicon-aluminum source, a seed crystal and water to form a gel; and sequentially subjecting the gel to standing, crystallization and a first calcination to obtain a crystallized product;

[0008] (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;

[0009] (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;

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

[0011]

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

[0013] The silicon-aluminum source comprises a seed crystal, a silicon source and an aluminum source, and the seed crystal is an aluminum-rich molecular sieve.

[0014] The present invention obtains Beta molecular sieve crystals by crystallization through the combination of template agent, structure directing agent, alkali reagent, aluminum source, silicon source and seed crystal. This type of molecular sieve has a good catalytic effect in C4 alkylation reaction. The Beta molecular sieve crystal is subjected to two exchange reactions to obtain the C4 alkylation aluminum-rich molecular sieve catalyst. Among them, the aluminum-rich molecular sieve is selected as the seed crystal. The aluminum-rich molecular sieve has a multi-level pore structure. While retaining the microporous skeleton structure, a larger mesoporous structure / macroporous structure is introduced, which can not only improve the diffusion and mass transfer rate of the reactant molecules in the alkylation oil preparation process, but also slow down the formation of carbon deposition and pore blocking, prolong the catalytic life, and improve the catalytic activity; the introduction of metal components in the aluminum-rich molecular sieve through exchange can increase the number of acid centers, promote hydrogen transfer reactions, and improve the selectivity of the products obtained from the alkylation oil preparation. The structure directing agent coordinates with the silicon source and the aluminum source to limit the growth of the molecular sieve during the synthesis process, and obtains a molecular sieve with a nano-multi-level pore structure. The molecular sieve with a nano-multi-level pore structure strengthens the diffusion of the products obtained from the alkylation oil preparation and prolongs the catalytic life of the catalyst. The present invention first exchanges the obtained Beta molecular sieve crystals in an ammonium salt solution to obtain an ammonium-type molecular sieve, exchanges the loaded metal component in a metal salt solution, and converts it into a hydrogen-type molecular sieve through a third calcination, namely a C4 alkylated aluminum-rich molecular sieve catalyst, which has an aluminum-rich nano-zeolite structure rich in multi-level pores.

[0015] The C4 alkylation aluminum-rich molecular sieve catalyst with an aluminum-rich nano-zeolite structure rich in multi-level pores prepared by the present invention 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. Among them, the improvement of the catalyst performance by the aluminum-rich nano-zeolite structure is mainly reflected in the following aspects: (1) Improving the activity and selectivity of the catalyst: The aluminum-rich nano-zeolite structure has highly dispersed nano-crystals and mesoporous structures, which can effectively increase the mass transfer efficiency of the reaction, thereby improving the activity and selectivity of the catalyst. (2) Extending the life of the catalyst: The aluminum-rich nano-zeolite has a high structural stability, which can reduce the carbon deposition phenomenon of the catalyst during use, thereby extending the service life of the catalyst. (3) Reducing energy consumption: The aluminum-rich nano-zeolite catalyst does not require strict use conditions, which solves the problem of strict conditions and high energy consumption required for the catalytic operation of traditional catalysts. The multi-level pore structure retains the microporous skeleton structure while introducing a larger mesoporous structure / macroporous structure, which can not only improve the diffusion and mass transfer rate of the reactant molecules, but also slow down the formation of carbon deposition and pore blocking, thereby extending the catalytic life and improving the catalytic activity.

[0016] Preferably, in the gel, the alkaline reagent is Na 2 O, the aluminum source is Al 2 O 3 The silicon source is SiO 2 The molar ratio of the template agent, the structure directing agent, the alkali reagent, the aluminum source, the silicon source, the 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 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.

[0018] Preferably, 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.

[0019] Preferably, the concentration of the ammonium salt solution in the first 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 metal in the metal salt solution includes copper, lanthanum, zinc, cobalt, cerium or iron.

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

[0022] Preferably, the first calcination, the second calcination and the third calcination further include washing and drying steps performed in sequence before the calcination.

[0023] The second technical solution of the present invention is to provide a C4 alkylated aluminum-rich molecular sieve catalyst prepared by a preparation method of the C4 alkylated aluminum-rich molecular sieve catalyst coupled with metal modification and multi-level porous nanostructure.

[0024] The third technical solution of the present invention is to provide the application of the C4 alkylated aluminum-rich molecular sieve catalyst in the field of petrochemical industry.

[0025] Preferably, the petrochemical industry includes the preparation of alkylate oil; the conditions for the preparation of alkylate oil are: the alkane-olefin molar ratio is 10 to 1000:1, and the mass space velocity of olefin is 0.1 to 0.5 h -1 , pressure is 0.5~5MPa, and temperature is 50~150℃.

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

[0027] 1. The C4 alkylation aluminum-rich molecular sieve catalyst prepared by the present invention has an aluminum-rich nano-zeolite structure rich in multi-level pores, 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 aluminum-rich C4 alkylation molecular sieve catalyst prepared by the present invention can be directly applied in the field of petrochemical industry. In the process of C4 alkylation catalysis to generate alkylate oil, the catalytic activity and catalytic life of the aluminum-rich C4 alkylation molecular sieve catalyst have achieved good application effects. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation 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 associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

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

[0035] Example 1

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

[0037] Example 2

[0038] The difference from Example 1 is that the "copper sulfate solution" is replaced by "lanthanum nitrate solution", and the rest is the same as Example 1.

[0039] Example 3

[0040] The difference from Example 1 is: "copper sulfate solution" is replaced by "zinc chloride solution", and the rest is the same as Example 1.

[0041] Example 4

[0042] The difference from Example 1 is that the "copper sulfate solution" is replaced by "ferric nitrate solution", and the rest is the same as Example 1.

[0043] Example 5

[0044] The difference from Example 1 is that "copper sulfate solution" is replaced by "cobalt sulfate solution", and the rest is the same as Example 1.

[0045] Example 6

[0046] The difference from Example 1 is that the "copper sulfate solution" is replaced by "cerium chloride solution", and the rest is the same as Example 1.

[0047] Example 7

[0048] The difference from Example 1 is that the template " is replaced by "Tetraethylammonium hydroxide ", and the rest is the same as in Example 1.

[0049] Example 8

[0050] The difference from Example 1 is that "disodium ethylenediaminetetraacetate" is replaced by "lysine", and the rest is the same as Example 1.

[0051] Comparative Example 1

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

[0053] Comparative Example 2

[0054] According to the steps of "exchanging to copper-type catalyst" in Example 1, the 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 for copper-type, washed with water until neutral and dried, and then calcined at 500°C for 3h to obtain the catalyst.

[0055] Comparative Example 3

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

[0057] Comparative Example 4

[0058] The difference from Example 1 is that no aluminum-rich molecular sieve is added as a seed crystal during the synthesis process, and the rest is the same as Example 1.

[0059] The catalysts obtained in the above examples and comparative examples were tested for performance, and the test methods and results are as follows:

[0060] Test method:

[0061] The product composition was measured by gas chromatography; the catalyst life was determined according to the time when the olefin conversion rate was not less than 99.5%; the measured octane number 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 catalyst life and octane number

[0063] catalyst Catalytic life (min) Octane 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 shown in Table 1, the octane number of the reaction product of the alkylation molecular sieve catalyst without metal modification (Comparative Example 1) is low, which is due to the lack of strong B acid centers, the inhibition of hydrogen transfer reaction, and the reduction of the selectivity of carbon eight products; the catalyst without nano multi-level pore structure (Comparative Example 2) has a short catalytic life, which is due to the inability of product molecules to diffuse out of the pores in time, resulting in product polymerization or polyalkylation, causing the catalyst to be carbonized and deactivated; the catalyst without multi-level pore structure and metal modification (Comparative Example 3) has a short catalytic life and a low octane number of the reaction product; the catalyst without adding seed aluminum-rich molecular sieve (Comparative Example 4) has a short catalytic life and a low octane number of the reactant. Compared with the catalyst without introducing multi-level pore structure and metal components and the catalyst without adding seed, the C4 alkylation aluminum-rich molecular sieve catalyst obtained in the example has a significantly longer catalytic life, and the octane number of the product is also very high, indicating that it has a high selectivity for the product.

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

[0066] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may 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 the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a C4 alkylated aluminum-rich molecular sieve catalyst coupled with metal modification and multi-level porous nanostructure, characterized in that: The steps include: (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, and the seed crystal is an aluminum-rich molecular sieve.

2. The method for preparing the C4 alkylated aluminum-rich molecular sieve catalyst coupled with metal modification and multi-level porous nanostructure 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 method for preparing the metal-modified C4 alkylated aluminum-rich molecular sieve catalyst coupled with a multi-level porous nanostructure 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 method for preparing the metal-modified C4 alkylated aluminum-rich molecular sieve catalyst coupled with a multi-level porous nanostructure according to claim 1, characterized in that: 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.

5. The method for preparing the metal-modified C4 alkylated aluminum-rich molecular sieve catalyst coupled with a multi-level porous nanostructure 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.

6. The method for preparing the metal-modified C4 alkylated aluminum-rich molecular sieve catalyst coupled with a multi-level porous nanostructure 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.

7. The method for preparing the metal-modified and multi-level porous nanostructure-coupled C4 alkylated aluminum-rich molecular sieve catalyst 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.

8. The method for preparing the metal-modified and multi-level porous nanostructure-coupled C4 alkylated aluminum-rich molecular sieve catalyst 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.

9. The C4 alkylated aluminum-rich molecular sieve catalyst prepared by the method for preparing the metal-modified and multi-level porous nanostructure coupled C4 alkylated aluminum-rich molecular sieve catalyst according to any one of claims 1 to 8.

10. Use of the C4 alkylated aluminum-rich molecular sieve catalyst according to claim 9 in the field of petrochemical industry.

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