CN116354782A - Process for preparing alkylbenzene - Google Patents

Process for preparing alkylbenzene Download PDF

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CN116354782A
CN116354782A CN202111625579.7A CN202111625579A CN116354782A CN 116354782 A CN116354782 A CN 116354782A CN 202111625579 A CN202111625579 A CN 202111625579A CN 116354782 A CN116354782 A CN 116354782A
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molecular sieve
groups
alkylbenzene
stack
low
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崔岩
韩明汉
邢世勇
沈宜泓
李梦晨
王晓化
郭成玉
于宏悦
张上
迟克彬
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Petrochina Co Ltd
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    • C07C2/54—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition of unsaturated hydrocarbons to saturated hydrocarbons or to hydrocarbons containing a six-membered aromatic ring with no unsaturation outside the aromatic ring
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    • B01J29/00—Catalysts comprising molecular sieves
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    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
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    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
    • C01B39/04—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof using at least one organic template directing agent, e.g. an ionic quaternary ammonium compound or an aminated compound
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    • C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
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Abstract

The invention provides a preparation method of alkylbenzene, which comprises the following steps: benzene and olefin raw materials are subjected to alkylation reaction under the action of a solid acid catalyst to obtain alkylbenzene; wherein the olefin raw material comprises long-chain olefin with carbon number not less than 6, the solid acid catalyst comprises a binder and a low-stack molecular sieve with MWW topological structure, the axial direction of a crystal band axis of the low-stack molecular sieve with MWW topological structure is the direction of a c axis, the thickness of the low-stack molecular sieve with MWW topological structure along the direction of the c axis is 1.5 nm-25 nm, and the maximum length of the low-stack molecular sieve with MWW topological structure on a plane vertical to the direction of the c axis is 200 nm-3000 nm. The method has the advantages of long single-pass service life of the catalyst, high raw material conversion rate, high selectivity of 2-alkylbenzene and 3-alkylbenzene, low cost and the like, and is beneficial to industrial application.

Description

Process for preparing alkylbenzene
Technical Field
The invention relates to a preparation method of alkylbenzene, belonging to the field of alkylbenzene production.
Background
Alkylation is a very important reaction in petrochemical industry, and commonly used catalysts can be classified into L-acid catalysts and B-acid catalysts, wherein the L-acid catalysts are anhydrous AlCl 3 The catalyst is mainly represented, has the advantages of low price, good catalytic activity, mature technology and the like, but generates a large amount of aluminum-containing waste liquid in the production process and has excessive side reactions, and the catalyst is basically eliminated by the market at present, and the B acid catalyst is prepared from HF and H 2 SO 4 And H 3 PO 4 At present, the industrial production of Linear Alkylbenzene (LAB) mainly adopts an HF catalyst, and has the characteristics of high catalytic activity, mature technology and the like, however, due to the strong corrosiveness of HF acid, the requirements on equipment are very high, particularly, the contact parts of the HF acid are all made of Monel alloy materials with high price, the construction investment cost and the maintenance cost are huge, in addition, various wastes are discharged in the production process, and the environmental protection cost is high.
In the 80 s of the 20 th century, UOP developed a Detal solid acid alkylation technology, and replaced the traditional HF catalyst with a solid acid catalyst, so that the problems of equipment corrosion, environmental pollution and the like caused by the HF catalyst are fundamentally solved, investment cost is reduced due to the reduction of equipment material requirements, and in addition, the selectivity of target products such as 2-alkylbenzene and the like is also to a certain degree relative to that of an HF catalytic processLifting is achieved. In view of the above-mentioned advantages of the solid acid catalytic alkylation process, it has become a research hot spot for catalytic synthesis of alkylbenzenes, for example, han Minghan et al (Applied Catalysis A, general.2003, 99-107.) have developed a catalyst comprising a beta molecular sieve as a main active component, which can catalyze synthesis of alkylbenzene products such as 2-alkylbenzene, however, the catalyst has a single-pass life of less than 20 hours; patent document CN101058523a discloses a method for preparing linear alkylbenzene, which uses linear olefin with 2-20 carbon atoms and benzene as raw materials, and adopts a solid acid catalyst to carry out alkylation reaction under the supercritical condition of 290-450 ℃ and 5-15 MPa to prepare linear alkylbenzene, wherein the solid acid catalyst is one of the following or a composite solid acid catalyst obtained by carrying and modifying one of the following: SBA-15 type molecular sieve, HY type molecular sieve, USY type molecular sieve, H beta type molecular sieve, H-Moderite type molecular sieve, HZSM-20 type molecular sieve, the preparation process has the defects of harsh reaction conditions, high energy consumption, high equipment requirement, high cost and the like; patent document CN103079698A discloses a method of controlling the 2-phenyl isomer content of linear alkylbenzenes and a catalyst used in the method, the method comprising: reacting a substantially linear olefin with an aryl compound under alkylation reaction conditions in the presence of a catalyst, the linear olefin comprising molecules having from 8 to 28 carbon atoms, the catalyst comprising a first catalyst component zeolite selected from the group consisting of rare earth-containing faujasites and mixtures thereof and a second catalyst component zeolite selected from the group consisting of UZM-8, zeolite MWW, zeolite BEA, zeolite OFF, zeolite MOR, zeolite LTL, zeolite MTW, BPH/UZM-4 and mixtures thereof, the catalyst used in the process requiring the incorporation of rare earth elements, the catalyst composition being complex; patent document CN108569945a discloses a process for producing linear alkylbenzene comprising the step of contacting long-chain olefin and benzene with a catalyst comprising, in parts by weight, 40 to 90 parts of a silicone zeolite and 10 to 60 parts of a binder, the requirements on the silicone zeolite being: the silicone zeolite comprises the following composition in molar relation: (1/n) Al2O3: siO2: (m/n) R, wherein n=5 to 250 m=0.01 to 50, and R is at least one of an alkyl group, an alkenyl group, or a phenyl group; si of the zeolite 29 At least the NMR solid nuclear magnetic spectrum is between-80 and +50ppmContaining one Si 29 Nuclear magnetic resonance spectrum peaks; the X-ray diffraction pattern of the zeolite has d-interval maximum values at 12.4+/-0.2, 10.5+/-0.3, 9.3+/-0.3, 6.8+/-0.2, 6.1+/-0.2, 5.5+/-0.2, 4.4+/-0.2, 4.0+/-0.2,3.5 +/-0.l, 3.4+/-0.1 and 3.3+/-0.1 angstroms, and the process adopts the organosilicon zeolite with a specific structure as an active main body of the catalyst and needs to introduce fluorine element for fluorine modification so as to ensure the stability and other performances; patent document CN112705252a discloses a liquid phase alkylation catalyst comprising a molecular sieve having MWW topology and a binder, wherein the content of the molecular sieve having MWW topology is 50 to 90 wt%, the content of the binder is 10 to 50 wt%, and the outer surface area pore volume of the liquid phase alkylation catalyst is 0.45 to 0.65cm, based on the total weight of the liquid phase alkylation catalyst 3 In addition, a boron source is required to be introduced in the preparation process of the molecular sieve with the MWW topological structure, and the boron source is actually a liquid phase alkylation catalyst formed by compositing the boron-containing MWW molecular sieve and a binder, and is used for alkylation reaction of benzene and short-chain olefin (ethylene).
Although solid acid catalytic synthesis of alkylbenzene has been reported, the preparation efficiency of alkylbenzene still needs to be further improved, especially when long-chain olefin is used as a raw material, the long-chain olefin molecules are larger, so that catalyst pore channels are more easily blocked, and the problems of catalyst deactivation and the like are solved, and the preparation method is still an important subject faced by the person skilled in the art in terms of improving the single-pass service life of the catalyst, the conversion rate of the raw material, the selectivity of 2-alkylbenzene and 3-alkylbenzene in an alkylated product, reducing the cost and the like.
Disclosure of Invention
The invention provides a preparation method of alkylbenzene, which has the advantages of long single-pass service life of catalyst, high raw material conversion rate, high selectivity of 2-alkylbenzene and 3-alkylbenzene, low cost and the like, and can effectively overcome the defects in the prior art.
In one aspect of the present invention, there is provided a method for producing alkylbenzene comprising: benzene and olefin raw materials are subjected to alkylation reaction under the action of a solid acid catalyst to obtain alkylbenzene; the olefin raw material comprises long-chain olefin with carbon number not less than 6, the solid acid catalyst comprises a binder and a low-stack molecular sieve with an MWW topological structure, the axial direction of a crystal band axis of the low-stack molecular sieve with the MWW topological structure is in a c-axis direction, the thickness of the low-stack molecular sieve with the MWW topological structure along the c-axis direction is 1.5 nm-25 nm, and the maximum length of the low-stack molecular sieve with the MWW topological structure on a plane perpendicular to the c-axis direction is 200 nm-3000 nm.
According to an embodiment of the present invention, the low stack molecular sieve having MWW topology is prepared according to a process comprising the steps of: (I) Mixing an alkali source, an aluminum source, a template agent and a silicon source with water to prepare crystallized gel; (II) allowing the crystallized gel to stand at a temperature T 1 Performing primary crystallization under the condition of (2) to obtain a primary crystallization product; wherein T is 1 The temperature is 120-180 ℃, and the time of the primary crystallization is 12-36 hours; (III) allowing the primary crystallized product to stand at a temperature T 2 Performing secondary crystallization under the condition of (2) to obtain a secondary crystallization product; wherein T is 2 ＝T 1 -T 3 ，0＜T 3 The temperature is less than or equal to 50 ℃, the time of the secondary crystallization is t which is more than 0 and less than or equal to 60 hours; (IV) cooling the secondary crystallization product to normal temperature, adding quaternary ammonium salt and a siliceous agent into the secondary crystallization product, sealing and stirring the mixture for 3 to 36 hours at 50 to 85 ℃, and then sequentially drying, primary roasting, ammonium exchange and secondary roasting the obtained product to obtain the low-stack molecular sieve with the MWW topological structure.
According to one embodiment of the invention, the silicon source is formed of SiO 2 The aluminum source is calculated as Al 2 O 3 The molar ratio of the silicon source to the aluminum source calculated as metal oxide is (22.5 to 97.5): 1, the molar ratio of the template agent to the silicon source is (0.08-0.45): 1, wherein the molar ratio of the alkali source to the silicon source is (0.03-0.20): 1, wherein the mole ratio of the water to the silicon source is (10-60): 1.
According to one embodiment of the invention, the silicon source is formed of SiO 2 The quaternary ammonium salt is calculated as quaternary ammonium cation, and the silicon agent is calculated as SiO 2 A meter, the quaternary ammonium saltThe molar ratio to the silicon source is (0.1-1.0): 1, the molar ratio of the silicon agent to the silicon source is (0.05-2.5): 1.
according to an embodiment of the invention, the silicon source comprises a silica sol and/or a solid silica gel; and/or, the aluminum source comprises sodium metaaluminate and/or aluminum sulfate; and/or the template comprises hexamethyleneimine or a mixture of hexamethyleneimine and cyclohexylamine; and/or, the alkali source comprises sodium hydroxide and/or potassium hydroxide; and/or the quaternary ammonium salt comprises at least one of tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, tetramethyl ammonium bromide, tetraethyl ammonium bromide, tetrapropyl ammonium bromide, tetrabutyl ammonium bromide, tetramethyl ammonium chloride, tetraethyl ammonium chloride, tetrapropyl ammonium chloride, tetrabutyl ammonium chloride; and/or the silicon agent comprises silica sol and/or tetraethoxysilane.
According to an embodiment of the present invention, the process for preparing the crystallized gel comprises: dissolving an alkali source and an aluminum source in water, stirring for 0-3 h, adding a template agent into the water, stirring for 0-24 h, adding a silicon source into the water, and stirring for 0-3 h to obtain the crystallized gel.
According to an embodiment of the present invention, the one-time baking process includes: roasting the product at 350-400 deg.c for 3-7 hr in inert atmosphere and then at 500-600 deg.c for 3-7 hr in oxygen-containing gas atmosphere.
According to one embodiment of the invention, the ammonium exchange is performed with an ammonium salt solution, the ammonium salt comprising ammonium nitrate, the temperature of the ammonium exchange being between 70 ℃ and 90 ℃.
According to one embodiment of the invention, the temperature of the secondary roasting is 500-600 ℃, and the time of the secondary roasting is 2-6 h.
According to one embodiment of the invention, siO is used in the low-stack molecular sieve with MWW topological structure 2 And Al 2 O 3 The molar ratio of silicon to aluminum is (19-75): 1.
According to an embodiment of the present invention, the solid acid catalyst is prepared according to a process comprising the steps of: mixing the low-stack molecular sieve with MWW topological structure with a binder, adding inorganic acid and water into the mixture, sequentially forming and drying, and roasting at 500-600 ℃ for 4-8 hours to obtain the solid acid catalyst.
According to one embodiment of the invention, in the solid acid catalyst, the mass percentage of the low-stack molecular sieve with the MWW topological structure is 10% -95%, and the balance is the binder.
According to an embodiment of the present invention, the binder comprises at least one of aluminum oxide, pseudo-boehmite, aluminum hydroxide.
According to one embodiment of the present invention, the long-chain olefin includes a linear olefin having 6 to 22 carbon atoms.
According to one embodiment of the present invention, the molar ratio of benzene to long-chain olefin is (5-50): 1.
According to one embodiment of the invention, the alkylation reaction conditions are: the temperature is 100-200 ℃, the pressure is 1-7 MPa, and the mass space velocity of the mixture of the benzene and the long-chain olefin is 0.5h -1 ～12h -1 。
According to the invention, the low-stack molecular sieve with the MWW topological structure with a specific structure is used as a solid acid catalyst, so that the alkylation of benzene and long-chain olefin can be efficiently catalyzed, the conversion rate of the long-chain olefin and the selectivity of 2-alkylbenzene and 3-alkylbenzene in an alkylation product are improved, meanwhile, the single-pass service life of the catalyst is long, the single-pass service life of the catalyst can reach more than 220 hours and even more than 500 hours, the conversion rate of the long-chain olefin is up to more than 99%, the selectivity of the 2-alkylbenzene is up to more than 42%, and the selectivity of the 2-alkylbenzene and the 3-alkylbenzene is up to more than 63%. In addition, the catalyst used in the invention has simple composition, does not need to introduce halogen, fluorine, boron and other elements, has low cost, has the advantages of mild alkylation reaction condition, high efficiency and the like, and is beneficial to industrial application.
Drawings
FIG. 1 is an x-ray diffraction (XRD) spectrum (abscissa indicates 2. Theta. Angle, and ordinate indicates peak Intensity) of the H-type molecular sieve prepared in example 1;
FIG. 2 is a Scanning Electron Microscope (SEM) image of the H-type molecular sieve prepared in example 1;
FIG. 3 is an XRD spectrum of the H-type molecular sieve prepared in example 2;
FIG. 4 is an SEM image of an H-type molecular sieve prepared in example 2;
FIG. 5 is an XRD pattern of the H-type beta zeolite molecular sieve used in comparative example 1;
FIG. 6 is an SEM image of an H-type beta zeolite molecular sieve used in comparative example 1;
FIG. 7 is an XRD spectrum of the zeolite molecular sieve of H-type MWW structure used in comparative example 2;
FIG. 8 is an SEM image of an H-type MWW structure zeolite molecular sieve used in comparative example 2;
FIG. 9 is an SEM image of an H-type molecular sieve prepared in comparative example 3.
Detailed Description
The present invention will be described in further detail below for the purpose of better understanding of the aspects of the present invention by those skilled in the art. The following detailed description is merely illustrative of the principles and features of the present invention, and examples are set forth for the purpose of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the examples of the invention without making any inventive effort, are intended to be within the scope of the invention.
The preparation method of alkylbenzene provided by the invention comprises the following steps: benzene and olefin raw materials are subjected to alkylation reaction under the action of a solid acid catalyst to obtain alkylbenzene; wherein the olefin raw material comprises long-chain olefin with carbon number not less than 6, the solid acid catalyst comprises a binder and a low-stack molecular sieve with MWW topological structure, the axial direction of a crystal band axis of the low-stack molecular sieve with MWW topological structure is the direction of a c axis, the thickness of the low-stack molecular sieve with MWW topological structure along the direction of the c axis is 1.5 nm-25 nm, and the maximum length of the low-stack molecular sieve with MWW topological structure on a plane vertical to the direction of the c axis is 200 nm-3000 nm.
In the invention, the thickness of the low-stack molecular sieve with MWW topological structure along the c-axis direction and the maximum length (or dimension) of the low-stack molecular sieve on a plane perpendicular to the c-axis direction can be measured by an electron microscope (SEM) scanning method. Specifically, the a-axis, the b-axis and the c-axis are mutually perpendicular to form a space rectangular coordinate system, the axial direction of the crystal band axis of the low-stack molecular sieve is the c-axis direction, the thickness of the low-stack molecular sieve in the c-axis direction (i.e. the axial direction of the crystal band axis) is 1.5 nm-25 nm, for example, 1.5nm, 3nm, 5nm, 10nm, 15nm, 20nm, 25nm or the range formed by any two of the above, the plane in which the a-axis and the b-axis are positioned is the plane vertical to the c-axis direction, and the dimension (i.e. the maximum length) of the low-stack molecular sieve in the plane is 200 nm-3000 nm, for example, 200nm, 500nm, 800nm, 1000nm, 1200nm, 1500nm, 1800nm, 2000nm, 2200nm, 2500nm, 2800nm, 3000nm or the range formed by any two of the above.
In the invention, the low-stack molecular sieve with the MWW topological structure is prepared according to the process comprising the following steps: (I) Mixing an alkali source, an aluminum source, a template agent and a silicon source with water to prepare crystallized gel; (II) crystallizing the gel at a temperature T 1 Performing primary crystallization under the condition of (2) to obtain a primary crystallization product; wherein T is 1 The temperature is 120-180 ℃, and the time of primary crystallization is 12-36 h; (III) allowing the primary crystallized product to stand at a temperature T 2 Performing secondary crystallization under the condition of (2) to obtain a secondary crystallization product; wherein T is 2 ＝T 1 -T 3 ，0＜T 3 The temperature is less than or equal to 50 ℃, the time of secondary crystallization is t which is more than 0 and less than or equal to 60 hours; (IV) cooling the secondary crystallization product to normal temperature, adding quaternary ammonium salt (or quaternary ammonium base) and a siliceous agent into the secondary crystallization product, sealing and stirring the mixture for 3 to 36 hours at 50 to 85 ℃, and then sequentially filtering, drying, primary roasting, ammonium exchange and secondary roasting the obtained product to obtain the low-stack molecular sieve with the MWW topological structure.
In general, when a solid acid catalyst is used for catalyzing alkylation of benzene and long-chain olefin, the long-chain olefin, long-chain byproducts generated by the reaction, macromolecules such as polycyclic aromatic hydrocarbon byproducts and the like are easy to block the pore channels of the catalyst, so that the phenomena of catalyst deactivation and the like are caused. The macroporous twelve-membered ring molecular sieve has stronger internal diffusion performance of pore channels, has a certain effect of relieving the problem of rapid catalyst deactivation caused by pore channel blockage, however, the traditional twelve-membered ring macroporous molecular sieve (such as faujasite, beta zeolite and the like) is still easy to deactivate due to the fact that the internal pore channels of crystals are blocked by macromolecules, and although the prior art has a solid acid catalyst which adopts different types of twelve-membered ring macroporous molecular sieves as main active components, elements such as halogen and the like are generally required to be introduced to modify the molecular sieve so as to ensure the diffusion performance, and the problems of complex preparation cost of the catalyst, high-corrosiveness halogen content, low stability of the molecular sieve and the like exist.
According to the invention, through the preparation process of the molecular sieve, the molecular sieve with an MWW topological structure and suitable structure and composition can be prepared, and the molecular sieve is compounded with a binder to form a solid acid catalyst, so that alkylation reaction of benzene and long-chain olefin can be efficiently catalyzed, the conversion rate of the long-chain olefin and the selectivity of target products such as 2-alkylbenzene and 3-alkylbenzene are improved, meanwhile, the solid acid catalyst also has the advantages of long single-pass service life and the like, and the inventor considers that the low-stack molecular sieve with the MWW topological structure prepared through the process has a special lamellar molecular sieve morphology, the semi-super cage structure distributed on the surface of the low-stack molecular sieve has good diffusion effect on macromolecules such as long-chain olefin and the like, and the exposure degree of active catalytic sites (acid sites) in the solid acid catalyst with unit mass can be improved, so that the solid acid catalyst has longer single-pass service life and excellent catalytic activity and other performances, and the efficient alkylation of benzene and long-chain olefin can be realized; in addition, the process does not need to introduce elements such as halogen (such as fluorine) and the like to modify the molecular sieve, and the catalyst has the advantages of simple composition, simple preparation process, low cost, good stability, excellent regeneration performance and the like, and is beneficial to industrial implementation.
In some embodiments, the silicon source is in SiO 2 The aluminum source is Al 2 O 3 Calculated as metal oxide (e.g., when the alkali source is an alkali metal (M) hydroxide (MOH), calculated as M) 2 O), the molar ratio of the silicon source to the aluminum source is (22.5-97.5): 1, e.g., 22.5:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 97.5:1, or any two of them, the molar ratio of templating agent to silicon source is (0.08-0.45): 1, for example 0.08: 1. 0.1: 1. 0.15: 1. 0.2: 1. 0.25: 1. 0.3: 1. 0.35: 1. 0.4: 1. 0.45:1 or any two of them, the molar ratio of the alkali source to the silicon source is (0.03-0.20): 1, for example 0.03: 1. 0.05: 1. 0.08: 1. 0.1: 1. 0.12: 1. 0.15: 1. 0.18: 1. 0.2:1 or any two of them, the molar ratio of water to silicon source is (10-60): 1, for example 10: 1. 20: 1. 30: 1. 40: 1. 50: 1. 60:1 or any two thereof.
In some embodiments, the silicon source is in SiO 2 Calculated as quaternary ammonium salt, based on quaternary ammonium cation (NR + ) Based on SiO as the silicon agent 2 The molar ratio of the quaternary ammonium salt to the silicon source is (0.1-1.0): 1, for example 0.1: 1. 0.3: 1. 0.5: 1. 0.7: 1. 1:1 or any two of them, the molar ratio of the silicon agent to the silicon source is (0.05-2.5): 1, for example 0.05: 1. 0.08: 1. 0.1: 1. 0.12: 1. 0.15: 1. 0.18: 1. 0.2: 1. 0.22: 1. 0.25:1 or any two thereof.
In the present invention, the aluminum source used may include sodium metaaluminate and/or aluminum sulfate, and may specifically be sodium metaaluminate, or aluminum sulfate, or a mixture of sodium metaaluminate and aluminum sulfate.
In the present invention, the alkali source used may include an inorganic base in particular, may include a soluble inorganic base, for example, including a hydroxide of an alkali metal. In some embodiments, the alkali source comprises an alkali source comprising sodium hydroxide and/or potassium hydroxide.
In the present invention, the template used may specifically comprise an organic template, for example, an organic amine template, and may particularly comprise hexamethyleneimine, and in some preferred embodiments, the template comprises hexamethyleneimine or a mixture of hexamethyleneimine and cyclohexylamine.
In the invention, the silicon source can specifically comprise an inorganic silicon source, which is beneficial to further saving the cost compared with the organic silicon source, and in addition, according to the research of the invention, the catalytic activity of the solid acid catalyst on benzene and long-chain olefin alkylation, the service life of the catalyst and other performances can be further improved by adopting the inorganic silicon source and the preparation process of the molecular sieve. In some preferred embodiments, the silicon source comprises a silica sol and/or a solid silica gel.
In the present invention, the quaternary ammonium salt may comprise tetraalkylammonium hydroxide and/or tetraalkylammonium halides, which may comprise tetraalkylammonium bromide and/or tetraalkylammonium chloride, wherein the alkyl group may be a C1-C4 alkyl group, such as methyl, ethyl, propyl, butyl, etc., and in some preferred embodiments, the quaternary ammonium salt comprises at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride.
In the present invention, the silicon agent used may include organic silicon including, for example, ethyl orthosilicate and/or inorganic silicon including, for example, silica sol. In some embodiments, the silicone agent comprises a silica sol and/or ethyl orthosilicate.
Specifically, in the preparation process, the raw materials are mixed and then are respectively heated at the temperature T 1 And T 2 Is crystallized in two stages under the condition of (1) and the temperature T of the secondary crystallization is controlled 2 Problem T of more than one crystallization 1 Low T 3 I.e. after the end of the primary crystallization, at the primary crystallization temperature T of step (III) 1 Reference upper and lower T of (2) 3 The primary crystallization product is crystallized again, and the low-stack molecular sieve with a proper structure can be prepared by matching with the subsequent treatments of closed stirring after adding quaternary ammonium salt and a silicon agent, and according to the research of the invention, the low-stack molecular sieve can be compounded with a binder to form a solid acid catalyst, so that the alkylation reaction of benzene and long-chain olefin can be catalyzed efficiently.
In some embodiments, the process of making a crystallized gel comprises: dissolving an alkali source and an aluminum source in water, stirring for 0-3 hours, such as 0.5 hours, 1 hours, 1.5 hours, 2 hours, 2.5 hours, 3 hours or a range formed by any two of the above, adding a template agent into the mixture, continuously stirring for 0-24 hours, such as a range formed by any two of 0.5 hours, 1 hours, 3 hours, 5 hours, 7 hours, 10 hours, 12 hours, 15 hours, 18 hours and 20 hours, adding a silicon source into the mixture, and continuously stirring for 0-3 hours, such as a range formed by any two of 0.5 hours, 1 hours, 1.5 hours, 2 hours, 2.5 hours and 3 hours, so as to obtain crystallized gel.
Optionally, in step (II), T 1 The crystallization time is in the range of 12h, 15h, 18h, 20h, 22h, 25h, 28h, 30h, 33h, 36h or any two of the ranges of 120 ℃, 125 ℃, 130 ℃, 135 ℃, 140 ℃, 145 ℃, 150 ℃, 155 ℃, 160 ℃, 165 ℃, 170 ℃, 175 ℃, 180 ℃ or any two of the ranges; in step (III), T 3 The secondary crystallization time t is 5h, 10h, 15h, 20h, 25, 30, 35, 40, 45, 50 or any two of them, and the secondary crystallization time t is 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h or any two of them.
After the crystallization in the two stages is finished, the obtained secondary crystallization product (crystallization mother liquor) is cooled to room temperature, quaternary ammonium salt and a silicon agent are added into the secondary crystallization product, and then the secondary crystallization product is transferred into a closed mixer for closed mixing (or the crystallization mother liquor is transferred into the closed mixer, and then quaternary ammonium salt and the silicon agent are added into the crystallization mother liquor, and then the closed mixing is carried out). Illustratively, the temperature of the closed stirring is in the range of 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃ or any two thereof, and the time of the closed stirring is in the range of 3h, 5h, 10h, 15h, 20h, 25h, 30h, 33h, 36h or any two thereof.
In the preparation process, after the closed stirring is completed, the obtained product is sequentially washed and filtered, and then the obtained solid product is sequentially subjected to drying, primary roasting, ammonium exchange, secondary roasting and the like, wherein the drying temperature can be 100-150 ℃, for example, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃ or any two of the above, and the drying time can be 3-5 h.
Wherein, after one firing, the templating agent is removed, in some preferred embodiments, the one firing process comprises: the product (i.e., the dried product obtained after the above drying) is baked at 350 to 400 ℃ for 3 to 7 hours under an inert atmosphere (denoted as low temperature baking), and then baked at 500 to 600 ℃ for 3 to 7 hours under an oxygen-containing gas atmosphere, wherein the inert atmosphere includes, for example, nitrogen, the oxygen-containing gas includes oxygen, the low temperature baking temperature is, for example, 350 ℃, 360 ℃, 370 ℃, 380 ℃, 390 ℃, 400 ℃ or any two of them, the low temperature baking time is, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or any two of them, the high temperature baking temperature is, for example, 500 ℃, 510 ℃, 520 ℃, 530 ℃, 540 ℃, 550 ℃, 560 ℃, 570 ℃, 580 ℃, 590 ℃, 600 ℃ or any two of them, the high temperature baking time is 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or any two of them, the inert low temperature baking and the oxygen-containing high temperature baking process can optimize the prepared solid acid catalyst, the performance of alkylbenzene is further improved,
the product after primary roasting is generally a sodium type molecular sieve with MWW topological structure, and can be converted into an H type molecular sieve after being treated by ammonium exchange and the like. In the specific implementation, ammonium salt solution can be adopted for carrying out ammonium exchange, namely, the product obtained after the high-temperature roasting is placed in the ammonium salt solution for carrying out ammonium exchange, and after the ammonium exchange, the ammonium exchange product is subjected to secondary roasting to obtain an H-type molecular sieve (namely, the low-stack molecular sieve with MWW topological structure); wherein the ammonium salt may include ammonium nitrate, the ammonium salt solution may be specifically an aqueous solution of ammonium salt, the temperature of ammonium exchange may be 70 ℃ to 90 ℃, for example, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃ or any two thereof, and the time of ammonium exchange may be generally 1h to 3h.
In some embodiments, the temperature of the secondary calcination may be in the range of 500 ℃ to 600 ℃, such as 500 ℃, 510 ℃, 520 ℃, 530 ℃, 540 ℃, 550 ℃, 560 ℃, 570 ℃, 580 ℃, 590 ℃, 600 ℃, or any two thereof, and the time of the secondary calcination may be in the range of 2h to 6h, such as 2h, 3h, 4h, 5h, 6h, or any two thereof.
In the present invention, the water used may be deionized water, but is not limited thereto.
In the present invention, the solid acid catalyst can be specifically prepared according to a process comprising the steps of: mixing a low-stack molecular sieve with an MWW topological structure with a binder, adding inorganic acid and water into the mixture, and sequentially performing molding, drying and roasting to obtain a solid acid catalyst; the inorganic acid may include nitric acid, the molding may be extrusion molding, the drying may be drying in the shade at 20-30deg.C, the baking temperature may be 500-600deg.C, such as 500 deg.C, 510 deg.C, 520 deg.C, 530 deg.C, 540 deg.C, 550 deg.C, 570 deg.C, 580 deg.C, 590 deg.C, 600 deg.C, or any two of them, and the baking time may be 4-8 h, such as 4h, 5h, 6h, 7h, 8h, or any two of them.
In some preferred embodiments, the low-stack molecular sieve with MWW topology is prepared with SiO 2 And Al 2 O 3 The molar ratio of silicon to aluminum is (19-75) 1, namely, the molar ratio of silicon to aluminum in the chemical composition of the low-stack molecular sieve satisfies the following conditions: siO (SiO) 2 :Al 2 O 3 = (19-75): 1, e.g., 19:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, or a range of any two of them. In the concrete implementation, the silicon-aluminum ratio of the prepared low-stack molecular sieve can be regulated and controlled according to the use amount of the raw materials such as the silicon source, the aluminum source and the like.
According to the studies of the present invention, the performance of the solid acid catalyst can be further optimized by controlling the content of the low-stack molecular sieve in the solid acid, to improve the alkylation efficiency of benzene and long-chain olefins, and in some preferred embodiments, the mass percentage of the low-stack molecular sieve having MWW topology in the solid acid catalyst is 10% to 95%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or a range of any two of them, with the balance being the binder. Preferably, the content of the low-stack molecular sieve in the solid acid catalyst is higher than the content of the binder, and more preferably the content of the low-stack molecular sieve is 85% to 95%.
In the present invention, the binder used may include an inorganic oxide-based binder, for example, at least one of aluminum oxide, pseudo-boehmite, aluminum hydroxide.
In the present invention, the long-chain olefin may specifically include a linear olefin having not less than 6 carbon atoms, and generally preferably includes a linear olefin having 6 to 22 carbon atoms, and the number of carbon atoms of the olefin molecule included in the long-chain olefin is, for example, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 or a range composed of any two thereof, that is, the long-chain olefin may include at least one of olefins having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 carbon atoms, and preferably the long-chain olefin includes a linear olefin having 8 to 18 carbon atoms. The long-chain olefin may be a long-chain α -linear olefin having a double bond at the end thereof, and the number of c=c double bonds may be generally 1, and may include at least one of 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene, for example.
In general, the molar ratio of benzene to long chain olefin in the alkylbenzene production process may be (5 to 50): 1, for example, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1 or any two of them.
In the present invention, the alkylation reaction is particularly carried out in a reactor, which includes, for example, a fixed bed reactor, but is not limited thereto. The alkylation reaction conditions may be: the temperature is 100-200 ℃, such as 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃ or any two of them, the pressure is 1-7 MPa, such as 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa or any two of them, the mass airspeed of the mixture of benzene and long-chain olefin is 0.5h -1 ～12h -1 For example 0.5h -1 、1h -1 、2h -1 、3h -1 、4h -1 、5h -1 、6h -1 、7h -1 、8h -1 、9h -1 、10h -1 、11h -1 、12h -1 Or a range of any two of these.
In the specific implementation, a mixture of benzene and long-chain olefin is introduced into a reactor, and the benzene and the long-chain olefin are contacted with a solid acid catalyst in the reactor to carry out alkylation reaction under the catalysis of the solid acid catalyst to prepare alkylbenzene. The alkylbenzene can specifically comprise linear alkylbenzene, wherein 2-alkylbenzene and 3-alkylbenzene have the advantages of good solubility, easy biodegradation, environmental friendliness and the like, are important chemical products, and the alkylbenzene prepared by the preparation process generally comprises 2-alkylbenzene and 3-alkylbenzene, and can improve the yield of target products such as 2-alkylbenzene and 3-alkylbenzene.
For the purpose of promoting an understanding of the principles of the invention, reference will now be made in detail to specific examples, some but not all of which are illustrated in the accompanying drawings. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the following examples, the raw materials used were as follows:
(1) Silicon source: silica sol (SiO therein) 2 40% by mass), solid silica gel (SiO therein 2 97% by mass);
(2) Template agent: hexamethyleneimine (purity 98%), cyclohexylamine (purity 99%);
(3) Aluminum source: sodium metaaluminate (Al therein 2 O 3 41% by mass), aluminum sulfate (Al therein) 2 O 3 15% by mass;
(4) Alkali source: sodium hydroxide (purity 99%), potassium hydroxide (purity 99%);
(5) Other: deionized water.
In the following examples, the selectivity to 2-alkylbenzene and the selectivity to 3-alkylbenzene were measured as follows: determination of the chromatographic peak area A of the alkylated product by High Performance Liquid Chromatography (HPLC) Total (S) (i.e., the sum of the peak areas of all alkylbenzenes produced by alkylation of benzene), the peak area A of 2-alkylbenzene therein was determined 2 And peak area A of 3-alkylbenzene 3 Selectivity to 2-alkylbenzene=a 2 /A Total (S) Selectivity of 2-alkylbenzene+3 alkylbenzene= (a) 2 +A 3 )/A Total (S) 。
In the following examples, long-chain olefin conversion= (m 0 -m 1 )/m 0 ，m 0 Is the total mole number of the long-chain olefin raw material, m 1 Is the mole number of long chain olefins remaining in the system after alkylation.
Example 1
(1) Preparation of low stack molecular sieves with MWW topology
Adding 36.5g of sodium hydroxide into 4000g of deionized water, stirring and dissolving, adding 75g of sodium metaaluminate into the deionized water, stirring and dissolving, continuously and strongly stirring for 1h, slowly adding 352g of hexamethyleneimine into the deionized water, continuously and strongly stirring for 0.5h, slowly adding 1500g of silica sol into the deionized water, and continuously and strongly stirring for 3h to obtain crystallized gel;
crystallizing (i.e. primary crystallizing) the crystallized gel at 160 ℃ for 36 hours, and then cooling to 154 ℃ for continuous crystallization (i.e. secondary crystallizing) for 24 hours; after crystallization, the obtained crystallization mother liquor is cooled to normal temperature, 2750g of tetrapropylammonium hydroxide solution (the mass concentration is 25%) and 1230g of tetraethoxysilane are slowly added into the crystallization mother liquor under the condition of continuous stirring, the mixture is stirred in a closed way for 18 hours under the water bath of 80 ℃, the obtained product is washed and filtered by deionized water of 80 ℃, dried for 4 hours under 120 ℃, then baked for 5 hours under the nitrogen atmosphere at 375 ℃, and then baked for 5 hours under the oxygen atmosphere at 540 ℃, and the low-stack sodium molecular sieve product with MWW topological structure is obtained;
Placing the sodium type molecular sieve product into a 1mol/L ammonium nitrate solution, performing ammonium exchange at 80 ℃ for 2 hours, and roasting the obtained ammonium exchange product at 550 ℃ for 4 hours to obtain an H type molecular sieve;
the XRD spectrum of the H-type molecular sieve is shown in figure 1, the SEM (scanning electron microscope) graph is shown in figure 2, the H-type molecular sieve is a low-stack molecular sieve with MWW topological structure, the thickness of the H-type molecular sieve along the c-axis direction is 5 nm-10 nm, and the maximum length of the H-type molecular sieve on a plane vertical to the c-axis direction is 500nm-2000nm.
(2) Preparation of solid acid catalyst
Mixing 90g of the H-type molecular sieve with 15g of pseudo-boehmite uniformly, kneading while gradually adding 55g of nitric acid solution, extruding strips and molding to obtain the final product
Figure BDA0003438728250000131
Cutting the cylindrical substrate into a cylindrical intermediate with the length of 2.5 mm; drying the intermediate in the shade at normal temperature for 24 hours, and roasting at 550 ℃ for 6 hours to obtain the solid acid catalyst B1.
(3) Alkylation reaction
Taking 2g of the solid acid catalyst B1, loading the solid acid catalyst B1 into a fixed bed reactor, introducing a mixture of benzene and 1-dodecene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-dodecene is 15:1, the reaction temperature is 145 ℃, the reaction pressure is 4.0MPa, and the mass space velocity of the mixture of benzene and 1-dodecene is 4.0h -1 ；
After 500h of reaction, the conversion of 1-dodecene was 99.65%, the selectivity for 2-alkylbenzene was 46.5% and the selectivity for 2-alkylbenzene+3-alkylbenzene was 67.3%.
Example 2
(1) Preparation of low stack molecular sieves with MWW topology
Adding 43.5g of sodium hydroxide into 3500g of deionized water, stirring and dissolving, adding 48.3g of sodium metaaluminate into the deionized water, stirring and dissolving, continuously and strongly stirring for 0.5h, slowly adding 182g of hexamethyleneimine and 202g of cyclohexylamine into the deionized water, continuously and strongly stirring for 1.5h, slowly adding 1500g of silica sol into the mixture, and continuously and strongly stirring for 5h to obtain crystallized gel;
crystallizing the crystallized gel at 158 ℃ for 26 hours, and then cooling to 148 ℃ for 20 hours; after crystallization, cooling the obtained crystallization mother liquor to normal temperature, slowly adding 725g of tetrapropylammonium bromide solid and 973g of tetraethoxysilane into the crystallization mother liquor under the condition of continuous stirring, sealing and stirring for 10 hours under the water bath of 80 ℃, washing the obtained product with deionized water of 80 ℃, filtering, drying the product at 120 ℃ for 4 hours, roasting the product at 375 ℃ for 5 hours under the nitrogen atmosphere, and roasting the product at 540 ℃ for 5 hours under the oxygen atmosphere to obtain a low-stack sodium molecular sieve product with an MWW topological structure;
Placing the sodium type molecular sieve product into a 1mol/L ammonium nitrate solution, performing ammonium exchange at 80 ℃ for 2 hours, and roasting the obtained ammonium exchange product at 550 ℃ for 4 hours to obtain an H type molecular sieve;
the XRD spectrum of the H-type molecular sieve is shown in figure 3, the SEM graph is shown in figure 4, the H-type molecular sieve is a low-stack molecular sieve with MWW topological structure, the thickness of the H-type molecular sieve along the c-axis direction is 15 nm-20 nm, and the maximum length of the H-type molecular sieve on a plane vertical to the c-axis direction is 500nm-2000nm.
(2) Preparation of solid acid catalyst
Mixing 90g of the H-type molecular sieve with 9g of aluminum oxide uniformly, kneading while gradually adding 65g of nitric acid solution, extruding strips and molding to obtain the final product
Figure BDA0003438728250000141
Cutting the cylindrical matrix into a cylindrical intermediate with the length of 2.5 mm; drying the intermediate in the shade for 24 hours at normal temperature, and roasting for 6 hours at 550 ℃ to obtain the solid acid catalyst B2.
(3) Alkylation reaction
Taking 2g of the solid acid catalyst B2, loading the solid acid catalyst B2 into a fixed bed reactor, and introducing a mixture of benzene and 1-dodecene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-dodecene is 20:1, the reaction temperature is 140 ℃, the reaction pressure is 3.5MPa, and the mass space velocity of the mixture of benzene and 1-dodecene is 3.0h -1 ；
After 220h of reaction, the conversion of 1-dodecene was 99.58%, the selectivity for 2-alkylbenzene was 43.7% and the selectivity for 2-alkylbenzene+3-alkylbenzene was 64.7%.
Example 3
Taking 2g of the solid acid catalyst B1 prepared in the example 1, loading the solid acid catalyst B1 into a fixed bed reactor, introducing a mixture of benzene and 1-decene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-decene is 12:1, the reaction temperature is 138 ℃, the reaction pressure is 5.0MPa, and the mass space velocity of the mixture of benzene and 1-decene is 4.0h -1 ；
After 320h of reaction, the 1-decene conversion was 99.23%, the 2-alkylbenzene selectivity was 48.3%, and the 2-alkylbenzene+3-alkylbenzene selectivity was 66.5%.
Example 4
Taking 2g of the solid acid catalyst B1 prepared in the example 1, loading the solid acid catalyst B1 into a fixed bed reactor, introducing a mixture of benzene and 1-octene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-octene is 9:1, the reaction temperature is 139 ℃, the reaction pressure is 5.0MPa, and the mass space velocity of the mixture of benzene and 1-octene is 5.0h -1 ；
After 350h of reaction, the 1-decene conversion was 99.62%, the 2-alkylbenzene selectivity was 42.2%, and the 2-alkylbenzene+3-alkylbenzene selectivity was 63.8%.
Example 5
Taking 2g of the solid acid catalyst B2 prepared in the example 2, loading the solid acid catalyst B2 into a fixed bed reactor, introducing a mixture of benzene and 1-hexadecene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-hexadecene is 25:1, the reaction temperature is 148 ℃, the reaction pressure is 3.5MPa, and the mass space velocity of the mixture of benzene and 1-hexadecene is 3.0h -1 ；
After 175h of reaction, the 1-hexadecene conversion was 99.24%, the selectivity to 2-alkylbenzene was 48.1% and the selectivity to 2-alkylbenzene+3-alkylbenzene was 70.0%.
Example 6
Taking 2g of the solid acid catalyst B2 prepared in the example 2, loading the solid acid catalyst B2 into a fixed bed reactor, introducing a mixture of benzene and 1-tetradecene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein, the mole ratio of benzene to 1-tetradecene is 25:1, the reaction temperature is 144 ℃, the reaction pressure is 4.0MPa, and the mass space velocity of the mixture of benzene and 1-tetradecene is 3.0h -1 ；
After 220h of reaction, the conversion of 1-tetradecene was 99.05%, the selectivity for 2-alkylbenzene was 47.2% and the selectivity for 2-alkylbenzene+3-alkylbenzene was 69.8%.
Example 7
2g of the solid acid catalyst B2 obtained in example 2 was charged into a fixed bed reactor, and was introduced into a reactorWherein, introducing a mixture of benzene and 1-octadecene for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-octadecene is 40:1, the reaction temperature is 154 ℃, the reaction pressure is 4.0MPa, and the mass space velocity of the mixture of benzene and 1-octadecene is 2.0h -1 ；
After 160h of reaction, the conversion of 1-octadecene was 99.35%, the selectivity for 2-alkylbenzene was 50.2% and the selectivity for 2-alkylbenzene+3-alkylbenzene was 73.6%.
Comparative example 1
The H-type zeolite prepared in example 1 was replaced with a commercially available H-type zeolite beta molecular sieve, and catalyst D1 was prepared by referring to step (2) in example 1 under the same conditions as in step (2) in example 1; wherein, XRD spectrum of the commercial H-type beta zeolite molecular sieve is shown in figure 5, and SEM (scanning electron microscope) graph is shown in figure 6;
taking 2g of the catalyst D1, loading the catalyst D1 into a fixed bed reactor, and introducing a mixture of benzene and 1-dodecene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-dodecene is 15:1, the reaction temperature is 145 ℃, the reaction pressure is 4.0MPa, and the mass space velocity of the mixture of benzene and 1-dodecene is 4.0;
after 16h of reaction, the conversion of 1-dodecene was 97.32%, the selectivity for 2-alkylbenzene was 47% and the selectivity for 2-alkylbenzene+3-alkylbenzene was 63%;
as can be seen from example 1 and comparative example 1, the solid acid catalyst B1 obtained in example 1 has better catalytic activity, and in particular, has a significantly longer single pass life than the catalyst D1 of comparative example 1.
Comparative example 2
The H-type molecular sieve prepared in example 1 was replaced with a commercially available H-type MWW-structured zeolite molecular sieve, and catalyst D2 was prepared by referring to step (2) in example 1 under the same conditions as in step (2) in example 1; wherein the XRD spectrum of the commercial H-shaped MWW structure zeolite molecular sieve is shown in figure 7, the SEM image is shown in figure 8, and the thickness of the commercial H-shaped MWW structure zeolite molecular sieve along the c-axis direction is more than 30 nm;
Taking 2g of the catalyst D2, loading the catalyst D2 into a fixed bed reactor, introducing a mixture of benzene and 1-dodecene into the fixed bed reactor for alkylation reaction to obtainAn alkylbenzene; wherein the molar ratio of benzene to 1-dodecene is 15:1, a reaction temperature of 145 ℃, a reaction pressure of 4.0MPa, and a mass space velocity of a mixture of benzene and 1-dodecene of 4.0h -1 ；
After the reaction for 105 hours, the conversion rate of 1-dodecene is 98.47%, the selectivity of 2-alkylbenzene is 41.9%, and the selectivity of 2-alkylbenzene+3-alkylbenzene is 60.2%;
as can be seen from example 1 and comparative example 1, the solid acid catalyst B1 prepared in example 1 has better catalytic activity, and in particular, has a significantly longer single pass life than the catalyst D2 of comparative example 2, i.e., the problem of rapid catalyst deactivation still exists with the conventional MWW structured molecular sieve, whereas the low-stack molecular sieve having the MWW structure prepared by the specific preparation process of example 1 can effectively solve the problem.
Comparative example 3
(1) Preparation of molecular sieves
Adding 36.5g of sodium hydroxide into 4000g of deionized water, stirring and dissolving, adding 75g of sodium metaaluminate into the solution, stirring and dissolving, continuously and strongly stirring for 1h, slowly adding 352g of hexamethyleneimine into the solution, continuously and strongly stirring for 0.5h, slowly adding 1500g of silica sol, and continuously and strongly stirring for 3h to obtain crystallized gel;
Crystallizing the crystallized gel at 155 ℃ for 72 hours; after crystallization, cooling the obtained crystallized product to normal temperature, washing and drying the product in sequence, roasting the product at 540 ℃ for 5 hours under an oxygen atmosphere to remove a template agent, placing the product in a 1mol/L ammonium nitrate solution, carrying out ammonium exchange at 80 ℃ for 2 hours, roasting the obtained ammonium exchange product at 550 ℃ for 4 hours to obtain an H-type molecular sieve, and measuring the H-type molecular sieve to be an MCM-22 molecular sieve, wherein an SEM image is shown in figure 9, and the thickness of the H-type molecular sieve along the c-axis direction is more than 30 nm;
(2) Preparation of solid acid catalyst
Mixing 90g of the H-type molecular sieve with 15g of pseudo-boehmite uniformly, kneading while gradually adding 55g of nitric acid solution, extruding strips and molding to obtain the final product
Figure BDA0003438728250000171
A cylindrical matrix, and cutting it into 2.5 lengthA cylindrical intermediate of mm; drying the intermediate in the shade at normal temperature for 24 hours, and roasting at 550 ℃ for 6 hours to obtain a catalyst D3;
(3) Alkylation reaction
Taking 2g of the catalyst D3, loading the catalyst D3 into a fixed bed reactor, and introducing a mixture of benzene and 1-dodecene into the fixed bed reactor for alkylation reaction to obtain alkylbenzene; wherein the molar ratio of benzene to 1-dodecene is 15:1, a reaction temperature of 145 ℃, a reaction pressure of 4.0MPa, and a mass space velocity of a mixture of benzene and 1-dodecene of 4.0h -1 ；
After 150h of reaction, the conversion rate of 1-dodecene is 98.17%, the selectivity of 2-alkylbenzene is 41.2%, and the selectivity of 2-alkylbenzene+3-alkylbenzene is 63.5%;
compared with the example 1, the quaternary ammonium salt and the silicon agent are not added in the comparative example 3, the synthesized molecular sieve is MCM-22 molecular sieve, the thickness of the molecular sieve along the c-axis direction is more than 30nm, when the catalyst D3 formed by compounding the molecular sieve and the binder is adopted to catalyze the alkylation reaction of benzene and 1-dodecene, the catalyst is deactivated after 150 hours of reaction, and the single-pass service life is far smaller than that of the solid acid catalyst B1 of the example 1.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A process for producing alkylbenzene comprising: benzene and olefin raw materials are subjected to alkylation reaction under the action of a solid acid catalyst to obtain alkylbenzene; the olefin raw material comprises long-chain olefin with carbon number not less than 6, the solid acid catalyst comprises a binder and a low-stack molecular sieve with an MWW topological structure, the axial direction of a crystal band axis of the low-stack molecular sieve with the MWW topological structure is in a c-axis direction, the thickness of the low-stack molecular sieve with the MWW topological structure along the c-axis direction is 1.5 nm-25 nm, and the maximum length of the low-stack molecular sieve with the MWW topological structure on a plane perpendicular to the c-axis direction is 200 nm-3000 nm.
2. The method of producing alkylbenzene according to claim 1, wherein said low-stack molecular sieve having MWW topology is produced according to a process comprising the steps of:
(I) Mixing an alkali source, an aluminum source, a template agent and a silicon source with water to prepare crystallized gel;
(II) allowing the crystallized gel to stand at a temperature T 1 Performing primary crystallization under the condition of (2) to obtain a primary crystallization product; wherein T is 1 The temperature is 120-180 ℃, and the time of the primary crystallization is 12-36 hours;
(III) allowing the primary crystallized product to stand at a temperature T 2 Performing secondary crystallization under the condition of (2) to obtain a secondary crystallization product; wherein T is 2 ＝T 1 -T 3 ，0＜T 3 The temperature is less than or equal to 50 ℃, the time of the secondary crystallization is t which is more than 0 and less than or equal to 60 hours;
(IV) cooling the secondary crystallization product to normal temperature, adding quaternary ammonium salt and a siliceous agent into the secondary crystallization product, sealing and stirring the mixture for 3 to 36 hours at 50 to 85 ℃, and then sequentially drying, primary roasting, ammonium exchange and secondary roasting the obtained product to obtain the low-stack molecular sieve with the MWW topological structure.
3. The method for producing alkylbenzene according to claim 2, wherein,
the silicon source is SiO 2 The aluminum source is calculated as Al 2 O 3 The molar ratio of the silicon source to the aluminum source calculated as metal oxide is (22.5 to 97.5): 1, the molar ratio of the template agent to the silicon source is (0.08-0.45): 1, wherein the molar ratio of the alkali source to the silicon source is (0.03-0.20): 1, wherein the mole ratio of the water to the silicon source is (10-60): 1, a step of; and/or the number of the groups of groups,
The silicon source is SiO 2 The quaternary ammonium salt is calculated as quaternary ammonium cation, and the silicon agent is calculated as SiO 2 The molar ratio of the quaternary ammonium salt to the silicon source is (0.1-1.0): 1, the molar ratio of the silicon agent to the silicon source is (0.05-2.5): 1, a step of; and/or the number of the groups of groups,
the silicon source comprises silica sol and/or solid silica gel; and/or the number of the groups of groups,
the aluminum source comprises sodium metaaluminate and/or aluminum sulfate; and/or the number of the groups of groups,
the template agent comprises hexamethyleneimine or a mixture of hexamethyleneimine and cyclohexylamine; and/or the number of the groups of groups,
the alkali source comprises sodium hydroxide and/or potassium hydroxide; and/or the number of the groups of groups,
the quaternary ammonium salt comprises at least one of tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, tetramethyl ammonium bromide, tetraethyl ammonium bromide, tetrapropyl ammonium bromide, tetrabutyl ammonium bromide, tetramethyl ammonium chloride, tetraethyl ammonium chloride, tetrapropyl ammonium chloride and tetrabutyl ammonium chloride; and/or the number of the groups of groups,
the silicon agent comprises silica sol and/or tetraethoxysilane.
4. The method for producing alkylbenzene according to claim 2, wherein,
the process for preparing the crystallized gel comprises the following steps: dissolving an alkali source and an aluminum source in water, stirring for 0-3 hours, adding a template agent into the water, continuously stirring for 0-24 hours, adding a silicon source into the water, and continuously stirring for 0-3 hours to obtain crystallized gel; and/or the number of the groups of groups,
The one-time roasting process comprises the following steps: roasting the product at 350-400 ℃ for 3-7 h under inert atmosphere, and roasting the product at 500-600 ℃ for 3-7 h under oxygen-containing gas atmosphere; and/or the number of the groups of groups,
carrying out the ammonium exchange by adopting an ammonium salt solution, wherein the ammonium salt comprises ammonium nitrate, and the temperature of the ammonium exchange is 70-90 ℃; and/or the number of the groups of groups,
the temperature of the secondary roasting is 500-600 ℃, and the time of the secondary roasting is 2-6 h.
5. The method for producing alkylbenzene according to any one of claims 1 to 4, wherein said low-stack molecular sieve having MWW topology is prepared by using SiO 2 And Al 2 O 3 The molar ratio of silicon to aluminum is (19-75): 1.
6. The method for producing alkylbenzene according to claim 1 or 2, wherein said solid acid catalyst is produced according to a process comprising the steps of: mixing the low-stack molecular sieve with MWW topological structure with a binder, adding inorganic acid and water into the mixture, sequentially forming and drying, and roasting at 500-600 ℃ for 4-8 hours to obtain the solid acid catalyst.
7. The method for producing alkylbenzene according to claim 1, wherein,
in the solid acid catalyst, the mass percentage of the low-stack molecular sieve with the MWW topological structure is 10% -95%, and the balance is binder; and/or the number of the groups of groups,
The binder comprises at least one of aluminum oxide, pseudo-boehmite, boehmite and aluminum hydroxide.
8. The method for producing alkylbenzene according to claim 1, wherein said long-chain olefin comprises a linear olefin having 6 to 22 carbon atoms.
9. The method for producing alkylbenzene according to claim 1, wherein the molar ratio of benzene to long-chain olefin is (5 to 50): 1.
10. The method for producing alkylbenzene according to claim 1, wherein the alkylation reaction conditions are: the temperature is 100-200 ℃, the pressure is 1-7 MPa, and the mass space velocity of the mixture of the benzene and the long-chain olefin is 0.5h -1 ～12h -1 。
CN202111625579.7A 2021-12-28 2021-12-28 Process for preparing alkylbenzene Pending CN116354782A (en)

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