A process for the synthesis of linear alkylaromatics

Abstract

A process for the synthesis of linear alkylaromatics by contacting an aromatic hydrocarbon and a long chain olefin under alkylation conditions in the presence of a solid acid catalyst having a hydrogenolysis metal supported thereon to form linear alkylaromatics, characterized in that the solid acid catalyst contains a Y-type zeolite having a unit cell size of 2.448-2.457 nm and a ratio of mesopore volume to total pore volume of 0.15-0.29, and the hydrogenolysis metal comprises 0.15-5 wt% of the solid acid catalyst.

Description

Technical Field

[0001] This invention relates to a method for synthesizing straight-chain alkyl aromatics, and more specifically, to a method for synthesizing straight-chain alkyl aromatics using a solid acid as a catalyst. Background Technology

[0002] Linear alkylbenzenes, obtained by alkylation of benzene and long-chain olefins, are important chemical intermediates in the synthesis of detergents. These intermediates can be further processed through sulfonation and neutralization to yield high-performance anionic surfactants—alkylbenzene sulfonates. The alkylation reaction of benzene and long-chain olefins laid the foundation for the synthetic detergent industry.

[0003] Currently, 83% of the world's linear alkylbenzene production uses the HF process, 9% uses the AlCl3 process, and 8% uses the Detal process.

[0004] Both the HF and AlCl3 processes suffer from drawbacks such as high environmental pollution, severe equipment corrosion, difficulty in product separation, and high investment costs. The Detal process, a solid acid process jointly developed by UOP (USA) and CEPSA (Spain), was industrialized in the mid-1990s. The Detal process uses fluorine-containing amorphous silica-alumina catalysts. However, its widespread adoption and development are limited by problems such as fluorine loss, discontinuous alkylation reactions and catalyst regeneration, high operating costs, and frequent regeneration. Therefore, green and environmentally friendly solid acid alkylation technology is the future trend.

[0005] In studies on the synthesis of straight-chain alkylbenzenes from benzene and long-chain olefins using solid acid catalysis, molecular sieves and heteropolyacid-type solid acid catalysts are frequently employed. However, their problems of easy deactivation and short single-cycle lifetime have not yet been effectively solved.

[0006] Current research largely focuses on catalytic materials or process optimization to improve single-cycle uptime, but this approach suffers from several problems, including poor catalytic material performance, frequent process operations, and high costs. For example, CN1043524C discloses a method for benzene alkylation using fluorinated silica-alumina and straight-chain monoolefins. Under alkylation conditions, benzene and C6 to C6... 20 A method for alkylating benzene involves contacting a linear monoolefin with a catalyst comprising silica and alumina in a weight ratio of 1:1 to 9:1 and a fluoride content of 1-6 wt% to induce benzene alkylation. This method achieves 98% olefin conversion, 85% or better selectivity for the resulting monoalkylbenzene, and at least 90% linearity with respect to the resulting monoalkylbenzene. However, the olefin conversion rate remains relatively low, and the method suffers from environmental pollution problems due to fluoride ion loss.

[0007] CN101535221B discloses a method for preparing alkylbenzenes on a solid acid catalyst with a low benzene to olefin ratio and low heavy matter formation. This method uses small crystals, acidic FAU molecular sieves as the catalyst under alkylation conditions.

[0008] CN111514924A discloses a catalytic synthesis method for long-chain alkyl aromatics, the method comprising: first, feeding the raw material aromatics into a fixed-bed alkylation reactor and filling the reactor; then, feeding the raw material aromatics and raw material C6-C... 24 A mixture of long-chain olefins and additive long-chain alkyl aromatic solvents or long-chain alkane solvents is fed into a fixed-bed reactor and contacted with an SBA-15 type mesoporous molecular sieve alkylation solid acid catalyst to carry out the alkylation reaction of aromatics and long-chain olefins, generating long-chain alkyl aromatics as the product. A portion of the effluent from the alkylation reactor is recycled back to the reactor as circulating fluid, and another portion is sent to the distillation separation system to separate excess feed and product as effluent.

[0009] US5648579A discloses a method for the alkylation reaction of benzene and 1-dodecene using a pulsed feed method. In this method, benzene is continuously fed while the olefin is stopped at intervals to achieve pulsed feed. The molar ratio of benzene to olefin is between 8 and 20, the number of carbon atoms in the straight-chain olefin is between 10 and 14, and the pulse feed interval is between 10 and 60 minutes. Summary of the Invention

[0010] The inventors discovered that catalysts obtained by supporting metals with hydrogenolysis activity on solid acids with specific physicochemical characteristics exhibit longer catalyst lifetimes and higher selectivity for straight-chain alkyl aromatics in the production of these catalysts. Based on this discovery, the present invention was developed.

[0011] Therefore, the purpose of this invention is to provide a method for synthesizing straight-chain alkyl aromatics with longer catalyst lifetime and straight-chain aromatic selectivity, based on the prior art.

[0012] To achieve the above objectives, the present invention provides a method for synthesizing straight-chain alkyl aromatics, which involves contacting aromatics and long-chain olefins under alkylation reaction conditions in the presence of a solid acid catalyst supported on a metal with hydrogenolysis properties to generate straight-chain alkyl aromatics. The method is characterized in that the solid acid catalyst contains Y-type zeolite with a cell size of 2.448–2.457 nm, and the ratio of its mesopore volume to total pore volume is 0.15–0.29. The metal with hydrogenolysis properties accounts for 0.15–5 wt% of the solid acid catalyst.

[0013] In this invention, the aromatic hydrocarbon is one or more monocyclic or polycyclic aromatic hydrocarbons, such as benzene, naphthalene, toluene, xylene, diethylbenzene, trimethylbenzene, tetramethylbenzene, and their isomers; preferably, the aromatic hydrocarbon is a monocyclic or bicyclic aromatic hydrocarbon. The total carbon number of the aromatic hydrocarbon is 6 to 18; preferably, the total carbon number of the aromatic hydrocarbon is 6 to 11; the aromatic hydrocarbon has 0 to 8 side chains, preferably 0 to 4. The most preferred aromatic hydrocarbon in this invention is benzene or toluene.

[0014] In this invention, the long-chain olefin includes C 10 ~C 14 One or more of the long-chain olefins. Examples of the long-chain olefins include decene, undecene, dodecene, tridecene, tetradecene, and their isomers.

[0015] In this invention, the solid acid catalyst comprises the Y-type zeolite and the inorganic oxide matrix.

[0016] Based on a solid acid catalyst, the content of the Y-type zeolite is 40–95 wt%.

[0017] Studies have found that alkylation reactions can be catalyzed not only by Brønsted acid but also by Lewis acid. Therefore, controlling the cell size of Y-type zeolite can ensure the integrity of the crystal structure and guarantee that the reaction has sufficient Brønsted acid active centers. Therefore, the Y-type zeolite in this invention has a cell size of 2.448–2.457 nm, preferably 2.452–2.455 nm.

[0018] The study also found that the deactivation of the alkylation reaction of benzene and long-chain olefins was caused by the blockage of catalyst pores by the heavy alkylbenzenes generated during the reaction. Since heavy alkylbenzenes are the key cause of catalyst deactivation, a certain proportion of mesopores can promote the timely diffusion of macromolecules such as heavy alkylbenzenes from the pores and delay catalyst coking. Therefore, the ratio of mesopore volume to total pore volume is 0.15–0.29, with a preferred ratio of 0.18–0.26. Both the mesopore volume and total pore volume were determined by static low-temperature nitrogen adsorption capacity analysis (BET) using an ASAP2420 adsorption instrument from Mack, Inc. The measurement process was as follows: the sample was first dried in an oven at 110°C for 2 hours to remove surface water. Then, a certain amount of sample was weighed and placed in a degassing unit, evacuated to a vacuum degree of less than 1.33 Pa, and treated at 90°C for 1 hour, followed by treatment at 330°C for 9–10 hours. The samples were subjected to nitrogen adsorption-desorption tests under liquid nitrogen cooling conditions to obtain adsorption-desorption curves. The specific surface area and pore volume were calculated using the BET formula.

[0019] The inorganic oxide matrix is ​​selected from one or more of silicon oxide, aluminum oxide, zirconium oxide, and titanium oxide.

[0020] A metal with hydrogenolysis properties supported on Y-type zeolite exhibits strong synergistic catalytic activity with Brønsted acid sites, resulting in better alkylation activity and selectivity under the reaction conditions of this invention. The metal with hydrogenolysis properties is selected from one or more Group VIB, VIIB, and VIII metals. The Group VIII metal is selected from one or more of Pt, Pd, and Ru, with Pt being preferred. Pt can both synergize with Brønsted acids and serve as a source of some Lewis acid sites, thus improving catalyst lifetime. The metal with hydrogenolysis properties constitutes 0.15–5 wt% of the solid acid catalyst, preferably 0.2–2 wt%.

[0021] The solid acid catalyst is obtained by impregnating a Y-type zeolite and an inorganic oxide matrix with an impregnation solution containing a precursor of a metal with hydrogenolytic properties, followed by drying, calcination, and reduction. Taking Pt as an example, the precursor of Pt can be selected from one or more of chloroplatinic acid, ammonium chloroplatinate, potassium chloroplatinate, platinum tetrachloride, or tetraammineplatinum nitrate. During the alkylation reaction, the metal with hydrogenolytic properties in the solid acid catalyst remains in a metallic state.

[0022] In this invention, the alkylation reaction conditions are: temperature 70–280°C, pressure 1.5–5 MPa, and feed mass hourly space velocity (WHSV) 1–30 h⁻¹. -1 Preferably, the alkylation reaction conditions are: temperature 90–180°C, pressure 2.0–4.5 rpm, and feed mass hourly space velocity (WHSV) 3–17 h⁻¹. -1 The raw material refers to a mixture of aromatics and long-chain olefins. In the mixture of aromatics and long-chain olefins, the molar ratio of aromatics to long-chain olefins is 1-100:1, preferably 1-60:1.

[0023] The linear alkylbenzene synthesis method provided by this invention has the advantage of high LAB selectivity and high 2-LAB ratio. The noble metal in the solid acid catalyst has strong hydrogenation activity and synergistic effect with the acidic center in the Y-type zeolite with specific physicochemical characteristics, which slows down the coking rate of the catalyst and improves the single-cycle life of the catalyst.

[0024] The linear alkylbenzene synthesis method of the present invention can be implemented in various reaction apparatuses, such as fluidized beds, fixed beds, and slurry beds. In one embodiment of the present invention, the method is implemented using a fixed bed, but the application of the method of the present invention is not limited thereto.

[0025] The technical effectiveness of this invention is evaluated using two indicators: the single-cycle lifetime of the solid acid catalyst and the distribution of linear alkylbenzene synthesis products. The single-cycle lifetime of the solid acid catalyst refers to the duration (h) during which the conversion rate of long-chain olefins is ≥99%. The distribution of linear alkylbenzene synthesis products is based on linear alkylbenzenes (LAB) and 2-LAB, and the products are analyzed by gas chromatography. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] The present invention will be described in detail below through embodiments. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention, but do not limit the scope of the present invention.

[0028] Example 1

[0029] This embodiment illustrates the method for synthesizing straight-chain alkyl aromatic hydrocarbons according to the present invention.

[0030] The solid acid catalyst was prepared by mixing Y-type zeolite (purchased from Sinopec Catalyst Branch, with a cell constant of 2.453 nm and a mesopore volume to total pore volume ratio of 0.22) and alumina at a weight ratio of 4:1, and then loading 0.4 wt% Pt onto the mixture using an impregnation method. The solid acid catalyst was designated A1, and the physicochemical properties of A1 are shown in Table 1.

[0031] The reactants were benzene and n-dodecene, and the alkylation reaction was carried out in a fixed-bed reactor. 5 g of solid acid catalyst A1 was packed into a fixed-bed reactor with an inner diameter of 10 mm and a length of 1 m. The reaction temperature was 120 °C, the reaction pressure was 3 MPa, and the feed mass hourly space velocity (WHSV) was 7 h⁻¹. -1 (The molar ratio of benzene is 40).

[0032] The catalyst single-cycle lifetime is determined by the olefin breakthrough time in the alkylation product. The catalyst single-cycle lifetime refers to the time (h) when the n-dodecene conversion rate of the linear alkylbenzene product is less than 99% after chromatography.

[0033] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 1. Components in the linear alkylbenzene product were analyzed using an online chromatographic analyzer (Agilent GC-7890B).

[0034] Comparative Example 1

[0035] The catalyst composition is the same as in Example 1, except that it does not support Pt and is designated as catalyst B1.

[0036] The alkylation reaction is the same as in Example 1.

[0037] The physicochemical properties of catalyst B1, catalyst single-cycle lifetime, and selectivity of LAB and 2-LAB are shown in Table 1.

[0038] Comparative Example 2

[0039] The catalyst composition is the same as in Example 1, except that the content of supported metal Pt is 0.05 wt%, and the catalyst is designated as B2.

[0040] The alkylation reaction is the same as in Example 1.

[0041] The physicochemical properties of catalyst B2, catalyst single-cycle lifetime, and selectivity of LAB and 2-LAB are shown in Table 1.

[0042] Comparative Example 3

[0043] The catalyst composition is the same as in Example 1, except that the ratio of mesopore volume to total pore volume of Y-type zeolite is 0.12, and the catalyst is designated as B3.

[0044] The alkylation reaction is the same as in Example 1.

[0045] The physicochemical properties of catalyst B3, catalyst single-cycle lifetime, and selectivity of LAB and 2-LAB are shown in Table 1.

[0046] Comparative Example 4

[0047] The catalyst composition is the same as in Example 1, except that the Y-type zeolite cell is 2.446 nm and the catalyst is designated as B4.

[0048] The alkylation reaction is the same as in Example 1.

[0049] The physicochemical properties of catalyst B4, catalyst single-cycle lifetime, and selectivity of LAB and 2-LAB are shown in Table 1.

[0050] Comparative Example 5

[0051] The catalyst composition is the same as in Example 1, except that the Y-type zeolite cell is 2.459 nm and the catalyst is designated as B5.

[0052] The alkylation reaction is the same as in Example 1.

[0053] The physicochemical properties of catalyst B5, catalyst single-cycle lifetime, and selectivity of LAB and 2-LAB are shown in Table 1.

[0054] Comparative Example 6

[0055] The catalyst composition is the same as in Example 1, except that the ratio of mesopore volume to total pore volume of Y-type zeolite is 0.33, and the catalyst is designated as B6.

[0056] The alkylation reaction is the same as in Example 1.

[0057] The physicochemical properties of catalyst B6, catalyst single-cycle lifetime, and selectivity of LAB and 2-LAB are shown in Table 1.

[0058] Example 2

[0059] The solid acid catalyst was prepared by mixing Y-type zeolite (purchased from Sinopec Catalyst Branch, with a cell constant of 2.448 nm and a mesopore volume to total pore volume ratio of 0.16) and alumina at a weight ratio of 4:1, and then loading 0.4 wt% Pt onto the mixture using an impregnation method. The solid acid catalyst was designated A2, and the physicochemical properties of A2 are shown in Table 1.

[0060] The alkylation reaction was carried out under the same conditions as in Example 1.

[0061] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 1.

[0062] Example 3

[0063] The solid acid catalyst was prepared by mixing Y-type zeolite (purchased from Sinopec Catalyst Branch, with a cell constant of 2.448 nm and a mesopore volume to total pore volume ratio of 0.28) and alumina at a weight ratio of 4:1, and then loading 0.4 wt% Pt onto the mixture using an impregnation method. The solid acid catalyst was designated A3, and the physicochemical properties of A3 are shown in Table 1.

[0064] The alkylation reaction was carried out under the same conditions as in Example 1.

[0065] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 1.

[0066] Example 4

[0067] The solid acid catalyst was prepared by mixing Y-type zeolite (purchased from Sinopec Catalyst Branch, with a cell constant of 2.456 nm and a mesopore volume to total pore volume ratio of 0.16) and alumina at a weight ratio of 4:1, and then loading 0.4 wt% Pt onto the mixture using an impregnation method. The solid acid catalyst was designated A4, and the physicochemical properties of A4 are shown in Table 1.

[0068] The alkylation reaction was carried out under the same conditions as in Example 1.

[0069] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 1.

[0070] Example 5

[0071] The solid acid catalyst was prepared by mixing Y-type zeolite (purchased from Sinopec Catalyst Branch, with a cell constant of 2.456 nm and a mesopore volume to total pore volume ratio of 0.28) and alumina at a weight ratio of 4:1, and then loading 0.4 wt% Pt onto the mixture using an impregnation method. The solid acid catalyst was designated A5, and the physicochemical properties of A5 are shown in Table 1.

[0072] The alkylation reaction was carried out under the same conditions as in Example 1.

[0073] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] As can be seen from the results in Table 1:

[0078] (1) Solid acid catalysts supported on noble metals have significantly better regeneration performance for the alkylation reaction of benzene and n-dodecene than catalysts without metals, as shown in Example 1 and Comparative Examples 1 and 2.

[0079] (2) Catalysts whose metal content, cell constant, and mesoporous ratio are not within the scope of this invention have significantly poor alkylation single-cycle lifetime, LAB selectivity, and 2-LAB selectivity, such as Comparative Examples 3 to 6.

[0080] (3) The synthesis method using catalysts with appropriate metal content, Y-type zeolite cell size, and Y-type zeolite mesopore ratio results in a longer single-cycle lifetime and better selectivity for straight-chain alkylbenzenes. In particular, catalyst A1 with a noble metal Pt content of 0.4%, a Y-type zeolite cell size of 2.453 nm, and a Y-type zeolite mesopore volume / total pore volume ratio of 0.22 not only achieves a cycle lifetime of 42 h, but also exhibits a LAB selectivity of up to 91.2% and a 2-LAB ratio of up to 26.2%.

[0081] Example 6

[0082] This embodiment uses catalyst A1, but differs in that the alkylation reaction conditions are changed: the reaction temperature is 150°C, the reaction pressure is 2.5 MPa, and the feed mass hourly space velocity is 7 h⁻¹. -1 (The molar ratio of benzene to olefins is 20).

[0083] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 2.

[0084] Example 7

[0085] This embodiment uses catalyst A1, but the alkylation reaction conditions are changed: the reaction temperature is 180°C, the reaction pressure is 2 MPa, and the feed mass hourly space velocity is 14 h⁻¹. -1 (The molar ratio of benzene is 40).

[0086] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 2.

[0087] Example 8

[0088] This embodiment uses catalyst A3, but differs in that the alkylation reaction conditions are changed: the reaction temperature is 150°C, the reaction pressure is 2.5 MPa, and the feed mass hourly space velocity is 14 h⁻¹. -1 (The molar ratio of benzene is 40).

[0089] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 2.

[0090] Example 9

[0091] This embodiment uses catalyst A4, but the alkylation reaction conditions are changed: the reaction temperature is 180°C, the reaction pressure is 2 MPa, and the feed mass hourly space velocity is 21 h⁻¹. -1 (The molar ratio of benzene to olefin is 60).

[0092] The catalyst single-cycle lifetime, LAB, and 2-LAB selectivity results are shown in Table 2.

[0093] Table 2

[0094]

Claims

1. A method for synthesizing straight-chain alkyl aromatics, comprising reacting aromatics and long-chain olefins under alkylation reaction conditions in the presence of a solid acid catalyst supported on a metal with hydrogenolytic properties to generate straight-chain alkyl aromatics, characterized in that, The solid acid catalyst contains Y-type zeolite with a cell size of 2.448–2.457 nm and a mesopore volume to total pore volume ratio of 0.15–0.29; the metal with hydrogenolysis properties accounts for 0.15–5 wt% of the solid acid catalyst; the long-chain olefin is C 10 ~C 14 One or more of the long-chain olefins.

2. The method according to claim 1, characterized in that, The aromatic hydrocarbon is one or more monocyclic or polycyclic aromatic hydrocarbons.

3. The method according to claim 1, characterized in that, The aromatic hydrocarbon is a monocyclic or bicyclic aromatic hydrocarbon.

4. The method according to any one of claims 1-3, characterized in that, The total number of carbon atoms in aromatic hydrocarbons is 6–18; the number of side chains in aromatic hydrocarbons is 0–8.

5. The method according to claim 4, characterized in that, The total number of carbon atoms in aromatic hydrocarbons is 6–11; the number of side chains in aromatic hydrocarbons is 0–4.

6. The method according to claim 1, characterized in that, The aromatic hydrocarbon is benzene or toluene.

7. The method according to claim 1, characterized in that, The long-chain olefins are selected from decene, undecene, dodecene, tridecene, tetradecene and their isomers.

8. The method according to claim 1, characterized in that, The solid acid catalyst contains 40–95 wt% Y-type zeolite.

9. The method according to claim 1, characterized in that, The solid acid catalyst comprises Y-type zeolite and an inorganic oxide matrix.

10. The method according to claim 9, characterized in that, The inorganic oxide matrix is ​​selected from one or more of silicon oxide, aluminum oxide, zirconium oxide, and titanium oxide.

11. The method according to claim 1, characterized in that, The Y-type zeolite has a cell size of 2.452–2.455 nm.

12. The method according to claim 1, characterized in that, The Y-type zeolite has a mesopore volume to total pore volume ratio of 0.18 to 0.

26.

13. The method according to claim 1, characterized in that, The metal with hydrogenolysis properties accounts for 0.2 to 2 wt% of the solid acid catalyst.

14. The method according to claim 1 or 13, characterized in that, The metal with hydrogenolysis properties is selected from one or more metals of Groups VIB, VIIB, and VIII.

15. The method according to claim 14, characterized in that, The group VIII metal is selected from one or more of Pt, Pd, and Ru.

16. The method according to claim 1, characterized in that, The alkylation reaction conditions are as follows: temperature 70–280°C, pressure 1.5–5 MPa, and feed mass hourly space velocity (WHSV) 1–30 h⁻¹. -1 The raw material is a mixture of aromatic hydrocarbons and long-chain olefins.

17. The method according to claim 16, characterized in that, The alkylation reaction conditions are as follows: temperature 90–180 °C, pressure 2.0–4.5 MPa, and feed mass hourly space velocity (WHSV) 3–17 h⁻¹. -1 .

18. The method according to claim 16, characterized in that, In the mixture of aromatic hydrocarbons and long-chain olefins, the molar ratio of aromatic hydrocarbons to long-chain olefins is 1-100:

1.

19. The method according to claim 17, characterized in that, In the mixture of aromatics and long-chain olefins, the molar ratio of aromatics to long-chain olefins is 1-60:1.

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