A method for synthesizing tert-butyl ethylbenzene

Abstract

The application discloses a synthesis process of tert-butyl ethylbenzene, which comprises the following steps: carrying out a cracking reaction on methyl tert-butyl ether in a cracking reactor, separating and purifying the obtained cracked product to obtain isobutene, drying the isobutene, mixing the isobutene with ethylbenzene, and then feeding the mixture into an alkylation reactor to carry out an alkylation reaction, returning part of the obtained alkylation product to the alkylation reactor, and separating and purifying the other part to obtain tert-butyl ethylbenzene; in the alkylation reaction, an alkylation catalyst used is prepared by mixing modified beta zeolite with H-MCM-22 zeolite. Under the process conditions of the application, isobutene obtained by cracking methyl tert-butyl ether is alkylated with ethylbenzene to generate tert-butyl ethylbenzene, the conversion rate of the isobutene is greater than 97%, the selectivity of the tert-butyl ethylbenzene is greater than 93%, the catalyst has stable activity and long service life, the production cost of the tert-butyl ethylbenzene is low, and the synthesis process can be used for industrial production of the tert-butyl ethylbenzene.

Description

Technical Field

[0001] This invention relates to a method for synthesizing tert-butylethylbenzene, specifically, a method for preparing tert-butylethylbenzene by alkylation of isobutylene obtained by cleavage of methyl tert-butyl ether and ethylbenzene. Background Technology

[0002] tert-Butylstyrene is a monomer used to prepare polymers and copolymers. Tert-Butylstyrene polymers synthesized from tert-Butylstyrene monomers have high glass transition temperatures and are soluble in aliphatic hydrocarbons, making them promising for applications in the development of new materials, dispersion polymerization, and environmentally friendly paints and oil additives. Due to the presence of substituents on the benzene ring, tert-Butylstyrene polymers are easier to modify than styrene polymers.

[0003] tert-Butylstyrene can be prepared by the dehydrogenation reaction of tert-Butylethylbenzene. Tert-Butylethylbenzene is synthesized by alkylation of ethylbenzene with isobutylene or tert-butanol under an acidic catalyst, followed by dehydrogenation of the tert-Butylethylbenzene under a catalyst to produce tert-Butylstyrene.

[0004] The alkylation reaction of ethylbenzene with isobutylene or tert-butanol can use strong acidic substances such as concentrated sulfuric acid and aluminum trichloride as alkylation catalysts. US3631213 and US4982034 disclose methods for synthesizing tert-butylethylbenzene by alkylation of isobutylene and ethylbenzene under the action of acidic catalysts such as H2SO4 and AlCl3. However, using liquid acids such as concentrated sulfuric acid and aluminum trichloride as catalysts will lead to serious corrosion of production equipment, inability to recycle catalysts, and environmental pollution.

[0005] Crystalline aluminosilicate catalysts or zeolite catalysts have also been used to catalyze the alkylation of aromatic compounds with olefins as alkylating agents.

[0006] US469908 discloses a reaction method using ZSM-12 zeolite as a catalyst, with a reaction temperature of 190℃~300℃, a reaction pressure of 300psig, an isobutylene conversion of 95%, a tert-butylethylbenzene selectivity of 90%, and a p-tert-butylethylbenzene to m-tert-butylethylbenzene ratio of approximately 9:1. Although these alkylation reactions achieve high selectivity under the action of zeolite-type catalysts, due to the high alkylation temperature of aromatics, deep cracking of the reaction products and oligomerization of isobutylene occur.

[0007] The Chinese Journal of Catalysis (2013) 2:294-304 reported the synthesis of tert-butylethylbenzene from ethylbenzene and tert-butanol catalyzed by ZSM-5 zeolite. The effects of ZSM-5 catalysts with different crystallinities on the para-position of tert-butylation of ethylbenzene were discussed, but the catalyst activity decreased rapidly. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for synthesizing tert-butylethylbenzene. This method uses a modified β-zeolite and H-MCM-22 zeolite mixed and extruded into strips as catalysts for alkylation reaction. Isobutylene from the cracking of methyl tert-butyl ether is alkylated with ethylbenzene to produce tert-butylethylbenzene. The catalyst has stable activity, high selectivity for tert-butylethylbenzene, and low production cost.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] The present invention discloses a process for synthesizing tert-butylethylbenzene, comprising the following steps:

[0011] Methyl tert-butyl ether is cracked in a cracking reactor. The cracking product is separated, purified and dried to obtain isobutylene. The isobutylene is then mixed with ethylbenzene and fed into an alkylation reactor for alkylation. Part of the alkylation product is returned to the alkylation reactor, and the other part is separated and purified to obtain tert-butylethylbenzene.

[0012] In the alkylation reaction, the alkylation catalyst used is prepared by mixing modified β zeolite with H-MCM-22 zeolite.

[0013] In a preferred embodiment, the pyrolysis catalyst used in the pyrolysis reaction is selected from solid acid catalysts.

[0014] In this invention, the type of solid acid catalyst is not limited; any catalyst used in the prior art for MTBE cracking is acceptable, such as acidic molecular sieves, Al2O3 / SiO2 (SiO2 supported on Al2O3), YL-2 type MTBE cracking catalyst, heteropolyacids, and solid phosphoric acid. YL-2 type MTBE cracking catalyst is preferred.

[0015] The YL-2 type MTBE cracking catalyst was provided by Sinopec Beijing Chemical Research Institute.

[0016] In a preferred embodiment, the pyrolysis reaction is carried out at a temperature of 170°C to 230°C and a space velocity of 2.0 h⁻¹. -1 ~3.0h -1 The pressure is 0.4MPa to 0.6MPa.

[0017] In a preferred embodiment, the obtained pyrolysis products are separated by heat exchange into a separator. The crude isobutylene product is discharged from the top of the separator and washed in a water washing tower. The product discharged from the top of the water washing tower is then sequentially sent to an isobutylene de-heavy tower and a de-light tower to separate the heavy components and light components, resulting in isobutylene.

[0018] In a further preferred embodiment, the methanol discharged from the lower part of the water washing tower enters the methanol recovery tower, and the recovered methanol is mixed with the liquid phase product discharged from the lower part of the separator and then enters the methanol refining tower to recover methanol.

[0019] The obtained isobutylene is a high-purity product obtained after separation and purification, with a purity of ≥99.5%.

[0020] In a preferred embodiment, the molar ratio of ethylbenzene to isobutylene is 5 to 20:1.

[0021] In a preferred embodiment, the alkylation reaction catalyst comprises the following raw material components by mass parts: gallium oxide 0-6 parts, zirconium oxide 0-6 parts, tungsten oxide 0-3 parts, β zeolite 30-61 parts, and H-MCM-22 zeolite 30-51 parts.

[0022] In a further preferred embodiment, the alkylation reaction catalyst has the following raw material composition by mass parts: gallium oxide 2-5 parts, zirconium oxide 2-5 parts, tungsten oxide 1-2 parts, β zeolite 40-60 parts, and H-MCM-22 zeolite 32-51 parts.

[0023] In a further preferred embodiment, the silica-alumina ratio of the β-zeolite is 10 to 100.

[0024] In a further preferred embodiment, the preparation process of the alkylation reaction catalyst is as follows: gallium oxide, zirconium oxide, tungsten oxide, β zeolite, and H-MCM-22 zeolite are mechanically mixed according to the designed ratio and then extruded into shape.

[0025] In a preferred embodiment, the alkylation reaction is carried out at a temperature of 130°C to 230°C and a space velocity of 2.0 h⁻¹. -1 ~8.0h -1 The pressure is 2.0MPa to 3.0MPa.

[0026] In a further preferred embodiment, the alkylation reaction is carried out at a temperature of 130°C to 170°C.

[0027] The alkylation catalyst provided by this invention has high activity, can catalyze the alkylation reaction at lower reaction conditions, and has stable catalytic activity and long lifespan, maintaining stable catalytic activity even during long-term continuous production.

[0028] In actual operation, the reaction conditions can be appropriately changed according to the change of isobutylene conversion rate. For example, when the isobutylene conversion rate drops significantly, the reaction temperature can be increased. For example, when the isobutylene conversion rate drops by 0.5 to 1 percentage point, the reaction temperature can be increased by 1 to 2°C to ensure the isobutylene conversion rate.

[0029] In a preferred embodiment, the recycling rate of the alkylation product is 30% to 80%, preferably 40% to 70%.

[0030] In this invention, the amount of alkylation product recycled refers to the percentage of alkylation product returned to the alkylation reactor in the total alkylation product obtained from the alkylation reaction.

[0031] In a preferred embodiment, a portion of the alkylation product is mixed with isobutylene and ethylbenzene and then fed into an alkylation reactor, while the other portion is fed into a separation tower for separation. The crude tert-butyl ethylbenzene product discharged from the bottom of the separation tower is then fed into a tert-butyl ethylbenzene heavy component removal tower and a light component removal tower to separate the heavy component and the light component, thereby obtaining tert-butyl ethylbenzene.

[0032] The obtained tert-butylethylbenzene is a high-purity product obtained after separation and purification, with a purity of ≥99%.

[0033] In a further preferred embodiment, the product discharged from the top of the separation tower is separated into light and heavy components by an ethylbenzene removal tower and a light component removal tower to obtain recovered ethylbenzene, which is then returned to the alkylation reactor.

[0034] Beneficial effects

[0035] In the alkylation reaction of this invention, the alkylation catalyst is prepared by mixing modified β-zeolite and H-MCM-22 zeolite. Based on this catalyst, an adapted and matched process flow and process parameters were designed. Under the process conditions of this invention, isobutylene cracked from methyl tert-butyl ether is alkylated with ethylbenzene to produce tert-butylethylbenzene. The isobutylene conversion rate is greater than 97%, the tert-butylethylbenzene selectivity is greater than 93%, the catalyst activity is stable, the lifetime is long, and the production cost of tert-butylethylbenzene is low, which can be used for the industrial production of tert-butylethylbenzene. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the process flow of the present invention:

[0037] In the diagram: 1- Cracking reactor; 2- Separator; 3- Water washing tower; 4- Isobutylene heavy removal tower; 5- Isobutylene light removal tower; 6- Alkylation reactor; 7- Separation tower; 8- Tert-butylethylbenzene heavy removal tower; 9- Tert-butylethylbenzene light removal tower; 10- Ethylbenzene heavy removal tower; 11- Ethylbenzene light removal tower; 12- Methanol recovery tower. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited thereto.

[0039] Figure 1In the process, methyl tert-butyl ether enters cracking reactor 1 for cracking. The cracking product, after heat exchange with the cracking feedstock, enters separator 2. Isobutylene product is discharged from the top of separator 2 and enters water washing tower 3 for washing. The product discharged from the top of water washing tower enters isobutylene de-heavy tower 4 and de-light tower 5 in sequence to separate heavy and light components, obtaining 99.7% isobutylene. This isobutylene is mixed with ethylbenzene dried by molecular sieve and enters alkylation reactor 6 for alkylation reaction. The alkylation product flows out of the reactor, is cooled, and is divided into two parts. One part is returned to the inlet of alkylation reactor, mixed with the reactants, and then enters alkylation reactor 6. The other part of the alkylation product enters separation tower 7. The crude tert-butyl ethylbenzene product discharged from the bottom of the separator enters tert-butyl ethylbenzene de-heavy tower 8 and de-light tower 9 in sequence to separate heavy and light components, obtaining 99.0% tert-butyl ethylbenzene.

[0040] Methanol discharged from the bottom of water washing tower 3 enters methanol recovery tower. The recovered methanol is mixed with the liquid phase product discharged from the bottom of separator 2 and then enters methanol refining tower 12 to recover methanol.

[0041] The product discharged from the top of the alkylation product separation tower 7 is separated into light and heavy components by the ethylbenzene removal tower 10 and the light component removal tower 11 to obtain recovered ethylbenzene, which is then returned to the alkylation reactor 6 for reuse.

[0042] Example 1

[0043] Preparation of high-purity isobutylene by cracking methyl tert-butyl ether

[0044] The methyl tert-butyl ether cracking reaction was carried out in a tubular reactor 1. YL-2 catalyst (Sinopec Beijing Chemical Research Institute) was charged into the Φ32mm reactor. The catalyst bed density was 2m, the cracking temperature was 220℃, the pressure was 0.5MPa, and the space velocity was 2.6h⁻¹. -1 The cracking products enter separator 2 after heat exchange. The isobutylene product is discharged from the top of separator 2 and enters water washing tower 3 for washing. The product discharged from the top of water washing tower enters isobutylene de-heavy tower 4 and de-light tower 5 in sequence to separate heavy components and light components, and obtains isobutylene with a purity of 99.8%.

[0045] Example 2

[0046] Preparation of catalyst for the alkylation reaction of ethylbenzene isobutylene:

[0047] Five parts gallium oxide, three parts zirconium oxide, one part tungsten oxide, 55 parts β-zeolite, and 36 parts H-MCM-22 zeolite were prepared; after mechanical mixing, they were extruded and molded. The silicon-to-aluminum ratio of the β-zeolite was 50.

[0048] Synthesis of tert-butylethylbenzene by alkylation of isobutylene and ethylbenzene

[0049] The alkylation reaction of ethylbenzene and isobutylene was carried out in a tubular reactor 6. A catalyst bed of modified β-zeolite and H-MCM-22 zeolite, extruded into strips, was loaded into the Φ25mm reactor. The catalyst bed height was 1.5m. Both ends of the catalyst bed were filled with quartz sand. After filling the reactor system with ethylbenzene, the temperature and pressure were gradually increased. At a reaction temperature of 150℃ and a pressure of 2.4MPa, ethylbenzene dried by molecular sieves was mixed with the high-purity isobutylene obtained in Example 1 and fed into the reactor. The molar ratio of ethylbenzene to isobutylene was 10:1, and the space velocity was 5.6h⁻¹. -1 Under the above conditions, the tert-butylethylbenzene synthesis reaction was carried out. The reaction conditions were appropriately adjusted according to the change in isobutylene conversion rate. For example, when the isobutylene conversion rate decreased significantly, the reaction temperature could be increased. Specifically, the reaction temperature was increased by 1-2°C for every 0.5-1 percentage point decrease in isobutylene conversion rate. The composition of the alkylation product, isobutylene conversion rate, tert-butylethylbenzene selectivity, and production time were analyzed by online chromatography. The crude product was cooled and divided into two parts. 50% of the crude product was recycled and returned to the inlet of the alkylation reactor, mixed with the reactants, and then entered alkylation reactor 6. The other part of the alkylation product entered separation tower 7. The tert-butylethylbenzene crude product discharged from the bottom of separation tower 7 successively entered tert-butylethylbenzene heavy component removal tower 8 and light component removal tower 9 to separate the heavy and light components, yielding 99% pure tert-butylethylbenzene.

[0050] Table 1

[0051] Production time, h 200 500 1000 1500 2000 Isobutene conversion, % 99.8 99.3 98.7 98.2 97.0 tert-Butyl ethylbenzene selectivity, % 95.6 95.3 95.1 94.8 94.3

[0052] Example 3

[0053] Preparation of catalyst for the alkylation reaction of ethylbenzene isobutylene:

[0054] Two parts gallium oxide, five parts zirconium oxide, two parts tungsten oxide, 40 parts β-zeolite, and 51 parts H-MCM-22 zeolite were prepared; after mechanical mixing, they were extruded and molded. The silicon-to-aluminum ratio of the β-zeolite was 100.

[0055] Synthesis of tert-butylethylbenzene by alkylation of isobutylene and ethylbenzene

[0056] The alkylation reaction of ethylbenzene and isobutylene was carried out in a tubular reactor 6. A catalyst bed of modified β-zeolite and H-MCM-22 zeolite, extruded into strips, was loaded into the Φ25mm reactor. The catalyst bed height was 1.5m. Both ends of the catalyst bed were filled with quartz sand. After filling the reactor system with ethylbenzene, the temperature and pressure were gradually increased. At a reaction temperature of 130℃ and a pressure of 2.0MPa, ethylbenzene dried by molecular sieves was mixed with the high-purity isobutylene obtained in Example 1 and fed into the reactor. The molar ratio of ethylbenzene to isobutylene was 5:1, and the space velocity was 2.0 h⁻¹. -1Under the above conditions, the tert-butylethylbenzene synthesis reaction was carried out. The reaction conditions were appropriately adjusted according to the change in isobutylene conversion rate. For example, when the isobutylene conversion rate decreased significantly, the reaction temperature could be increased. Specifically, the reaction temperature was increased by 1-2°C for every 0.5-1 percentage point decrease in isobutylene conversion rate. The composition of the alkylation product, isobutylene conversion rate, tert-butylethylbenzene selectivity, and production time were analyzed by online chromatography. Table 2 shows the results. After cooling, the crude product was divided into two parts. 70% of the crude product was recycled and returned to the inlet of the alkylation reactor, mixed with the reactants, and then entered alkylation reactor 6. The other part of the alkylation product entered separation tower 7. The tert-butylethylbenzene crude product discharged from the bottom of separation tower 7 successively entered tert-butylethylbenzene heavy component removal tower 8 and light component removal tower 9 to separate the heavy and light components, yielding 99% pure tert-butylethylbenzene.

[0057] Table 2

[0058] Production time, h 200 500 1000 1500 2000 Isobutene conversion, % 99.7 99.2 98.6 98.0 97.4 tert-Butyl ethylbenzene selectivity, % 94.8 94.6 94.3 94.0 93.5

[0059] Example 4

[0060] Preparation of catalyst for the alkylation reaction of ethylbenzene isobutylene:

[0061] Four parts gallium oxide, two parts zirconium oxide, two parts tungsten oxide, 60 parts β-zeolite, and 32 parts H-MCM-22 zeolite were prepared; after mechanical mixing, they were extruded and molded. The silicon-to-aluminum ratio of the β-zeolite was 10.

[0062] Synthesis of tert-butylethylbenzene by alkylation of isobutylene and ethylbenzene

[0063] The alkylation reaction of ethylbenzene and isobutylene was carried out in a tubular reactor 6. A catalyst bed of modified β-zeolite and H-MCM-22 zeolite, extruded into strips, was loaded into the Φ25mm reactor. The catalyst bed height was 1.5m. Both ends of the catalyst bed were filled with quartz sand. After filling the reactor system with ethylbenzene, the temperature and pressure were gradually increased. At a reaction temperature of 170℃ and a pressure of 3.0MPa, ethylbenzene dried by molecular sieves was mixed with the high-purity isobutylene obtained in Example 1 and fed into the reactor. The molar ratio of ethylbenzene to isobutylene was 20:1, and the space velocity was 8.0 h⁻¹. -1Under the above conditions, the tert-butylethylbenzene synthesis reaction was carried out. The reaction conditions were appropriately adjusted according to the change in isobutylene conversion rate. For example, when the isobutylene conversion rate decreased significantly, the reaction temperature could be increased. Specifically, the reaction temperature was increased by 1-2°C for every 0.5-1 percentage point decrease in isobutylene conversion rate. The composition of the alkylation product, isobutylene conversion rate, tert-butylethylbenzene selectivity, and production time were analyzed by online chromatography. Table 3 shows the results. After cooling, the crude product was divided into two parts. 40% of the crude product was recycled and returned to the inlet of the alkylation reactor, where it was mixed with the reactants and then entered alkylation reactor 6. The other part of the alkylation product entered separation tower 7. The tert-butylethylbenzene crude product discharged from the bottom of separation tower 7 successively entered tert-butylethylbenzene heavy component removal tower 8 and light component removal tower 9 to separate the heavy and light components, yielding 99% pure tert-butylethylbenzene.

[0064] Table 3

[0065] Production time, h 200 500 1000 1500 2000 Isobutene conversion, % 99.8 99.5 99.1 98.6 98.3 tert-Butyl ethylbenzene selectivity, % 94.0 93.8 93.7 93.5 93.2

[0066] Comparative Example 1

[0067] Other conditions were the same as in Example 3. ZSM-12 catalyst was used. The isobutylene conversion, tert-butylethylbenzene selectivity and production time are shown in Table 4.

[0068] Table 4

[0069] Production time, h 200 500 1000 1500 2000 Isobutene conversion, % 99.9 99.7 99.6 98.9 98.5 tert-Butyl ethylbenzene selectivity, % 65.8 68.8 68.3 67.5 66.1

[0070] Comparative Example 2

[0071] Other conditions were the same as in Example 3. A β-zeolite catalyst was used. The isobutylene conversion, tert-butylethylbenzene selectivity, and production time are shown in Table 5.

[0072] Table 5

[0073] Production time, h 200 500 1000 1500 2000 Isobutene conversion, % 99.6 99.6 99.5 98.8 98.56 tert-Butyl ethylbenzene selectivity, % Production time, h Isobutene conversion, % tert-Butyl ethylbenzene selectivity, % 75.0 77.8 76.2 75.5 73.2

Claims

1. A process for synthesizing tert-butylethylbenzene, characterized in that: Includes the following steps: Methyl tert-butyl ether is cracked in a cracking reactor. The cracking product is separated, purified and dried to obtain isobutylene. The isobutylene is then mixed with ethylbenzene and fed into an alkylation reactor for alkylation. Part of the alkylation product is returned to the alkylation reactor, and the other part is separated and purified to obtain tert-butylethylbenzene. In the alkylation reaction, the preparation process of the alkylation reaction catalyst is as follows: gallium oxide, zirconium oxide, tungsten oxide, β zeolite, and H-MCM-22 zeolite are prepared according to the design ratio, mechanically mixed, and then extruded into shape. The alkylation reaction catalyst has the following raw material composition by mass parts: gallium oxide 2-5 parts, zirconium oxide 2-5 parts, tungsten oxide 1-2 parts, β zeolite 40-60 parts, and H-MCM-22 zeolite 32-51 parts. The alkylation reaction was carried out at a temperature of 130°C to 230°C and a space velocity of 2.0 h⁻¹. -1 ~8.0h -1 The pressure is 2.0MPa to 3.0MPa.

2. The synthesis process of tert-butylethylbenzene according to claim 1, characterized in that: In the pyrolysis reaction, the pyrolysis catalyst used is selected from solid acid catalysts.

3. The synthesis process of tert-butylethylbenzene according to claim 1, characterized in that: The pyrolysis reaction was carried out at a temperature of 170℃ to 230℃ and a space velocity of 2.0 h⁻¹. -1 ~3.0h -1 The pressure is 0.4MPa to 0.6MPa.

4. The synthesis process of tert-butylethylbenzene according to claim 1, characterized in that: The obtained cracking products are separated by heat exchange into a separator. The crude isobutylene product is discharged from the top of the separator and enters a water washing tower for washing. The product discharged from the top of the water washing tower enters the isobutylene heavy component removal tower and light component removal tower in sequence to separate the heavy component and light component, and the obtained isobutylene. The methanol discharged from the bottom of the water washing tower enters the methanol recovery tower. The recovered methanol is mixed with the liquid phase product discharged from the bottom of the separator and then enters the methanol refining tower to recover methanol.

5. The synthesis process of tert-butylethylbenzene according to claim 1, characterized in that: The molar ratio of ethylbenzene to isobutylene is 5 to 20:

1.

6. The synthesis process of tert-butylethylbenzene according to claim 1, characterized in that: The recycling rate of the alkylation product is 30% to 80%.

7. The synthesis process of tert-butylethylbenzene according to claim 1, characterized in that: The product discharged from the top of the separation tower is separated into light and heavy components by the ethylbenzene removal tower and the light component removal tower to obtain recovered ethylbenzene, which is then returned to the alkylation reactor.

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