A modified Y-type molecular sieve and its preparation method and its application in liquid phase transalkylation of benzene and diethylbenzene to produce ethylbenzene

Abstract

The present application discloses a modified Y-type molecular sieve and its preparation method and its application in liquid-phase transalkylation of benzene and diethylbenzene to produce ethylbenzene. The modified Y-type molecular sieve catalyst is obtained by hydrothermal treatment, acid treatment and silanization treatment of NaY-type molecular sieve. Raw materials containing benzene and mixed diethylbenzene are reacted at a reaction temperature of 190-260°C, a reaction pressure of 2.0-5MPa, and a liquid phase weight space velocity of 1-8h. ‑1 , under the condition that the weight ratio of benzene to mixed diethylbenzene is 1 to 6, ethylbenzene is contacted and reacted with a modified Y-type molecular sieve catalyst in a fixed bed reactor. The catalyst of the present invention has the remarkable characteristics of high diethylbenzene conversion rate and less impurities in the product ethylbenzene during the catalytic transalkylation reaction of benzene and diethylbenzene.

Description

Technical Field

[0001] The present application relates to a modified Y-type molecular sieve and a preparation method thereof and application thereof in liquid phase transalkylation of benzene and diethylbenzene to produce ethylbenzene, belonging to the field of chemistry and chemical engineering. Background Art

[0002] Ethylbenzene is an important chemical raw material and an indispensable key raw material for the production of styrene. Most ethylbenzene manufacturers produce ethylbenzene for the purpose of producing styrene. A small amount is used as a solvent, diluent and to produce diethylbenzene. About 90% of ethylbenzene is used to produce styrene, and styrene is an important basic organic chemical raw material, mainly used in the field of polymer materials to produce polystyrene and its copolymers, such as ABS, AS, styrene-butadiene rubber and its unsaturated polyester. In addition, styrene is also widely used as an organic reaction intermediate in the pharmaceutical, coating, pigment and textile industries. With the growing demand for styrene monomer in the automotive industry, insulation industry, packaging industry and daily necessities industry, the world's ethylbenzene production capacity is also increasing.

[0003] In industry, most ethylbenzene is synthesized through the alkylation reaction of benzene and ethylene. With the increasing demand for styrene, ethylbenzene is in short supply. In the industrial production of ethylbenzene, whether it is ethylene or ethanol alkylation, a certain amount of diethylbenzene will be produced. These diethylbenzenes need to be separated from the product and continue to be mixed with benzene and then reacted through an alkylation catalyst to produce ethylbenzene. Doing so not only improves the life of the alkylation catalyst, but also reduces the occurrence of side reactions in the alkylation reaction, increases the yield of ethylbenzene, and reduces energy consumption.

[0004] The core of the transalkylation reaction of benzene and diethylbenzene to produce ethylbenzene is the catalyst. A large number of patents disclose the preparation methods of transalkylation catalysts, such as:

[0005] The method adopted in patent CN 104230633 A is that polyethylbenzene and benzene are used as reaction raw materials, the reaction temperature is 100-260°C, the reaction pressure is 2.0-4.5MPa, and the liquid phase weight space velocity is 1-10 hours. -1 Under the condition of a benzene / polyethylbenzene weight ratio of 1 to 10, the reaction raw materials contact the catalyst to undergo a liquid phase transalkylation reaction to produce ethylbenzene. The transalkylation catalyst is a binderless Y-type molecular sieve with a SiO2 / Al2O3 molar ratio of 3 to 20. The optimal result is a diethylbenzene conversion rate of 68.35% and an ethylbenzene selectivity of 99.15% after feeding for 10 hours.

[0006] CN 104230637 B discloses a method for liquid-phase alkylation of polyethylbenzenes and benzene. The catalyst comprises the following components: a) 30 to 90 parts of β-type molecular sieve, and b) 10 to 70 parts of a binder. The β-type molecular sieve raw powder is obtained by treating with ammonia. The optimal result is that the conversion rate of diethylbenzene reaches 78.41% and the selectivity of ethylbenzene reaches 99.65%.

[0007] The method adopted by CN 104276922 A is that polyethylbenzene and benzene are used as reaction raw materials, the reaction temperature is 100-260°C, the reaction pressure is 2.0-4.5MPa, and the liquid phase weight space velocity is 1-10 hours. -1 Under the condition of a benzene / polyethylbenzene weight ratio of 1 to 10, the reaction raw materials contact the catalyst to undergo a liquid phase transalkylation reaction to produce ethylbenzene. The transalkylation catalyst is a binderless Beta molecular sieve with a SiO2 / Al2O3 molar ratio of 5 to 200. The optimal result is a diethylbenzene conversion rate of 72.11% and an ethylbenzene selectivity of 97.11% after feeding for 10 hours.

[0008] The diethylbenzene alkyl transfer catalyst used in CN 104230637 A is a Beta molecular sieve containing a binder. The raw powder is subjected to ammonia gas, and the optimal result after the reaction is stabilized is that the diethylbenzene conversion rate is 42.67%, and the ethylbenzene selectivity reaches 99.22%.

[0009] CN1310051 uses a gas-phase transalkylation process, and the catalyst active component used is ZSM-5 molecular sieve. The molecular sieve is treated with water vapor and modified with organic acid, which greatly improves the performance of the gas-phase alkylation catalyst. However, the gas-phase transalkylation reaction requires a very high reaction temperature, and the xylene / ethylbenzene reaches 750ppm.

[0010] The above-mentioned transalkylation reaction catalysts include beta zeolite, Y zeolite and ZSM-5 zeolite, etc. By modifying the above-mentioned zeolite catalysts, the conversion rate of raw material diethylbenzene or the selectivity of product ethylbenzene is effectively improved. However, so far, there are few reports on catalysts that can simultaneously improve the conversion rate of raw material diethylbenzene and the selectivity of product ethylbenzene, and have a low xylene content. Summary of the invention

[0011] The invention provides a catalyst for preparing ethylbenzene by liquid-phase transalkylation of benzene and diethylbenzene and a preparation method thereof. The catalyst has high diethylbenzene conversion rate and good product ethylbenzene selectivity in the process of catalyzing the liquid-phase transalkylation of benzene and diethylbenzene to prepare ethylbenzene, thereby solving the problem in the existing production technology that it is difficult to achieve both high conversion rate of raw material diethylbenzene and high selectivity of product ethylbenzene.

[0012] In one aspect of the present application, a modified Y-type molecular sieve catalyst is provided.

[0013] The modified Y-type molecular sieve catalyst is obtained by subjecting the NaY-type molecular sieve to hydrothermal treatment, acid treatment and silanization treatment.

[0014] Another aspect of the present application provides a method for preparing the above-mentioned modified Y-type molecular sieve catalyst, the preparation method comprising:

[0015] (1) exchanging NaY molecular sieve with ammonium, and calcining I to obtain an ammonium-exchanged catalyst;

[0016] (2) The catalyst obtained in step (1) is subjected to hydrothermal treatment, acid treatment, and calcination II in sequence to obtain the modified Y-type molecular sieve catalyst precursor;

[0017] (3) adding the modified Y-type molecular sieve catalyst precursor obtained in step (2) into an organic solvent solution containing a silicon source for silanization treatment;

[0018] (4) Obtaining the modified Y-type molecular sieve catalyst.

[0019] Optionally, repeat steps (1) to (3) 1 to 3 times;

[0020] Preferably, the ammonium exchange is performed 2 to 4 times, the hydrothermal treatment is performed 1 to 3 times, the acid treatment is performed 1 to 3 times, and the silanization treatment is performed 1 to 3 times.

[0021] Optionally, ammonium exchange is performed 3 times, water vapor treatment is performed 2 times, and silanization is performed 2 times.

[0022] Optionally, the temperature of the calcination I is 450-650° C., and the calcination I time is ………~……;

[0023] Optionally, the calcination temperature is 450-650°C;

[0024] Optionally, the temperature of the calcination II is 450-650° C., and the calcination II time is ……… ...

[0025] Optionally, the temperature of the calcination II is 500-600°C;

[0026] Optionally, the hydrothermal treatment temperature is 450-700° C., and the hydrothermal treatment time is 1-6 hours;

[0027] Optionally, the hydrothermal treatment temperature is 500-600° C., and the hydrothermal treatment time is 2-4;

[0028] Optionally, during the hydrothermal treatment, the water vapor concentration is 60-100%, and the water vapor mass space velocity is 0.1-1.5h -1 ;

[0029] Optionally, the water vapor concentration is 80-100%, and the water vapor mass space velocity is 0.2-1h-1 ;

[0030] Optionally, the acid treatment is performed using an organic acid;

[0031] Optionally, the organic acid is selected from at least one of citric acid, oxalic acid, acetic acid, and ethylenediaminetetraacetic acid;

[0032] Optionally, the organic acid is citric acid or oxalic acid;

[0033] Optionally, the organic acid concentration is 0.1 to 1 mol / L;

[0034] Optionally, the organic acid concentration is 0.2-0.8 mol / L;

[0035] Optionally, the acid treatment temperature is 50 to 90° C., and the acid treatment time is 1 to 6 hours.

[0036] Optionally, the acid treatment temperature is 60-80° C., and the acid treatment time is 2-3 hours.

[0037] Optionally, the silicon source is siloxane;

[0038] Optionally, the silicon source is selected from at least one of tetraethyl orthosilicate, polymethylhydrogensiloxane, polymethyl silicone oil, chloropropyltriethoxysilane, and methyltrimethoxysilane;

[0039] Optionally, the silicon source is selected from tetraethyl orthosilicate or polymethylhydrogensiloxane.

[0040] Optionally, in the organic solvent solution containing the silicon source, the mass concentration of the silicon source is 2 to 8%;

[0041] Optionally, the mass concentration of the silicon source is 4-6%.

[0042] Optionally, the organic solvent is selected from at least one of n-hexane, n-heptane, n-octane, cyclohexane, methylcyclohexane, benzene and toluene.

[0043] Optionally, the organic solvent is cyclohexane or benzene.

[0044] Optionally, the silanization treatment temperature is 50 to 90° C., and the silanization treatment time is 4 to 10 hours.

[0045] Optionally, the silanization treatment temperature is 60-80° C., and the silanization treatment time is 6-8 hours.

[0046] As a specific embodiment, the preparation method comprises:

[0047] Industrial NaY type molecular sieve, auxiliary agent and dilute nitric acid are extruded into strips in a certain proportion, and then put into an ammonium salt aqueous solution for exchange under water bath conditions at a certain temperature, and then washed, filtered, dried and roasted. The exchanged catalyst is then placed in a water vapor atmosphere at a certain temperature for a certain period of time, and then treated in an organic acid solution at a certain temperature, and then roasted. The molecular sieve is taken out and placed in an organic solvent solution containing a certain amount of silicon source and treated at a certain temperature for a certain period of time. This process is repeated 1 to 3 times to obtain the product.

[0048] The Y-type molecular sieve extrusion molding method in the method of the present invention is a conventional method used in the prior art, and there is no special restriction on it. For example, the mass fraction of the molecular sieve raw powder is 60-90%, the auxiliary agent is pseudo-boehmite and sesbania powder, the concentration of dilute nitric acid is 3-6%, and the dosage is 60-90%. The ammonium salt exchange treatment method in the method of the present invention is a conventional method used in the prior art, and there is no special restriction on it. For example, use an ammonium salt solution with a mass concentration of 3-15%, treat at 50-90°C for 1-6 hours, and then wash with water, filter, and dry. The ammonium salt is at least one of ammonium nitrate, ammonium chloride, ammonium oxalate, and ammonium sulfate.

[0049] In another aspect of the present application, a method for preparing ethylbenzene by liquid phase transalkylation of benzene and diethylbenzene is provided.

[0050] The raw material containing benzene and diethylbenzene is contacted with a catalyst in a reactor to react to obtain ethylbenzene;

[0051] The catalyst is selected from the above-mentioned modified Y-type molecular sieve catalyst or the modified Y-type molecular sieve catalyst obtained according to the above-mentioned preparation method.

[0052] The obtained catalyst can be used in the liquid phase alkylation process of mixed diethylbenzene components produced by the alkylation process of ethylene or ethanol to produce ethylbenzene and benzene.

[0053] Optionally, the mass ratio of benzene to diethylbenzene is 1 to 6;

[0054] Optionally, the mass ratio of benzene to diethylbenzene is 2 to 4;

[0055] Optionally, the mass space velocity of the raw material is 1 to 8 h -1 ;

[0056] Optionally, the mass space velocity of the raw material is 3 to 6 h -1 .

[0057] Optionally, the diethylbenzene is a mixed diethylbenzene produced by a pure ethylene or ethanol alkylation process to produce ethylbenzene.

[0058] Optionally, the reaction temperature is 190-260° C.; the reaction pressure is 2-5.0 MPa.

[0059] Optionally, the reaction temperature is 200-240° C.; the reaction pressure is 3-4 MPa.

[0060] The beneficial effects of this application include:

[0061] Since the silanized silicon source can combine with the hydroxyl groups on the surface of the molecular sieve, this process occurs not only on the outer surface of the molecular sieve, but also in the pores. Different silanized silicon sources can partially enter the inner surface of the molecular sieve and cover part of the original active sites. The advantage of such treatment is that the active center of the molecular sieve can be dispersed, so that the residence time of the reaction materials in the pores of the molecular sieve becomes shorter, which is beneficial to the mass transfer process and reduces the occurrence of side reactions. The Y-type molecular sieve treated by the method of the present invention is successively treated with ultrastabilization and silanization, and is used for the liquid-phase transalkylation reaction of benzene and mixed diethylbenzene, which can significantly improve the conversion rate of diethylbenzene and the selectivity of ethylbenzene. DETAILED DESCRIPTION

[0062] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0063] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0064] Example 1

[0065] 30g NaY, 3g sesbania powder, 8g pseudo-boehmite, and 25g 5% dilute nitric acid were mixed together and extruded into strips, which were then placed in an 80°C water bath and exchanged with 200g 1mol / L ammonium nitrate solution for 2h. The strips were washed, filtered, dried, and calcined at 550°C for 3h. The strips were then taken out and placed in a reaction tube. -1 Pure water was introduced at a rate of 500°C for 2 hours, then treated in 100 ml of 0.2 mol / L oxalic acid aqueous solution at 60°C for 2 hours, filtered, dried, and calcined at 550°C for 3 hours. Finally, it was treated in 150 g of benzene containing 3% ethyl orthosilicate at 60°C for 6 hours, dried, and calcined at 550°C for 3 hours to obtain the final liquid-phase transalkylation catalyst.

[0066] Example 2

[0067] The remaining conditions were the same as in Example 1, except that the number of ammonium exchanges was changed to 3 times.

[0068] Example 3

[0069] The remaining conditions were the same as in Example 2, except that the number of water vapor treatments was changed to 2 times and the number of oxalic acid treatments was changed to 2 times, i.e., the order was ammonium exchange, water vapor treatment, acid treatment, ammonium exchange, water vapor treatment, acid treatment, and ammonium exchange.

[0070] Example 4

[0071] The remaining conditions are the same as in Example 3, except that the temperature of the steam treatment is changed to 600°C.

[0072] Example 5

[0073] The remaining conditions were the same as in Example 4, except that the temperature of the oxalic acid treatment was changed to 80°C.

[0074] Example 6

[0075] The remaining conditions were the same as in Example 5, except that the mass fraction of ethyl orthosilicate in benzene was changed to 5% and the temperature of the silanization treatment was 80°C.

[0076] Example 7

[0077] The remaining conditions were the same as in Example 6, except that the number of silanization treatments was changed to 2, i.e., a silanization treatment was performed after each water vapor treatment.

[0078] Comparative Example 1

[0079] 30g NaY, 3g sesbania powder, 8g pseudo-boehmite, and 25g 5% dilute nitric acid were mixed together and extruded into strips, which were then placed in an 80°C water bath and exchanged with 200g 1mol / L ammonium nitrate solution for 2h. The strips were washed, filtered, dried, and calcined at 550°C for 3h. The strips were then taken out and placed in a reaction tube. -1 Pure water was introduced at a rate of 600°C for 2 hours, then treated in 100 ml of 0.2 mol / L oxalic acid aqueous solution at 80°C for 2 hours, filtered, dried, and calcined at 550°C for 3 hours. The final catalyst was exchanged 3 times, and treated with water vapor and acid twice each.

[0080] Comparative Example 2

[0081] Patent CN1310051 uses a gas-phase transalkylation process, and the catalyst active component used is ZSM-5 molecular sieve, which is treated with water vapor and modified with organic acid. The reaction conditions are a temperature of 435°C, a reaction pressure of 0.6MPa, and a total space velocity of 28h. -1 , the molar ratio of benzene / mixed diethylbenzene is 5.

[0082] Test Case

[0083] The reaction performance of the catalyst was evaluated using a fixed bed reactor that was fed from bottom to top. The reactor was a stainless steel tube with an inner diameter of 10 mm and a length of 500 mm. 3 grams of catalyst was loaded into the constant temperature section. The catalysts of Examples 1 to 7 and Comparative Example 1 were loaded into the reactor. Nitrogen was filled into the reactor to a certain pressure, replaced twice and leaked. After the temperature was raised to the reaction temperature, the alkyl transfer material was started. The reaction conditions were a temperature of 230° C., a reaction pressure of 3 MPa, and a liquid phase weight space velocity of 4 h-1 , the weight ratio of benzene / mixed diethylbenzene is 3. After 24 hours of stable feeding reaction, samples were taken for gas chromatography analysis. The data are shown in Table 1:

[0084] Table 1 Transalkylation reaction data of benzene and diethylbenzene

[0085]

[0086]

[0087] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A modified Y-type molecular sieve catalyst, characterized in that: The modified Y-type molecular sieve catalyst is obtained by subjecting the NaY-type molecular sieve to hydrothermal treatment, acid treatment and silanization treatment; The modified Y-type molecular sieve catalyst is obtained by the following steps: (1) exchanging NaY molecular sieve with ammonium, and calcining I to obtain an ammonium-exchanged catalyst; (2) The catalyst obtained in step (1) is subjected to hydrothermal treatment, acid treatment, and calcination II in sequence to obtain the modified Y-type molecular sieve catalyst precursor; (3) adding the modified Y-type molecular sieve catalyst precursor obtained in step (2) into an organic solvent solution containing a silicon source for silanization treatment; (4) obtaining the modified Y-type molecular sieve catalyst; Repeat steps (1) to (3) 1 to 3 times; The acid treatment is carried out using an organic acid; The organic acid is selected from at least one of citric acid, oxalic acid, acetic acid, and ethylenediaminetetraacetic acid; The silicon source is selected from at least one of tetraethyl orthosilicate, polydimethylhydrogensiloxane, polymethyl silicone oil, chloropropyltriethoxysilane and methyltrimethoxysilane.

2. The modified Y-type molecular sieve catalyst according to claim 1, characterized in that The temperature of the calcination I is 450-650° C., and the calcination I time is 3-6 hours; The temperature of the calcination II is 450-650°C, and the calcination II time is 3-6h; The hydrothermal treatment temperature is 450-700°C and the hydrothermal treatment time is 1-6h; During the hydrothermal treatment, the water vapor concentration is 60-100%, and the water vapor mass space velocity is 0.1-1.

5.

3. The modified Y-type molecular sieve catalyst according to claim 1, characterized in that: The organic acid concentration is 0.1 to 1 mol / L; The acid treatment temperature is 50-90° C., and the acid treatment time is 1-6 hours.

4. The modified Y-type molecular sieve catalyst according to claim 1, characterized in that: In the organic solvent solution containing the silicon source, the mass concentration of the silicon source is 2 to 8%; The organic solvent is selected from at least one of n-hexane, n-heptane, n-octane, cyclohexane, methylcyclohexane, benzene and toluene.

5. The modified Y-type molecular sieve catalyst according to claim 1, characterized in that: The silanization treatment temperature is 50-90° C., and the silanization treatment time is 4-10 hours.

6. A method for preparing ethylbenzene by liquid phase transalkylation of benzene and diethylbenzene, characterized in that: The raw material containing benzene and diethylbenzene is contacted with a catalyst in a reactor to react to obtain ethylbenzene; The catalyst is selected from the modified Y-type molecular sieve catalyst according to any one of claims 1 to 5.

7. The method according to claim 6, characterized in that The mass ratio of benzene to diethylbenzene is 1 to 6; The mass space velocity of the raw material is 1 to 8 h-1; The diethylbenzene is a mixed diethylbenzene produced by the production of ethylbenzene through a pure ethylene or ethanol alkylation process.

8. The method according to claim 6, characterized in that The reaction temperature is 190-260° C.; the reaction pressure is 2-5.0 MPa.

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