Catalyst for preparing ethylbenzene by alkylation of dilute ethylene gas phase method, preparation method of catalyst and method for preparing ethylbenzene by alkylation of dilute ethylene gas phase method

Abstract

The invention provides a catalyst for preparing ethylbenzene through alkylation of dilute ethylene by a gas phase method, a preparation method of the catalyst and a method for preparing ethylbenzene through alkylation of dilute ethylene by the gas phase method, and relates to the technical field of catalytic materials. The b-axis thickness of the novel ZSM-5 molecular sieve is 50-300 nm, the a-axis length of the novel ZSM-5 molecular sieve is 300-2000 nm, the orthogonal twin crystal thickness of the novel ZSM-5 molecular sieve is 50-300 nm, and the novel ZSM-5 molecular sieve has an orthogonal two-dimensional nanosheet structure; the novel ZSM-5 molecular sieve is an organic silicon modified ZSM-5 molecular sieve. According to the invention, the technical problem that the ethylene-containing dry gas cannot be directly subjected to alkylation reaction because of carrying a small amount of propylene and butene is solved, and the technical effects that the ethylene conversion rate is greater than 99%, the ethylbenzene selectivity is greater than 99% and the content of xylene in the ethylbenzene product is lower than 300ppm are achieved.

Description

Technical Field

[0001] This invention relates to the technical field of catalytic materials, and in particular to a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene and its preparation method, as well as a method for the gas-phase alkylation of dilute ethylene to ethylbenzene. Background Technology

[0002] Styrene is an important organic chemical monomer, widely used in the production of polystyrene (PS), engineering plastics (ABS), styrene-butadiene rubber (SBR), and unsaturated polyester resins, while ethylbenzene is the most important raw material for the production of styrene.

[0003] In current ethylene-containing dry gas alkylation processes for ethylbenzene production, the dry gas gas-phase method requires stringent quality control of the raw material dry gas to ensure product quality and reduce catalyst carbon buildup. This necessitates the construction of a complex propylene removal system to remove as much propylene and butene as possible from the dry gas. Furthermore, the benzene-to-ethylene molar ratio (SMR) in the feed is often too high, resulting in a significant increase in energy consumption due to the large amount of benzene circulating within the unit. Simultaneously, the content of the byproduct xylene affects the purity of the target product, ethylbenzene. Therefore, there is an urgent need to develop novel catalysts to improve adaptability to impurities in ethylene-containing dry gas, reduce the SMR, and decrease the content of the byproduct xylene.

[0004] The prior art CN101768043A discloses a method for producing ethylbenzene by reacting dilute ethylene with benzene. It uses dilute ethylene from dry gas from an oil refinery as raw material. After water washing and selective removal of propylene, the ethylene is fed into a hydrocarbonation reactor in stages. In the presence of a zeolite catalyst, it undergoes a hydrocarbonation reaction with benzene. The reaction temperature rise is reduced by using dry gas and low-temperature gaseous benzene for heat extraction. After vapor-liquid separation of the hydrocarbonation product, the tail gas is discharged through a low-temperature absorption device. The liquid product is separated sequentially by a separation system to obtain recycled benzene, ethylbenzene, propylbenzene, diethylbenzene, and a heavy component. Diethylbenzene is mixed with benzene and fed into a reverse hydrocarbonation reactor, where it undergoes a reverse hydrocarbonation reaction on a molecular sieve catalyst to further convert into ethylbenzene.

[0005] The prior art CN101665398A discloses a purification method for ethylene-containing feed gas in the ethylene-to-ethylbenzene process. This method involves a three-tower process: an absorption tower, an ethylene desorption tower, and a propylene desorption tower. The absorption tower uses benzene as the absorbent. The saturated absorbent after absorbing propylene from the feed gas sequentially enters the ethylene and propylene desorption towers. The gas at the top of the ethylene desorption tower returns to the inlet of the absorption tower. The absorbent desorbed in the propylene desorption tower is returned to the absorption tower for recycling. This method can increase the propylene removal rate in the feed gas to over 98% and reduce the ethylene loss rate to less than 2%, even when the propylene volume content in the feed gas is as high as 3%.

[0006] Prior art CN110283035A discloses a processing device and method for raw material dry gas used in the production of ethylbenzene. The processing device includes: a propylene stripping tower; the propylene stripping tower is equipped with a raw material dry gas inlet pipeline; a gas-liquid cyclone separator with its inlet connected to the outlet of the propylene stripping tower; a coalescer with its inlet connected to the outlet of the gas-liquid cyclone separator; an alkali adsorption device with its inlet connected to the outlet of the coalescer; and a preheater with its inlet connected to the outlet of the alkali adsorption device. This processing device first removes C3 and higher components from the raw material dry gas, then removes liquid components, and finally adsorbs alkaline impurities to remove them from the dry gas. The preheated raw material dry gas is then used for the production of ethylbenzene. This raw material dry gas can effectively avoid catalyst poisoning and deactivation in the hydrocarbonation reactor, enabling long-term stable operation of the dry gas-to-ethylbenzene unit, while simultaneously improving the ethylene conversion rate.

[0007] In summary, to address issues such as poor catalyst adaptability to ethylene-containing dry gas impurities, high xylene content in the product, and a large benzene-to-olefin ratio, current processes for the gas-phase alkylation of dilute ethylene to ethylbenzene all employ a propylene removal system to purify the raw material dry gas and remove as much propylene and butene as possible from the dry gas. As a result, the initial equipment investment is large, the process is complex, and the production cost is high.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] One of the objectives of this invention is to provide a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene, which solves the technical problem that ethylene-containing dry gas cannot directly undergo alkylation reaction due to carrying small amounts of propylene and butene. This achieves the technical effects of ethylene conversion rate greater than 99%, ethylbenzene selectivity greater than 99%, and xylene content in ethylbenzene product less than 300 ppm.

[0010] The second objective of this invention is to provide a method for preparing a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene, which is simple, has a high success rate, and is suitable for industrial production.

[0011] The third objective of this invention is to provide a method for producing ethylbenzene by gas-phase alkylation of dilute ethylene, which avoids the propylene removal system required in traditional processes, shortens the process flow, and significantly reduces construction and production costs. It also improves the adaptability to propylene in ethylene-containing dry gas to 3% (volume fraction) and the adaptability to butene in ethylene-containing dry gas to 2% (volume fraction), achieving a technical effect of ethylene conversion greater than 99%, ethylbenzene selectivity greater than 99%, and xylene content in the ethylbenzene product less than 300 ppm.

[0012] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene, wherein the active component of the catalyst includes a novel ZSM-5 molecular sieve; The novel ZSM-5 molecular sieve has a b-axis thickness of 50nm-300nm, an a-axis length of 300nm-2000nm, and an orthogonal twin thickness of 50nm-300nm, exhibiting an orthogonal two-dimensional nanosheet structure. The novel ZSM-5 molecular sieve is an organosilicon-modified ZSM-5 molecular sieve.

[0013] Furthermore, the catalyst comprises the following components: The novel ZSM-5 molecular sieve consists of 70wt%-90wt%, binder 10wt%-25wt%, and extrusion aid 0-5wt%.

[0014] Furthermore, the binder includes at least one of boehmite and γ-Al2O3; Preferably, the extrusion aid includes at least one of guar gum powder, lanthanum nitrate, and cerium nitrate.

[0015] In a second aspect, a method for preparing a catalyst according to any one of the above claims, characterized by comprising the following steps: (1) Mix the silicon source, template agent and solvent, crystallize them to obtain a nanocrystalline seed emulsion; A mixture of silicon source, template agent, organic amine, solvent and nanocrystalline seed emulsion is mixed and aged to obtain a colloid mixture. Aluminum source, solvent and mixed colloid are mixed to obtain silicon-aluminum mixed gel. The silicon-aluminum mixed gel is aged and crystallized, solid-liquid separated, dried and calcined to obtain ZSM-5 molecular sieve. (2) Mix the organosilicon source with the ZSM-5 molecular sieve from step (1), modify the molecular sieve, shape it, separate the solid and liquid, dry it, and calcine it to obtain a new ZSM-5 molecular sieve. (3) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid from step (2) to obtain a mixture; (4) The acid solution is mixed with the mixture from step (3), and then extruded, dried and calcined to obtain the catalyst.

[0016] Furthermore, in step (1), the silicon source includes at least one of silica sol, tetraethyl orthosilicate, and silica gel; Preferably, the template agent includes at least one of ethylamine, tetrapropylammonium hydroxide, n-butylamine, and tetrapropylammonium bromide.

[0017] Furthermore, in step (2), the mass ratio of the ZSM-5 molecular sieve to the organosilicon source is 1:(0.02-0.15); Preferably, the organosilicon source includes at least one selected from tetraethyl orthosilicate, methyltriethoxysilane, dimethyldimethoxysilane, and tetramethylsiloxane.

[0018] Thirdly, a method for producing ethylbenzene by gas-phase alkylation of dilute ethylene, wherein the method employs the catalyst described in any of the above-mentioned embodiments to catalyze the alkylation reaction of dilute ethylene with benzene.

[0019] Furthermore, the method includes the following steps: After washing with water, the ethylene-containing dry gas is directly alkylated with benzene under the catalysis of the catalyst to obtain ethylbenzene.

[0020] Furthermore, the volume fraction of ethylene in the ethylene-containing dry gas is 5%-70%, preferably 5%-50%; Preferably, the volume fraction of propylene in the ethylene-containing dry gas is 0-3%, more preferably 0-2%; Preferably, the volume fraction of butene in the ethylene-containing dry gas is 0-2%, more preferably 0-1%.

[0021] Furthermore, the molar ratio of benzene to ethylene is 2-8; Preferably, the alkylation reaction is carried out at a temperature of 260°C-390°C; Preferably, the mass hourly space velocity (MSV) of the ethylene is 0.1 h⁻¹. 1 -1.5h 1 ; Preferably, the pressure of the alkylation reaction is 0.5 MPaG-1.5 MPaG.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects: The catalyst provided by this invention for the gas-phase alkylation of dilute ethylene to ethylbenzene is a highly efficient alkylation catalyst. The active component is a novel ZSM-5 molecular sieve with uniform particle size, an orthogonal two-dimensional nanosheet morphology, and a unique pore structure. The b-axis thickness is 50 nm-300 nm, the a-axis length is 300 nm-2000 nm, and the orthogonal twin thickness is 50 nm-300 nm. The novel ZSM-5 molecular sieve is an organosilicon-modified ZSM-5 molecular sieve. Using organosilicon to modify the catalyst not only rationally adjusts the acid content and acid strength, but also… Furthermore, the pore volume and pore size distribution were optimized. Under the combined effect of various properties, this alkylation catalyst effectively improved the selectivity of the alkylation reaction for ethylbenzene, significantly suppressed the occurrence of side reactions, reduced the formation of xylene and carbon deposits, improved the adaptability to impurities in ethylene-containing dry gas, and effectively reduced the benzene-to-olefin ratio. In summary, the catalyst of this invention solves the technical problem that ethylene-containing dry gas cannot be directly alkylated due to carrying small amounts of propylene and butene, achieving technical effects such as ethylene conversion rate greater than 99%, ethylbenzene selectivity greater than 99%, and xylene content in ethylbenzene products less than 300 ppm.

[0023] The method for preparing a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene provided by this invention is simple, has a high success rate, and is suitable for industrial production.

[0024] The method for producing ethylbenzene by gas-phase alkylation of dilute ethylene provided by this invention avoids the propylene removal system required in traditional processes, shortens the process flow, and significantly reduces construction and production costs. It also improves the adaptability of propylene in ethylene-containing dry gas to 3% (volume fraction) and the adaptability of butene in ethylene-containing dry gas to 2% (volume fraction), achieving technical effects such as ethylene conversion greater than 99%, ethylbenzene selectivity greater than 99%, and xylene content in the ethylbenzene product less than 300 ppm. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a SEM image of the novel ZSM-5 molecular sieve obtained in Example 1 of the present invention; Figure 2 This is a SEM image of the novel ZSM-5 molecular sieve obtained in Example 2 of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] According to a first aspect of the present invention, a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene is provided, wherein the active component of the catalyst comprises a novel ZSM-5 molecular sieve. The novel ZSM-5 molecular sieve has a b-axis thickness of 50nm-300nm, an a-axis length of 300nm-2000nm, and an orthogonal twin thickness of 50nm-300nm, exhibiting an orthogonal two-dimensional nanosheet structure. The novel ZSM-5 molecular sieve is an organosilicon-modified ZSM-5 molecular sieve.

[0029] The novel ZSM-5 molecular sieve has an MFI topology. Based on the characteristics of MFI molecular sieves, the adsorption and diffusion rates of molecules within the molecular sieve can be controlled by adjusting the thickness of the b-axis. Through organosilicon modification, the acidity and acid strength of the catalyst's outer surface are rationally adjusted, while its pore volume and pore size distribution are optimized. This ensures the number of effective acidic sites and avoids the formation of byproducts in the alkylation reaction, thereby improving the catalyst's performance.

[0030] The catalyst of this invention is a highly efficient alkylation catalyst. The active component is a novel ZSM-5 molecular sieve with uniform particle size, an orthogonal two-dimensional nanosheet morphology, and a unique pore structure. The b-axis thickness is 50nm-300nm, the a-axis length is 300nm-2000nm, and the orthogonal twin thickness is 50nm-300nm. The novel ZSM-5 molecular sieve is an organosilicon-modified ZSM-5 molecular sieve. The modification of the catalyst with organosilicon not only rationally adjusts the acid content and acid strength but also optimizes the pore volume and pore size distribution. Under the combined effect of various properties, this alkylation catalyst effectively improves the selectivity of the alkylation reaction to ethylbenzene, significantly inhibits the occurrence of side reactions, reduces the formation of xylene and carbon deposits, improves the adaptability to dry gas impurities, and effectively reduces the benzene-to-olefin ratio.

[0031] In summary, the catalyst of this invention solves the technical problem that ethylene-containing dry gas cannot be directly alkylated due to carrying small amounts of propylene and butene, achieving technical effects such as ethylene conversion rate greater than 99%, ethylbenzene selectivity greater than 99%, and xylene content in ethylbenzene products less than 300 ppm.

[0032] In a preferred embodiment, the catalyst comprises the following components: The novel ZSM-5 molecular sieve consists of 70wt%-90wt%, binder 10wt%-25wt%, and extrusion aid 0-5wt%.

[0033] In a preferred embodiment, the binder includes, but is not limited to, at least one of boehmite and γ-Al2O3; the extrusion aid includes, but is not limited to, at least one of guar gum powder, lanthanum nitrate, and cerium nitrate.

[0034] According to a second aspect of the present invention, a method for preparing the catalyst according to any one of the above claims is provided, comprising the following steps: (1) Mix the silicon source, template agent and solvent, crystallize them to obtain a nanocrystalline seed emulsion; A mixture of silicon source, template agent, organic amine, solvent and nanocrystalline seed emulsion is mixed and aged to obtain a colloid mixture. Aluminum source, solvent and mixed colloid are mixed to obtain silicon-aluminum mixed gel. The silicon-aluminum mixed gel is aged and crystallized, solid-liquid separated, dried and calcined to obtain ZSM-5 molecular sieve. (2) Mix the organosilicon source with the ZSM-5 molecular sieve from step (1), modify the molecular sieve, shape it, separate the solid and liquid, dry it, and calcine it to obtain a new ZSM-5 molecular sieve. (3) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid from step (2) to obtain a mixture; (4) The acid solution is mixed with the mixture from step (3), and then extruded, dried and calcined to obtain the catalyst.

[0035] The catalyst preparation method of this invention is simple, has a high success rate, and is suitable for industrial production.

[0036] In a preferred embodiment, in step (1), the silicon source includes, but is not limited to, at least one of silica sol, tetraethyl orthosilicate and silica gel; the template agent includes, but is not limited to, at least one of ethylamine, tetrapropylammonium hydroxide, n-butylamine and tetrapropylammonium bromide.

[0037] In a preferred embodiment, in step (2), the mass ratio of ZSM-5 molecular sieve to organosilicon source can be 1:(0.02-0.15), for example, the mass ratio can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, but is not limited to this; the organosilicon source includes, but is not limited to, at least one of tetramethylsiloxane, methyltriethoxysilane, dimethyldimethoxysilane and tetramethylsiloxane.

[0038] In a preferred embodiment, the drying temperature can be 80℃-120℃, for example, 80℃, 90℃, 100℃, 110℃, 120℃, but is not limited thereto; the drying time can be 4h-12h, for example, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, but is not limited thereto.

[0039] In step (2), the roasting temperature can be 350℃-540℃, for example, 350℃, 380℃, 400℃, 420℃, 450℃, 480℃, 500℃, 540℃, but is not limited to this; the roasting time can be 4h-12h, for example, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, but is not limited to this.

[0040] In step (4), an acid solution with a concentration of 3wt%-20wt% is mixed with the mixture from step (3), extruded into strips, and then dried and calcined in sequence to obtain the finished catalyst; wherein, drying can be carried out at 80℃-120℃ for 1h-24h; calcination can be carried out at 350℃-540℃ for 4h-12h.

[0041] The preparation method of this invention is simple and helps to reduce the production cost of the catalyst. At the same time, by controlling specific conditions, the finished catalyst has an orthogonal two-dimensional nanosheet structure, which exhibits strong impurity resistance, good stability, high selectivity and long service life when used for benzene alkylation to ethylbenzene.

[0042] According to a third aspect of the present invention, a method for producing ethylbenzene by gas-phase alkylation of dilute ethylene is provided, the method employing the catalyst described in any one of the preceding claims to catalyze the alkylation reaction of benzene, comprising the following steps: After washing with water, ethylene-containing dry gas is directly alkylated with benzene under the catalysis of the catalyst to obtain ethylbenzene.

[0043] The present invention provides a method for producing ethylbenzene by gas-phase alkylation of dilute ethylene, which avoids the propylene removal system required in traditional processes, shortens the process flow, and significantly reduces construction and production costs. It also improves the adaptability of propylene in ethylene-containing dry gas to 3% (volume fraction) and the adaptability of butene in ethylene-containing dry gas to 2% (volume fraction), achieving technical effects such as ethylene conversion greater than 99%, ethylbenzene selectivity greater than 99%, and xylene content in the ethylbenzene product less than 300 ppm.

[0044] In a preferred embodiment, the volume fraction of ethylene in the ethylene-containing dry gas can be 5%-70%, with typical but non-limiting volume fractions such as 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, and 70%, and more preferably 5%-50%.

[0045] In a preferred embodiment, the volume fraction of propylene in the ethylene-containing dry gas can be 0-3%, typically but not limitingly, such as 0, 1%, 2%, 3%, and more preferably 0-2%.

[0046] In a preferred embodiment, the volume fraction of butene in the ethylene-containing dry gas can be 0-2%, typically but not limitingly, such as 0, 1%, or 2%, and more preferably 0-1%.

[0047] In a preferred embodiment, the molar ratio of benzene to ethylene can be 2-8, for example, 2, 3, 4, 5, 6, 7, 8, but is not limited thereto.

[0048] In a preferred embodiment, the alkylation reaction temperature can be 260°C-390°C, with typical but non-limiting temperatures such as 260°C, 280°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, and 390°C.

[0049] In a preferred embodiment, the mass hourly space velocity (MSV) of ethylene can be 0.1 h⁻¹. 1 -1.5h 1 For example, it can be 0.1h 1 0.2h 1 0.3h 1 0.4h 1 0.5h 1 0.6h 1 0.8h 1 1.0h 1 1.2h 1 1.4h 1 1.5h 1 .

[0050] In a preferred embodiment, the pressure of the alkylation reaction can be 0.5 MPaG-1.5 MPaG, with typical but non-limiting pressures such as 0.5 MPaG, 0.6 MPaG, 0.7 MPaG, 0.8 MPaG, 0.9 MPaG, 1.0 MPaG, 1.1 MPaG, 1.2 MPaG, 1.3 MPaG, 1.4 MPaG, and 1.5 MPaG.

[0051] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0052] Example 1 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to produce ethylbenzene. The raw materials for its preparation include, by mass, 75 parts of novel ZSM-5 molecular sieve, 25 parts of binder, and 1 part of extrusion aid; the binder is boehmite; and the extrusion aid is guar gum powder.

[0053] The preparation method of the catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene includes the following steps: (1) A mixed solution was prepared according to the mass ratio of raw material ZSM-5 molecular sieve to organosilicon source of 1:0.05. The solution was stirred and mixed at a constant temperature of 60℃ for 4 hours. Then, solid-liquid separation, drying and calcination were carried out to obtain a new type of ZSM-5 molecular sieve. The organosilicon source was tetraethyl orthosilicate. (2) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid according to the formula to obtain the mixture; (3) Mix 10wt% nitric acid with the mixture obtained in step (2), extrude into strips, add 30% of the mass of the mixture, dry and calcine in sequence, cool to room temperature to obtain the finished catalyst; the drying is done at 100℃ for 12h, and the calcination is done at 540℃ for 6h.

[0054] The novel ZSM-5 molecular sieve in this embodiment was characterized by SEM, and the SEM image is shown below. Figure 1 As shown, by Figure 1 It can be seen that the obtained ZSM-5 molecular sieve has a uniform morphology, with a b-axis thickness of about 100 nm, an a-axis length of about 300 nm, and a c-axis width of about 150 nm.

[0055] Example 2 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene. The raw materials for its preparation, by mass, include 70 parts of a novel ZSM-5 molecular sieve, 30 parts of a binder, and 0.5 parts of an extrusion aid; the binder is γ-ray dimethyl ether (γ-ray dimethyl ether). Al2O3; the extrusion aid is lanthanum nitrate.

[0056] The preparation method of the catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene includes the following steps: (1) A mixed solution was prepared according to the mass ratio of raw material ZSM-5 molecular sieve to organosilicon source of 1:0.02. The solution was stirred and mixed at a constant temperature of 60℃ for 8 hours. Then, solid-liquid separation, drying and calcination were carried out to obtain a new type of ZSM-5 molecular sieve. The organosilicon source was tetraethyl orthosilicate. (2) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid according to the formula to obtain the mixture; (3) Mix 8wt% nitric acid with the mixture obtained in step (2), extrude into strips, add 50% of the mass of the mixture, dry and calcine in sequence, cool to room temperature to obtain the finished catalyst; drying is done at 120℃ for 8h; calcination is done at 450℃ for 10h.

[0057] The novel ZSM-5 molecular sieve in this embodiment was characterized by SEM, and the SEM image is shown below. Figure 2 As shown.

[0058] Example 3 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to produce ethylbenzene. The raw materials for its preparation include, by mass, 60 parts of novel ZSM-5 molecular sieve, 40 parts of binder, and 2 parts of extrusion aid; the binder is boehmite; and the extrusion aid is cerium nitrate.

[0059] The preparation method of the catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene includes the following steps: (1) A mixed solution was prepared according to the mass ratio of raw material ZSM-5 molecular sieve to organosilicon source of 1:0.08. The solution was stirred and mixed at a constant temperature of 50℃ for 12h. Then, solid-liquid separation, drying and calcination were carried out to obtain a new type of ZSM-5 molecular sieve. The organosilicon source was tetraethyl orthosilicate. (2) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid according to the formula to obtain the mixture; (3) Mix 3wt% nitric acid with the mixture obtained in step (2), extrude into strips, add 60% of the mass of the mixture, dry and calcine in sequence, cool to room temperature to obtain the finished catalyst; drying is done at 100℃ for 12h; calcination is done at 400℃ for 12h.

[0060] Example 4 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene. The raw materials for its preparation, by mass percentage, include 80 parts of a novel ZSM-5 molecular sieve, 20 parts of a binder, and 1 part of an extrusion aid; the binder is γ-ray dimethyl ether (γ-ray dimethyl ether). Al2O3; the extrusion aid is lanthanum nitrate.

[0061] The preparation method of the catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene includes the following steps: (1) A mixed solution was prepared according to the mass ratio of raw material ZSM-5 molecular sieve to organosilicon source of 1:0.10. The solution was stirred and mixed at a constant temperature of 40℃ for 24h. Then, solid-liquid separation, drying and calcination were carried out to obtain a new type of ZSM-5 molecular sieve. The organosilicon source is tetraethyl orthosilicate. (2) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid according to the formula to obtain the mixture; (3) Mix 12wt% nitric acid with the mixture obtained in step (2), extrude into strips, add 20% of the mass of the mixture, dry and calcine in sequence, cool to room temperature to obtain the finished catalyst; drying is done at 80℃ for 24h; calcination is done at 500℃ for 10h.

[0062] Example 5 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to produce ethylbenzene. The raw materials for its preparation include, by mass, 90 parts of a novel ZSM-5 molecular sieve, 10 parts of a binder, and 0.5 parts of an extrusion aid; the binder is boehmite; and the extrusion aid is cerium nitrate.

[0063] The preparation method of the catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene includes the following steps: (1) A mixed solution was prepared according to the mass ratio of raw material ZSM-5 molecular sieve to organosilicon source of 1:0.12. The solution was stirred and mixed at a constant temperature of 40℃ for 24h. Then, solid-liquid separation, drying and calcination were carried out to obtain a new type of ZSM-5 molecular sieve. The organosilicon source was tetraethyl orthosilicate. (2) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid according to the formula to obtain the mixture; (3) Mix 5wt% nitric acid with the mixture obtained in step (2), extrude into strips, add 35% of the mass of the mixture, dry and calcine in sequence, cool to room temperature to obtain the finished catalyst; drying is done at 120℃ for 24h; calcination is done at 500℃ for 6h.

[0064] Example 6 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to produce ethylbenzene. The raw materials for its preparation include, by mass, 75 parts of novel ZSM-5 molecular sieve, 25 parts of binder, and 0.5 parts of extrusion aid; the binder is boehmite; and the extrusion aid is cerium nitrate.

[0065] The preparation method of the catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene includes the following steps: (1) A mixed solution was prepared according to the mass ratio of raw material ZSM-5 molecular sieve to organosilicon source of 1:0.15. The solution was stirred and mixed at a constant temperature of 60℃ for 6 hours. Then, solid-liquid separation, drying and calcination were carried out to obtain a new type of ZSM-5 molecular sieve. The organosilicon source was tetraethyl orthosilicate. (2) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid according to the formula to obtain the mixture; (3) Mix 12wt% nitric acid with the mixture obtained in step (2), extrude into strips, add 40% of the mass of the mixture, dry and calcine in sequence, cool to room temperature to obtain the finished catalyst; drying is done at 120℃ for 12h; calcination is done at 540℃ for 10h.

[0066] Example 7 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene and its preparation method. Except for the use of methyltriethoxysilane as the organosilicon source, the rest is the same as in Example 1.

[0067] Example 8 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene and its preparation method. Except for the use of methyltriethoxysilane as the organosilicon source, the rest is the same as in Example 2.

[0068] Example 9 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to produce ethylbenzene and its preparation method. Except for the use of dimethyldimethoxysilane as the organosilicon source, the rest is the same as in Example 1.

[0069] Example 10 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene and its preparation method. Except for the use of dimethyldimethoxysilane as the organosilicon source, the rest is the same as in Example 2.

[0070] Example 11 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to produce ethylbenzene. Except that no extrusion aid is added to the raw materials for catalyst preparation, everything else is the same as in Example 1.

[0071] Example 12 This embodiment provides a catalyst for the gas-phase alkylation of dilute ethylene to produce ethylbenzene. Except that the amount of extrusion aid in the raw materials for catalyst preparation is 5 parts, the rest are the same as in Example 1.

[0072] Test case The catalysts of Examples 1-12 were evaluated respectively.

[0073] Before evaluation, the catalyst was pretreated, which included the following steps: the catalyst was placed in the isothermal section of the reaction tube, nitrogen gas at 1.2 MPa was introduced into the reaction tube and the flow rate of nitrogen gas was controlled at 100 L / h. The temperature was increased from room temperature to 300℃ at a rate of 30℃ / h and held for 2h. The impurities physically adsorbed by the catalyst were removed through the pretreatment.

[0074] The pretreated catalyst was used in the gas-phase alkylation of benzene with dilute ethylene to produce ethylbenzene. The reaction conditions were: 100 mL of the isothermal zone, 360 °C, 1.2 MPa, a benzene to ethylene molar ratio of 6, and an ethylene mass hourly space velocity (HHSV) of 0.6 h⁻¹. -1 The volume fraction of ethylene is 23%, the volume fraction of propylene is 3%, and the volume fraction of butene is 2%.

[0075] The ethylene conversion rate is calculated as follows: (1 - number of moles of ethylene in the product tail gas / number of moles of ethylene in the feed) × 100%.

[0076] The selectivity of ethylbenzene is calculated as follows: (Amount of ethylbenzene in alkylation products + Amount of diethylbenzene) / (Amount of products exiting the reactor - Amount of benzene) × 100%.

[0077] The content of xylene byproduct in the product ethylbenzene is calculated as follows: (moles of ethylbenzene in the product + total moles of diethylbenzene) / (total moles of aromatics in the product - moles of benzene in the product) × 10 6 .

[0078] The propylene conversion rate is calculated as follows: (1 - number of moles of propylene in the product tail gas / number of moles of propylene in the feed) × 100%.

[0079] The test results are shown in Table 1.

[0080] As shown in Table 1, the catalyst of the present invention is used in the gas-phase alkylation reaction of benzene and dilute ethylene to produce ethylbenzene. The ethylene conversion rate is above 98.8%, the ethylbenzene selectivity is above 98.5%, the xylene content in the ethylbenzene product is less than 300 ppm, and the propylene conversion rate is above 97%.

[0081] Table 1

[0082] In summary, the catalyst of this invention uses a novel ZSM-5 molecular sieve as the active component. Compared with the traditional HZSM-5 catalyst, the ZSM-5 molecular sieve is modified by organosilicon, which adjusts the acidity and acid strength of the outer surface of the molecular sieve and modifies the pores, greatly improving the selectivity and stability of the catalyst. The novel ZSM-5 molecular sieve has moderate acid strength and adjustable acidity, and can change the number and strength of effective acid sites without the need for ammonium exchange, steam treatment, or rare earth modification, thus reducing production costs. The catalyst preparation process of this invention is simple and has good prospects for industrialization.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalyst for the gas-phase alkylation of dilute ethylene to ethylbenzene, characterized in that, The active component of the catalyst includes a novel ZSM-5 molecular sieve; The novel ZSM-5 molecular sieve has a b-axis thickness of 50nm-300nm, an a-axis length of 300nm-2000nm, and an orthogonal twin thickness of 50nm-300nm, exhibiting an orthogonal two-dimensional nanosheet structure. The novel ZSM-5 molecular sieve is an organosilicon-modified ZSM-5 molecular sieve.

2. The catalyst according to claim 1, characterized in that, The catalyst comprises the following components: The novel ZSM-5 molecular sieve consists of 70wt%-90wt%, binder 10wt%-25wt%, and extrusion aid 0-5wt%.

3. The catalyst according to claim 2, characterized in that, The binder includes at least one of boehmite and γ-Al2O3; Preferably, the extrusion aid includes at least one of guar gum powder, lanthanum nitrate, and cerium nitrate.

4. A method for preparing the catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix the silicon source, template agent and solvent, crystallize them to obtain a nanocrystalline seed emulsion; A mixture of silicon source, template agent, organic amine, solvent and nanocrystalline seed emulsion is mixed and aged to obtain a colloid mixture. Aluminum source, solvent and mixed colloid are mixed to obtain silicon-aluminum mixed gel. The silicon-aluminum mixed gel is aged and crystallized, solid-liquid separated, dried and calcined to obtain ZSM-5 molecular sieve. (2) Mix the organosilicon source with the ZSM-5 molecular sieve from step (1), modify the molecular sieve, shape it, separate the solid and liquid, dry it, and calcine it to obtain a new ZSM-5 molecular sieve. (3) Mix the novel ZSM-5 molecular sieve, binder and extrusion aid from step (2) to obtain a mixture; (4) The acid solution is mixed with the mixture from step (3), and then extruded, dried and calcined to obtain the catalyst.

5. The preparation method according to claim 4, characterized in that, In step (1), the silicon source includes at least one of silica sol, tetraethyl orthosilicate, and silica gel; Preferably, the template agent includes at least one of ethylamine, tetrapropylammonium hydroxide, n-butylamine, and tetrapropylammonium bromide.

6. The preparation method according to claim 4, characterized in that, In step (2), the mass ratio of the ZSM-5 molecular sieve to the organosilicon source is 1:(0.02-0.15); Preferably, the organosilicon source includes at least one selected from tetraethyl orthosilicate, methyltriethoxysilane, dimethyldimethoxysilane, and tetramethylsiloxane.

7. A method for producing ethylbenzene by gas-phase alkylation of dilute ethylene, characterized in that, The method uses the catalyst described in any one of claims 1-3 to catalyze the alkylation reaction of dilute ethylene with benzene.

8. The method according to claim 7, characterized in that, The method includes the following steps: After washing with water, the ethylene-containing dry gas is directly alkylated with benzene under the catalysis of the catalyst to obtain ethylbenzene.

9. The method according to claim 8, characterized in that, The volume fraction of ethylene in the ethylene-containing dry gas is 5%-70%, preferably 5%-50%; Preferably, the volume fraction of propylene in the ethylene-containing dry gas is 0-3%, more preferably 0-2%; Preferably, the volume fraction of butene in the ethylene-containing dry gas is 0-2%, more preferably 0-1%.

10. The method according to claim 8, characterized in that, The molar ratio of benzene to ethylene is 2-8; Preferably, the alkylation reaction is carried out at a temperature of 260°C-390°C; Preferably, the mass hourly space velocity (MSV) of the ethylene is 0.1 h⁻¹. 1 -1.5h 1 ; Preferably, the pressure of the alkylation reaction is 0.5 MPaG-1.5 MPaG.

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