Method and system for preparing p-methyl-ethylbenzene through alkylation

Abstract

The invention relates to the technical field of chemical catalysis, in particular to a method and system for preparing p-methyl-ethylbenzene through alkylation. According to the method, reactants and a catalyst react under the conditions that the temperature is 300-500 DEG C and the pressure is 0.1-2.0 MPa, and p-methyl-ethylbenzene is obtained, the reactants comprise an aromatic hydrocarbon raw material and an alkylation reagent; the catalyst is spherical particles, reactants are in countercurrent contact with the catalyst, and the mass space velocity of the aromatic hydrocarbon raw material is 1.0-20 h <-1 >. The method can efficiently convert an aromatic hydrocarbon raw material and an alkylating reagent under mild conditions, directly obtains p-methyl-ethylbenzene in one step, and is high in reaction efficiency and low in energy consumption; the selectivity of p-methyl-ethylbenzene is high, the product purity is high, the yield is high, and the catalyst is renewable; the system is simple in structure and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of chemical catalysis technology, and more specifically, to a method and system for the alkylation preparation of p-toluene. Background Technology

[0002] Ethylbenzene comprises three isomers: ortho, meta, and para. It is a basic raw material for chemical products such as resins, coatings, adhesives, preservatives, and detergents. Among them, p-methylethylbenzene can be catalytically dehydrogenated to obtain p-methylstyrene. This monomer can replace styrene in the synthesis of high-performance polymers such as poly(p-methylstyrene), unsaturated polyesters, and thermoplastic elastomers. The resulting materials have excellent properties such as low density, low toxicity, low volatility, and heat resistance. It has shown substitution potential in cutting-edge fields such as the nuclear industry and high-end coatings and is regarded as an important supplement to the styrene consumption market.

[0003] However, the continuous and highly selective preparation of high-purity p-methyl ethyl phenyl in industry still faces challenges. Physical separation methods are difficult to scale up due to low raw material content and high separation energy consumption. Although chemical synthesis methods mainly use toluene-ethylene / ethanol alkylation or xylene-ethyl phenyl shape-selective disproportionation, existing technologies are either limited by microporous molecular sieve catalysts leading to insufficient para-selectivity, or require additional adsorption separation processes resulting in complex processes and increased ortho- and meta-position byproducts. Neither of these methods can balance purity, yield, and process economy, becoming a key bottleneck restricting the upgrading of the p-methyl styrene industry chain.

[0004] For example, existing patent CN105367373B discloses a method for producing ethylbenzene from toluene and ethanol. Toluene and ethanol are used as reactants, and microporous molecular sieves with MWW, BEA, MOR, or FAU topologies are used as the main catalyst component to produce ethylbenzene under certain reaction conditions. However, this technology produces products with low selectivity for ethylbenzene, making it difficult to obtain high-purity ethylbenzene.

[0005] Existing patent CN107759433 discloses a shape-selective disproportionation method for p-xylene and ethylbenzene. Under reaction conditions of 260~500℃ and 0.1MPa~10MPa, a modified ten-membered ring molecular sieve is used as a catalyst to produce toluene, p-toluene, benzene, and diethylbenzene through a shape-selective disproportionation reaction of p-xylene and ethylbenzene.

[0006] Existing patent CN119330803A discloses a method for synthesizing high-purity p-methylstyrene. Toluene and catalytic dry gas are alkylated with a modified ZSM-5 catalyst to produce ethylbenzene. Ethylbenzene is then adsorbed and separated to obtain high-purity p-ethylbenzene. Finally, p-ethylbenzene is dehydrogenated at high temperature under an iron-based catalyst to obtain high-purity p-methylstyrene. This method can yield high-purity p-ethylbenzene and further p-methylstyrene, but it requires alkylation followed by adsorption and separation purification. This makes the process route relatively complex and also results in the production of significant amounts of m-ethylbenzene and o-ethylbenzene as byproducts.

[0007] It is evident that there is currently no effective method for the preparation of p-toluene. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method and system for preparing p-toluene by alkylation.

[0009] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for preparing p-toluene by alkylation, wherein reactants and catalyst are reacted at a temperature of 300-500°C and a pressure of 0.1-2.0 MPa to obtain p-toluene; the reactants include aromatic raw materials and alkylating reagents.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the molar ratio of the aromatic feedstock to the alkylating agent is 15:1 to 1:1.

[0012] Furthermore, when the aromatic raw material is toluene, the alkylating agent is one or more of ethanol, ethylene, and a mixture of gases containing ethylene; when the aromatic raw material is ethylbenzene, the alkylating agent is methanol.

[0013] Furthermore, the catalyst comprises an active component, a modifying component, and a binding and heat-resistant component; the active component comprises one or more of ZSM-5, ZSM-11, and ZSM-23, the modifying component comprises silicon oxide and / or phosphorus oxide, and the binding and heat-resistant component is one of boehmite, alumina sol, and silica sol.

[0014] Furthermore, in the catalyst, the mass percentage of the active component is 20-50%, the mass percentage of the modified component is 5-20%, and the balance is the adhesive heat-resistant component.

[0015] Furthermore, the catalyst is a spherical particle with an average particle size of 0.2~4 mm.

[0016] Furthermore, during the reaction, the reactants are in countercurrent contact with the catalyst, and the mass hourly space velocity (HHSV) of the aromatic feedstock is 1.0–20 h⁻¹. -1 .

[0017] Furthermore, the following steps are included: The aromatic feedstock and the alkylating agent are fed into a moving bed reactor, and the catalyst is continuously moved from top to bottom, so that the aromatic feedstock and the alkylating agent come into countercurrent contact with the catalyst from bottom to top and react to obtain the reaction product; The reaction products are separated in a product separation unit to obtain p-toluene and aromatic products, and the aromatic products are used as the aromatic raw materials for further reaction. The catalyst that has completed the reaction is regenerated, and the regenerated catalyst is reacted again.

[0018] Furthermore, the regeneration temperature is 400~550℃.

[0019] The present invention also provides a system for the alkylation preparation of p-toluene, comprising a moving bed reactor, a product separation unit and a catalyst regeneration unit, wherein the product separation unit and the catalyst regeneration unit are respectively connected to the moving bed reactor; the moving bed reactor is provided with a catalyst.

[0020] Furthermore, the product separation unit includes one or more distillation columns.

[0021] The beneficial effects of this invention are as follows: (1) The alkylation method for preparing p-toluene of the present invention can efficiently convert aromatic raw materials and alkylating reagents under mild conditions, and directly obtain p-toluene in one step. It has high reaction efficiency and low energy consumption. (2) The alkylation method for preparing p-toluene of the present invention effectively solves the problems of low product purity and short catalyst life in the production technology of p-toluene, and the selectivity of p-toluene is >97%; (3) The method for preparing p-toluene by alkylation of the present invention uses spherical particles as catalyst, which are not easily pulverized during the catalytic process and have a wide regeneration temperature window, thereby achieving a synergistic improvement in activity, shape selectivity and long lifespan; (4) The alkylation system for preparing p-toluene of the present invention has a simple structure, high reaction efficiency, high catalytic selectivity, and the obtained p-toluene has high purity and yield. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the alkylation preparation system for p-toluene in an embodiment of the present invention; The attached diagram lists the components represented by each number as follows: 1. Moving bed reactor; 2. Catalyst regenerator; 3. Distillation column. Detailed Implementation

[0023] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0024] The alkylation preparation method of p-toluene of the present invention involves reacting reactants and catalysts at a temperature of 300-500°C and a pressure of 0.1-2.0 MPa to obtain p-toluene; the reactants include aromatic raw materials and alkylating reagents.

[0025] The alkylation preparation method of p-toluene of the present invention can efficiently convert aromatic feedstock and alkylating reagent under mild conditions, directly obtaining p-toluene in one step. This method avoids the equipment and investment burden caused by high pressure and high temperature, and suppresses side reactions through a precisely matched reaction window, keeping the para-selectivity stable at over 97%, significantly reducing the energy consumption and cost of subsequent separation. At the same time, this condition range is coupled with a moving bed catalyst continuous regeneration system, which can maintain catalytic activity for a long time, ensuring stable operation of the unit over a long period of time, and combining high yield, high purity and process economy.

[0026] Preferably, the molar ratio of aromatic feedstock to alkylating agent is 15:1 to 1:1.

[0027] By controlling the molar ratio of aromatic feedstock to alkylating reagent within a wide range of 15:1 to 1:1, the feed ratio can be flexibly adjusted while maintaining a high conversion rate of the alkylation reaction. This can suppress multiple alkylation byproducts and improve selectivity for methyl ethyl phenyl under high aromatic ratios, while also increasing the unit's processing capacity at near-stoichiometric ratios. This balances catalyst lifetime and product purity, maximizing the process operating window and optimizing economic efficiency.

[0028] Preferably, when the aromatic feedstock is toluene, the alkylating agent is one or more of ethanol, ethylene, or a mixture of gases containing ethylene; when the aromatic feedstock is ethylbenzene, the alkylating agent is methanol.

[0029] In the method of this invention, toluene can be flexibly combined with ethanol, ethylene, or ethylene-containing mixtures, which are widely available and inexpensive, and ethylbenzene can be efficiently coupled with methanol, giving the method a wide range of applications.

[0030] Preferably, the ethylene-containing mixed gas is catalytic dry gas, the molar content of ethylene is 25%, and the molar ratio of ethylene to ethanol is 1:1.

[0031] Preferably, the catalyst includes an active component, a modified component, and a binding and heat-resistant component; the active component includes one or more of ZSM-5, ZSM-11, and ZSM-23.

[0032] ZSM-5, ZSM-11, and ZSM-23 are all microporous molecular sieves with high silica-to-alumina ratios and MFI topologies.

[0033] ZSM-5's intersecting straight and sinusoidal channels along the a and b axes endow it with unique shape-selective catalytic properties, effectively suppressing macromolecular byproducts in reactions such as alkylation, disproportionation, and cracking. With its adjustable acidity and excellent hydrothermal stability, it has become the core active component of the catalyst for the synthesis of p-toluene and ethylbenzene.

[0034] ZSM-11 consists of two intersecting straight channels, similar to ZSM-5 but without sinusoidal channels. It has adjustable acidity and good hydrothermal stability. In alkylation reactions, it can provide a shape-selective environment, suppress macromolecular byproducts, and improve para-selectivity. At the same time, it has few crystal structure defects and excellent anti-coking properties, making it suitable as an active component in the catalyst for the synthesis of p-toluene and ethylbenzene.

[0035] ZSM-23 consists of one-dimensional parallel teardrop-shaped channels composed of ten-membered rings that are not cross-linked. Its framework contains five-membered, six-membered, and ten-membered rings, and its silicon-to-aluminum ratio is typically 40–150. With its adjustable acidity, excellent hydrothermal stability, and shape-selective catalytic performance, it is widely used in reactions such as alkylation, isomerization, cracking, and aromatic conversion. In the synthesis of p-toluene, it can selectively generate para-products and suppress side reactions.

[0036] The catalyst of this invention uses ZSM-5, ZSM-11, and ZSM-23 as active cores, and has good catalytic effect and regeneration ability.

[0037] Preferably, the modified components include silicon oxides and / or phosphorus oxides; the catalyst of the present invention, by supplementing the above-mentioned active components with Si and P oxides, can maintain high para-selectivity.

[0038] Preferably, the adhesive heat-resistant component is one of boehmite, alumina sol, and silica sol.

[0039] Boehmite is a hydrated alumina transition phase with incomplete crystallization and a wrinkled, lamellar structure. It appears as a white colloid or powder and is commonly used as a catalyst carrier, binder, or anti-metal contamination agent. It has moderate acidity and good thermal stability.

[0040] Aluminum sol is formed by uniformly dispersing nano-sized alumina particles in water. It features small particle size, large specific surface area, and abundant surface hydroxyl groups. As a catalyst binder, it can form a strong Al-O-Al network after low-temperature drying, which tightly binds the active components to the support, significantly improving the crushing strength and wear resistance of the catalyst. At the same time, it has mild acidity and good thermal stability. It not only does not mask the active sites, but also provides additional acidity and pore structure, and has little impact on reaction performance. It requires a small amount, is easy to form, and is suitable for various granulation methods such as extrusion and spray drying. It is the preferred binder for preparing high-strength spherical or microsphere catalysts such as moving bed and fluidized bed catalysts.

[0041] Silica sol is a highly dispersed system of nano-sized SiO2 particles in water, with a large specific surface area and abundant surface silanol groups. When used as a catalyst binder, it significantly improves the catalyst's crushing strength, wear resistance, and thermal stability. As an inert oxide, it does not provide strong acid centers or interfere with the main reaction. It has good chemical stability, is not easily sintered at high temperatures, and forms a high specific surface area mesoporous silica framework after calcination. It can also adjust the pore structure and improve mass transfer. It requires a small amount and is easy to mold, making it suitable for preparing high-strength microspheres or spherical catalysts. It is particularly suitable for reaction systems with strict requirements for acidity and selectivity, such as alkylation and shape-selective catalysis.

[0042] The aforementioned binding and heat-resistant components enable the catalyst of the present invention to be prepared into spherical particles, which are not easily pulverized during the catalytic process, have a wide regeneration temperature window, and achieve a synergistic improvement in activity, shape selectivity and long lifespan.

[0043] Preferably, in the catalyst, the mass percentage of the active component is 20-50%, the mass percentage of the modified component is 5-20%, and the balance is a binding and heat-resistant component.

[0044] The active component accounts for 20–50%, ensuring sufficient ZSM-5, ZSM-11, and ZSM-23 shape-selective acid centers to maintain high para-selectivity while avoiding diffusion restriction caused by excessive micropores. The 5–20% Si and P oxide modifying components moderately neutralize strong acids, inhibit carbon deposition, and finely adjust pore size, making the catalyst active and stable during continuous operation at 300–500℃. The remaining heat-resistant binder phase imparts high crushing strength and wear resistance to 0.2–4 mm spherical particles, preventing pulverization during moving bed regeneration at 400–550℃. The synergistic ratio of these three components achieves a balance between high selectivity, long lifespan, and mechanical strength, significantly reducing catalyst consumption.

[0045] Preferably, the catalyst is spherical particles with an average particle size of 0.2~4 mm.

[0046] The spherical catalyst with the above average particle size balances low resistance in the moving bed with a suitable external surface area: the lower limit of the particle size ensures uniform airflow distribution and less channeling, while the upper limit suppresses internal diffusion and maintains high utilization rate; the spheres have no sharp edges, resulting in low rolling friction, reduced bed pressure and less pulverization, high mass and heat transfer efficiency in continuous countercurrent contact, and are matched with the regenerator cycle to achieve long-term stable operation and reduce energy consumption and catalyst loss.

[0047] Preferably, during the reaction, the reactants and catalyst are in countercurrent contact, and the mass hourly space velocity (HHSV) of the aromatic feedstock is 1.0–20 h⁻¹. -1 .

[0048] Countercurrent contact ensures that the catalyst always encounters the most concentrated reactant, and the catalyst to be deactivated encounters the low-concentration reactant about to be discharged. The driving force decreases progressively, maximizing the utilization of active sites while suppressing side reactions. Simultaneously, the reaction time is 1.0–20 h. -1 The wide mass space velocity window can ensure high conversion rate at low flow rates and increase throughput at high flow rates without significantly reducing parasite selectivity. Combined with continuous regeneration, it achieves a unified approach of high capacity, high selectivity, and long-term stable operation.

[0049] The alkylation preparation method of p-toluene of the present invention includes the following steps: Aromatic feedstock and alkylating reagent are fed into a moving bed reactor. The catalyst is continuously moved from top to bottom, so that the aromatic feedstock and the alkylating reagent come into countercurrent contact with the catalyst from bottom to top and react to obtain the reaction product.

[0050] The reaction products were separated in a product separation unit to obtain p-toluene and aromatic products, and the aromatic products were used as aromatic raw materials for further reaction.

[0051] The catalyst that has completed the reaction is regenerated, and the regenerated catalyst is reacted again.

[0052] Preferably, the regeneration temperature is 400~550℃.

[0053] The alkylation preparation system for p-toluene of the present invention includes a moving bed reactor, a product separation unit, and a catalyst regeneration unit, wherein the product separation unit and the catalyst regeneration unit are respectively connected to the moving bed reactor; the moving bed reactor is equipped with a catalyst.

[0054] Preferably, the product separation unit includes one or more distillation columns 3.

[0055] Preferably, the moving bed reaction device is a moving bed reactor 1.

[0056] The alkylation preparation system for p-toluene of the present invention can implement the preparation method of the present invention. The specific working process of the system is as follows: Aromatic feedstock and alkylating reagent are fed into moving bed reactor 1. The catalyst is continuously moved from top to bottom, so that the aromatic feedstock and alkylating reagent come into countercurrent contact with the catalyst from bottom to top. The alkylation reaction takes place under the action of the catalyst to obtain the reaction product.

[0057] The resulting reaction products enter distillation column 3. In distillation column 3, the reaction products are separated into p-toluene and aromatic products, wherein the aromatic products are returned to moving bed reactor 1 for recycling, and the p-toluene is collected.

[0058] In some embodiments, the reaction products also include water.

[0059] The present invention will be illustrated by specific embodiments below.

[0060] Example 1 This embodiment employs the method of the present invention and as follows: Figure 1 The system shown is used to prepare p-toluene, and the specific process is as follows: Toluene and ethylene are fed into moving bed reactor 1, and the catalyst is continuously moved from top to bottom, so that toluene and ethylene come into countercurrent contact with the catalyst from bottom to top, and alkylation reaction is carried out under the action of the catalyst to obtain the reaction product.

[0061] In this embodiment, the reaction temperature was 500°C and the mass hourly space velocity of the aromatic feedstock was 20 h⁻¹. -1 The molar ratio of aromatic feedstock to alkylating reagent is 2:1, and the reaction pressure is 0.1 MPa.

[0062] The catalyst in this embodiment is a spherical particle with an average particle size of 0.2 mm. The active component of the catalyst is ZSM-5, which accounts for 30% of the total mass of the catalyst. The catalyst also contains silicon oxide and phosphorus oxide, with silicon oxide accounting for 2% and phosphorus oxide accounting for 3% of the total mass of the catalyst. The remaining component is boehmite.

[0063] The resulting reaction products enter the product separation unit, which in this embodiment is a distillation column 3. In the distillation column 3, the reaction products are separated into p-toluene and toluene. Toluene is returned to the moving bed reactor 1 for recycling, while p-toluene is collected.

[0064] Meanwhile, the biocatalyst after reaction in the moving bed reactor 1 enters the catalyst regenerator 2 for regeneration. The regenerated catalyst is returned to the moving bed reactor 1 for catalysis again, realizing the reuse of the catalyst.

[0065] In the catalyst regenerator 2 of this embodiment, the regeneration temperature is 450°C.

[0066] The p-toluene obtained in this embodiment was tested, and the purity and yield of the p-toluene product in this embodiment are shown in Table 1.

[0067] Example 2 This embodiment uses the method and system of the present invention to prepare p-methylethylbenzene, and the specific process is as follows: Toluene and ethanol are fed into moving bed reactor 1, and the catalyst is continuously moved from top to bottom, so that toluene and ethanol come into countercurrent contact with the catalyst from bottom to top, and alkylation reaction is carried out under the action of the catalyst to obtain the reaction product.

[0068] In this embodiment, the reaction temperature was 450°C and the mass hourly space velocity of the aromatic feedstock was 4 h⁻¹. -1The molar ratio of aromatic feedstock to alkylating reagent is 3:1, and the reaction pressure is 0.5 MPa.

[0069] The catalyst in this embodiment is a spherical particle with an average particle size of 1.2 mm. The active component of the catalyst is ZSM-11, which accounts for 50% of the total mass of the catalyst. The catalyst also contains silicon oxide and phosphorus oxide, with silicon oxide accounting for 12% and phosphorus oxide accounting for 8% of the total mass of the catalyst. The remaining component is aluminum sol.

[0070] The resulting reaction products enter the product separation unit, which in this embodiment is a distillation column 3. In the distillation column 3, the reaction products are separated into toluene, water, and p-toluene. Toluene is returned to the moving bed reactor 1 for recycling, while p-toluene is collected.

[0071] Meanwhile, the biocatalyst after reaction in the moving bed reactor 1 enters the catalyst regenerator 2 for regeneration. The regenerated catalyst is returned to the moving bed reactor 1 for catalysis again, realizing the reuse of the catalyst.

[0072] In the catalyst regenerator 2 of this embodiment, the regeneration temperature is 550°C.

[0073] The p-toluene obtained in this embodiment was tested, and the purity and yield of the p-toluene product in this embodiment are shown in Table 1.

[0074] Example 3 This embodiment uses the method and system of the present invention to prepare p-methylethylbenzene, and the specific process is as follows: Ethylbenzene and methanol are fed into a moving bed reactor 1, and the catalyst is continuously moved from top to bottom, so that benzene and methanol come into countercurrent contact with the catalyst from bottom to top, and alkylation reaction is carried out under the action of the catalyst to obtain the reaction product.

[0075] In this embodiment, the reaction temperature was 300°C and the mass hourly space velocity of the aromatic feedstock was 1 h⁻¹. -1 The molar ratio of aromatic feedstock to alkylating agent is 15:1, and the reaction pressure is 2.0 MPa.

[0076] The catalyst in this embodiment is a spherical particle with an average particle size of 4 mm. The active component of the catalyst is ZSM-13, which accounts for 20% of the total mass of the catalyst. The catalyst also contains silicon oxide and phosphorus oxide, with silicon oxide accounting for 4% of the total mass of the catalyst and phosphorus oxide accounting for 1%. The remaining components are silica sol.

[0077] The resulting reaction products enter the product separation unit, which in this embodiment is a distillation column 3. In the distillation column 3, the reaction products are separated into p-toluene and ethylbenzene, wherein the ethylbenzene is returned to the moving bed reactor 1 for recycling, and the p-toluene is collected.

[0078] Meanwhile, the biocatalyst after reaction in the moving bed reactor 1 enters the catalyst regenerator 2 for regeneration. The regenerated catalyst is returned to the moving bed reactor 1 for catalysis again, realizing the reuse of the catalyst.

[0079] In the catalyst regenerator 2 of this embodiment, the regeneration temperature is 400°C.

[0080] The p-toluene obtained in this embodiment was tested, and the purity and yield of the p-toluene product in this embodiment are shown in Table 1.

[0081] Example 4 This embodiment uses the method and system of the present invention to prepare p-methylethylbenzene, and the specific process is as follows: Toluene, an ethylene-containing gas mixture, and ethanol are introduced into a moving bed reactor 1. The catalyst is continuously moved from top to bottom, so that the toluene, ethylene-containing gas mixture, and ethanol come into countercurrent contact with the catalyst from bottom to top. An alkylation reaction is carried out under the action of the catalyst to obtain the reaction product.

[0082] In this embodiment, the reaction temperature is 400°C and the mass hourly space velocity (MHSV) of the aromatic feedstock is 2.5 h⁻¹. -1 The molar ratio of aromatic feedstock to alkylating agent is 1:1, the ethylene-containing mixed gas is catalytic dry gas, the molar content of ethylene is 25%, the molar ratio of ethylene to ethanol is 1:1, and the reaction pressure is 0.8 MPa.

[0083] The catalyst in this embodiment is a spherical particle with an average particle size of 0.8 mm. The active component of the catalyst is ZSM-5, which accounts for 40% of the total mass of the catalyst. The catalyst also contains silicon oxide and phosphorus oxide, with silicon oxide accounting for 8% of the total mass of the catalyst and phosphorus oxide accounting for 6%. The remaining component is boehmite.

[0084] The resulting reaction products enter the product separation unit, which in this embodiment is a distillation column 3. In the distillation column 3, the reaction products are separated into p-toluene and toluene. Toluene is returned to the moving bed reactor 1 for recycling, while p-toluene is collected.

[0085] Meanwhile, the biocatalyst after reaction in the moving bed reactor 1 enters the catalyst regenerator 2 for regeneration. The regenerated catalyst is returned to the moving bed reactor 1 for catalysis again, realizing the reuse of the catalyst.

[0086] In the catalyst regenerator 2 of this embodiment, the regeneration temperature is 400°C.

[0087] The p-toluene obtained in this embodiment was tested, and the purity and yield of the p-toluene product in this embodiment are shown in Table 1.

[0088] Comparative Example 1 This comparative example is the same as Example 1, except that the reactor is a fixed-bed reactor and does not have a catalyst regeneration device.

[0089] The purity and yield of the p-toluene product in this comparative example are shown in Table 1.

[0090] Comparative Example 2 This comparative example is the same as Example 2, except that the reactor is a fixed-bed reactor and does not have a catalyst regeneration device.

[0091] The purity and yield of the p-toluene product in this comparative example are shown in Table 1.

[0092] Table 1. Purity and yield of p-toluene products for each example and comparative example. In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0093] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0094] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0095] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0096] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0097] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing p-toluene by alkylation, characterized in that, The reactants and catalyst are reacted at a temperature of 300-500℃ and a pressure of 0.1-2.0 MPa to obtain p-toluene; the reactants include aromatic raw materials and alkylating agents.

2. The method for preparing p-toluene by alkylation according to claim 1, characterized in that, The molar ratio of the aromatic feedstock to the alkylating agent is 15:1 to 1:

1.

3. The method for preparing p-toluene by alkylation according to claim 2, characterized in that, When the aromatic feedstock is toluene, the alkylating agent is one or more of ethanol, ethylene, and a mixture of gases containing ethylene; when the aromatic feedstock is ethylbenzene, the alkylating agent is methanol.

4. The method for preparing p-toluene by alkylation according to claim 1, characterized in that, The catalyst comprises an active component, a modifying component, and a binding and heat-resistant component; the active component comprises one or more of ZSM-5, ZSM-11, and ZSM-23; the modifying component comprises silicon oxide and / or phosphorus oxide; and the binding and heat-resistant component comprises one of boehmite, alumina sol, and silica sol.

5. The method for preparing p-toluene by alkylation according to claim 4, characterized in that, In the catalyst, the active component has a mass percentage of 20-50%, the modified component has a mass percentage of 5-20%, and the balance is the adhesive heat-resistant component.

6. The method for preparing p-toluene by alkylation according to claim 4, characterized in that, The catalyst is a spherical particle with an average particle size of 0.2~4 mm.

7. A method for preparing p-toluene by alkylation according to any one of claims 1-6, characterized in that, During the reaction, the reactants are in countercurrent contact with the catalyst, and the mass hourly space velocity (HHSV) of the aromatic feedstock is 1.0–20 h⁻¹. -1 .

8. The method for preparing p-toluene by alkylation according to claim 7, characterized in that, Includes the following steps: The aromatic feedstock and the alkylating agent are fed into a moving bed reactor, and the catalyst is continuously moved from top to bottom, so that the aromatic feedstock and the alkylating agent come into countercurrent contact with the catalyst from bottom to top and react to obtain the reaction product; The reaction products are separated in a product separation unit to obtain p-toluene and aromatic products, and the aromatic products are used as the aromatic raw materials for further reaction. The catalyst that has completed the reaction is regenerated, and the regenerated catalyst is reacted again.

9. The method for preparing p-toluene by alkylation according to claim 8, characterized in that, The regeneration temperature is 400~550℃.

10. A system for alkylation to prepare p-toluene, characterized in that, It includes a moving bed reactor, a product separation unit, and a catalyst regeneration unit, wherein the product separation unit and the catalyst regeneration unit are respectively connected to the moving bed reactor; the moving bed reactor contains a catalyst.

11. The system for preparing p-toluene by alkylation according to claim 10, characterized in that, The product separation unit includes one or more distillation columns (3).

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