A process system for producing aromatic hydrocarbons by dehydroaromatization of c2-c5 light hydrocarbons

Abstract

The utility model discloses a kind of C2-C5 light hydrocarbon dehydrogenation aromatization production aromatic hydrocarbon's process system, including raw material pipeline connection separation two systems, separation two systems connect separation three systems, and separation three systems are connected dehydrogenation reactor and aromatization reactor respectively;Separation two systems are used to separate C1~C5 each component, and separation three systems are used to separate the olefin and paraffin of C2~C5 each component.The utility model combines two kinds of process technologies of dehydrogenation and aromatization, utilizes pure olefin aromatization, improves aromatization reaction conversion rate, simultaneously improves aromatic hydrocarbon yield and selectivity.

Description

Technical Field

[0001] This utility model belongs to the field of aromatics production technology, specifically to a process system for producing aromatics through the dehydrogenation and aromatization of C2-C5 light hydrocarbons. Background Technology

[0002] Aromatic hydrocarbons are a class of aromatic hydrocarbons. Their core characteristic is the presence of a benzene ring or a benzene-like conjugated π-electron system in the molecule. Their structural stability is derived from Hückel's rule (4n + 2π electrons). Typical examples include benzene, toluene, xylene (BTX), and polycyclic aromatic hydrocarbons (such as naphthalene and anthracene). Aromatic hydrocarbons are one of the most important basic raw materials in the petrochemical industry. They have a benzene ring structure, high octane number, and chemical reactivity, and are widely used in industries such as plastics, fibers, rubber, and pharmaceuticals.

[0003] Aromatization is a catalytic process that converts non-aromatic hydrocarbons into aromatic hydrocarbons. Its core involves the formation of benzene ring structures through reactions such as cyclization and dehydrogenation. Its technological development is of great significance for improving the utilization rate of petroleum resources and alleviating the supply-demand imbalance of aromatic hydrocarbons. The aromatization reaction typically involves three stages: activation, cracking and oligomerization, and cyclization and dehydrogenation. The activation stage primarily involves the formation of carbocations at the acid centers of molecular sieves from the feedstock hydrocarbons (such as propane and butene). Cracking and oligomerization mainly involve the cracking of carbocations into smaller molecule olefins (such as ethylene and propylene), which then undergo oligomerization to generate C6-C8 olefins. Cycling and dehydrogenation primarily involve the cyclization of olefins to form aromatic precursors, which are then dehydrogenated to produce products such as benzene and toluene. Key influencing factors in aromatization include the feedstock structure (olefins > alkanes, isomers > normal hydrocarbons), catalyst acidity, and reaction temperature.

[0004] Currently, aromatization technology is divided into fixed bed, moving bed and fluidized bed processes. The yield of aromatics is 40-60%, and the overall yield of aromatic products is relatively low due to factors such as harsh reaction conditions.

[0005] CN112830858A discloses a method for producing aromatics by dehydrogenation and aromatization of light hydrocarbons. Under dehydrogenation reaction conditions, a light hydrocarbon stream is dehydrogenated to obtain an olefin-containing stream. Under aromatization reaction conditions, the olefin-containing stream is contacted with an aromatization catalyst to undergo an oligomerization / aromatization reaction, yielding an aromatic-containing stream. The recycled hydrocarbons are returned to the dehydrogenation reactor. However, because the aromatization reaction leaves some olefins, these olefins entering the dehydrogenation reactor will affect the dehydrogenation reaction and exacerbate catalyst deactivation due to carbon buildup. In severe cases, the dehydrogenation reaction will terminate. Due to the characteristics of the dehydrogenation catalyst, this method can only perform a single-pass conversion reaction and cannot achieve the effect of light hydrocarbon recycling. Recycling will lead to low overall conversion and low yield. Furthermore, the highest single-pass yield of dehydrogenation is only 40%, while the remaining undehydrogenated alkanes will enter the aromatization reactor to participate in the reaction. This will complicate the aromatization reaction and severely affect the efficiency and yield of the aromatization reaction. Utility Model Content

[0006] This invention aims to address the problems of numerous side reactions, low reaction conversion rate, and low yield of aromatic products in aromatization by providing a process system for the dehydrogenation aromatization of C2-C5 light hydrocarbons to produce aromatics.

[0007] The technical solution of this utility model to solve the above-mentioned technical problems is: A process system for producing aromatics by dehydrogenation and aromatization of C2-C5 light hydrocarbons includes a feedstock pipeline connected to a second separation system, the second separation system connected to a third separation system, and the third separation system connected to a dehydrogenation reactor and an aromatization reactor, respectively. Separation system II is used to separate C1 to C5 components, and separation system III is used to separate olefins and alkanes from C2 to C5 components.

[0008] Specifically, the dehydrogenation reactor can use a mixture of one or more C2-C5 alkanes for the dehydrogenation reaction, and can employ catalysts with dehydrogenation capabilities for one or more alkanes. The catalyst for the dehydrogenation reactor can be selected as needed, and can be any one, two, three, or a mixture of more than one type of C2-C5 alkanes.

[0009] The dehydrogenation reactor operates at a reaction pressure of 0.05–0.5 MPa (G), a reaction temperature of 500–700 °C, and a mass hourly space velocity of 0.5–2 h⁻¹. -1 .

[0010] Preferably, the dehydrogenation reactor pressure is 0.05–0.2 MPa (G), the reaction temperature is 550–650 °C, and the mass hourly space velocity is 0.7–1.5 h⁻¹. -1 .

[0011] Specifically, the aromatization reactor can use a mixture of one or more C2-C5 olefins for the aromatization reaction, and can use a catalyst with aromatization function for one or more olefins. The catalyst of the aromatization reactor can be selected as needed to aromatize any one, two, three or more mixed alkanes of C2-C5 olefins.

[0012] The aromatization reactor operates at a reaction pressure of 0.1–1.0 MPa (G), a reaction temperature of 450–600 °C, and a mass hourly space velocity of 0.5–2 h⁻¹. -1 .

[0013] Preferably, the aromatization reactor has a reaction pressure of 0.1–0.5 MPa (G), a reaction temperature of 450–550 °C, and a mass hourly space velocity of 1–2 h⁻¹. -1 .

[0014] Furthermore, the second separation system is also connected to the first separation system, wherein the first separation system is used to separate aromatic products and light components.

[0015] Specifically, the light components separated by the first separation system enter the second separation system for further separation, and are coarsely separated into C1 to C5 components.

[0016] Furthermore, the product pipeline of the dehydrogenation reactor is connected to the second separation system.

[0017] Specifically, after the alkanes are reacted in the dehydrogenation reactor, the mixed products enter the second separation system for coarse separation of C1 to C5 components.

[0018] Furthermore, the product pipeline of the aromatization reactor is connected to a separation system.

[0019] Specifically, the products of the aromatization reactor are mainly aromatic products and unreacted and by-reaction products. The light components are directly separated from the aromatic products. The separation system directly separates the aromatic products and light components, and the separated aromatic products are directly discharged from the unit.

[0020] Furthermore, the dry gas pipeline is connected to the second separation system.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are: I. Employing three separation systems—product separation, component separation, and distillation—effectively separates the various components from the raw materials and products. Alkane components enter the dehydrogenation reactor for dehydrogenation without interference from other olefins. The catalyst for the dehydrogenation reactor is easy to select, has a long lifespan, and a long regeneration cycle. Olefin yield can be increased by 1–5%, resulting in a significant dehydrogenation effect.

[0022] 2. Olefin components enter the aromatization reactor for aromatization reaction. The catalyst of the aromatization reactor is easy to select, the catalyst coking rate is low, and the aromatization reaction conditions are suitable. The olefin conversion rate can reach more than 95%, which is more conducive to olefin conversion. The yield of aromatics can be increased to more than 70%, effectively improving the yield of aromatic products. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of this utility model; Attached image description: The system consists of: 1. Dehydrogenation reactor; 2. Aromatization reactor; 3. Separation system 1; 4. Separation system 2; 5. Separation system 3. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] The specific embodiments of this utility model are as follows: Figure 1 As shown, a process system for producing aromatics from C2-C5 light hydrocarbons via dehydrogenation and aromatization includes a feedstock pipeline connected to a second separation system 4, which in turn connects to a third separation system 5. The third separation system 5 is connected to a dehydrogenation reactor 1 and an aromatization reactor 2. The second separation system 4 is used to separate C1-C5 components, and the third separation system 5 is used to separate olefins and alkanes from C2-C5 components. The second separation system 4 is also connected to a first separation system 3. The product pipeline of the dehydrogenation reactor 1 is connected to the second separation system 4. The product pipeline of the aromatization reactor 2 is connected to the first separation system 3. The second separation system 4 is connected to a dry gas pipeline.

[0028] The process for producing aromatics by dehydrogenation and aromatization of C2-C5 light hydrocarbons using the above system includes the following steps: A mixture of C1-C5 light hydrocarbon feedstocks enters separation system 2 (4) for separation, roughly separating the C2-C5 components. C1 and hydrogen are separated and dried. The roughly separated C2-C5 components enter separation system 3 (5) for distillation. The olefins obtained from distillation enter aromatization reactor 2 to participate in the aromatization reaction. The alkanes obtained from distillation enter dehydrogenation reactor 1 to participate in the dehydrogenation reaction. The reaction products of aromatization reactor 2 enter separation system 1 (3) for separation to obtain aromatic products. The reaction products of dehydrogenation reactor 1 enter separation system 2 (4) for further separation.

[0029] The present invention will be described in detail through examples. In the following examples, both dehydrogenation and aromatization use catalysts from REZEL.

[0030] Example 1: According to such Figure 1The process system shown, following the steps described above, uses a mixture of C3 alkanes and olefins as feedstock. The dehydrogenation reactor temperature is set at 590℃, the reaction pressure at 0.05 MPa, and the mass hourly space velocity (WHSV) at 1 h⁻¹. -1 The aromatization reactor temperature was set at 510℃, the reaction pressure at 0.3MPa, and the mass hourly space velocity at 1.2h⁻¹. -1 The reaction results after 360 minutes of continuous reaction are shown in Table 1 below.

[0031] Comparative Example 1 Following the method of Example 1, a mixture of C3 alkanes and olefins was used as raw material for direct aromatization. The aromatization reactor temperature was set at 510°C, the reaction pressure at 0.3 MPa, and the mass hourly space velocity (WHSV) at 1.2 h⁻¹. -1 The reaction results after 360 minutes of continuous reaction are shown in Table 1 below.

[0032] Example 2: like Figure 1 The process system shown, following the steps described above, uses a mixture of C4 alkanes and olefins as feedstock. The dehydrogenation reactor temperature is set at 580℃, the reaction pressure at 0.05 MPa, and the mass hourly space velocity (WHSV) at 1 h⁻¹. -1 The aromatization reactor temperature was set at 500℃, the reaction pressure at 0.3MPa, and the mass hourly space velocity at 1.2h⁻¹. -1 The reaction results after 360 minutes of continuous reaction are shown in Table 1 below.

[0033] Comparative Example 2 Following the method of Example 1, a mixture of C4 alkanes and olefins was used as raw material for direct aromatization. The aromatization reactor temperature was set at 500°C, the reaction pressure at 0.3 MPa, and the mass hourly space velocity (WHSV) at 1.2 h⁻¹. -1 The reaction results after 360 minutes of continuous reaction are shown in Table 1 below.

[0034] Example 3: like Figure 1 The process system shown, following the steps described above, uses a mixture of C4-C5 alkanes and olefins as feedstock. The dehydrogenation reactor temperature is set at 580℃, the reaction pressure at 0.05 MPa, and the mass hourly space velocity (WHSV) at 1 h⁻¹. -1 The aromatization reactor temperature was set at 500℃, the reaction pressure at 0.3MPa, and the mass hourly space velocity at 1.2h⁻¹. -1 The reaction results after 360 minutes of continuous reaction are shown in Table 1 below.

[0035] Example 4: like Figure 1The process system shown, following the steps described above, uses a mixture of C3-C5 alkanes and olefins as feedstock. The dehydrogenation reactor temperature is set at 590℃, the reaction pressure at 0.05 MPa, and the mass hourly space velocity (WHSV) at 1 h⁻¹. -1 The aromatization reactor temperature was set at 510℃, the reaction pressure at 0.3MPa, and the mass hourly space velocity at 1.2h⁻¹. -1 The reaction results after 360 minutes of continuous reaction are shown in Table 1 below.

[0036] As can be seen from Table 1, the dehydrogenation aromatization process system provided by this utility model has an aromatization conversion rate of over 95%, an aromatic yield of over 70%, and an aromatic selectivity of over 74%. The aromatic conversion rate, yield, and selectivity are far superior to those of the direct aromatization technology of light hydrocarbons.

[0037] The present invention has been described above in conjunction with the preferred embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations made in accordance with the essence of the present invention.

[0038] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A process system for the dehydrogenation and aromatization of C2-C5 light hydrocarbons to produce aromatics, characterized in that, The system includes a raw material pipeline connected to the second separation system (4), the second separation system (4) connected to the third separation system (5), and the third separation system (5) connected to the dehydrogenation reactor (1) and the aromatization reactor (2), respectively. Separation system 2 (4) is used to separate C1 to C5 components, and separation system 3 (5) is used to separate olefins and alkanes from C2 to C5 components.

2. The process system for producing aromatics by dehydrogenation aromatization of C2-C5 light hydrocarbons according to claim 1, characterized in that, The second separation system (4) is also connected to the first separation system (3).

3. The process system for producing aromatics by dehydrogenation of C2-C5 light hydrocarbons according to claim 1, characterized in that, The product pipeline of the dehydrogenation reactor (1) is connected to the separation system (4).

4. The process system for producing aromatics by dehydrogenation aromatization of C2-C5 light hydrocarbons according to claim 1, characterized in that, The product pipeline of the aromatization reactor (2) is connected to a separation system (3).

5. The process system for producing aromatics by dehydrogenation aromatization of C2-C5 light hydrocarbons according to claim 1, characterized in that, Separate the two systems (4) and connect the dry gas pipeline.

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