Method for producing naphthalene series by using byproduct C12 < + > heavy aromatics of reforming device

Abstract

The invention discloses a method for producing naphthalene series by using a reformer byproduct C12 + heavy aromatics, which comprises the following steps: firstly, introducing the C12 + heavy aromatics into a fractionating tower, and separating out fractions less than 330 DEG C and fractions greater than or equal to 330 DEG C; generating bicyclic aromatic hydrocarbon from the tricyclic aromatic hydrocarbon in the fraction of which the temperature is greater than or equal to 330 DEG C in a selective hydrogenation reactor, and feeding the bicyclic aromatic hydrocarbon into a cracking dealkylation reactor; introducing the fraction of which the temperature is less than 330 DEG C into a cracking dealkylation reactor; a hydrocracking dealkylation reaction is carried out in the cracking dealkylation reactor, and reaction products are separated to obtain hydrogen, dry gas, liquefied gas, C5-C10 fractions, naphthalene, methylnaphthalene, dimethylnaphthalene, fractions of 275-330 DEG C and fractions of more than or equal to 330 DEG C. According to the method disclosed by the invention, the reformed C12 < + > heavy aromatics with low additional value can be converted into products such as high-value naphthalene, methylnaphthalene and dimethylnaphthalene, byproducts such as dry gas, liquefied gas and C5-C10 fraction products, and value-added utilization of the reformed C12 < + > heavy aromatics is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of reformed heavy aromatics refining, and specifically relates to a method for producing naphthalene series products from by - product C 12 + heavy aromatics in a reforming unit. Background Art

[0002] Reformed heavy aromatics refer to aromatics with nine or more carbon atoms produced as by - products in an aromatics complex, and are a valuable aromatic resource. In recent years, with the continuous improvement of China's refining capacity and the successive commissioning of continuous reforming units in large petrochemical enterprises, the output of reformed heavy aromatics has increased significantly. Efficient utilization of the above resources is an important way to improve the overall economic efficiency of enterprises.

[0003] Currently, using toluene or benzene and C9 + heavy aromatics as raw materials to increase the production of xylene through transalkylation reaction is an effective method for utilizing heavy aromatics and has been widely used. UOP's Tatoray process abroad and Shanghai Research Institute's S - TDT process in China are typical toluene disproportionation and transalkylation processes. Specifically, using toluene and C9 + aromatics (mainly C9 aromatics) as raw materials, the content of C 10 + aromatics and indane content in the feed need to be strictly controlled during the reaction to prevent catalyst deactivation. The traditional disproportionation and transalkylation processes fail to effectively utilize C 12 + heavy aromatics, resulting in waste of aromatic resources.

[0004] Using C 10 and higher heavy aromatics as raw materials to increase the production of light aromatics through light - weightening reaction is another effective method for utilizing heavy aromatics. CN201910977804.X proposes a C 10 + heavy aromatics hydro - light - weightening method and its system. First, selectively hydrogenate and saturate bicyclic and higher aromatics, retaining one aromatic ring, and then convert them into BTX light aromatics through light - weightening reaction. This method selectively hydrogenates and saturates bicyclic aromatics, wasting precious aromatic resources and consuming a large amount of hydrogen.

[0005] Domestic petroleum naphthalene usually starts from petroleum pyrolysis C 10It is extracted by extraction and adsorption methods, and finally purified by solvent absorption washing or sublimation crystallization. Most of the foreign petroleum naphthalene products are obtained by dealkylation reaction, rather than just by separation and purification methods. The catalytic hydrodealkylation Unidak process developed by Union Oil Company of the United States is a method for producing naphthalene by catalytic dealkylation. The process flow includes three parts: fractionation, reaction, and crystallization. The processing raw material of the Unidak process is heavy reformate with a distillation range of 212°C to 305°C. For each ton of raw material, 0.387t of product naphthalene, 0.047t of light gasoline, 0.422t of heavy aromatic gasoline, 0.066t of fuel oil, 0.085t of fuel gas, and 0.011t of hydrogen consumption can be obtained.

[0006] Generally speaking, at present, reforming C 12 + For the treatment method of heavy aromatics, the following problems exist:

[0007] (1) The processing capacity is insufficient and cannot be effectively utilized; (2) Selective hydrogenation of bicyclic aromatics is required during the processing, which not only wastes precious aromatic resources but also consumes a large amount of hydrogen, and there is a certain irrationality in the processing route; (3) The foreign catalytic dealkylation technology for producing naphthalene has high requirements for raw materials and cannot process aromatic fractions with three or more rings. Summary of the Invention

[0008] The present invention is proposed to solve the problem that it is difficult to treat the by-product C of the reforming unit 12 + in the existing technology for the high-value utilization of heavy aromatics. Its purpose is to provide a method for producing naphthalene series products from the by-product C of the reforming unit 12 + of heavy aromatics.

[0009] The present invention is achieved through the following technical solutions:

[0010] A method for producing naphthalene series products from the by-product C of the reforming unit 12 + of heavy aromatics, comprising the following steps:

[0011] (ⅰ) Feeding the reforming C 12 + heavy aromatics into the pre-fractionating tower, and separating to obtain a fraction of <330°C and a fraction of ≥330°C through the pre-fractionating tower;

[0012] The theoretical number of plates of the pre-fractionating tower is 10 to 15, the absolute pressure is 10 mmHg to 100 mmHg, and the reflux ratio is 0.5 to 2.0;

[0013] (ii) The fraction with a boiling point of ≥330°C separated from the pre-fractionation tower is preheated or heat-exchanged with the reaction product of the cracking dealkylation unit to 80°C - 100°C and then enters the selective hydrogenation reactor filled with selective hydrogenation catalyst. The selective hydrogenation reactor selectively hydrogenates the tricyclic aromatic hydrocarbons in the fraction with a boiling point of ≥330°C to form bicyclic aromatic hydrocarbons, and the bicyclic aromatic hydrocarbons enter the cracking dealkylation reactor connected in series with the selective hydrogenation reactor;

[0014] The fraction with a boiling point of <330°C separated from the fractionation tower is directly introduced into the cracking dealkylation reactor filled with cracking dealkylation bifunctional catalyst. Under the action of the cracking dealkylation bifunctional catalyst, the fraction with a boiling point of <330°C undergoes hydrocracking dealkylation reaction to produce products such as naphthalene, methylnaphthalene, and dimethylnaphthalene;

[0015] (iii) The product of the cracking dealkylation reactor is separated by a separation system to obtain hydrogen, dry gas, liquefied gas, C5 - C10 fraction, naphthalene, methylnaphthalene, dimethylnaphthalene, 275°C - 330°C fraction, and ≥330°C fraction; hydrogen is recycled to the selective hydrogenation reactor; the 275°C - 330°C fraction is recycled back to the cracking dealkylation reactor, and the ≥330°C fraction is returned to the selective hydrogenation reactor to further produce naphthalene, methylnaphthalene, and dimethylnaphthalene products.

[0016] In the above technical solution, the separation system includes a high-pressure separator, a low-pressure separator, and a fractionation system connected in series in sequence. After the product of the cracking dealkylation reactor is heat-exchanged and cooled, it enters the high-pressure separator for gas-liquid separation. The hydrogen-rich gas separated from the top is recycled, and the liquid effluent at the bottom flows to the low-pressure separator for further gas-liquid separation; the dry gas, a small amount of hydrogen, and liquefied gas are separated from the top of the low-pressure separator, and the liquid effluent at the bottom flows to the fractionation system for product cutting and fractionation; after separation, liquefied gas, C5 - C10 fraction, naphthalene, methylnaphthalene, dimethylnaphthalene, 275°C - 330°C fraction, and ≥330°C fraction are obtained.

[0017] In the above technical solution, the reforming C in step (i) 12 + The heavy aromatics are the heavy aromatic fractions with a distillation range of 220°C - 380°C from the aromatics complex unit.

[0018] In the above technical solution, the components included in the selective hydrogenation catalyst and the mass percentages of each component are:

[0019] Non-precious metal active component 0.5% - 15.0%;

[0020] Support 85% - 99.5%.

[0021] The non-precious metal active component is any one or more of Ni single substance, W single substance, or Mo single substance.

[0022] The support is amorphous silica-alumina.

[0023] The present invention is directed to the selective hydrogenation saturation of tricyclic aromatic hydrocarbons in reformed C 12 + heavy aromatics. An amorphous silica-alumina material with relatively low acidity and larger pore size is selected as the carrier, and a certain amount of non-noble metal is loaded as the active component. Through the control of process conditions, the purpose of selectively hydrogenating and saturating one aromatic ring in tricyclic aromatic hydrocarbon molecules can be achieved.

[0024] In the above technical solution, the reaction temperature of the selective hydrogenation reactor is 100-280 °C, the hydrogen partial pressure is 0.5-6.0 MPa, the liquid aromatic hydrocarbon volume space velocity is 0.5-4.0 h -1 , and the hydrogen-hydrocarbon volume ratio is 300-1500.

[0025] In the above technical solution, the components included in the cracking dealkylation bifunctional catalyst and the mass percentages of each component are:

[0026] Metal active component 0.05%-10.0%;

[0027] Support Hβ molecular sieve 10%-30%;

[0028] Amorphous silica-alumina 60%-80%;

[0029] The metal active component is any one or more of Pt element, Pd element or Ni element.

[0030] In the above technical solution, the reaction temperature of the cracking dealkylation reactor is 360 °C - 550 °C, the hydrogen partial pressure is 0.50 MPa - 6.0 MPa, the liquid hourly space velocity is 0.5 h -1 -3.0 h -1 , and the hydrogen-hydrocarbon volume ratio is 300-1500.

[0031] The beneficial effects of the present invention are:

[0032] The present invention provides a method for producing naphthalene series products from the by-product C 12 + heavy aromatics of a reforming unit, which can convert the reformed C 12 + heavy aromatics into high-value-added naphthalene, methylnaphthalene, and dimethylnaphthalene products, and by-products dry gas, liquefied gas, and C5-C 10 fraction products, realizing the value-added utilization of the by-product C 12 + heavy aromatics of the reforming unit; the present invention is developed for the reformed C 12 + heavy aromatic raw materials, is applicable to the processing of oils with a relatively high content of bicyclic and higher aromatic hydrocarbons, and can solve the problem that it is difficult to handle the by-product C 12+ The problem of high-value utilization of heavy aromatics is solved to improve the economic benefits of enterprises; the bicyclic ring and some methyl groups in the bicyclic aromatic hydrocarbon molecules are retained to improve the carbon atom utilization rate of the raw materials. Description of the Drawings

[0033] Figure 1 It is a schematic process flow diagram of the method of the present invention.

[0034] Wherein:

[0035] 1. Pre-fractionating tower; 2. Selective hydrogenation reactor; 3. Crack dealkylation reactor; 4. High-pressure separator; 5. Low-pressure separator; 6. Fractionation system.

[0036] For those of ordinary skill in the art, without creative efforts, other relevant drawings can be obtained based on the above drawings. Detailed Embodiments

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the drawings of the specification and through specific embodiments.

[0038] Example 1

[0039] A method for producing naphthalene series products from by-product C 12 + heavy aromatics of a reforming unit is as follows Figure 1 shown, and includes the following steps:

[0040] (i) The reforming C 12 + heavy aromatics are introduced into the pre-fractionating tower 1, and the fraction below 330 °C and the fraction above 330 °C are separated by the pre-fractionating tower 1;

[0041] (ii) The fraction above 330 °C separated by the pre-fractionating tower 1 enters the selective hydrogenation reactor 2 filled with selective hydrogenation catalyst after preheating or heat exchange with the reaction product of the crack dealkylation unit. The selective hydrogenation reactor 2 selectively hydrogenates the tricyclic aromatics in the fraction above 330 °C to generate bicyclic aromatics, and the bicyclic aromatics enter the crack dealkylation reactor 3 connected in series with the selective hydrogenation reactor 2;

[0042] The fraction below 330 °C separated by the fractionating tower 1 is directly introduced into the crack dealkylation reactor 3 filled with crack dealkylation bifunctional catalyst. Under the action of the crack dealkylation bifunctional catalyst, the fraction below 330 °C undergoes hydrocracking dealkylation reaction to generate products such as naphthalene, methylnaphthalene, and dimethylnaphthalene;

[0043] (iii) The product of the crack dealkylation reactor 3 is separated by the post-fractionating tower 4 to obtain hydrogen, dry gas, liquefied gas, C5 - C 10Fractions, naphthalene, methylnaphthalene, dimethylnaphthalene, the fraction of 275°C to 330°C, and the fraction of ≥330°C; hydrogen is recycled to the selective hydrogenation reactor 2; the fraction of 275°C to 330°C is recycled and returned to the cracking dealkylation reactor 3, and the fraction of ≥330°C is returned to the selective hydrogenation reactor 2 to further produce naphthalene, methylnaphthalene, and dimethylnaphthalene products;

[0044] The separation system includes a high-pressure separator 4, a low-pressure separator 5, and a fractionation system 6 connected in series in sequence. The product of the cracking dealkylation reactor 3 is heat-exchanged and cooled and then enters the high-pressure separator 4 for gas-liquid separation. The hydrogen-rich gas separated from the top is recycled, and the bottom liquid effluent goes to the low-pressure separator 5 for further gas-liquid separation; the dry gas, a small amount of hydrogen, and liquefied gas are separated from the top of the low-pressure separator 5, and the bottom liquid effluent goes to the fractionation system 6 for product cutting and fractionation; after separation, liquefied gas, C5 - C 10 Fractions, naphthalene, methylnaphthalene, dimethylnaphthalene, the fraction of 275°C to 330°C, and the fraction of ≥330°C;

[0045] In this embodiment, the reformed C 12 + The main properties of the raw material oil for heavy aromatics are shown in Table 1.

[0046] Table 1: Main properties of the raw material oil

[0047] Feedstock Reformed heavy aromatics (fraction after naphthalene) <![CDATA[Density (20 °C), g / cm 3 > 1.08 Sulfur content, μg / g 2.5 Nitrogen content, μg / g 0.3 Distillation range / °C 210～362 Group composition, m% Saturated hydrocarbons 0.5 Monoaromatic hydrocarbons 1.0 Diaromatic hydrocarbons 88.1 Triaromatic hydrocarbons 10.4

[0048] In this embodiment, the components included in the selective hydrogenation catalyst and the mass percentage of each component are: Ni content 1.0 wt%, W content 3.2 wt%, amorphous silica-alumina content 95.8 wt%.

[0049] In this embodiment, the reaction temperature of the selective hydrogenation reactor (2) is 150°C, the reaction pressure is 4.0 MPa, the volume space velocity is 2.0 h -1 , and the hydrogen-oil ratio is 600.

[0050] In this embodiment, the components included in the cracking dealkylation bifunctional catalyst and the mass percentage of each component are: noble metal Pt content 0.1 wt%, Ni content 6.2 wt%, β zeolite content 30 wt%, amorphous silica-alumina content 63.7 wt%.

[0051] In this embodiment, the reaction temperature of the cracking dealkylation reactor (3) is 580°C, the reaction pressure is 4.0 MPa, the volume space velocity is 1.0 h -1 , and the hydrogen-oil ratio is 400.

[0052] Conduct experiments according to the method described in this embodiment. After stabilization, perform material accounting, as shown in Table 2.

[0053] Example 2

[0054] Except for the selective hydrogenation catalyst and the cracking dealkylation bifunctional catalyst, the other conditions in this example are the same as those in Example 1.

[0055] In this example, the components included in the selective hydrogenation catalyst and the mass percentage of each component are as follows: the Ni content is 2.8 wt%, the Mo content is 5.7 wt%, the W content is 4.5%, and the amorphous silica-alumina content is 87.0 wt%.

[0056] In this example, the components included in the cracking dealkylation bifunctional catalyst and the mass percentage of each component are as follows: the noble metal Pd content is 0.3 wt%, the Ni content is 6.0 wt%, the β-zeolite content is 30 wt%, and the shaped silica-alumina content is 63.7 wt%.

[0057] Conduct experiments according to the method described in this example. After stabilization, conduct material accounting, as shown in Table 2.

[0058] Table 2: Material balance

[0059] Embodiment Example 1 Example 2 Feedstock <![CDATA[Reformed C 12 + Heavy aromatics]]> <![CDATA[Reformed C 12 + Heavy aromatics]]> Input side Raw material, wt.% 100 100 Hydrogen, wt.% 3.2 3.4 Total 103.2 103.4 Output side Dry gas, wt.% 14.8 15.2 Liquefied gas, wt.% 4.5 4.9 C5 - C10 fraction, wt.% 3.4 4.5 Naphthalene, wt.% 40.5 39.2 Methylnaphthalene, wt.% 20.6 20.4 Dimethylnaphthalene, wt.% 19.4 19.2 Total 103.2 103.4

[0060] It can be seen from Examples 1 to 2 that by using the method provided by the present invention, reforming C 12 + heavy aromatics can be processed. Under the condition of consuming a small amount of hydrogen, a large amount of high-value naphthalene series products can be obtained, and the naphthalene series product yield reaches more than 78 wt%.

[0061] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for producing naphthalene series compounds from by - product C of a reforming unit, characterized in that: 12 + The method for producing naphthalene series compounds from heavy aromatics, characterized in that: It includes the following steps: (ⅰ) Reforming C 12 + The heavy aromatics are fed into the pre-fractionating column (1), and the fraction below 330 °C and the fraction at 330 °C or above are separated through the pre-fractionating column (1). (ⅱ) The fraction with a temperature ≥ 330°C separated by the pre-fractionation tower (1) enters the selective hydrogenation reactor (2) filled with a selective hydrogenation catalyst. The selective hydrogenation reactor (2) selectively hydrogenates the tricyclic aromatic hydrocarbons in the fraction with a temperature ≥ 330°C to form bicyclic aromatic hydrocarbons, and the bicyclic aromatic hydrocarbons enter the cracking dealkylation reactor (3); The fraction with a temperature < 330°C separated by the fractionation tower (1) is directly introduced into the cracking dealkylation reactor (3) filled with a cracking dealkylation bifunctional catalyst; (ⅲ) The products of the cracking and dealkylation reactor (3) are separated by the post-separation system to obtain hydrogen, dry gas, liquefied gas, C5-C 10 fraction, naphthalene, methylnaphthalene, dimethylnaphthalene, 275°C - 330°C fraction, and ≥330°C fraction; hydrogen is recycled to the selective hydrogenation reactor (2); the 275°C - 330°C fraction is recycled back to the cracking and dealkylation reactor (3), and the ≥330°C fraction is returned to the selective hydrogenation reactor (2).

2. By-product C of the reforming unit according to claim 1 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The reformed C in the step (i) 12 + The heavy aromatics is the heavy aromatic fraction with a distillation range of 220°C to 380°C in the aromatics complex unit.

3. By-product C of the reforming unit according to claim 1 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The components included in the selective hydrogenation catalyst and the mass percentages of each component are as follows: Non-noble metal active component: 0.5% - 15.0%; Support: 85% - 99.5%.

4. By-product C of the reforming unit according to claim 3 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The non-noble metal active component is any one or more of Ni, W or Mo.

5. By-product C of the reforming unit according to claim 3 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The support is amorphous silica-alumina.

6. By-product C of the reforming unit according to claim 1 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The reaction temperature of the selective hydrogenation reactor (2) is 100°C to 280°C, the hydrogen partial pressure is 0.5 MPa to 6.0 MPa, the liquid aromatic hydrocarbon volume hourly space velocity is 0.5 h -1 to 4.0 h -1 , and the hydrogen-hydrocarbon volume ratio is 300 to 1500.

7. By-product C of the reforming unit according to claim 1 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The components included in the cracking dealkylation bifunctional catalyst and the mass percentages of each component are as follows: Metal active component: 0.05% - 10.0%; Support Hβ zeolite: 10% - 30%; Amorphous silica-alumina: 60% - 80%.

8. By-product C of the reforming unit according to claim 7 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The metal active component is any one or more of Pt, Pd or Ni.

9. The by-product C of the reforming unit according to claim 1 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The reaction temperature of the cracking dealkylation reactor (3) is 360°C to 550°C, the hydrogen partial pressure is 0.50 MPa to 6.0 MPa, the liquid hourly space velocity is 0.5 h -1 ~3.0 h -1 , and the hydrogen-hydrocarbon volume ratio is 300 to 1500.

10. By-product C of the reforming unit according to claim 1 12 + A method for producing naphthalene series compounds from heavy aromatics, characterized in that: The separation system includes a high-pressure separator (4), a low-pressure separator (5) and a fractionation system (6) connected in series in sequence. After the product of the catalytic dealkylation reactor (3) is heat-exchanged and cooled, it enters the high-pressure separator (4) for gas-liquid separation. The hydrogen-rich gas separated from the top is recycled, and the bottom liquid effluent flows to the low-pressure separator (5) for further gas-liquid separation; the dry gas, a small amount of hydrogen and liquefied gas are separated from the top of the low-pressure separator (5), and the bottom liquid effluent flows to the fractionation system (6) for product cutting and fractionation; after separation, liquefied gas, C5~C 10 fraction, naphthalene, methylnaphthalene, dimethylnaphthalene, 275°C~330°C fraction and ≥330°C fraction are obtained.

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