Method for extracting aromatic hydrocarbon in heavy oil

Abstract

The invention relates to the technical field of petrochemical industry, and discloses a method for extracting heavy oil aromatic hydrocarbon. The method comprises the following steps: (1) preparing a composite solvent of halogen-containing metal inorganic salt and a polar organic solvent; (2) mixing the composite solvent with heavy oil rich in aromatic hydrocarbon, extracting to obtain an oil-phase-rich product and a solvent-phase-rich product, and removing the composite solvent to obtain extract oil and raffinate oil; wherein on the basis of the total amount of the composite solvent, the content of the inorganic salt is 2.5 wt%-16.5 wt%, and the content of the organic solvent is 83.5 wt%-97.5 wt%; wherein the solubility parameter of the polar organic solvent is greater than or equal to 20 (J.cm <-3 >) 0.5, and the density is greater than or equal to 1g / cm < 3 >. According to the method, the heavy oil is extracted through the composite solvent compounded by the polar organic solvent and the halogen-containing metal inorganic salt, mutual dissolution with heavy oil with high aromatic hydrocarbon content can be avoided, and the separation selectivity of the polycyclic aromatic hydrocarbon in the heavy oil is improved.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a method for extracting aromatic hydrocarbons from heavy oil. Background Technology

[0002] With the deterioration of crude oil processing quality, catalytic cracking units generate large quantities of heavy diesel fractions and catalytic recycle oils rich in polycyclic aromatic hydrocarbons (PAHs). These PAH components are difficult to ring-open crack to produce gasoline and chemical feedstocks, resulting in low added value; furthermore, recycling them increases energy consumption and costs. In the petroleum refining field, heavy oils such as vacuum distillate are often treated with solvent extraction technology, utilizing the differences in solubility of different hydrocarbon components in solvents to separate aromatics from saturated hydrocarbons. For example, furfural and N-methylpyrrolidone are used for extraction and refining to produce lubricating oil base oils. For catalytic heavy diesel and recycle oils, an extraction separation process can separate PAH components from saturated and monocyclic aromatic hydrocarbon components. Saturated and monocyclic aromatic hydrocarbons can be catalytically recycled to produce low-carbon olefins and benzene-toluene-xylene mixtures (BTX). PAHs serve as high-quality carbon sources for carbon materials, reducing molecular structure changes and lowering energy consumption and processing costs.

[0003] It has been found in publicly available technologies (CN104073285A, CN101861374A) that catalytic heavy diesel oil and catalytic recycle oil (aromatic content greater than 70%) with high aromatic content are miscible with low-polarity solvents such as furfural and N-methylpyrrolidone, making separation difficult. For high-polarity solvents, such as dimethyl sulfoxide, these solvents can achieve extraction and separation of heavy diesel oil fractions, but the raffinate oil has a high aromatic content and poor quality, resulting in unsatisfactory extraction performance.

[0004] CN104945327A discloses a solvent and method for extracting and separating aromatics and alkanes from diesel fractions. The solvent is an ionic liquid, which is an imidazole or pyridine cation. The solubility of aromatics in diesel fractions is improved by changing the number of carbon atoms on the substituents.

[0005] CN111089890A discloses a method for testing solubility parameters and a method for processing heavy diesel fractions. By screening two polar organic solvents with different solubility parameters, a two-stage extraction process is adopted, in which a high-polarity solvent and a low-polarity solvent are used to extract and separate the feed oil in sequence, thereby achieving the separation of aromatics and saturated hydrocarbons in heavy diesel.

[0006] CN104073285A discloses a method for extracting and separating aromatics from diesel fuel. The method uses a two-stage extraction process to separate aromatics from catalytic cracking diesel fuel. The extraction solvent is an organic amine compound or an ether compound, and the co-solvent is water. However, the extraction solvent has a density close to that of catalytic heavy diesel fuel and recycled oil, which makes it impossible to achieve effective separation.

[0007] The above-mentioned extraction and separation process mainly adopts a composite extraction process. By adjusting the solvent composition and polarity, the separation of heavy oil rich in aromatics can be achieved. However, the subsequent separation and recovery of composite solvents are difficult, have high energy consumption, and require large investment.

[0008] CN101172928A discloses a method for separating benzene-cyclohexane / n-heptane by salt extraction, which involves forming a salt-containing composite solvent with KSCN and N,N-dimethylimide, and then using a multi-stage cross-flow or countercurrent extraction method to separate benzene-cyclohexane / n-heptane.

[0009] CN1746158A discloses an indole salt extraction and separation method, which involves mixing a salt extractant (KSCN, NaSCN, FeCl3, CaCl2, potassium acetate or sodium acetate) with an aqueous alcohol solution, a nonpolar alkane solvent, etc., to form a composite extractant, which is used to extract coal tar wash oil or methylnaphthalene containing indole fractions, thereby improving the selectivity and separation efficiency of indole.

[0010] The above extraction and separation can be achieved by using a composite solvent that combines specific inorganic salts and organic solvents, avoiding the problem of miscibility between raw materials and solvents. However, for heavy oil systems rich in aromatics, there is currently a lack of suitable and efficient salt-containing composite solvent systems.

[0011] Therefore, there is an urgent need for a salt-containing composite solvent that can avoid miscibility with heavy oil and improve the separation selectivity of aromatics in heavy oil. Summary of the Invention

[0012] The purpose of this invention is to overcome the problem in existing technologies where the extraction and separation of aromatic-rich heavy oils is difficult due to solvent miscibility, and to provide a method for extracting aromatics from heavy oils. This method involves compounding a halogenated inorganic metal salt with a polar organic solvent to obtain a composite solvent. This composite solvent avoids miscibility with heavy oils containing high aromatic content, while simultaneously improving the selectivity for separating polycyclic aromatic hydrocarbons (PAHs) from the heavy oil.

[0013] To achieve the above objectives, the present invention provides a method for extracting aromatic hydrocarbons from heavy oil, wherein the method includes the following steps:

[0014] (1) Preparation of a composite solvent containing halogenated metal inorganic salts and polar organic solvents;

[0015] (2) The composite solvent is mixed with heavy oil rich in aromatics and then extracted to obtain an oil-rich phase product and a solvent-rich phase product. The composite solvent is removed to obtain extracted oil and raffinate oil.

[0016] Based on the total amount of the composite solvent, the content of inorganic salt is 2.5wt%-16.5wt%, and the content of organic solvent is 83.5wt%-97.5wt%.

[0017] Wherein, the solubility parameter of the polar organic solvent is ≥20 (J·cm). -3 ) 0.5 Density ≥ 1 g / cm³ 3 .

[0018] Preferably, the heavy oil has a carbon number distribution of 10-80 and an aromatic hydrocarbon content of 50wt%-99wt%.

[0019] Preferably, the mass ratio of the composite solvent to the heavy oil is 0.1-5:1.

[0020] Through the above technical solution, the present invention has the following beneficial effects:

[0021] (1) The method for extracting aromatics from heavy oil provided by the present invention uses a composite solvent composed of a polar organic solvent and a halogenated metal inorganic salt to extract the heavy oil. By adjusting the content of the halogenated metal inorganic salt, the solubility parameter is changed to ≥20 (J·cm). -3 ) 0.5 And density ≥1g / cm³ 3 The polarity of the organic solvent reduces the miscibility of aromatics and solvent in heavy oil, causing the mixture to separate into layers. This avoids the solvent from being miscible with heavy oil containing high aromatic content, which is beneficial for the effective extraction and separation of aromatics from heavy oil.

[0022] (2) The method for extracting aromatics from heavy oil provided by the present invention is particularly suitable for heavy oil rich in aromatics. The aromatic extraction and separation efficiency is high, and the composite solvent is easy to separate and recover and can be recycled. The process is simple to operate and requires less equipment investment. The halogen-containing metal inorganic salt composite solvent and extraction conditions provided by the present invention are particularly beneficial for extracting and separating polycyclic aromatics from heavy oil, and the aromatic content in the extracted oil reaches more than 90 wt%. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] This invention provides a method for separating aromatics from heavy oil, wherein the method includes the following steps:

[0025] (1) Preparation of a composite solvent containing halogenated metal inorganic salts and polar organic solvents;

[0026] (2) The composite solvent is mixed with heavy oil rich in aromatics and then extracted to obtain an oil-rich phase product and a solvent-rich phase product. The composite solvent is removed to obtain extracted oil and raffinate oil.

[0027] Based on the total amount of the composite solvent, the content of inorganic salt is 2.5wt%-16.5wt%, and the content of organic solvent is 83.5wt%-97.5wt%.

[0028] Wherein, the solubility parameter of the polar organic solvent is ≥20 (J·cm). -3 ) 0.5 Density ≥ 1 g / cm³ 3 .

[0029] The method for separating aromatics from heavy oil according to the present invention involves extracting the heavy oil using a composite solvent composed of a polar organic solvent and a halogenated inorganic metal salt. By controlling the content of the halogenated inorganic metal salt in the solvent, the solubility parameter can be changed to ≥20 (J·cm⁻¹). -3 ) 0.5 And density ≥1g / cm³ 3 The polarity of the polar organic solvent is utilized by combining specific halogenated metal inorganic salts with the polar organic solvent to reduce the miscibility between aromatics and solvents in heavy oil, effectively extracting and separating aromatics from heavy oil, especially improving the separation selectivity of polycyclic aromatic hydrocarbons in heavy oil, and the aromatic content in the extracted oil reaches more than 90 wt%.

[0030] In this invention, step (1) involves preparing the composite solvent by mixing a halogen-containing inorganic metal salt with a polar organic solvent to form the composite solvent. The mixing method is not particularly limited and can be any method conventionally used in the art, such as stirring and / or ultrasonic dispersion.

[0031] In some embodiments of the present invention, preferably, based on the total amount of the composite solvent, the content of the inorganic salt is 2.5wt%-16.5wt%, for example, it can be 2.5wt%, 5wt%, 7.5wt%, 10wt%, 12.5wt%, 15wt%, 16.5wt%, or any value within the range of any two values, preferably 5wt%-15wt%; the content of the organic solvent is 83.5wt%-97.5wt%, for example, it can be 83.5wt%, 85wt%, 86wt%, 88.5wt%, 91wt%, 93.5wt%, 95wt%, 96wt%, 97.5wt%, or any value within the range of any two values, preferably 85wt%-95wt%. In this invention, controlling the content of halogenated metal inorganic salts and polar organic solvents in the composite solvent within the above-mentioned range is beneficial for regulating the polarity of the composite solvent, thereby reducing the miscibility between aromatics and solvents in heavy oil and facilitating the effective extraction and separation of aromatics in heavy oil. Based on the total amount of the composite solvent, if the content of the inorganic salt is greater than 16.5 wt%, the composite solvent becomes too polar, affecting separation efficiency and selectivity; if the content of the inorganic salt is less than 2.5 wt%, the composite solvent becomes too polar, making it easier for the solvent and feedstock oil to become miscible.

[0032] In this invention, the type of halogen-containing inorganic metal salt is not particularly limited and can be any halogen-containing inorganic metal salt known in the art. Preferably, the halogen-containing inorganic metal salt is selected from at least one of zinc chloride, aluminum chloride, anhydrous ferric chloride, and ferric oxide hydrate, and more preferably zinc chloride and / or aluminum chloride. The halogen-containing inorganic metal salt can be a hydrate or anhydrous, more preferably anhydrous zinc chloride and / or anhydrous aluminum chloride, and even more preferably anhydrous zinc chloride.

[0033] In this invention, the type of polar organic solvent is not particularly limited, as long as it meets the range of solubility and density specified above. Preferably, the polar organic solvent is selected from at least one of furfural, N-methylpyrrolidone, phenol and dimethyl sulfoxide, and more preferably furfural.

[0034] In some embodiments of the present invention, preferably, the solubility parameter of the polar organic solvent is ≥20 (J·cm⁻¹). -3 ) 0.5 Density ≥ 1 g / cm³ 3 More preferably, the solubility parameter of the polar organic solvent is 22-29 (J·cm⁻¹). -3 ) 0.5 Its density is 1.1-2 g / cm³. 3In this invention, the polar organic solvent is the main solvent in the composite solvent. The polar organic solvent has the characteristics of low boiling point, high density, suitable polarity and high solubility parameter, which is beneficial to subsequent separation and recovery and has good extraction selectivity.

[0035] In this invention, the halogen-containing inorganic metal salt and the polar organic solvent have a high degree of miscibility. By controlling the content of the halogen-containing inorganic metal salt in the composite solvent, the polarity of the composite solvent is adjusted, the miscibility between the aromatics in the heavy oil and the solvent is reduced, and the mixture is separated into layers, thereby effectively extracting and separating the aromatics in the heavy oil.

[0036] In a preferred embodiment of the present invention, the halogen-containing inorganic metal salt is anhydrous zinc chloride, and the polar organic solvent is furfural. In this invention, the composite solvent obtained by combining furfural and anhydrous zinc chloride significantly reduces the miscibility of aromatics and the solvent in heavy oil rich in aromatics, which is more conducive to the extraction and separation of polycyclic aromatics from heavy oil. The resulting extracted oil has a higher aromatic content, while the raffinate oil has a lower aromatic content.

[0037] In this invention, in step (2), the composite solvent is mixed with heavy oil. The mixing method is not particularly limited and can be any mixing method commonly used in the art, such as stirring and / or ultrasonic dispersion.

[0038] In this invention, the mass ratio of the composite solvent to the heavy oil has a wide selection range. Preferably, the mass ratio of the composite solvent to the heavy oil is 0.1-5:1, for example, it can be 0.1:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any value within any range of two values, preferably 0.5-3:1. In this invention, controlling the mass ratio of the composite solvent to the heavy oil within the above range can avoid the miscibility of the solvent and the feedstock oil, and at the same time facilitate the extraction and separation of aromatics in the heavy oil, thereby increasing the aromatic content in the extracted oil.

[0039] In this invention, the aromatics in the heavy oil can be monocyclic aromatics or polycyclic aromatics, preferably polycyclic aromatics. Polycyclic aromatics in this invention refer to aromatics with two or more rings. In this invention, preferably, the carbon number distribution of the heavy oil is 10-80, and the aromatic content is 50wt%-99wt%. More preferably, the carbon number distribution of the heavy oil is 14-30, and the aromatic content is 70wt%-90wt%. In this invention, the heavy oil has the characteristics of high aromatic content and high density. The hydrocarbon content in this invention is determined according to the standard "Determination of Hydrocarbons in Saturated Hydrocarbon Fractions of Gas Oil (Mass Spectrometry) SH / T 0659".

[0040] In this invention, the distillation range of the heavy oil is not particularly limited, and various heavy oils known in the art can be used in this invention. Preferably, the distillation range of the heavy oil is >200°C, more preferably 260-540°C.

[0041] In this invention, the type of heavy oil is not particularly limited, as long as it meets the above-mentioned distillation range. Preferably, the heavy oil is selected from at least one of catalytic cracked diesel, catalytic cracked recycle oil, and vacuum distillate, more preferably catalytic cracked diesel and / or catalytic cracked recycle oil.

[0042] In this invention, step (2) includes: mixing a composite solvent with heavy oil, allowing the mixture to settle, and then separating the liquid to obtain an oil-rich phase product and a solvent-rich phase product.

[0043] In this invention, the extraction conditions are not particularly limited. Preferably, the extraction temperature is 50-150℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 85℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, or any value within any range of two such values, preferably 80-100℃. In this invention, the composite solvent and heavy oil are particularly suitable for extraction under high-temperature conditions. Controlling the extraction temperature within the above range is beneficial for improving the solubility and selectivity of aromatics and increasing the extraction efficiency.

[0044] In this invention, the mixing method is not particularly limited; for example, it can be stirring. The stirring conditions are not particularly limited, as long as the composite solvent and heavy oil can be fully contacted at the extraction temperature. Preferably, the stirring time is 30-100 min, more preferably 40-80 min. In this invention, the stirring can be performed using a thermostatic magnetic stirrer.

[0045] In this invention, the sedimentation time is not particularly limited, as long as it ensures that the mixed composite solvent and heavy oil separate into an upper oil-rich phase product and a lower organic-rich phase product. For example, the sedimentation time can be 30-120 minutes, preferably 50-80 minutes. The sedimentation can be carried out in a separatory funnel.

[0046] In this invention, the removal of the composite solvent includes removing halogen-containing inorganic metal salts and polar organic solvents from the oil-rich phase product and the organic-rich phase product. Preferably, the specific steps of removing the composite solvent include: distilling the obtained oil-rich phase product and solvent-rich phase product separately to recover the polar organic solvent, and then filtering to remove the halogen-containing inorganic metal salts to obtain extracted oil and raffinate oil.

[0047] In this invention, preferably, the step of removing the composite solvent further includes: washing the product obtained after filtering to remove the halogen-containing inorganic metal salts with water, and then subjecting the water-washed product to thermal stripping to obtain extracted oil and residual oil. The purpose of water washing in this invention is to further remove the remaining inorganic salts, and the method and conditions for water washing can be those known in the art. The purpose of thermal stripping in this invention is to evaporate and remove water from the water-washed product to obtain extracted oil and residual oil; the method and conditions for thermal stripping can be those known in the art, and will not be elaborated further here.

[0048] In some embodiments of the present invention, preferably, the recovered polar organic solvent and halogen-containing inorganic metal salt are recycled to step (1) to provide at least a portion of the composite solvent. The method for extracting heavy oil aromatics according to the present invention allows for easy separation and recovery of the composite solvent, enabling recycling; the process is simple to operate and requires minimal equipment investment.

[0049] In this invention, the distillation method can be any distillation method conventionally used in the art, as long as it can remove the polar organic solvent from the oil-rich phase product and the solvent-rich phase product. Preferably, the distillation pressure is atmospheric pressure, and the distillation temperature is 5-10°C higher than the boiling point of the aforementioned polar organic solvent.

[0050] In this invention, the contents of the extracted oil and the residual oil have a wide range of selection. Preferably, based on the total amount of the extracted oil and the residual oil, the content of the extracted oil is 80-90 wt%.

[0051] In this invention, the use of the halogen-containing metal salt composite solvent and extraction conditions avoids the problem of difficulty in separation due to solvent miscibility during the extraction and separation of aromatic-rich heavy oils, resulting in a higher aromatic content in the extracted oil. Preferably, the aromatic content in the extracted oil is ≥90wt%, more preferably, the aromatic content in the extracted oil is 91wt%-96wt%.

[0052] In a preferred embodiment of the present invention, the method for extracting heavy oil aromatics includes the following steps:

[0053] (1) Preparation of a composite solvent containing halogenated metal inorganic salts and polar organic solvents;

[0054] (2) The composite solvent and heavy oil are mixed at a mass ratio of 0.1-5:1 and then extracted to obtain an oil-rich phase product and a solvent-rich phase product. The composite solvent is removed to obtain extracted oil and raffinate oil.

[0055] Based on the total amount of the composite solvent, the content of inorganic salt is 2.5wt%-16.5wt%, and the content of organic solvent is 83.5wt%-97.5wt%.

[0056] Wherein, the solubility parameter of the polar organic solvent is ≥20 (J·cm). -3 ) 0.5 Density ≥ 1 g / cm³ 3 ;

[0057] The heavy oil has a carbon number distribution of 10-80 and an aromatic hydrocarbon content of 50wt%-99wt%.

[0058] The present invention will be described in detail below through embodiments.

[0059] In this invention, unless otherwise specified, the atmospheric pressure refers to gauge pressure.

[0060] The main analytical method of this invention:

[0061] Hydrocarbon composition: Analyzed and determined according to the standard "Determination of Hydrocarbons in Saturated Hydrocarbon Fractions of Gas Oil (Mass Spectrometry) SH / T 0659";

[0062] Extracted oil yield = (mass of extracted oil / mass of heavy oil rich in aromatics) × 100%;

[0063] Rag oil yield = (mass of rag oil / mass of heavy oil rich in aromatics) × 100%.

[0064] The main raw materials and their sources in this invention are as follows:

[0065] Catalytic cracked diesel and catalytic cracked recycle oil: both were taken from the catalytic cracking unit of Sinopec Yanshan Petrochemical. The catalytic cracked diesel was a diesel fraction with a temperature >260℃, and the catalytic cracked recycle oil was a recycle oil fraction with a temperature >260℃. The properties and composition of the catalytic cracked diesel and recycle oil used in the embodiments and comparative examples of this invention are shown in Table 1.

[0066] Furfural reagent: Industrial furfural, solubility parameter is 23.6 (J·cm⁻¹). -3 ) 0.5 Its density is 1.16 g / cm³. 3 Taken from the furfural refining unit of Sinopec Yanshan Petrochemical;

[0067] N-methylpyrrolidone: Solubility parameter is 22.9 (J·cm⁻¹). -3 ) 0.5 Its density is 1.028 g / cm³. 3 Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0068] Anhydrous zinc chloride and anhydrous aluminum chloride: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0069] Example 1

[0070] (1) Weigh 20g of anhydrous zinc chloride and 180g of furfural to prepare a composite solvent with a salt content of 10wt%.

[0071] (2) The composite solvent and 200g of catalytic cracking diesel oil were added to a 1000mL glass jacket. The extraction temperature was set at 85℃. The mixture was stirred and mixed for 60min using a constant temperature magnetic stirrer. The mixture was then transferred to a separatory funnel and allowed to settle for 60min. The upper layer was the oil-rich phase product and the lower layer was the solvent-rich phase product. The mixture was separated and the oil-rich phase product and solvent-rich phase product obtained after separation were distilled under normal pressure to recover the remaining furfural. The oil-rich phase product and solvent-rich phase product after furfural removal were filtered, washed with water, and stripped to remove anhydrous zinc chloride to obtain extracted oil and raffinate oil. The yield of extracted oil was 84.9% and the yield of raffinate oil was 15.1%.

[0072] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0073] Example 2

[0074] (1) Weigh 25g of anhydrous zinc chloride and 175g of furfural to prepare a composite solvent with a salt content of 12.5wt%.

[0075] (2) The composite solvent and 200g of catalytic cracking diesel oil were added to a 1000mL glass jacket. The extraction temperature was set to 100℃. The mixture was stirred and mixed for 60min using a constant temperature magnetic stirrer. The mixture was then transferred to a separatory funnel and allowed to settle for 60min. The upper layer was the oil-rich phase product and the lower layer was the solvent-rich phase product. The mixture was separated and the oil-rich phase product and solvent-rich phase product obtained after separation were distilled under normal pressure to recover the remaining furfural. The oil-rich phase product and solvent-rich phase product after furfural removal were filtered, washed with water, and stripped to remove anhydrous zinc chloride to obtain extracted oil and raffinate oil. The yield of extracted oil was 83% and the yield of raffinate oil was 17%.

[0076] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0077] Example 3

[0078] (1) Weigh 5g of anhydrous zinc chloride and 95g of furfural to prepare a composite solvent with a salt content of 5wt%.

[0079] (2) The composite solvent and 200g of catalytic cracking diesel oil were added to a 1000mL glass jacket. The extraction temperature was set at 80℃. The mixture was stirred and mixed for 60min using a constant temperature magnetic stirrer. The mixture was then transferred to a separatory funnel and allowed to settle for 60min. The upper layer was the oil-rich phase product and the lower layer was the solvent-rich phase product. The mixture was separated and the oil-rich phase product and solvent-rich phase product obtained after separation were distilled under normal pressure to recover the remaining furfural. The oil-rich phase product and solvent-rich phase product after furfural removal were filtered, washed with water, and stripped to remove anhydrous zinc chloride to obtain extracted oil and raffinate oil. The yield of extracted oil was 79.5% and the yield of raffinate oil was 20.5%.

[0080] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0081] Example 4

[0082] (1) Weigh 45g of anhydrous zinc chloride and 255g of furfural to prepare a composite solvent with a salt content of 15wt%.

[0083] (2) The composite solvent and 100g of catalytic cracking recycle oil were added to a 1000mL glass jacket. The extraction temperature was set at 100℃. The mixture was stirred and mixed for 60min using a constant temperature magnetic stirrer. The mixture was then transferred to a separatory funnel and allowed to settle for 60min. The upper layer was the oil-rich phase product and the lower layer was the solvent-rich phase product. The mixture was separated and the oil-rich phase product and solvent-rich phase product obtained after separation were distilled under normal pressure to recover the remaining furfural. The oil-rich phase product and solvent-rich phase product after furfural removal were filtered, washed with water, and stripped to remove anhydrous zinc chloride to obtain extracted oil and raffinate oil. The yield of extracted oil was 86.7% and the yield of raffinate oil was 13.3%.

[0084] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0085] Example 5

[0086] The method of Example 1 is different except that in step (1), 6g of anhydrous zinc chloride and 194g of furfural are weighed to prepare a composite solvent with a salt content of 3wt%; the extracted oil and the raffinate are obtained, wherein the yield of the extracted oil is 87.5% and the yield of the raffinate is 12.5%.

[0087] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0088] Example 6

[0089] The method of Example 1 is different except that in step (1), 32g of anhydrous zinc chloride and 168g of furfural are weighed to prepare a solvent with a salt content of 16wt%; extract oil and raffinate oil are obtained, wherein the yield of extract oil is 71.8% and the yield of raffinate oil is 28.2%.

[0090] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0091] Example 7

[0092] The method of Example 1 is different except that in step (1), the feedstock catalytic cracking diesel is replaced with an equal amount of catalytic cracking recycle oil, furfural is replaced with an equal amount of N-methylpyrrolidone, and anhydrous zinc chloride is replaced with an equal amount of anhydrous aluminum chloride; extract oil and raffinate are obtained, wherein the yield of extract oil is 69.7 wt% and the yield of raffinate oil is 30.3%.

[0093] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0094] Example 8

[0095] The method of Example 1 is followed, except that in step (2), the extraction temperature is changed from 85°C to 50°C; the extracted oil and the raffinate are obtained, wherein the yield of the extracted oil is 71.2% and the yield of the raffinate is 28.8%.

[0096] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0097] Comparative Example 1

[0098] Add 100g furfural and 100g catalytic cracking diesel to a 1000mL glass jacket, set the extraction temperature to 70℃, turn on the stirrer, stir and mix for 60min, then let it settle for 60min; the solvent and solute are miscible and cannot be separated.

[0099] Comparative Example 2

[0100] The method of Example 1 is different in that, in step (1), 4g of anhydrous zinc chloride and 196g of furfural are weighed to prepare a composite solvent with a salt content of 2wt%; after extraction and sedimentation, the solvent and solute are miscible and cannot be separated.

[0101] Comparative Example 3

[0102] The method of Example 1 is different except that in step (1), 50g of anhydrous zinc chloride and 150g of furfural are weighed to prepare a composite solvent with a salt content of 25wt%; the extracted oil and the raffinate oil are obtained, wherein the yield of the extracted oil is 40.1% and the yield of the raffinate oil is 59.9%.

[0103] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0104] Comparative Example 4

[0105] The method of Example 1 is different except that in step (1), anhydrous zinc chloride is replaced with an equal amount of KSCN to obtain extracted oil and raffinate oil, wherein the yield of extracted oil is 50.6% and the yield of raffinate oil is 49.4%.

[0106] The extracted oil and raffinate were subjected to hydrocarbon composition analysis, and the results are shown in Table 2.

[0107] Table 1 shows the properties and composition of the catalytic cracked diesel and reclaimed oil used.

[0108] project Catalytic cracked diesel Catalytic cracking recycle oil w(saturated hydrocarbons) / % 13.9 9.1 w(total aromatics) / % 86.1 90.9 w(monocyclic aromatic hydrocarbons) / % 5.3 5.4 w(bicyclic or higher aromatic hydrocarbons) / % 80.8 85.5

[0109] Table 2

[0110]

[0111] Table 2 (continued)

[0112]

[0113] As can be seen from the results in Table 1, the method for extracting aromatics from heavy oil provided by this invention reduces the miscibility between aromatics and solvents in heavy oil, effectively extracts and separates aromatics from heavy oil, and the aromatic content in the extracted oil reaches more than 90 wt%.

[0114] Based on the contents of Examples 1, 5-8 and Table 2 of this invention, it can be seen that the content of inorganic salts in the composite solvents used in Examples 5 and 6 is not within the preferred range provided by this invention. The aromatic content of the extracted oil in Example 5 is slightly lower than that in Example 1. The aromatic content of the raffinate oil in Example 6 is higher than that in Example 1, failing to effectively enrich the aromatics in the raw material into the extracted oil. Example 7 did not use the preferred polar organic solvent provided by this invention. The extraction temperature used in Example 8 is not within the preferred range provided by this invention, resulting in a slightly lower total aromatic content in the extracted oil compared to Example 1, and a higher total aromatic content in the raffinate oil compared to Example 1.

[0115] Based on the contents of Example 1, Comparative Examples 1-4, and Table 2 of this invention, it can be seen that Comparative Example 1 did not add inorganic salts, and the content of inorganic salts in the composite solvent of Comparative Example 2 was not within the range provided by this invention, resulting in the solvent and solute being miscible and unable to be separated; the content of inorganic salts in the composite solvent used in Comparative Example 3 was not within the range provided by this invention, resulting in an excess of inorganic salts, which led to a high content of aromatics in the extracted oil, but the yield of the extracted oil was extremely low; Comparative Example 4 did not use the halogen-containing metal inorganic salts provided by this invention, resulting in a low content of aromatics in the extracted oil and a high content of aromatics in the raffinate oil, failing to effectively enrich the aromatics in the feedstock into the extracted oil.

[0116] As can be seen from the contents of Examples 1-4 and Table 2, the preferred method for extracting aromatics from heavy oil provided by the present invention effectively extracts and separates aromatics from heavy oil, resulting in a high content of aromatics in the extracted oil and a low content of aromatics in the raffinate oil.

[0117] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for extracting aromatic hydrocarbons from heavy oil, characterized in that, The method includes the following steps: (1) Preparation of a composite solvent containing halogenated metal inorganic salts and polar organic solvents; (2) The composite solvent is mixed with heavy oil rich in aromatics and then extracted to obtain an oil-rich phase product and a solvent-rich phase product. The composite solvent is removed to obtain extracted oil and raffinate oil. Based on the total amount of the composite solvent, the content of inorganic salt is 2.5wt%-16.5wt%, and the content of organic solvent is 83.5wt%-97.5wt%. Wherein, the solubility parameter of the polar organic solvent is ≥20 (J·cm). -3 ) 0.5 Density ≥ 1 g / cm³ 3 .

2. The method according to claim 1, wherein, Based on the total amount of the composite solvent, the content of the inorganic salt is 5wt%-15wt%; the content of the organic solvent is 85wt%-95wt%.

3. The method described in requirement 1 or 2, wherein, The mass ratio of the composite solvent to the heavy oil is 0.1-5:1, preferably 0.5-3:

1.

4. The method according to any one of claims 1-3, wherein, The halogen-containing inorganic metal salt is selected from at least one of zinc chloride, aluminum chloride, anhydrous ferric chloride, and ferric oxide hydrate, preferably zinc chloride and / or aluminum chloride.

5. The method according to any one of claims 1-4, wherein, The polar organic solvent is selected from at least one of furfural, N-methylpyrrolidone, phenol, and dimethyl sulfoxide.

6. The method according to any one of claims 1-5, wherein, The solubility parameter of the polar organic solvent is 22-29 (J·cm⁻¹). -3 ) 0.5 Density is 1.1-2 g / cm³ 3 .

7. The method according to any one of claims 1-6, wherein, The heavy oil has a carbon number distribution of 10-80, preferably 14-30; the aromatic content in the heavy oil is 50wt%-99wt%, preferably 70wt%-90wt%.

8. The method according to any one of claims 1-7, wherein, The heavy oil has a distillation range of >200℃, preferably 260-540℃; Preferably, the heavy oil is selected from at least one of catalytic cracked diesel, catalytic cracked recycle oil, and vacuum distillate, and more preferably from catalytic cracked diesel and / or catalytic cracked recycle oil.

9. The method according to any one of claims 1-8, wherein, The extraction temperature is 50-150℃, more preferably 80-100℃.

10. The method according to any one of claims 1-9, wherein, The mixing time in step (2) is 30-100 min, preferably 40-80 min; Preferably, the specific steps for removing the composite solvent include: distilling the obtained oil-rich phase product and solvent-rich phase product separately to recover the polar organic solvent, and then filtering to remove the halogen-containing metal inorganic salt to obtain the extracted oil and the raffinate oil. Preferably, the recovered polar organic solvent and halogen-containing metal inorganic salt are recycled to step (1) to provide at least a portion of the composite solvent; Preferably, based on the total amount of extracted oil and raffinate oil, the content of the extracted oil is 80-90 wt%. Preferably, the extracted oil contains ≥90 wt% aromatic hydrocarbons.

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