A method for processing and utilizing wash oil fractions to increase their value

Abstract

The present invention provides a method for processing and utilizing a wash oil fraction to increase its value, and the processing and utilizing method comprises the following steps: pre-treating the wash oil raw material, and then separating it by a first liquid chromatography tower, and then sampling in sections according to the product fraction to obtain a mixed fraction containing a solvent fraction and a product fraction; separating the mixed fraction by a second liquid chromatography tower to obtain a high-purity product and a solvent containing impurities, and the solvent of the second liquid chromatography tower is the solvent fraction; crystallizing the solvent containing impurities to obtain a recovered solvent and a recovered crude product; returning the recovered crude product to the second liquid chromatography tower for separation to obtain a high-purity product; and recycling the recovered solvent to the first liquid chromatography tower. The processing and utilizing method applies liquid chromatography separation technology to the high-purity separation process of the wash oil fraction, and can obtain a high-purity product with a purity of ≥99.9% that cannot be obtained by the current "distillation + crystallization" technology.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical separation, and in particular relates to a method for processing and utilizing wash oil fractions to increase their value. Background Art

[0002] Coal tar is one of the important by-products of coking. According to incomplete statistics, my country's coal tar production reached 16 million tons in 2020, of which the 230-330°C fraction (wash oil fraction) of coal tar accounted for about 10%, or about 1.6 million tons. The deep processing of coal tar has a profound impact on my country's economic development. With the rapid development of new materials and the steel industry, people are paying more and more attention to the utilization of coal tar resources. At present, my country's coal tar deep processing is still in the rough processing stage. After further processing by small enterprises, they can only produce about a dozen industrial-grade crude products.

[0003] However, with the rapid development of advanced energy and electronic materials industries, PAHs are widely used in electronic information industries such as photoresists, packaging materials, and electronic luminescent materials. Coal tar is rich in PAHs, some of which, such as β-methylnaphthalene, α-methylnaphthalene, acenaphthene, dibenzofuran, and fluorene, cannot or cannot be obtained economically from petrochemical raw materials. For example, researchers conducted a comprehensive comparative analysis of the technologies for producing 2,6-dimethylnaphthalene by chemical synthesis, petroleum extraction, and coal tar extraction. The results showed that the method of extracting 2,6-dimethylnaphthalene from coal tar has the advantages of the lowest total cost, the shortest process flow, and cheap and readily available raw materials, and is the most economical method.

[0004] Electronic-grade chemicals, especially ultra-clean high-purity chemicals, are fine chemical products supporting the electronic information industry. The higher the standard requirements for electronic chemicals, the higher the requirements for the purity and cleanliness of raw materials, which puts forward higher requirements for the high-quality preparation of polycyclic aromatic hydrocarbons. At present, the preparation technology of high-quality monomer raw materials is still mastered by countries such as Japan, South Korea, and Germany. my country can only produce low-end and medium-end products. Although domestic professional colleges and universities have inherent advantages in subject integration, there are still several technical barriers to the industrialization of technology. Existing research is limited to the laboratory research stage, and there are no reports on industrialization.

[0005] At present, the main technical route for extracting chemicals from wash oil fractions in China is "pretreatment of wash oil raw materials - distillation and enrichment of target components - crystallization of enriched components to extract high-purity chemicals", and the main methods for crystallization of enriched components are solvent crystallization and melt crystallization.

[0006] CN1884234A discloses a method for extracting industrial fluorene from washing oil by solvent crystallization. The method first uses a non-polar solvent for crystallization and then uses a polar solvent for washing. Finally, industrial fluorene with a purity of ≥97% can be obtained, and the product yield is 25%. CN101182278A discloses a method for extracting fluorene by solvent crystallization. The method is improved on the basis of CN1884234A, and the method of pre-treatment of washing oil raw materials, optimization of crystallization cooling curve, and reduction of crystallization terminal temperature is added, so that the product yield is increased to 75%. Patent CN101643380A discloses a process for producing industrial fluorene from coal tar washing oil. First, the raw materials are continuously distilled to enrich the fluorene fraction, and the enriched fraction is solvent crystallized again. The purity of the fluorene product can reach 95% and the yield is 65%. However, the solvent crystallization method requires a large amount of solvent, which is easy to cause environmental pollution; and the flash point of the solvent used is low, which has a great safety hazard.

[0007] CN101786935A discloses a method for extracting fluorene, anthracene and carbazole from mixed anthracene oil, using 89% crude fluorene as raw material, adopting melt crystallization method, and cooling crystallization to obtain industrial fluorene with a purity of 95%. Although the melt crystallization method does not use solvents, it overcomes the environmental problems caused by solvents, and the product yield is also high, but the melt crystallization needs to go through multiple melting and multiple crystallizations to improve the purity of the product, and multiple intermediate products will be produced. Therefore, more equipment is required and the investment is large. If the melting point difference between the target product and the impurity is small, it will also cause a substantial increase in equipment investment.

[0008] In summary, the separation and purification of PAHs in wash oil fractions reported in China are mainly based on processes such as solvent crystallization, melt crystallization, and distillation-recrystallization, but the product purity is ≤98%, and it is impossible to obtain a product with higher purity.

[0009] Studies have shown that the extraction of high-purity PAHs from coal tar wash oil fractions is much more difficult than the fine separation of general chemical products. The main difficulties are as follows:

[0010] (1) Washing oil contains hundreds of compounds with extremely complex composition. It is a viscous multiphase system. Its thermodynamic properties, rheological properties, mass transfer and heat transfer properties are much more complicated than those of general chemical systems.

[0011] (2) PAHs are mostly heat-sensitive substances, which are greatly affected by factors such as temperature and pressure. During the deep processing, after multiple distillation, separation, concentration, repeated cooling, crystallization and other operations, they are easily oxidized or chemically reacted, resulting in impurities, and the products are prone to discoloration, odor, etc.

[0012] (3) The content of PAHs in wash oil is generally low, with the maximum content generally ≤25%. The distillation separation process often has problems such as complicated steps, high impurity content of the product, low yield, and poor economic efficiency;

[0013] (4) The wash oil fraction contains a large number of isomers and azeotropes. The boiling points of these isomers and azeotropes are the same or similar, and it is almost impossible to achieve high-purity separation using distillation or crystallization technology.

[0014] Therefore, developing a novel wash oil fraction separation method with high separation efficiency and low energy consumption is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0015] The object of the present invention is to provide a method for processing and utilizing wash oil fractions in a high-value manner. The processing and utilization method fully utilizes the high-purity and high-efficiency separation characteristics of liquid chromatography, applies liquid chromatography separation technology to the high-purity separation process of wash oil fractions, and utilizes the components contained in the wash oil itself as a solvent. A high-purity product with a purity of ≥99.9% that cannot be obtained by the current "distillation + crystallization" technology can be obtained, and no additional solvent is required (except for the initial solvent of the first liquid chromatography tower). The cost, energy consumption and environmental pollution problems caused by the use and recovery of a large amount of solvents in ordinary distillation + crystallization technology can be solved.

[0016] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0017] The present invention provides a method for processing and utilizing wash oil fractions to increase their value, the method comprising the following steps:

[0018] (1) pre-treating the wash oil raw material, and then separating it using a first liquid chromatography tower, and then sampling in sections according to the product fraction to obtain a mixed fraction containing a solvent fraction and a product fraction;

[0019] (2) separating the mixed fractions described in step (1) using a second liquid chromatography tower to obtain a high-purity product and an impure solvent;

[0020] The solvent of the second liquid chromatography tower in step (2) is the solvent fraction in step (1);

[0021] (3) subjecting the impure solvent in step (2) to crystallization to obtain a recovered solvent and a recovered crude product;

[0022] (4) The recovered crude product in step (3) is returned to the second liquid chromatography tower for separation to obtain a high-purity product; and the recovered solvent in step (3) is reused in the first liquid chromatography tower.

[0023] In the present invention, the crude product containing residual product components is recovered; the recovered solvent is returned to the first liquid chromatography tower and recycled as the solvent of the target product, thereby greatly reducing costs, energy consumption and environmental pollution caused by solvent recovery.

[0024] The method for processing and utilizing the high-value washing oil fraction provided by the present invention utilizes the high-purity and high-efficiency separation characteristics of liquid chromatography, applies liquid chromatography separation technology to the high-purity separation process of the washing oil fraction, and uses the substances contained in the washing oil raw material itself as the solvent for the subsequent separation process of each product component, which not only solves the problems of low solubility of the solvent and solute, low separation efficiency, etc., but also solves the cost and pollution problems caused by the large amount of solvent used in the traditional "distillation + crystallization" method; in addition, the impure solvent obtained by separation is recycled and utilized through the solvent recovery section of the crystallization method, thereby realizing the full utilization of the washing oil raw material and no pollutant emission. The processing and utilization method has a simple process, high separation efficiency, low energy consumption, and can obtain a high-purity product.

[0025] As a preferred technical solution of the present invention, the pretreatment in step (1) includes dehydration and de-impurity treatment.

[0026] In the present invention, the wash oil raw material enters a pretreatment tower for dehydration and impurity removal pretreatment to obtain refined wash oil.

[0027] Preferably, the type of the stationary phase in the first liquid chromatography tower in step (1) includes any one of C18 (ODS), C8 (MOS), C4 (Butyl) or C6H5 (Phenyl).

[0028] Preferably, the height of the first liquid chromatography tower in step (1) is 200-400 cm, for example, it can be 220 cm, 240 cm, 260 cm, 280 cm, 300 cm, 320 cm, 340 cm, 360 cm or 380 cm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] Preferably, the diameter of the first liquid chromatography tower in step (1) is 0.6-1.6 m, for example, 0.8 m, 1.0 m, 1.2 m, 1.4 m or 1.5 m, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0030] As a preferred technical solution of the present invention, the initial solvent of the first liquid chromatography tower in step (1) includes alcohol and / or ether.

[0031] Preferably, the elution method of the first liquid chromatography tower in step (1) is isocratic elution.

[0032] Preferably, the column temperature during the detection process of the first liquid chromatography tower in step (1) is 200-320°C, for example, it can be 220°C, 240°C, 260°C, 280°C, 300°C or 310°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0033] Preferably, the flow rate during the detection process of the first liquid chromatography tower in step (1) is 0.25-2 mL / min, for example, it can be 0.3 mL / min, 0.5 mL / min, 0.7 mL / min, 0.9 mL / min, 1 mL / min, 1.3 mL / min, 1.5 mL / min, 1.7 mL / min or 1.8 mL / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, the detector of the first liquid chromatography tower in step (1) is an ultraviolet detector.

[0035] Preferably, the scanning range of the ultraviolet detector is 220-400nm, for example, it can be 240nm, 260nm, 280nm, 300nm, 320nm, 340nm, 360nm or 380nm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0036] As a preferred technical solution of the present invention, the segmented sampling in step (1) is: selective segmented sampling is performed at the bottom of the first liquid chromatography tower according to the difference in the elution time of the product fractions.

[0037] It is worth noting that, due to the large differences in properties and structures of the components in the wash oil, different forces of magnitude and strength are generated between the components and the chromatographic packing. When the wash oil flows through the packing, the components undergo repeated distribution equilibrium between the two phases, resulting in differences in the retention time of the components by the packing, and thus they flow out of the chromatographic column in a certain order. Based on the differences in the elution time of the components, they are grouped according to their physical properties, and selectively sampled at the bottom of the chromatographic column to obtain the product fractions.

[0038] In the present invention, after selective segmented sampling of each product fraction segment, each segment of the product fraction intercepted needs to contain two types of substances: "solvent fraction + product fraction".

[0039] As a preferred technical solution of the present invention, the solvent fraction in step (1) is a fraction contained in the wash oil itself.

[0040] In the present invention, the solvent fraction in step (1) can be cut in sections according to the boiling point range.

[0041] It is worth noting that the solvent fraction in step (1) is used as the solvent required for the product component separation process in the second liquid chromatography tower separation process, which not only solves the problems of low solubility of solvent and solute and low separation efficiency, but also solves the cost and pollution problems caused by large solvent loss in the traditional "distillation + crystallization" method.

[0042] Preferably, the solvent fraction in step (1) comprises any one of naphthalene, methylnaphthalene or dimethylnaphthalene, or a combination of at least two of them, wherein typical but non-limiting combinations are: a combination of naphthalene and methylnaphthalene, a combination of methylnaphthalene and dimethylnaphthalene, a combination of naphthalene, methylnaphthalene and dimethylnaphthalene, etc.

[0043] As a preferred technical solution of the present invention, the product fraction in step (1) includes any one of biphenyl, carbazole, quinoline, isoquinoline, fluorene, dibenzofuran or acenaphthene, or a combination of at least two of them, wherein typical but non-limiting combinations are: a combination of biphenyl and carbazole, a combination of quinoline and isoquinoline, a combination of fluorene and dibenzofuran, a combination of fluorene and acenaphthene, etc.

[0044] As a preferred technical solution of the present invention, the type of the stationary phase in the second liquid chromatography tower in step (2) includes any one of C18, C8, C4 or C6H5.

[0045] Preferably, the height of the second liquid chromatography tower in step (2) is 200-400 cm, for example, it can be 220 cm, 240 cm, 260 cm, 280 cm, 300 cm, 320 cm, 340 cm, 360 cm or 380 cm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0046] Preferably, the diameter of the second liquid chromatography tower in step (2) is 0.6-1.6 m, for example, 0.8 m, 1.0 m, 1.2 m, 1.4 m or 1.5 m, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0047] As a preferred technical solution of the present invention, the elution method of the second liquid chromatography tower in step (2) is gradient elution.

[0048] In the present invention, the second liquid chromatography tower uses gradient elution to separate the target product, which can selectively separate the target product. At the same time, the present invention does not limit the specific conditions of gradient elution, and those skilled in the art can adjust it according to actual conditions.

[0049] Preferably, the column temperature during the detection process of the second liquid chromatography tower in step (2) is 230-300°C, for example, it can be 235°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 295°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0050] Preferably, the flow rate during the detection process of the second liquid chromatography tower in step (2) is 0.2-1.5 mL / min, for example, it can be 0.25 mL / min, 0.3 mL / min, 0.5 mL / min, 0.7 mL / min, 0.9 mL / min, 1 mL / min, 1.1 mL / min, 1.3 mL / min or 1.4 mL / min, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0051] Preferably, the detector of the second liquid chromatography tower in step (2) is an ultraviolet detector.

[0052] Preferably, the scanning range of the ultraviolet detector is 220-400nm, for example, it can be 240nm, 260nm, 280nm, 300nm, 320nm, 340nm, 360nm or 380nm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0053] As a preferred technical solution of the present invention, the purity of the high-purity product in step (2) is ≥99.9%.

[0054] It is worth noting that after separation in the second liquid chromatography tower, selective segmented sampling is performed at the bottom of the chromatography column to obtain a high-purity product with a purity of ≥99.9%.

[0055] As a preferred technical solution of the present invention, the processing and utilization method comprises the following steps:

[0056] (1) pre-treating the wash oil raw material, and then separating it using a first liquid chromatography tower, and then selectively sampling at the bottom of the first liquid chromatography tower according to the difference in the elution time of the product fraction to obtain a mixed fraction containing a solvent fraction and a product fraction;

[0057] Step (1) the initial solvent of the first liquid chromatography tower includes alcohol and / or ether, and separation is performed by isocratic elution;

[0058] Step (1) The first liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 200-320° C.; flow rate is 0.25-2 mL / min; wavelength of ultraviolet detector is 220-400 nm;

[0059] The solvent fraction in step (1) is a fraction contained in the wash oil itself; the solvent fraction in step (1) includes any one of naphthalene, methylnaphthalene or dimethylnaphthalene, or a combination of at least two of them;

[0060] The product fraction of step (1) comprises any one or a combination of at least two of biphenyl, carbazole, quinoline, isoquinoline, fluorene, dibenzofuran or acenaphthene;

[0061] (2) separating the mixed fractions described in step (1) using a second liquid chromatography tower to obtain a product with a purity of ≥99.9% and an impure solvent;

[0062] Step (2) The solvent of the second liquid chromatography tower is the solvent fraction of step (1), and separation is performed by gradient elution;

[0063] Step (2) The second liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 230-300° C.; flow rate is 0.2-1.5 mL / min; wavelength of the ultraviolet detector is 220-400 nm;

[0064] (3) subjecting the impure solvent described in step (2) to crystallization to obtain a recovered solvent and a recovered crude product;

[0065] (4) The recovered crude product in step (3) is returned to the second liquid chromatography tower for separation to obtain a high-purity product; and the recovered solvent in step (3) is reused in the first liquid chromatography tower.

[0066] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] (1) The processing and utilization method provided by the present invention makes full use of the high-purity and high-efficiency separation characteristics of liquid chromatography, applies liquid chromatography separation technology to the high-purity separation process of wash oil fractions, realizes high-efficiency separation, and obtains a high-purity product with a purity of ≥99.9%;

[0069] (2) The processing and utilization method provided by the present invention uses the substances contained in the wash oil fraction itself as the solvent for the subsequent separation process of each product component, which not only solves the problem of low solubility of the solvent and the solute and low separation efficiency, but also solves the cost, energy consumption and environmental pollution problems caused by the large-scale use of solvents;

[0070] (3) The impure solvent separated by the processing and utilization method provided by the present invention is recycled through a crystallization solvent recovery section, thereby achieving full utilization of the washing oil raw materials and no pollutant emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 A roadmap for a method for processing and utilizing wash oil fractions with high value provided by the present invention;

[0072] Among them, 1-pretreatment, 2-first liquid chromatography tower, 3-mixed fraction, 4-second liquid chromatography tower, 5-high-purity product, 6-containing impure solvent, 7-crystallization treatment, 8-recovery of solvent, 9-recovery of crude product. DETAILED DESCRIPTION

[0073] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0074] The present invention provides a method for processing and utilizing wash oil fractions to increase their value. The processing route is as follows: Figure 1 As shown, the processing and utilization method comprises the following steps:

[0075] (1) pre-treating the wash oil raw material, and then separating it using a first liquid chromatography tower, and then sampling in sections according to the product fraction to obtain a mixed fraction containing a solvent fraction and a product fraction;

[0076] (2) separating the mixed fractions described in step (1) using a second liquid chromatography tower to obtain a product and an impure solvent;

[0077] The solvent of the second liquid chromatography tower in step (2) is the solvent fraction in step (1);

[0078] (3) subjecting the impure solvent described in step (2) to crystallization to obtain a recovered solvent and a recovered crude product;

[0079] (4) The recovered crude product in step (3) is returned to the second liquid chromatography tower for separation to obtain a high-purity product; and the recovered solvent in step (3) is reused in the first liquid chromatography tower.

[0080] In the following examples and comparative examples of the present invention, the crude product yield is based on the raw material content, and the high-purity product yield is based on the crude product content.

[0081] Example 1

[0082] This embodiment provides a method for processing and utilizing wash oil fractions to increase their value. In this embodiment, methylnaphthalene in the wash oil is selected as a solvent, and the target products are acenaphthene, dibenzofuran and fluorene. The processing and utilizing method comprises the following steps:

[0083] (1) 1.3 kg of the wash oil raw material enters a pretreatment tower for dehydration and impurity removal pretreatment to obtain a refined wash oil, and then the refined wash oil enters a first liquid chromatography tower for separation, and then selective segmented sampling is performed at the bottom of the tower according to the difference in the elution time of the product fractions to obtain a mixed fraction of methylnaphthalene + acenaphthene, a mixed fraction of methylnaphthalene + dibenzofuran, and a mixed fraction of methylnaphthalene + fluorene, respectively;

[0084] Step (1) The initial solvent of the first liquid chromatography tower is ethanol, and separation is performed by isocratic elution. The model of the stationary phase in the first liquid chromatography tower is C18. The height of the first liquid chromatography tower is 300 cm and the diameter is 1.0 m.

[0085] Step (1) The first liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 260° C.; flow rate is 1 mL / min; wavelength of the ultraviolet detector is 220-400 nm;

[0086] (2) the mixed fraction described in step (1) enters a second liquid chromatography tower for separation, and selective segmented sampling is performed at the bottom of the tower to obtain impure solvent, high-purity acenaphthene, high-purity dibenzofuran and high-purity fluorene products respectively;

[0087] The solvent of the second liquid chromatography tower in step (2) is the methylnaphthalene fraction in step (1), and separation is performed by gradient elution. The model of the stationary phase in the second liquid chromatography tower is C18. The height of the second liquid chromatography tower is 300 cm and the diameter is 1.0 m.

[0088] Step (2) The second liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 240° C.; flow rate is 0.8 mL / min; wavelength of the ultraviolet detector is 220-400 nm;

[0089] (3) subjecting the impure solvent described in step (2) to crystallization to obtain a recovered solvent and a recovered crude product;

[0090] (4) The recovered crude product in step (3) is returned to the second liquid chromatography tower for separation to obtain a high-purity product; the recovered solvent (methylnaphthalene) in step (3) is returned to the first liquid chromatography tower as a solvent for the target product.

[0091] The products obtained after each step of the present invention are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] Example 2

[0096] This embodiment provides a method for processing and utilizing a wash oil fraction to increase its value. In this embodiment, naphthalene series substances at 240° C. to 270° C. in the wash oil are selected as solvents, and the target products are acenaphthene, dibenzofuran and fluorene. The processing and utilizing method comprises the following steps:

[0097] (1) 1.3 kg of the wash oil raw material enters a pretreatment tower for dehydration and impurity removal pretreatment to obtain a refined wash oil, and then the refined wash oil enters a first liquid chromatography tower for separation, and then selective segmented sampling is performed at the bottom of the tower according to the difference in the elution time of the product fractions to obtain a mixed fraction of naphthalene series + acenaphthene, a mixed fraction of naphthalene series + dibenzofuran, and a mixed fraction of naphthalene series + fluorene, respectively;

[0098] Step (1) The initial solvent of the first liquid chromatography tower is methanol, and separation is performed by isocratic elution. The model of the stationary phase in the first liquid chromatography tower is C8. The height of the first liquid chromatography tower is 300 cm and the diameter is 1.0 m.

[0099] Step (1) The first liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 270° C.; flow rate is 1.2 mL / min; wavelength of ultraviolet detector is 220-400 nm;

[0100] (2) the mixed fraction described in step (1) enters a second liquid chromatography tower for separation, and selective segmented sampling is performed at the bottom of the tower to obtain impure solvent, high-purity acenaphthene, high-purity dibenzofuran and high-purity fluorene products respectively;

[0101] Step (2) Solvent of the second liquid chromatography tower: The naphthyl series fraction of step (1) is separated by gradient elution, the model of the stationary phase in the first liquid chromatography tower is C8, the height of the first liquid chromatography tower is 300 cm, and the diameter is 1.0 m;

[0102] Step (2) The second liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 270° C.; flow rate is 1 mL / min; wavelength of the ultraviolet detector is 220-400 nm;

[0103] (3) subjecting the impure solvent described in step (2) to crystallization to obtain a recovered solvent and a recovered crude product;

[0104] (4) the recovered crude product in step (3) is returned to the second liquid chromatography tower for separation to obtain a high-purity product; the recovered solvent in step (3) is returned to the first liquid chromatography tower as a solvent for the target product;

[0105] The products obtained after each step of the present invention are shown in Table 2.

[0106] Table 2

[0107]

[0108]

[0109] Example 3

[0110] This embodiment provides a method for processing and utilizing a wash oil fraction in a high-value manner. Except that the initial solvent of the first liquid chromatography tower in step (1) is pure water, other conditions are the same as those in Example 1.

[0111] The crude product obtained after the treatment of step (1) in this example is shown in Table 3.

[0112] Table 3

[0113]

[0114] When the initial solvent of the first liquid chromatography column is a pure weak polar solvent, it is not conducive to the high-purity separation of the target product. This is because weak polar solvents are usually composed of non-polar molecules. Due to the small molecular polarity, similar compounds in the sample will show similar affinity on the chromatographic column, resulting in their relative positions on the chromatographic column being very close, making it difficult to effectively separate. Strong polar solvents can form hydrogen bonds and other interactions with polar functional groups in compounds, which can make the separation higher and thus improve purity.

[0115] Example 4

[0116] This embodiment provides a method for processing and utilizing a wash oil fraction in a high-value manner. Except that the second liquid chromatography tower in step (2) adopts an isocratic elution method for separation, other conditions are the same as those in embodiment 1.

[0117] The high-purity product obtained after processing in step (2) of this embodiment is shown in Table 4.

[0118] Table 4

[0119]

[0120] When the second liquid chromatography tower uses isocratic elution for separation, the separation of each target product cannot be effectively achieved, and the purity of the target product obtained is low. The gradient elution method can set appropriate gradient conditions according to the characteristics of the sample, effectively separate the target components with different properties in the wash oil fraction, and can flexibly adjust the gradient conditions, which is more suitable for the high-purity and high-efficiency separation of various complex components in the present invention.

[0121] Comparative Example 1

[0122] This comparative example provides a method for processing and utilizing the wash oil fraction in a high-value manner, except that the mixed fraction in step (1) does not contain a solvent fraction, and the acenaphthene fraction, the benzofuran fraction, and the fluorene fraction are obtained respectively, and the solvent of the second liquid chromatography tower in step (2) is ethanol, other conditions are the same as those in Example 1.

[0123] The high-purity product obtained after step (2) of this comparative example is shown in Table 5.

[0124] Table 5

[0125]

[0126] When ethanol is used as the solvent in the second liquid chromatography tower, a high-purity product with a purity of ≥99.9% can also be obtained. However, the introduction of the solvent greatly increases the cost and energy consumption of purchasing and recovering the solvent, and brings about environmental pollution problems, which significantly reduces the economic efficiency of the process of the present invention.

[0127] Comparative Example 2

[0128] This comparative example provides a method for processing and utilizing the wash oil fraction in a high-value manner. Except that step (2) is not performed, other conditions are the same as those in Example 1.

[0129] The product obtained after step (1) of this comparative example is shown in Table 6.

[0130] Table 6

[0131]

[0132] Comparative Example 3

[0133] This comparative example provides a method for processing and utilizing the high-value washing oil fraction, which uses the traditional "pretreatment-distillation-crystallization" technology to separate and purify acenaphthene, dibenzofuran, and fluorene products in the washing oil. The processing and utilization method comprises the following steps:

[0134] (1) 1.3 kg of wash oil raw material enters the pretreatment tower for dehydration and impurity removal pretreatment to obtain refined wash oil;

[0135] (2) the refined wash oil in step (1) enters a primary distillation tower, the heavy components at the bottom of the primary distillation tower enter an acenaphthene distillation tower, and a crude acenaphthene product is obtained at the top of the acenaphthene tower;

[0136] (3) The heavy components in the acenaphthene tower kettle enter the dibenzofuran distillation tower, and the crude dibenzofuran product is obtained at the top of the tower;

[0137] (4) The heavy components in the dibenzofuran tower bottom enter the fluorene distillation tower, and the crude fluorene product is obtained at the top of the tower. The heavy components in the tower bottom enter the subsequent washing oil deep processing section;

[0138] (5) crude acenaphthene, dibenzofuran and fluorene are purified by crystallization to obtain refined acenaphthene, refined dibenzofuran and refined fluorene products;

[0139] The products obtained after each step of the comparative example are shown in Table 7;

[0140] Table 7

[0141]

[0142] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for processing and utilizing wash oil fractions to increase their value, characterized in that: The processing and utilization method comprises the following steps: (1) pre-treating the wash oil raw material, and then separating it using a first liquid chromatography tower, and then sampling in sections according to the product fraction to obtain a mixed fraction containing a solvent fraction and a product fraction; (2) separating the mixed fractions described in step (1) using a second liquid chromatography tower to obtain a high-purity product and an impure solvent; The solvent of the second liquid chromatography tower in step (2) is the solvent fraction in step (1); (3) subjecting the impure solvent in step (2) to crystallization to obtain a recovered solvent and a recovered crude product; (4) the recovered crude product in step (3) is returned to the second liquid chromatography tower for separation to obtain a high-purity product; the recovered solvent in step (3) is reused in the first liquid chromatography tower; Wherein, the elution mode of the first liquid chromatography tower in step (1) is isocratic elution; Wherein, the elution method of the second liquid chromatography tower in step (2) is gradient elution.

2. The processing and utilization method according to claim 1, characterized in that: The pretreatment in step (1) includes dehydration and decontamination.

3. The processing and utilization method according to claim 1, characterized in that: Step (1) The type of the stationary phase in the first liquid chromatography tower includes any one of C18, C8, C4 or C6H5.

4. The processing and utilization method according to claim 1, characterized in that: Step (1) The height of the first liquid chromatography tower is 200-400 cm.

5. The processing and utilization method according to claim 1, characterized in that: Step (1) The diameter of the first liquid chromatography tower is 0.6-1.6m.

6. The processing and utilization method according to claim 1, characterized in that: Step (1) The initial solvent of the first liquid chromatography tower includes alcohol and / or ether.

7. The processing and utilization method according to claim 1, characterized in that: In step (1), the column temperature during the detection process of the first liquid chromatography tower is 200-320°C.

8. The processing and utilization method according to claim 1, characterized in that: Step (1) The flow rate during the detection process of the first liquid chromatography tower is 0.25-2 mL / min.

9. The processing and utilization method according to claim 1, characterized in that: The detector of the first liquid chromatography tower in step (1) is an ultraviolet detector.

10. The processing and utilization method according to claim 9, characterized in that: The scanning range of the ultraviolet detector is 220-400nm.

11. The processing and utilization method according to claim 1, characterized in that: The segmented sampling in step (1) is: selective segmented sampling is performed at the bottom of the first liquid chromatography tower according to the difference in the elution time of the product fractions.

12. The processing and utilization method according to claim 1, characterized in that: The solvent fraction in step (1) is a fraction contained in the wash oil itself.

13. The processing and utilization method according to claim 1, characterized in that: The solvent fraction in step (1) comprises any one of naphthalene, methylnaphthalene or dimethylnaphthalene, or a combination of at least two thereof.

14. The processing and utilization method according to claim 1, characterized in that: The product fraction of step (1) includes any one of biphenyl, carbazole, quinoline, isoquinoline, fluorene, dibenzofuran or acenaphthene, or a combination of at least two thereof.

15. The processing and utilization method according to claim 1, characterized in that: Step (2) The type of the stationary phase in the second liquid chromatography tower includes any one of C18, C8, C4 or C6H5.

16. The processing and utilization method according to claim 1, characterized in that: Step (2) The height of the second liquid chromatography tower is 200-400 cm.

17. The processing and utilization method according to claim 1, characterized in that: Step (2) The diameter of the second liquid chromatography tower is 0.6-1.6m.

18. The processing and utilization method according to claim 1, characterized in that: In step (2), the column temperature during the detection process of the second liquid chromatography tower is 230-300°C.

19. The processing and utilization method according to claim 1, characterized in that: Step (2) The flow rate during the detection process of the second liquid chromatography tower is 0.2-1.5 mL / min.

20. The processing and utilization method according to claim 1, characterized in that: The detector of the second liquid chromatography tower in step (2) is an ultraviolet detector.

21. The processing and utilization method according to claim 20, characterized in that: The scanning range of the ultraviolet detector is 220-400nm.

22. The processing and utilization method according to claim 1, characterized in that: The purity of the high-purity product in step (2) is ≥99.9%.

23. The processing and utilization method according to claim 1, characterized in that: The processing and utilization method comprises the following steps: (1) pre-treating the wash oil raw material, and then separating it using a first liquid chromatography tower, and then selectively sampling at the bottom of the first liquid chromatography tower according to the difference in the elution time of the product fraction to obtain a mixed fraction containing a solvent fraction and a product fraction; Step (1) the initial solvent of the first liquid chromatography tower includes alcohol and / or ether, and separation is performed by isocratic elution; Step (1) The first liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 200-320° C.; flow rate is 0.25-2 mL / min; wavelength of ultraviolet detector is 220-400 nm; The solvent fraction in step (1) is a fraction contained in the wash oil itself; the solvent fraction in step (1) includes any one of naphthalene, methylnaphthalene or dimethylnaphthalene, or a combination of at least two thereof; The product fraction of step (1) comprises any one or a combination of at least two of biphenyl, carbazole, quinoline, isoquinoline, fluorene, dibenzofuran or acenaphthene; (2) separating the mixed fractions described in step (1) using a second liquid chromatography tower to obtain a product with a purity of ≥99.9% and an impure solvent; Step (2) The solvent of the second liquid chromatography tower is the solvent fraction of step (1), and separation is performed by gradient elution; Step (2) The second liquid chromatography tower adopts the following chromatographic separation conditions for separation: column temperature is 230-300° C.; flow rate is 0.2-1.5 mL / min; wavelength of the ultraviolet detector is 220-400 nm; (3) subjecting the impure solvent described in step (2) to crystallization to obtain a recovered solvent and a recovered crude product; (4) The recovered crude product in step (3) is returned to the second liquid chromatography tower for separation to obtain a high-purity product; and the recovered solvent in step (3) is reused in the first liquid chromatography tower.

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