A method for extracting alkanes with low aromatic and cycloalkane content from wax oil and its application.

Abstract

This invention provides a method for extracting alkanes with low aromatic and cycloalkane content from wax oil and its application. The method first performs a primary extraction on the wax oil using a primary extraction solvent to obtain non-polar and polar components. Then, it performs a secondary extraction on the non-polar components using a secondary extraction solvent to obtain alkane and aromatic components. Finally, it performs a tertiary extraction on the alkane components using a tertiary extraction solvent to obtain alkane and cycloalkane components. This method effectively removes polar components, aromatics, and cycloalkanes from wax oil, thereby improving the cracking performance of the obtained alkane-rich components.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, specifically relating to a method for extracting alkanes with low aromatic and cycloalkanes content from wax oil and its application. Background Technology

[0002] Steam cracking is a major technology for producing ethylene and propylene. Steam cracking feedstocks mainly include light hydrocarbons (such as ethane, propane, and butane), naphtha, diesel oil, condensate, and hydrotreated tail oil. Using wax oil as a steam cracking feedstock to produce ethylene and other chemical products is an important method to increase ethylene production and improve efficiency. However, the aromatic components in wax oil fractions, especially polycyclic aromatic hydrocarbons (PAHs), are undesirable components in steam cracking feedstocks. They easily reduce ethylene yields, increase coking in furnace tubes, and shorten operating cycles. Therefore, treating wax oil is essential to improve the efficiency of steam cracking.

[0003] Currently, patents disclose methods for producing ethylene cracking feedstock from wax oil through solvent extraction and for increasing the cetane number of the product. However, no methods for producing ethylene cracking feedstock from wax oil fractions have been reported.

[0004] CN201711009855.0 discloses a method for preparing bright oil. The goal of this technology is to obtain primary raffinate oil by solvent deasphalting heavy oil, then to obtain secondary raffinate oil by solvent deasphalting the raffinate oil, and finally to obtain dewaxed oil by dewaxing the secondary raffinate oil. The dewaxing method involves either cooling dewaxing to obtain wax paste, or adsorption separation of the secondary raffinate oil to obtain the product. However, cooling dewaxing and adsorption separation are difficult to effectively separate cycloalkanes and alkanes; therefore, it is necessary to develop cycloalkane removal technology to further improve the yield of trienes.

[0005] CN201910661627.4 discloses a combined process for the hydrotreating of residual oil and the production of bright oil and aromatic mineral oil. The goal of this technology is to produce bright oil and aromatic mineral oil. The first and second stage extraction solvents are one or more of furfural, N-methylpyrrolidone, and phenol, primarily for the removal of aromatic hydrocarbons. A two-stage dewaxing process is then performed using a mixture of butanone and toluene as the solvent. During this process, it is difficult to separate alkanes and cycloalkanes; therefore, a technology for removing cycloalkanes needs to be developed.

[0006] CN201811508969.4 discloses a method for processing straight-run diesel fuel. The goal of this technology is to extract low-aromatic raffinate from straight-run diesel fuel as feedstock for ethylene cracking, thereby increasing the yield of trienes from steam cracking. However, in the examples, the aromatic content of the feedstock decreased from 11% to 1.5%, effectively increasing the yield of trienes in the cracking products. But at the same time, the cycloalkanes increased from 38% to 41%, making it difficult to convert them into the target olefin products. Therefore, it is necessary to develop a cycloalkanes removal technology to further improve the yield of trienes.

[0007] The aforementioned patents have limitations in removing cycloalkanes, and even exhibit cycloalkane enrichment, which restricts further improvement in the yield of trienes in the cracking unit. Therefore, further development of cycloalkane removal technology is needed. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a method for extracting alkanes with low aromatic and cycloalkane content from wax oil and its application. This method can effectively remove polar components, aromatics, and cycloalkanes from wax oil, thereby improving the cracking performance of the obtained alkanes-rich components.

[0009] To achieve the above objectives, the present invention provides a method for extracting alkanes with low aromatic and cycloalkane content from wax oil, comprising the following steps:

[0010] (1) The wax oil was subjected to primary extraction using a primary extraction solvent to obtain non-polar and polar components.

[0011] (2) The nonpolar-rich component is subjected to secondary extraction using a secondary extraction solvent to obtain an alkane-rich component and an aromatic-rich component;

[0012] (3) The alkane-rich component is subjected to three-stage extraction using a three-stage extraction solvent to obtain a chain alkane-rich component and a cycloalkane-rich component.

[0013] The primary extraction solvent includes a primary main solvent and a primary secondary solvent, wherein the primary main solvent and the primary secondary solvent are C3-C5 alkanes, respectively.

[0014] The secondary extraction solvent includes a secondary primary solvent and a secondary secondary solvent, each of which is independently selected from one or more of furfural, N,N-dimethylformamide, morpholino, methylpyrrolidone, ethylene glycol methyl ether, and sulfolane.

[0015] The tertiary extraction solvent includes a tertiary primary solvent and a tertiary secondary solvent. The tertiary primary solvent is sulfolane and / or dimethyl sulfoxide, and the tertiary secondary solvent is a C6-C10 alkanes and / or a C6-C10 cycloalkanes.

[0016] According to a specific embodiment of the present invention, preferably, the primary solvent and the primary secondary solvent are different.

[0017] According to a specific embodiment of the present invention, preferably, the secondary primary solvent and the secondary secondary solvent are different.

[0018] According to a specific embodiment of the present invention, preferably, the composition of the wax oil, calculated by mass percentage, includes 49-53% alkanes, 37-42% cycloalkanes, and 7-10% aromatics.

[0019] According to a specific embodiment of the present invention, preferably, the wax oil is a straight-run wax oil and / or a hydrogenated wax oil.

[0020] According to a specific embodiment of the present invention, preferably, the amount of the primary auxiliary solvent added in the primary extraction solvent accounts for 10-90 wt% of the primary main solvent, more preferably 30-60 wt%.

[0021] According to a specific embodiment of the present invention, preferably, the amount of the secondary auxiliary solvent added in the secondary extraction solvent accounts for 5-40 wt% of the amount of the secondary main solvent, more preferably 10-30 wt%.

[0022] According to a specific embodiment of the present invention, preferably, the amount of the tertiary auxiliary solvent added in the tertiary extraction solvent accounts for 5-40 wt% of the tertiary main solvent, more preferably 10-30 wt%.

[0023] According to a specific embodiment of the present invention, preferably, the temperature of the first-stage extraction is 40-70°C, more preferably 50-60°C.

[0024] According to a specific embodiment of the present invention, preferably, the temperature of the secondary extraction is 70-130°C, more preferably 90-120°C.

[0025] According to a specific embodiment of the present invention, preferably, the temperature of the three-stage extraction is 70-130°C, more preferably 110-130°C.

[0026] According to a specific embodiment of the present invention, preferably, in step (1), the agent-to-oil ratio is 1:1-10:1, more preferably 3:1-6:1.

[0027] According to a specific embodiment of the present invention, preferably, in step (2), the agent-to-oil ratio is 0.5:1-5:1, more preferably 2:1-3:1.

[0028] According to a specific embodiment of the present invention, preferably, in step (3), the agent-to-oil ratio is 0.5:1-5:1, more preferably 1:1-3:1.

[0029] According to a specific embodiment of the present invention, preferably, the primary solvent is one or a combination of two or more of propane, butane, isobutane, pentane, and isopentane, and the primary secondary solvent is one or a combination of two or more of propane, butane, pentane, and isopentane.

[0030] According to a specific embodiment of the present invention, preferably, the secondary primary solvent is one or a combination of two or more of furfural, N,N-dimethylformamide, methylpyrrolidone, ethylene glycol methyl ether, and sulfolane, and the secondary secondary auxiliary solvent is one or a combination of two or more of furfural, N,N-dimethylformamide, methylpyrrolidone, ethylene glycol methyl ether, and sulfolane.

[0031] According to a specific embodiment of the present invention, preferably, the tertiary primary solvent is dimethyl sulfoxide, and the tertiary secondary solvent is one or a combination of two or more of n-hexane, n-octane, n-decane, cyclohexane and their derivatives.

[0032] The present invention also provides the application of the above-described method for extracting alkanes with low aromatic and low cycloalkanes content from wax oil in the preparation of ethylene cracking feedstock from wax oil.

[0033] According to a specific embodiment of the present invention, preferably, the alkane-rich component is used as a feedstock for ethylene cracking.

[0034] According to a specific embodiment of the present invention, preferably, the primary extraction employs a solvent deasphalting device; the secondary or tertiary extraction employs a solvent extraction device.

[0035] The present invention has the following beneficial effects:

[0036] The three-stage extraction of this invention significantly improves the selectivity and solubility of the three-stage extraction solvent for components such as cycloalkanes by adding cycloalkanes and / or alkanes as tertiary auxiliary solvents to the three-stage extraction solvent. The cycloalkanes content of the obtained alkanes decreases, and their aromatic content also decreases. The addition of the tertiary auxiliary solvent not only creates a synergistic effect between the primary and auxiliary solvents, but also achieves further removal of cycloalkanes and aromatics, which can effectively improve the cracking performance of the product. Attached Figure Description

[0037] Figure 1 A schematic diagram of the process for separating nonpolar components, aromatics, and cycloalkanes from wax oil. Detailed Implementation

[0038] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0039] The raw materials used in the following examples and comparative examples were straight-run wax oil and hydrogenated wax oil, the specific compositions of which are shown in Table 1; the evaluation and analysis method was GC-MS analysis. A schematic diagram of the process for separating nonpolar components, aromatics, and cycloalkanes from wax oil according to this invention is shown below. Figure 1 As shown; unless otherwise specified, all "%" values ​​below refer to mass fractions.

[0040] Table 1 Composition of Wax Oil Raw Materials

[0041]

[0042] Example 1

[0043] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0044] (1) Primary extraction using straight-run wax oil as raw material: using propane as primary solvent and butane as primary auxiliary solvent (addition amount is 90% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 1 and a temperature of 70℃ to separate non-polar component H-1 and polar component I-1.

[0045] (2) Using H-1 as raw material, secondary extraction was carried out: using furfural as the secondary main solvent, secondary extraction was carried out at a solvent-to-oil ratio of 0.5 and a temperature of 130℃ to separate the aromatic component K-1 and the alkane component J-1.

[0046] (3) Three-stage extraction using J-1 as raw material: using sulfolane as the primary solvent and n-hexane as the secondary solvent (addition amount is 5% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 5 and a temperature of 70℃ to separate the cycloalkane-rich component M-1 and the aliphatic component L-1. The aliphatic component L-1 has a aliphatic content of 68.5%, a cycloalkane content of 24.8%, a monocyclic aromatic hydrocarbon content of 3.6%, a polycyclic aromatic hydrocarbon content of 3.1%, and a gum content of 0%.

[0047] Example 2

[0048] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0049] (1) Primary extraction using hydrogenated wax oil as raw material: using propane as primary solvent, primary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 60°C to separate non-polar component H-2 and polar component I-2.

[0050] (2) Using H-2 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and N,N-dimethylformamide was used as the secondary auxiliary solvent (the amount added was 10% of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 130℃ to separate the aromatic component K-2 and the alkane component J-2.

[0051] (3) Three-stage extraction using J-2 as raw material: using dimethyl sulfoxide as the primary solvent and n-octane + cyclohexane (mass ratio 1:1) as the secondary solvent (addition amount is 10% of the primary solvent) for three-stage extraction at a solvent-to-oil ratio of 4 and a temperature of 80℃, the cycloalkane-rich component M-2 and the aliphatic component L-2 were separated. The aliphatic component L-2 had a aliphatic content of 73.4%, a cycloalkane content of 22.2%, a monocyclic aromatic hydrocarbon content of 2.9%, a polycyclic aromatic hydrocarbon content of 1.5%, and a gum content of 0%.

[0052] Example 3

[0053] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0054] (1) Primary extraction using straight-run wax oil as raw material: using propane as primary solvent and pentane as primary auxiliary solvent (addition amount is 70% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 3 and a temperature of 50℃ to separate non-polar component H-3 and polar component I-3.

[0055] (2) Using H-3 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 20% of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate K-3, which is rich in aromatic components and J-3, which is rich in alkane components.

[0056] (3) Three-stage extraction using J-3 as raw material: using sulfolane as the primary solvent and n-decane as the secondary solvent (addition amount is 20% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 3 and a temperature of 90℃ to separate the cycloalkane-rich component M-3 and the aliphatic component L-3. The aliphatic component L-3 has an aliphatic content of 67.3%, a cycloalkane content of 25.2%, a monocyclic aromatic hydrocarbon content of 4%, a polycyclic aromatic hydrocarbon content of 3.5%, and a gum content of 0%.

[0057] Example 4

[0058] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0059] (1) Primary extraction using hydrogenated wax oil as raw material: using propane as primary solvent and isobutane as primary auxiliary solvent (addition amount is 60% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 4 and a temperature of 40℃ to separate non-polar component H-4 and polar component I-4.

[0060] (2) Using H-4 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 30% of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 3 and a temperature of 110°C to separate the aromatic component K-4 and the alkane component J-4.

[0061] (3) Three-stage extraction using J-4 as raw material: using dimethyl sulfoxide as the primary solvent and cyclohexane as the secondary solvent (30% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 100°C to separate the cycloalkane-rich component M-4 and the aliphatic component L-4. The aliphatic component L-4 had a 74.8% aliphatic content, a 21% cycloalkane content, a 3% monocyclic aromatic content, a 1.2% polycyclic aromatic content, and a 0% gum content.

[0062] Example 5

[0063] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0064] (1) Primary extraction using straight-run wax oil as raw material: using butane as primary solvent and propane as primary auxiliary solvent (addition amount is 50% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 5 and a temperature of 70℃ to separate non-polar component H-5 and polar component I-5.

[0065] (2) Using H-5 as raw material, secondary extraction was carried out: N,N-dimethylformamide was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 0.4 of the amount of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 100℃ to separate K-5, which is rich in aromatic components and J-5, which is rich in alkane components.

[0066] (3) Three-stage extraction using J-5 as raw material: using sulfolane as the primary solvent and methylcyclohexane as the secondary solvent (40% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 110°C to separate the cycloalkane-rich component M-5 and the aliphatic component L-5. The aliphatic component L-5 had a 69.1% aliphatic content, a 25% cycloalkane content, a 3.9% monocyclic aromatic content, a 2% polycyclic aromatic content, and a 0% gum content.

[0067] Example 6

[0068] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0069] (1) Primary extraction using hydrogenated wax oil as raw material: using butane as primary main solvent and isobutane as primary secondary solvent (addition amount is 40% of primary main solvent), primary extraction is carried out at a solvent-to-oil ratio of 6 and a temperature of 60℃ to separate non-polar component H-6 and polar component I-6.

[0070] (2) Using H-6 as raw material, secondary extraction was carried out: using methylpyrrolidone as the secondary main solvent and ethylene glycol methyl ether as the secondary auxiliary solvent (the amount added was 5% of the secondary main solvent), secondary extraction was carried out at a solvent-to-oil ratio of 3 and a temperature of 90°C to separate K-6, which is rich in aromatic components and J-6, which is rich in alkane components.

[0071] (3) Three-stage extraction using J-6 as raw material: using dimethyl sulfoxide as the primary solvent and p-dimethylcyclohexane as the secondary solvent (addition amount is 5% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 0.5 and a temperature of 120℃ to separate the cycloalkane-rich component M-6 and the aliphatic component L-6. The aliphatic component L-6 has an aliphatic content of 75.1%, a cycloalkane content of 20.9%, a monocyclic aromatic hydrocarbon content of 2.9%, a polycyclic aromatic hydrocarbon content of 1.1%, and a gum content of 0%.

[0072] Example 7

[0073] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0074] (1) Primary extraction using straight-run wax oil as raw material: using butane as primary solvent and pentane as primary auxiliary solvent (addition amount is 30% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 7 and a temperature of 50℃ to separate non-polar component H-7 and polar component I-7.

[0075] (2) Using H-7 as raw material, secondary extraction was carried out: ethylene glycol methyl ether was used as the secondary main solvent and sulfolane was used as the secondary auxiliary solvent (the amount added was 0.2 of the amount of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 4 and a temperature of 80°C to separate K-7, which is rich in aromatic components and J-7, which is rich in alkane components.

[0076] (3) Three-stage extraction using J-7 as raw material: using sulfolane as the primary solvent and 1,3,5-trimethylcyclohexane as the secondary solvent (addition amount is 10% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 5 and a temperature of 130℃ to separate the cycloalkane-rich component M-7 and the aliphatic component L-7. The aliphatic component L-7 had an aliphatic content of 68.7%, a cycloalkane content of 23.9%, a monocyclic aromatic hydrocarbon content of 3.8%, a polycyclic aromatic hydrocarbon content of 3.6%, and a gum content of 0%.

[0077] Example 8

[0078] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0079] (1) Primary extraction using hydrogenated wax oil as raw material: using butane as primary main solvent and pentane as primary secondary solvent (addition amount is 20% of primary main solvent), primary extraction is carried out at a solvent-to-oil ratio of 8 and a temperature of 40℃ to separate non-polar component H-8 and polar component I-8.

[0080] (2) Using H-8 as raw material, secondary extraction was carried out: using sulfolane as the secondary main solvent and furfural as the secondary auxiliary solvent (the amount added was 30% of the secondary main solvent), secondary extraction was carried out at a solvent-to-oil ratio of 5 and a temperature of 70°C to separate K-8, which is rich in aromatic components and J-8, which is rich in alkane components.

[0081] (3) Three-stage extraction using J-8 as raw material: using dimethyl sulfoxide as the primary solvent and 1,2,4,5-tetramethylcyclohexane as the secondary solvent (added at 20% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 4 and a temperature of 70°C to separate the cycloalkane-rich component M-8 and the aliphatic component L-8. The aliphatic component L-8 had an aliphatic content of 74.4%, a cycloalkane content of 21.1%, a monocyclic aromatic hydrocarbon content of 2.5%, a polycyclic aromatic hydrocarbon content of 2%, and a gum content of 0%.

[0082] Example 9

[0083] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0084] (1) Primary extraction using straight-run wax oil as raw material: using pentane as primary solvent and propane as primary auxiliary solvent (addition amount is 10% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 9 and a temperature of 70℃ to separate non-polar component H-9 and polar component I-9.

[0085] (2) Using H-9 as raw material, secondary extraction was carried out: ethylene glycol methyl ether was used as the secondary main solvent and sulfolane was used as the secondary auxiliary solvent (the amount added was 0.1 of the amount of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 0.5 and a temperature of 130°C to separate K-9, which is rich in aromatic components and J-9, which is rich in alkane components.

[0086] (3) Three-stage extraction using J-9 as raw material: using sulfolane as the primary solvent and methylcyclohexane as the secondary solvent (30% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 3 and a temperature of 80°C to separate the cycloalkane-rich component M-9 and the aliphatic component L-9. The aliphatic component L-9 had an aliphatic content of 68.9%, a cycloalkane content of 24.4%, a monocyclic aromatic hydrocarbon content of 3.5%, a polycyclic aromatic hydrocarbon content of 3.2%, and a gum content of 0%.

[0087] Example 10

[0088] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0089] (1) Primary extraction using hydrogenated wax oil as raw material: using pentane as primary solvent and butane as primary auxiliary solvent (addition amount is 20% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 10 and a temperature of 60℃ to separate non-polar component H-10 and polar component I-10.

[0090] (2) Using H-10 as raw material, secondary extraction was carried out: using sulfolane as the secondary main solvent and N,N-dimethylformamide as the secondary auxiliary solvent (the amount added was 10% of the secondary main solvent), secondary extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 130℃ to separate K-10, which is rich in aromatic components and J-10, which is rich in alkane components.

[0091] (3) Three-stage extraction using J-10 as raw material: using dimethyl sulfoxide as the primary solvent and p-dimethylcyclohexane as the secondary solvent (40% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 90°C to separate the cycloalkane-rich component M-10 and the aliphatic component L-10. The aliphatic component L-10 had a 73.9% aliphatic content, a 22.8% cycloalkane content, a 2.3% monocyclic aromatic content, a 1% polycyclic aromatic content, and a 0% gum content.

[0092] Example 11

[0093] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0094] (1) Primary extraction using straight-run wax oil as raw material: using pentane as primary solvent and butane as primary auxiliary solvent (addition amount is 40% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 6 and a temperature of 50℃ to separate non-polar component H-11 and polar component I-11.

[0095] (2) Using H-11 as raw material, a two-stage extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 0.1 of the secondary main solvent). The two-stage extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate the aromatic component K-11 and the alkane component J-11.

[0096] (3) Three-stage extraction using J-11 as raw material: using sulfolane as the primary solvent and 1,3,5-trimethylcyclohexane + methylcyclohexane (mass ratio 1:1) as the secondary solvent (addition amount is 20% of the primary solvent) for three-stage extraction at a solvent-to-oil ratio of 1 and a temperature of 100℃, the cycloalkane-rich component M-11 and the aliphatic component L-11 were separated. The aliphatic component L-11 had a 69.5% aliphatic content, a 24.9% cycloalkane content, a 3.2% monocyclic aromatic content, a 2.4% polycyclic aromatic content, and a 0% gum content.

[0097] Example 12

[0098] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0099] (1) Primary extraction using hydrogenated wax oil as raw material: using pentane as primary solvent and isobutane as primary auxiliary solvent (addition amount is 60% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 1 and a temperature of 40℃ to separate non-polar component H-12 and polar component I-12.

[0100] (2) Using H-12 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 30% of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 3 and a temperature of 110°C to separate the aromatic component K-12 and the alkane component J-12.

[0101] (3) Three-stage extraction using J-12 as raw material: using sulfolane as the primary solvent and 1,2,4,5-tetramethylcyclohexane as the secondary solvent (addition amount is 10% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 0.5 and a temperature of 110℃ to separate the cycloalkane-rich component M-12 and the aliphatic component L-12. The aliphatic component L-12 had an aliphatic content of 75.6%, a cycloalkane content of 21%, a monocyclic aromatic hydrocarbon content of 2.1%, a polycyclic aromatic hydrocarbon content of 1.3%, and a gum content of 0%.

[0102] Example 13

[0103] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0104] (1) Primary extraction using straight-run wax oil as raw material: Isobutane is used as the primary solvent and propane is used as the primary auxiliary solvent (the amount added is 50% of the primary solvent). Primary extraction is carried out at a solvent-to-oil ratio of 2 and a temperature of 70°C to separate the non-polar component H-13 and the polar component I-13.

[0105] (2) Using H-13 as raw material, secondary extraction was carried out: N,N-dimethylformamide was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 0.4 of the amount of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 100℃ to separate K-13, which is rich in aromatic components and J-13, which is rich in alkane components.

[0106] (3) Three-stage extraction using J-13 as raw material: using sulfolane as the primary solvent and n-hexane as the secondary solvent (30% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 5 and a temperature of 120°C to separate the cycloalkane-rich component M-13 and the aliphatic component L-13. The aliphatic component L-13 had a 68.2% aliphatic content, a 25.8% cycloalkane content, a 3.6% monocyclic aromatic content, a 2.4% polycyclic aromatic content, and a 0% gum content.

[0107] Example 14

[0108] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0109] (1) Primary extraction using hydrogenated wax oil as raw material: Isobutane is used as the primary solvent and pentane is used as the primary auxiliary solvent (the amount added is 40% of the primary solvent). Primary extraction is carried out at a solvent-to-oil ratio of 3 and a temperature of 60°C to separate the non-polar component H-14 and the polar component I-14.

[0110] (2) Using H-14 as raw material, secondary extraction was carried out: using methylpyrrolidone as the secondary main solvent and ethylene glycol methyl ether as the secondary auxiliary solvent (the amount added was 5% of the secondary main solvent), secondary extraction was carried out at a solvent-to-oil ratio of 3 and a temperature of 90°C to separate K-14, which is rich in aromatic components and J-14, which is rich in alkane components.

[0111] (3) Three-stage extraction using J-14 as raw material: using dimethyl sulfoxide as the primary solvent and n-octane as the secondary solvent (30% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 4 and a temperature of 130°C to separate the cycloalkane-rich component M-14 and the aliphatic component L-14. The aliphatic component L-14 had a 75% aliphatic content, a 21.4% cycloalkane content, a 2% monocyclic aromatic content, a 1.6% polycyclic aromatic content, and a 0% gum content.

[0112] Example 15

[0113] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0114] (1) Primary extraction using straight-run wax oil as raw material: Isopentane is used as the primary solvent and isobutane is used as the primary auxiliary solvent (the amount added is 30% of the primary solvent). Primary extraction is carried out at a solvent-to-oil ratio of 4 and a temperature of 50°C to separate H-15, which is rich in non-polar component and I-15, which is rich in polar component.

[0115] (2) Using H-15 as raw material, a two-stage extraction was carried out: using ethylene glycol methyl ether as the secondary main solvent and sulfolane as the secondary auxiliary solvent (the amount added was 0.2 of the amount of the secondary main solvent), the two-stage extraction was carried out at a solvent-to-oil ratio of 4 and a temperature of 80°C to separate the aromatic component K-15 and the alkane component J-15.

[0116] (3) Three-stage extraction using J-15 as raw material: using sulfolane as the primary solvent and n-decane + n-octane (mass ratio 1:1) as the secondary solvent (addition amount is 40% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 3 and a temperature of 110℃ to separate the cycloalkane-rich component M-15 and the aliphatic component L-15. The aliphatic component L-15 has an aliphatic content of 69.1%, a cycloalkane content of 26%, a monocyclic aromatic hydrocarbon content of 2.9%, a polycyclic aromatic hydrocarbon content of 2%, and a gum content of 0%.

[0117] Example 16

[0118] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0119] (1) Primary extraction using hydrogenated wax oil as raw material: Isopentane is used as the primary solvent and propane is used as the primary auxiliary solvent (the amount added is 20% of the primary solvent). Primary extraction is carried out at a solvent-to-oil ratio of 5 and a temperature of 40°C to separate the non-polar component H-16 and the polar component I-16.

[0120] (2) Using H-16 as raw material, secondary extraction was carried out: using sulfolane as the secondary main solvent and furfural as the secondary auxiliary solvent (the amount added was 30% of the secondary main solvent), secondary extraction was carried out at a solvent-to-oil ratio of 5 and a temperature of 70°C to separate the aromatic component K-16 and the alkane component J-16.

[0121] (3) Three-stage extraction using J-16 as raw material: using dimethyl sulfoxide as the primary solvent and cyclohexane as the secondary solvent (addition amount is 10% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120℃ to separate the cycloalkane-rich component M-16 and the aliphatic component L-16. The aliphatic component L-16 has an aliphatic content of 74.2%, a cycloalkane content of 20%, a monocyclic aromatic hydrocarbon content of 4.6%, a polycyclic aromatic hydrocarbon content of 1.2%, and a gum content of 0%.

[0122] Example 17

[0123] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0124] (1) Primary extraction using straight-run wax oil as raw material: using pentane as primary solvent and butane as primary auxiliary solvent (addition amount is 40% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 6 and a temperature of 50℃ to separate non-polar component H-17 and polar component I-17.

[0125] (2) Using H-17 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 10% of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate K-17, which is rich in aromatic components and J-17, which is rich in alkane components.

[0126] (3) Three-stage extraction using J-17 as raw material: using sulfolane as the primary solvent and n-hexane as the secondary solvent (addition amount is 20% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 100℃ to separate the cycloalkane-rich component M-17 and the aliphatic component L-17. The aliphatic component L-17 has an aliphatic content of 66.7%, a cycloalkane content of 27.0%, a monocyclic aromatic hydrocarbon content of 3.7%, a polycyclic aromatic hydrocarbon content of 2.6%, and a gum content of 0%.

[0127] Example 18

[0128] This embodiment provides a method for extracting alkanes from wax oil, which includes the following steps:

[0129] (1) The wax oil after mixing straight-run wax oil and hydrogenated wax oil at a mass ratio of 1:1 was used as raw material for primary extraction: pentane was used as the primary main solvent and butane was used as the primary secondary solvent (the amount added was 40% of the primary main solvent). The primary extraction was carried out at a solvent-to-oil ratio of 6 and a temperature of 50°C to separate the non-polar component H-18 and the polar component I-18.

[0130] (2) Using H-18 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 10% of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate the aromatic component K-18 and the alkane component J-18.

[0131] (3) Three-stage extraction using J-18 as raw material: using sulfolane as the primary solvent and 1,3,5-trimethylcyclohexane + methylcyclohexane (mass ratio 1:1) as the secondary solvent (addition amount is 20% of the primary solvent) for three-stage extraction at a solvent-to-oil ratio of 1 and a temperature of 100℃, the cycloalkane-rich component M-18 and the aliphatic component L-18 were separated. The aliphatic component L-18 had a 71.2% aliphatic content, a 24.2% cycloalkane content, a 3.6% monocyclic aromatic content, a 2.0% polycyclic aromatic content, and a 0% gum content.

[0132] Comparative Example 1

[0133] This comparative example provides a method for extracting alkanes from wax oil, which includes the following steps:

[0134] (1) Primary extraction using straight-run wax oil as raw material: using pentane as primary solvent and butane as primary auxiliary solvent (addition amount is 40% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 6 and a temperature of 50℃ to separate non-polar component H1 and polar component I1.

[0135] (2) Using H1 as raw material, a two-stage extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (10% of the amount added to the secondary main solvent). The two-stage extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate the aromatic component K1 and the alkane component J1. The alkane content of component J1 was 59.2%, the cycloalkanes content was 31.6%, the monocyclic aromatics content was 5.5%, the polycyclic aromatics content was 3.7%, and the gum content was 0%.

[0136] Comparative Example 2

[0137] This comparative example provides a method for extracting alkanes from wax oil, which includes the following steps:

[0138] (1) Extraction using straight-run wax oil as raw material: using pentane as the main solvent and butane as the auxiliary solvent (40% of the amount added as the main solvent), extraction was carried out at a solvent-to-oil ratio of 6 and a temperature of 50°C to separate the non-polar component H2 and the polar component I2.

[0139] (2) Using H2 as raw material, extraction was carried out with sulfolane as the main solvent and 1,3,5-trimethylcyclohexane + methylcyclohexane (mass ratio 1:1) as the auxiliary solvent (the amount added was 20% of sulfolane). The extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 100℃ to separate the cycloalkane-rich component M2 and the aliphatic component L2. The aliphatic component L2 had a 58.3% aliphatic hydrocarbon content, a 28.8% cycloalkane content, a 6.6% monocyclic aromatic hydrocarbon content, a 6.3% polycyclic aromatic hydrocarbon content, and a 0% gum content.

[0140] Comparative Example 3

[0141] This comparative example provides a method for extracting alkanes from wax oil, which includes the following steps:

[0142] (1) Extraction using straight-run wax oil as raw material: Furfural as the main solvent and methylpyrrolidone as the auxiliary solvent (10% of the amount added to the main solvent) were used for extraction at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate aromatic component K3 and alkane component J3.

[0143] (2) Extraction was carried out using J3 as raw material, with sulfolane as the main solvent and 1,3,5-trimethylcyclohexane + methylcyclohexane (mass ratio 1:1) as the auxiliary solvent (addition amount was 20% of sulfolane). Extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 100℃ to separate the cycloalkane-rich component M3 and the aliphatic component L3. The aliphatic component L3 had a aliphatic content of 57.7%, a cycloalkane content of 27.3%, a monocyclic aromatic hydrocarbon content of 7.9%, a polycyclic aromatic hydrocarbon content of 7.1%, and a gum content of 0%.

[0144] Comparative Example 4

[0145] This comparative example provides a method for extracting alkanes from wax oil, which includes the following steps:

[0146] (1) Primary extraction using straight-run wax oil as raw material: using pentane as primary solvent and butane as primary auxiliary solvent (addition amount is 40% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 6 and a temperature of 50℃ to separate non-polar component H4 and polar component I4.

[0147] (2) Using H4 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 0.1 of the amount of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate the aromatic component K4 and the alkane component J4.

[0148] (3) Three-stage extraction using J4 as raw material: using butanone as the primary solvent and toluene as the secondary solvent (80% of the primary solvent), three-stage extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 20°C to separate the cycloalkane-rich component M4 and the aliphatic component L4. The aliphatic component L4 had a 62.5% aliphatic content, a 29.9% cycloalkane content, a 4.3% monocyclic aromatic hydrocarbon content, a 3.3% polycyclic aromatic hydrocarbon content, and a 0% gum content.

[0149] Comparative Example 5

[0150] This comparative example provides a method for extracting alkanes from wax oil, which includes the following steps:

[0151] (1) Primary extraction using straight-run wax oil as raw material: using pentane as primary solvent and butane as primary auxiliary solvent (addition amount is 40% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 6 and a temperature of 50℃ to separate non-polar component H5 and polar component I5.

[0152] (2) Using H5 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 10% of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate K5, which is rich in aromatic components and J5, which is rich in alkane components.

[0153] (3) Using J5 as raw material, freeze separation was carried out at -20℃ to separate M5, which is rich in cycloalkanes, and L5, which is rich in alkanes. The alkanes content of component L5 is 59.7%, the cycloalkanes content is 31.8%, the monocyclic aromatics content is 4.7%, the polycyclic aromatics content is 3.8%, and the gum content is 0%.

[0154] Comparative Example 6

[0155] This comparative example provides a method for extracting alkanes from wax oil, which includes the following steps:

[0156] (1) Primary extraction using straight-run wax oil as raw material: using pentane as primary solvent and butane as primary auxiliary solvent (addition amount is 40% of primary solvent), primary extraction is carried out at a solvent-to-oil ratio of 6 and a temperature of 50℃ to separate non-polar component H6 and polar component I6.

[0157] (2) Using H6 as raw material, secondary extraction was carried out: furfural was used as the secondary main solvent and methylpyrrolidone was used as the secondary auxiliary solvent (the amount added was 0.1 of the amount of the secondary main solvent). Secondary extraction was carried out at a solvent-to-oil ratio of 2 and a temperature of 120°C to separate the aromatic component K6 and the alkane component J6.

[0158] (3) Three-stage extraction using J6 as raw material: using sulfolane as the main solvent in the three-stage extraction, the three-stage extraction was carried out at a solvent-to-oil ratio of 1 and a temperature of 100℃ to separate the cycloalkane-rich component M6 and the aliphatic component L6. The aliphatic component L6 had a 63.1% aliphatic content, a 29.8% cycloalkane content, a 4.1% monocyclic aromatic hydrocarbon content, a 3.0% polycyclic aromatic hydrocarbon content, and a 0% gum content.

[0159] The specific schemes of the embodiments and comparative examples are shown in Tables 2 and 3.

[0160]

[0161]

[0162] As shown in Tables 2 and 3, based on the results of Example 11 and Comparative Example 6, the addition of cycloalkane-based auxiliary solvents to the extraction solvent in three-stage extraction significantly increased the selectivity and solubility of cycloalkane and other components. Compared with three-stage extraction using only a single solvent, the cycloalkane content in the alkane component decreased by 2.3 percentage points. Simultaneously, the results also showed a 2.5 percentage point decrease in aromatics in the alkane component. The addition of this tertiary auxiliary solvent not only created a synergistic effect between the primary and auxiliary solvents in the tertiary extraction but also achieved further removal of cycloalkane and aromatics, effectively improving the cracking performance of the product.

Claims

1. A method for extracting alkanes with low aromatic and cycloalkanes content from wax oil, comprising the following steps: (1) The wax oil was subjected to primary extraction using a primary extraction solvent to obtain a mixture rich in non-polar and polar components. (2) The nonpolar-rich component is subjected to secondary extraction using a secondary extraction solvent to obtain an alkane-rich component and an aromatic-rich component; (3) The alkane-rich component is subjected to three-stage extraction using a three-stage extraction solvent to obtain a chain alkane-rich component and a cycloalkane-rich component; The primary extraction solvent includes a primary main solvent and a primary secondary solvent, wherein the primary main solvent and the primary secondary solvent are C3-C5 alkanes, respectively. The secondary extraction solvent includes a secondary primary solvent and a secondary secondary solvent, each of which is independently selected from one or more of furfural, N,N-dimethylformamide, morpholino, methylpyrrolidone, ethylene glycol methyl ether, and sulfolane. The tertiary extraction solvent includes a tertiary primary solvent and a tertiary secondary solvent. The tertiary primary solvent is sulfolane and / or dimethyl sulfoxide, and the tertiary secondary solvent is C6-C10 alkanes and / or C6-C10 cycloalkanes. In the tertiary extraction solvent, the amount of the tertiary secondary solvent added accounts for 5-40 wt% of the tertiary primary solvent. The temperature for the three-stage extraction is 70-130℃; The wax oil comprises, by mass percentage, 49-53% alkanes, 37-42% cycloalkanes and 7-10% aromatics; The temperature for the first-stage extraction is 40-70℃; The temperature for the secondary extraction is 70-130℃.

2. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, The primary solvent is different from the primary secondary solvent.

3. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, The secondary primary solvent is different from the secondary secondary solvent.

4. The method for extracting alkanes with low aromatic and low cycloalkanes content from wax oil according to claim 1, wherein, The wax oil is a straight-run wax oil and / or a hydrogenated wax oil.

5. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, In the primary extraction solvent, the amount of the primary auxiliary solvent added accounts for 10-90 wt% of the primary main solvent.

6. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1 or 5, wherein, In the primary extraction solvent, the amount of the primary auxiliary solvent added accounts for 30-60 wt% of the primary main solvent.

7. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, In the secondary extraction solvent, the amount of the secondary auxiliary solvent added accounts for 5-40 wt% of the amount of the secondary main solvent.

8. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1 or 7, wherein, In the secondary extraction solvent, the amount of the secondary auxiliary solvent added accounts for 10-30 wt% of the amount of the secondary main solvent.

9. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, In the tertiary extraction solvent, the amount of the tertiary auxiliary solvent added accounts for 10-30 wt% of the tertiary main solvent.

10. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, The temperature of the first-stage extraction is 50-60℃.

11. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, The temperature for the secondary extraction is 90-120℃.

12. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, The temperature for the three-stage extraction is 110-130℃.

13. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, In step (1), the agent-to-oil ratio is 1:1-10:

1.

14. The method for extracting alkanes with low aromatic and cycloalkanes content from wax oil according to claim 1 or 13, wherein, In step (1), the agent-to-oil ratio is 3:1-6:

1.

15. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, In step (2), the agent-to-oil ratio is 0.5:1-5:

1.

16. The method for extracting alkanes with low aromatic and low cycloalkanes content from wax oil according to claim 1 or 15, wherein, In step (2), the agent-to-oil ratio is 2:1-3:

1.

17. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, In step (3), the agent-to-oil ratio is 0.5:1-5:

1.

18. The method for extracting alkanes with low aromatic and cycloalkanes content from wax oil according to claim 1 or 17, wherein, In step (3), the agent-to-oil ratio is 1:1-3:

1.

19. The method for extracting alkanes with low aromatic and low cycloalkane content from wax oil according to claim 1, wherein, The primary solvent is one or a combination of two or more of propane, butane, isobutane, pentane, and isopentane, and the secondary solvent is one or a combination of two or more of propane, butane, pentane, and isopentane.

20. The method for extracting alkanes with low aromatic and cycloalkanes content from wax oil according to claim 1, wherein, The secondary primary solvent is one or a combination of two or more of furfural, N,N-dimethylformamide, methylpyrrolidone, ethylene glycol methyl ether, and sulfolane, and the secondary secondary auxiliary solvent is one or a combination of two or more of furfural, N,N-dimethylformamide, methylpyrrolidone, ethylene glycol methyl ether, and sulfolane.

21. The method for extracting alkanes with low aromatic and low cycloalkanes content from wax oil according to any one of claims 1-20, in the preparation of ethylene cracking feedstock from wax oil; The alkane-rich component is used as a feedstock for ethylene cracking.

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