A method for preparing low pour point, high aromatic, and environmentally friendly rubber oil by a combination of extraction and dewaxing.

Abstract

A method for preparing low-pour-point, high-aromatic, environmentally friendly rubber oil by a combination of extraction and dewaxing is characterized by the use of three solvents: the main extraction solvent (hereinafter referred to as the main solvent) is N-methylpyrrolidone, the secondary extraction solvent is C7-C12 alkanes, and the solubilizer is one or a mixture of two or three of benzene, toluene, and xylene; the extracted oil is used as the feed oil, and the extraction process is carried out using an extraction tower. The main extraction solvent enters the upper part of the extraction tower, the feed oil enters the middle and lower parts, and the secondary solvent enters the lower part; the material at the bottom of the extraction tower is recovered by solvent to obtain secondary extracted oil; the material flowing out from the top of the extraction tower is mixed with the pumped solubilizer and part of the main solvent in a static mixer and then cooled to -15 to 10°C in a cooler, and then filtered to obtain wax paste and filtrate; the wax paste is heated and evaporated to recover the solvent to obtain wax; the filtrate is heated and evaporated to recover the solvent to obtain dewaxed oil, i.e., low-pour-point, high-aromatic, environmentally friendly rubber oil.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, and more specifically to a method for preparing low pour point, high aromatic, and environmentally friendly rubber oil by a combination of extraction and dewaxing, classified under international patent category C10G. Background Technology

[0002] Rubber oil is a type of oil used in rubber processing and production, including rubber filler oil and processing oil. It generally uses mineral oil, but vegetable oil and synthetic oil are also used. Rubber oil that meets REACH regulations is called environmentally friendly rubber oil, or petroleum-based plasticizer in China. This means that when added to oils directly put on the market or used in tire manufacturing, the benzo[a]pyrene (BaP) content should be less than 1 mg / kg, and the content of eight polycyclic aromatic hydrocarbons (benzo[a]pyrene (BaP), benzo[e]pyrene (BeP), benzo[a]anthracene (BaA), benzo[k]fluoranthene (BkFA), and benzo[b]fluoranthene (BbFA) should also be controlled. (CHR), benzo[j]fluoranthene (BjFA), dibenzo[a,h]anthracene (DBahA)), the total content should be less than 10 mg / kg. High-aromatic environmentally friendly rubber oil refers to environmentally friendly rubber oil containing more aromatic components, and its aromatic carbon content (C A It generally has a high content of oil, good compatibility with rubber, and the processed rubber products will not produce oil (sweat), and the rubber has good stability.

[0003] High-aromatic environmentally friendly rubber oils generally use extracted oil as raw material. Extracted oil is a heavy oil with high aromatic content that is a byproduct of the lubricant production process. In the traditional lubricant production process, furfural, phenol, and N-methylpyrrolidone are used as extraction solvents to extract wax oil, resulting in extracted oil and raffinate. The raffinate can be used as a base oil for lubricants after dewaxing, while the extracted oil contains a large amount of heavy aromatics and gums, and is a high-viscosity heavy oil.

[0004] However, when lubricant production adopts a forward production process, that is, a process of solvent refining followed by dewaxing, the produced extract oil will contain wax. When extract oil containing this wax is used as raw material to produce rubber plasticizers, the produced rubber plasticizers have a high pour point due to their high wax content. Rubber processing companies need to heat them before use. The presence of wax will also affect the performance of rubber. Therefore, it is of great significance to produce low wax content, low pour point, and high aromatic rubber oils.

[0005] To produce low pour point rubber oil, either the extracted oil or the rubber oil can be dewaxed first. Oil dewaxing typically employs methods such as solvent dewaxing, urea dewaxing, hydroisomerization dewaxing, and hydropowder dewaxing. However, because extracted oil contains a large amount of gum and heavy aromatics, these methods are unsuitable. Solvent dewaxing is a commonly used traditional method, frequently employed for lubricating oils. It generally uses a composite solvent, typically composed of acetone, butanone, and methyl isobutyl ketone, combined with toluene and benzene. Commonly used composite solvents are butanone-toluene and acetone-benzene. Methyl isobutyl ketone can also be used alone as a dewaxing solvent. The composite solvent is mixed with the oil to be dewaxed, then cooled to crystallize, followed by filtration to separate the wax paste and filtrate. These processes are generally used for wax oils with high wax content and low viscosity, or for residual oils, where the resulting wax crystals are large and easily filtered. For extracted oil and rubber oil produced using extracted oil as raw material, due to the large amount of heavy aromatics and gums, the viscosity is high, the color is dark, and the wax content is low. Moreover, the wax in the extracted oil is mainly isomer wax. When using a composite solvent composed of acetone, butanone, methyl isobutyl ketone, toluene, and benzene as the dewaxing solvent, there is a problem that the wax crystals are small and easily clog the pores of the filter cloth, making it difficult to filter. There is also a problem of large temperature difference during dewaxing. Therefore, dewaxing of extracted oil and rubber oil has become a major problem. To solve this problem, the Petrochemical Research Institute of China Petroleum & Chemical Corporation conducted research and used the traditional toluene-butanone composite solvent as the dewaxing solvent. The dewaxing solvent was mixed with the extracted oil and cooled. During the dewaxing process, a dewaxing aid was added as a filter aid to solve the problem of difficult filtration. However, this process has problems such as large amount of filter aid used (5% addition) and high production cost (Guan Cuishi et al., Technical Development of Environmentally Friendly Rubber Filler Oil Produced from High Pour Point Aromatic Rich Raw Material, Petroleum Refining and Chemical Industry, 2013, 44(8): 33-36). Rubber oil dewaxing also encounters the same problems as oil extraction dewaxing.

[0006] Whether it's dewaxing extracted oil or dewaxing rubber oil, these oils need to undergo solvent dewaxing again, which increases equipment investment and energy consumption. New facilities also occupy a lot of land resources. If the wax in the rubber oil is removed during the production process, production costs will be reduced, investment will be lowered, and land resources will be saved.

[0007] Regarding the process of producing rubber oil from waxy extracted oil, our research group has proposed a new patent (ZL 201710703433.7) that can produce high-aromatic rubber filler oil. This patent application proposes a new method, which is a further improvement on the patent. By adding a dewaxing step to the process, it can solve the problem of small wax crystals that are difficult to filter in the current traditional dewaxing solvents used in rubber oil dewaxing, and prepare a low-pour-point, high-aromatic, environmentally friendly rubber oil. The specific invention content is as follows. Summary of the Invention

[0008] 1. A method for preparing low pour point, high aromatic, and environmentally friendly rubber oil by a combination of extraction and dewaxing, characterized by the use of three solvents: the main extraction solvent (hereinafter referred to as the main solvent) is N-methylpyrrolidone, the secondary extraction solvent is C7-C12 alkanes, and the solubilizer is one or a mixture of two or three of benzene, toluene, and xylene; the extracted oil is used as the feed oil, and the specific method is as follows:

[0009] (1) An extraction tower is used for the extraction process. The main extraction solvent enters the upper part of the extraction tower, the feed oil enters the middle and lower parts, and the auxiliary solvent enters the lower part.

[0010] (2) The bottom material (extracted liquid) of the extraction tower is recycled to obtain secondary extracted oil;

[0011] (3) The material (raffinate) flowing out from the top of the extraction tower is mixed with the pumped solubilizer and part of the main solvent in a static mixer and then cooled to -15 to 10°C in a cooler. Then it enters the filter to obtain wax paste and filtrate.

[0012] (4) The wax paste is heated and evaporated to recover the solvent, thus obtaining wax;

[0013] (5) The filtrate is heated and evaporated to recover the solvent, and dewaxed oil, i.e. low pour point high aromatic rubber oil, is obtained.

[0014] 2. The method for preparing low pour point high aromatic environmentally friendly rubber oil by extraction and dewaxing as described in 1, characterized in that the mass ratio of the main solvent entering the upper part of the extraction tower to the raw material oil is 2-3.5:1.

[0015] 3. The method for preparing low pour point high aromatic environmentally friendly rubber oil by extraction and dewaxing as described in 1, characterized in that the temperature of the lower part of the extraction tower is 40-60℃ and the temperature of the upper part is 60-80℃.

[0016] 4. The method for preparing low pour point high aromatic environmentally friendly rubber oil by extraction and dewaxing according to 1, characterized in that the volume ratio of the main solvent and the solubilizer mixed with the top material of the tower is 40-50:60-50.

[0017] 5. The method for preparing low pour point high aromatic environmentally friendly rubber oil by extraction and dewaxing according to 1, characterized in that the volume ratio of solubilizer to raw material oil is 1 to 3:1.

[0018] Beneficial effects of the invention

[0019] The method provided by this invention can solve the problems of small wax crystals and difficulty in filtration in the dewaxing of extracted oil and rubber oil using traditional dewaxing solvents, while producing high-aromatic environmentally friendly rubber oil. The resulting rubber oil has large wax crystals, low oil content, a small dewaxing temperature difference, and a low pour point. Compared with traditional solvent dewaxing, the filtration speed is increased by 30-50%, and the dewaxing temperature difference is reduced by 5-10℃. Another advantage of this patented method is that the residual liquid can be dewaxed using the original solvent without solvent recovery. This reduces investment and saves energy. Compared with distilling the residual liquid to recover the solvent, obtaining residual oil, and then using the residual oil for traditional solvent dewaxing with a toluene-methyl-ethyl ketone mixed solvent, energy consumption is reduced by more than 20%. Attached Figure Description

[0020] Appendix Figure 1 This is a schematic diagram of the production process of this invention patent, wherein: 1. Solubilizer tank; 2. Main solvent tank; 3. Raw material oil tank; 4. Secondary solvent tank; 5, 6, 7, 8. Pump; 9. Extraction tower; 10, 11, 12, 14. Heat exchanger; 13. Mixer; 15. Filter.

[0021] As shown in the figure, the main solvent enters from the top of the extraction tower via pump 6, the feed oil enters from the middle of the extraction tower via pump 7, and the auxiliary solvent enters from the bottom of the extraction tower via pump 8. The effluent flowing out from the bottom of the extraction tower is recovered by solvent to obtain secondary extracted oil. The raffinate flowing out from the top of the extraction tower, together with the solubilizer (from pump 5) and part of the main solvent, enters the heat exchanger 14 via mixer 13 for cooling and then enters the filter 15 for filtration to obtain wax paste and filtrate. The wax paste is recovered by solvent to obtain wax, and the filtrate is recovered by solvent to obtain low pour point high aromatic environmentally friendly rubber oil. The extraction section between the upper feed inlet (main solvent inlet) and the middle and lower feed inlet (feed oil inlet) of the extraction tower is called the first extraction section, and the extraction section between the feed oil inlet and the lower feed inlet (auxiliary solvent inlet) is called the second extraction section. Detailed Implementation

[0022] To further illustrate the present invention, a detailed description is provided below with reference to specific embodiments:

[0023] Example 1

[0024] The process uses a small extraction tower from the laboratory, as shown in the attached diagram. Figure 1As shown, the extraction tower has an inner diameter of 33 mm and is packed with wire mesh. The first extraction section is 2 m high, and the second extraction section is 1 m high. The main solvent is NMP, and the secondary solvent is heptane. The feedstock is extracted oil from a certain refinery's reduced-pressure extraction line, which has a pour point of 38℃. The NMP:feedstock:heptane ratio is 2.5:1:0.5 (by weight). The temperature of the second extraction section ranges from 50-55℃ from bottom to top, while the temperature of the first extraction section ranges from 55-70℃ from bottom to top. Raffinate is obtained at the top of the tower, and extractant is obtained at the bottom. Benzene and NMP were added to the raffinate. The amount of benzene added was 100% (by volume) of the feed oil flow rate, and the amount of NMP added was 100% of the amount of benzene. After mixing in a mixer, the mixture was cooled to -15°C in a heat exchanger and then filtered to obtain wax paste and filtrate. The wax paste was used to recover the solvent to obtain wax, with a wax yield of 12% of the feed oil. The filtrate was used to evaporate and recover the solvent to obtain environmentally friendly rubber oil with a yield of 55%. Its PCA content was 2.9%, benzo[a]pyrene content was 0.2 μg / g, and the total content of eight carcinogens was 2.1 μg / g. The content of each of the eight carcinogen monomers was less than 1 μg / g, and the aromatic carbon ratio C A With a purity of 25.0% and a pour point of 4℃, it meets the requirements for low-pour-point, high-aromatic, environmentally friendly rubber oil. Studies have found that the wax crystals are large, resulting in a smooth filtration process without clogging the filter.

[0025] Example 2

[0026] The process uses a small extraction tower from the laboratory, as shown in the attached diagram. Figure 1 As shown, the extraction tower has an inner diameter of 33 mm and is packed with wire mesh. The first extraction section is 2 m high, and the second extraction section is 1 m high. The main solvent is NMP, and the secondary solvent is a mixture of C6-C10 alkanes. The feedstock is extracted oil from a certain refinery, with a pour point of 38℃. The ratio of NMP:feedstock oil:secondary solvent is 2.5:1:0.3 (by weight). The temperature of the second extraction section ranges from 40-55℃ from bottom to top, while the temperature of the first extraction section ranges from 55-80℃ from bottom to top. Raffinate is obtained at the top of the tower, and extractant is obtained at the bottom. Toluene and NMP were added to the raffinate. The amount of toluene added was 300% of the feed oil flow rate, and the amount of NMP added was 200% of the feed oil volume. After mixing in a mixer, the mixture was cooled to -10°C in a heat exchanger and then filtered to obtain wax paste and filtrate. The wax paste was used to recover the solvent to obtain wax, with a wax yield of 10% of the feed oil. The filtrate was used to evaporate and recover the solvent to obtain environmentally friendly rubber oil with a yield of 56%. Its PCA content was 2.4%, benzo[a]pyrene content was 0.2 μg / g, and the total content of eight carcinogens was 2.1 μg / g. The content of each of the eight carcinogen monomers was less than 1 μg / g, and the aromatic carbon ratio C was [not specified]. A With a purity of 25.0% and a pour point of 8℃, it meets the requirements for low-pour-point, high-aromatic, environmentally friendly rubber oil. Studies have found that the wax crystals are large, resulting in a smooth filtration process without clogging the filter.

[0027] Example 3

[0028] The process uses a small extraction tower from the laboratory, as shown in the attached diagram. Figure 1 As shown, the extraction tower has an inner diameter of 33 mm and is packed with wire mesh. The first extraction section is 2 m high, and the second extraction section is 1 m high. The main solvent is NMP, and the secondary solvent is petroleum ether. The feedstock is extracted oil from a certain refinery's reduced-pressure line (4-line extraction), which has a pour point of 38℃. The NMP:feedstock:heptane ratio is 2.0:1:0.4 (by weight). The temperature of the second extraction section ranges from 50-55℃ from bottom to top, while the temperature of the first extraction section ranges from 55-70℃ from bottom to top. Raffinate is obtained at the top of the tower, and extractant is obtained at the bottom. Xylene and NMP were added to the raffinate. The amount of xylene added was 150% of the feed oil flow rate, and the amount of NMP added was 150% of the feed oil volume. After mixing in a mixer, the mixture was cooled to 10°C in a heat exchanger and then filtered to obtain wax paste and filtrate. The wax paste was used to recover the solvent to obtain wax, with a wax yield of 6% of the feed oil. The filtrate was used to evaporate and recover the solvent to obtain environmentally friendly rubber oil with a yield of 58%. Its PCA content was 2.4%, benzo[a]pyrene content was 0.2 μg / g, and the total content of eight carcinogens was 2.1 μg / g. The content of each of the eight carcinogen monomers was less than 1 μg / g, and the aromatic carbon ratio C was [not specified]. A With a purity of 25.0% and a pour point of 18℃, it meets the requirements for low-pour-point, high-aromatic, environmentally friendly rubber oil. Studies have found that the wax crystals are large, resulting in a smooth filtration process without clogging the filter.

[0029] Example 4

[0030] The process uses a small extraction tower from the laboratory, as shown in the attached diagram. Figure 1 As shown, the extraction tower has an inner diameter of 33 mm and is packed with wire mesh. The first extraction section is 2 m high, and the second extraction section is 1 m high. The main solvent is NMP, and the secondary solvent is petroleum ether. The feedstock is extracted oil from a certain refinery's reduced-pressure extraction line, which has a pour point of 38℃. The NMP:feedstock:petroleum ether ratio is 2.0:1:0.4 (by weight). The temperature of the second extraction section ranges from 50-55℃ from bottom to top, while the temperature of the first extraction section ranges from 55-70℃ from bottom to top. Raffinate is obtained at the top of the tower, and extractant is obtained at the bottom. A solubilizer and NMP (a mixture of benzene and toluene) were added to the raffinate at 150% of the feedstock flow rate. The NMP was added at 150% of the feedstock flow rate. After mixing, the mixture was cooled to 10°C in a heat exchanger and then filtered to obtain wax paste and filtrate. The wax paste was recovered to obtain wax at a yield of 6% of the feedstock flow rate. The filtrate was evaporated to recover the solvent and obtain environmentally friendly rubber oil at a yield of 58%. Its PCA content was 2.4%, benzo[a]pyrene content was 0.2 μg / g, and the total content of eight carcinogens was 2.1 μg / g. The content of each of the eight carcinogen monomers was less than 1 μg / g. The aromatic carbon percentage C... AWith a purity of 25.0% and a pour point of 18℃, it meets the requirements for low-pour-point, high-aromatic, environmentally friendly rubber oil. Studies have found that the wax crystals are large, resulting in a smooth filtration process without clogging the filter.

[0031] Example 5

[0032] The process uses a small extraction tower from the laboratory, as shown in the attached diagram. Figure 1 As shown, the extraction tower has an inner diameter of 33 mm and is packed with wire mesh. The first extraction section is 2 m high, and the second extraction section is 1 m high. The main solvent is NMP, and the secondary solvent is C12 alkanes. The feedstock is extracted oil from a certain refinery, with a pour point of 38℃. The NMP:feedstock:C12 ratio is 2.0:1:0.4 (by weight). The temperature in the second extraction section ranges from bottom to top from 60-70℃, and the temperature in the first extraction section ranges from bottom to top from 70-80℃. Raffinate is obtained at the top of the tower, and extractant is obtained at the bottom. The residual liquid was mixed with a solubilizer and NMP. The solubilizer was a mixture of benzene, toluene, and xylene in a 1:1:1 ratio, and the amount added was 200% of the feed oil flow rate. The amount of NMP was 150% of the feed oil volume. After mixing in a mixer, the mixture was cooled to 0°C in a heat exchanger and then filtered to obtain wax paste and filtrate. The wax paste was recovered from the solvent to obtain wax, with a wax yield of 10% of the feed oil. The filtrate was evaporated to recover the solvent to obtain environmentally friendly rubber oil with a yield of 56%. Its PCA content was 2.8%, benzo[a]pyrene content was 0.3 μg / g, and the total content of eight carcinogens was 4.2 μg / g. The content of each of the eight carcinogen monomers was less than 1 μg / g, and the aromatic carbon ratio C was [not specified]. A With a purity of 24.5% and a pour point of 10℃, it meets the requirements for low-pour-point, high-aromatic, environmentally friendly rubber oil. Studies have found that the wax crystals are large, resulting in a smooth filtration process without clogging the filter.

[0033] As can be seen from the above embodiments, the method of this patent can be used to prepare low pour point, high aromaticity, and environmentally friendly rubber oil. Of course, this invention may have other various embodiments. Without departing from the spirit and essence of this invention, those skilled in the art can make various corresponding changes and modifications according to this invention, but these corresponding changes and modifications should all fall within the protection scope of this invention.

Claims

1. A method for preparing low pour point, high aromatic, and environmentally friendly rubber oil by a combination of extraction and dewaxing, characterized in that... Three solvents are used: the main extraction solvent is N-methylpyrrolidone, the secondary extraction solvent is C7-C12 alkanes, and the solubilizer is one or a mixture of two or three of benzene, toluene, and xylene; the extracted oil is used as the feedstock, as detailed below: The extraction process is carried out using an extraction tower. The main extraction solvent enters the upper part of the extraction tower, the feed oil enters the middle and lower parts, and the secondary extraction solvent enters the lower part. The bottom material of the extraction tower is recycled by solvent to obtain secondary extracted oil; The material flowing out from the top of the extraction tower is mixed with the pumped solubilizer and part of the main extraction solvent in a static mixer and then cooled to -15~10℃ in a cooler. It then enters a filter to obtain wax paste and filtrate. The wax paste is heated and evaporated to recover the solvent, thus obtaining the wax. The solvent is recovered by heating and evaporating the filtrate to obtain dewaxed oil, which is a low pour point, high aromatic, environmentally friendly rubber oil.

2. The method for preparing low pour point, high aromatic, and environmentally friendly rubber oil by combined extraction and dewaxing according to claim 1, characterized in that... The mass ratio of the main extraction solvent to the feed oil entering the upper part of the extraction tower is 2-3.5:

1.

3. The method for preparing low pour point, high aromatic, environmentally friendly rubber oil by combined extraction and dewaxing according to claim 1, characterized in that... The temperature at the bottom of the extraction tower is 40-60℃, and the temperature at the top is 60-80℃.

4. The method for preparing low pour point, high aromatic, environmentally friendly rubber oil by combined extraction and dewaxing according to claim 1, characterized in that... The volume ratio of the main extraction solvent to the solubilizer mixed with the material flowing out from the top of the extraction tower is 40~50:60~50.

5. The method for preparing low pour point, high aromatic, environmentally friendly rubber oil by combined extraction and dewaxing according to claim 1, characterized in that... The volume ratio of solubilizer to feedstock oil is 1~3:1.

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