A process for the dewaxing of extract oil and rubber oil

Abstract

The present application relates to a kind of methods for extracting oil and rubber oil dewaxing, it is characterized in that using the composite solvent of polar solvent and solubilizer is dewaxing solvent, polar solvent uses N-methyl pyrrolidone, solubilizer is the mixture of one, two or three of benzene, toluene, xylene, above wax precipitation temperature, the composite solvent is mixed with extracting oil or rubber oil, then crystallization is cooled, filtration is obtained wax cream and filtrate, wax cream and filtrate are respectively heated and evaporated to recover solvent and obtain wax and dewaxed oil.

Description

A method for dewaxing oil and rubber oil Technical Field

[0001] This invention relates to the field of petrochemicals, and more specifically to a method for extracting oil and dewaxing rubber oil, classified under International Patent Classification C10G. Background Technology

[0002] Extracted oil is a heavy oil with high aromatic content, a byproduct of lubricant production. In traditional lubricant production, furfural, phenol, and N-methylpyrrolidone are used as extraction solvents to extract wax oil, yielding extracted oil and raffinate. The raffinate, after dewaxing, can be used as a base oil for lubricants, while the extracted oil contains a large amount of heavy aromatics and gums, making it a high-viscosity heavy oil. Extracted oil can be used as an asphalt modifier in the production of heavy-grade asphalt, improving its elongation and penetration. Additionally, extracted oil is a raw material for producing rubber plasticizers. Further extraction of the extracted oil can remove polycyclic aromatic hydrocarbons (PAHs), resulting in rubber oil (also called rubber plasticizer) with a low PAH content.

[0003] However, when lubricant production adopts a forward-sequence process, i.e., a process of solvent refining followed by dewaxing, the produced extract oil will contain wax. This wax will adversely affect the properties of asphalt, affecting its wax content and deteriorating its low-temperature performance. In addition, when extract oil containing this wax is used as raw material to produce rubber oil (rubber plasticizer), the produced rubber oil has a high pour point due to its high wax content. The presence of wax will also affect the performance of rubber. Therefore, dewaxing extract oil and rubber oil to produce low-pour-point dewaxed extract oil and rubber oil is of great significance.

[0004] Dewaxing of oil products typically employs methods such as solvent dewaxing, urea dewaxing, hydroisomerization dewaxing, and hydropowder dewaxing. However, these methods are unsuitable because the extracted oil contains a large amount of gum and heavy aromatics. Solvent dewaxing is a commonly used traditional method, frequently employed for lubricating oils. Solvent dewaxing 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 suitable for waxy 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 from extracted oil through re-extraction, due to the large amount of heavy aromatics and gums, high viscosity, dark color, and low wax content, and because the wax in extracted oil and rubber oil is mainly isomer wax with a low pour point, when using a composite solvent composed of acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, and benzene as a dewaxing solvent, there are problems such as fine wax crystals clogging the pores of the filter cloth, making filtration difficult, and large temperature differences during dewaxing. Therefore, dewaxing of extracted oil and rubber oil has become a major challenge. To address this issue, the Research Institute of Petroleum Processing of China Petrochemical Corporation conducted research and used a 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 from High Pour Point Aromatic Hydrocarbon Raw Material, Petroleum Refining and Chemical Industry, 2013, 44(8): 33-36).

[0005] To address the problems existing in the dewaxing process of extracted oil and rubber oil, this patent application proposes a new method: using N-methylpyrrolidone (NMP) as a polar solvent and benzene, toluene, and xylene as solubilizers. The composite solvent composed of the polar solvent and solubilizers serves as the dewaxing solvent, which can solve the problem of small wax crystals that are difficult to filter in the dewaxing of extracted oil using traditional dewaxing solvents. The specific invention content is as follows. Summary of the Invention

[0006] 1. A method for dewaxing oil and rubber oil, characterized by using a mixture of two solvents to form a composite solvent, one being a polar solvent of N-methylpyrrolidone, and the other being a solubilizer, which is one, two, or three of benzene, toluene, and xylene; the method is achieved through cooling crystallization, filtration, and solvent recovery, as detailed below:

[0007] (1) The composite solvent is mixed with the extracted oil or rubber oil to obtain a mixture, and the mixing temperature is slightly higher than the wax precipitation temperature of the oil;

[0008] (2) Cool the mixture to -20 to 10°C and keep it for 5-30 minutes;

[0009] (3) Filter the cooled mixture to obtain wax paste and filtrate;

[0010] (4) The wax paste is heated and evaporated to recover the solvent, thus obtaining wax;

[0011] (5) The filtrate is heated and evaporated to recover the solvent, and dewaxed oil is obtained.

[0012] 2. The method according to 1, characterized in that the volume ratio of polar solvent to solubilizer is 30-70:70-30.

[0013] 3. The method according to 1, characterized in that the volume ratio of the composite solvent to the extracted oil is 2 to 4:1.

[0014] When using this method, the cooling rate can be adjusted by combining it with existing lubricating oil solvent dewaxing results, which can result in larger wax crystals and better filtration.

[0015] Beneficial effects of the invention

[0016] The method provided by this invention can solve the problem of small wax crystals and difficulty in filtration in traditional dewaxing solvents used in oil extraction. The resulting dewaxed oil has larger wax crystals, lower oil content, a smaller dewaxing temperature difference, and a lower 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℃. Detailed Implementation

[0017] To further illustrate the present invention, a detailed description is provided below with reference to specific embodiments:

[0018] Example 1

[0019] A certain extracted oil has a pour point of 28℃. 100g of this oil was taken and 300ml of a composite solvent was added. The composite solvent consisted of NMP and benzene in a volume ratio of 50:50. The mixture was heated to 40℃, stirred until homogeneous, and then cooled to -16℃ at a rate of 2℃ / min. After cooling to -16℃, the mixture was held for 10 minutes, then filtered using a glass acid-resistant funnel (model G3) under vacuum for 11 minutes at a filtration rate of 37ml / min. The filtered wax paste and filtrate were heated and evaporated to recover the solvent, yielding wax and dewaxed oil. The wax had a melting point of 45℃, and the dewaxed oil had a pour point of 2℃. The wax yield was 10.25%.

[0020] Comparative Example 1

[0021] Using the same extracted oil and filter as in Example 1, 100g of the oil was added to 300ml of a composite solvent consisting of methyl ethyl ketone (MEK) and toluene in a volume ratio of 50:50. The mixture was heated to 40°C, stirred until homogeneous, and then cooled to -16°C at a rate of 2°C / min. After cooling to -16°C, the mixture was held for 10min and then filtered. The same acid-resistant glass funnel as in Example 1 (washed and dried before use) was used for vacuum filtration at a time of 17min and a filtration rate of 24ml / min. The filtered wax paste and filtrate were heated and evaporated to recover the solvent, yielding wax and dewaxed oil. The melting point of the wax was 42°C, and the pour point of the dewaxed oil was 5°C. The wax yield was 15.2%.

[0022] As can be seen from Example 1 and Comparative Example 1, the method of the present invention can improve the dewaxing rate, reduce the oil content in the wax, and improve the dewaxing effect.

[0023] Example 2

[0024] Using the same extracted oil and filter as in Example 1, 100g of the oil was taken and 300ml of a composite solvent consisting of NMP and toluene in a volume ratio of 30:70. The mixture was heated to 40°C, stirred until homogeneous, and then cooled to -16°C at a rate of 3°C / min. After cooling to -16°C, the mixture was held for 5 minutes and then filtered. The same acid-resistant glass funnel as in Example 1 (washed and dried before use) was used for vacuum filtration at a time of 12 minutes and a filtration rate of 34ml / min. The filtered wax paste and filtrate were heated and evaporated to recover the solvent, yielding wax and dewaxed oil. The melting point of the wax was 45°C, and the pour point of the dewaxed oil was 1°C. The wax yield was 11.6%.

[0025] Example 3

[0026] Using the same extracted oil and filter as in Example 1, 100g of the oil was taken and 300ml of a composite solvent was added. The composite solvent consisted of NMP and xylene, with a volume ratio of 70:30. The mixture was heated to 40°C, stirred until homogeneous, and then cooled to -16°C at a rate of 3°C / min. After cooling to -16°C, the mixture was held for 10min and then filtered. The same acid-resistant glass funnel as in Example 1 (which had been washed and dried before use) was used for vacuum filtration. The filtration time was 9min, and the filtration rate was 45ml / min. The filtered wax paste and filtrate were heated and evaporated to recover the solvent, yielding wax and dewaxed oil. The melting point of the wax was 45°C, and the pour point of the dewaxed oil was 0°C. The wax yield was 12.3%.

[0027] Example 4

[0028] A certain rubber oil has a pour point of 36℃. 100g of this oil was taken and 300ml of a composite solvent was added. The composite solvent consisted of NMP, benzene, and toluene, with a volume ratio of 40:30:30. The mixture was heated to 50℃, then stirred until homogeneous, and cooled to -10℃ at a rate of 1℃ / min. After cooling to -10℃, the mixture was held for 20min, then filtered. The same acid-resistant glass funnel as in Example 1 (washed and dried before use) was used for vacuum filtration at a time of 10min and a filtration rate of 40ml / min. The filtered wax paste and filtrate were heated and evaporated to recover the solvent, yielding wax and dewaxed oil. The wax had a melting point of 46℃, and the dewaxed oil had a pour point of 9℃. The wax yield was 15.2%.

[0029] Example 5

[0030] A certain rubber oil has a pour point of 36℃. 100g of this oil was taken and 400ml of a composite solvent was added. The composite solvent consisted of NMP and benzene, toluene, and xylene, with a volume ratio of 50:20:20:10. The mixture was heated to 50℃, stirred until homogeneous, and then cooled to -10℃ at a rate of 1℃ / min. After cooling to -10℃, the mixture was held for 30 minutes, followed by filtration. The same acid-resistant glass funnel as in Example 1 (washed and dried before use) was used for vacuum filtration at a time of 12 minutes and a filtration rate of 42ml / min. The filtered wax paste and filtrate were heated and evaporated to recover the solvent, yielding wax and dewaxed oil. The wax had a melting point of 46℃, and the dewaxed oil had a pour point of 10℃. The wax yield was 12.3%.

[0031] Using this rubber oil, with a methyl ethyl ketone-toluene mixture as the dewaxing solvent, the same solvent-to-oil ratio, and cooling rate, the filtration time was 17 min, the filtration rate was 29.8 ml / min, and the pour point of the dewaxed oil was 12°C. This indicates that the method of this patent has a greater filtration rate.

[0032] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the present invention.

Claims

1. A method for dewaxing oil or rubber oil, characterized in that... A composite solvent is prepared by mixing two solvents: one is N-methylpyrrolidone, a polar solvent, and the other is a solubilizer, which is one, two, or three of benzene, toluene, and xylene. The process involves cooling crystallization, filtration, and solvent recovery, specifically as follows: The composite solvent is mixed with the extracted oil or rubber oil to obtain a mixture at a temperature slightly higher than the wax precipitation temperature of the extracted oil; the mixture is cooled to -20~10℃ and maintained for 5-30 minutes; the cooled mixture is filtered to obtain wax paste and filtrate; the wax paste is heated and evaporated to recover the solvent, yielding wax; the filtrate is heated and evaporated to recover the solvent, yielding dewaxed oil.

2. The method for dewaxing oil or rubber oil according to claim 1, characterized in that... The volume ratio of polar solvent to solubilizer is 30~70:70~30.

3. The method for dewaxing oil or rubber oil according to claim 1, characterized in that... The volume ratio of the composite solvent to the extracted oil is 2~4:1.