METHOD FOR PREPARING LOW-POUR POINT, HIGH-AROMATIC, AND ENVIRONMENTAL-FRIENDLY RUBBER OIL BY COMBINING EXTRACTION AND DEWAXING

Abstract

A method for preparing an environmental-friendly rubber oil, including: conducting extraction in an extraction tower, where a primary extraction solvent is introduced into an upper section of the extraction tower, a raw oil is introduced into a middle-lower section of the extraction tower, and a secondary extraction solvent is introduced into a lower section of the extraction tower; subjecting a material at a bottom of the extraction tower to solvent recovery to obtain a secondary extract oil; mixing a substance flowing out from a top of the extraction tower, a solubilizer and a part of the primary extraction solvent, cooling to 15 C. to 10 C., and filtering to obtain a wax paste and a filtrate; subjecting the wax paste to heating evaporation and solvent recovery to obtain a wax; and subjecting the filtrate to heating evaporation and solvent recovery, obtaining the environmental-friendly rubber oil.

Claims

1. A method for preparing an environmental-friendly rubber oil by combining extraction and dewaxing, comprising the following steps: (1) conducting the extraction in an extraction tower, wherein a primary extraction solvent is introduced into an upper section of the extraction tower, a raw oil is introduced into a middle-lower section of the extraction tower, and a secondary extraction solvent is introduced into a lower section of the extraction tower, wherein the primary extraction solvent is N-methylpyrrolidone (NMP), the raw oil is an extract oil, and the secondary extraction solvent is a C7-C12 alkane; (2) subjecting a material at a bottom of the extraction tower to a first solvent recovery to obtain a secondary extract oil; (3) mixing a substance flowing out from a top of the extraction tower, a solubilizer and a part of the primary extraction solvent sent by a pump in a static mixer, subjecting a resulting mixture to cooling to a temperature of 15 C. to 10 C. in a cooler, and then filtering in a filter to obtain a wax paste and a filtrate, wherein the solubilizer is at least one selected from the group consisting of benzene, toluene, and xylene; (4) subjecting the wax paste to a second solvent recovery by a first heating evaporation to obtain a wax; and (5) subjecting the filtrate to a third solvent recovery by a second heating evaporation to obtain a dewaxed oil, namely the low-pour point, environmental-friendly rubber oil.

2. The method for preparing the environmental-friendly rubber oil by combining extraction and dewaxing of claim 1, wherein a mass ratio of the primary extraction solvent introducing into the upper section of the extraction tower to the raw oil is in a range of 2:1 to 3.5:1.

3. The method for preparing the environmental-friendly rubber oil by combining extraction and dewaxing of claim 1, wherein the lower section of the extraction tower is at a temperature of 40 C. to 60 C., and the upper section of the extraction tower is at a temperature of 60 C. to 80 C.

4. The method for preparing the environmental-friendly rubber oil by combining extraction and dewaxing of claim 1, wherein a volume ratio of the part of the primary extraction solvent to the solubilizer mixed with the substance flowing out from the top of the extraction tower is in a range of 40-50:60-50.

5. The method for preparing the environmental-friendly rubber oil by combining extraction and dewaxing of claim 1, wherein a volume ratio of the solubilizer to the raw oil is in a range of 1:1 to 3:1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIGURE shows a schematic diagram for a production process of the method according to the present disclosure, where numeral references are listed below: 1 refers to a solubilizer tank, 2 refers to a primary extraction solvent tank, 3 refers to a raw oil tank, 4 refers to a secondary solvent tank, 5, 6, 7, 8 refer to pumps, 9 refers to an extraction tower, 10, 11, 12, 14 refer to heat exchangers, 13 refers to a mixer and 15 refers to a filter.

[0021] As shown in the FIGURE, the primary extraction solvent enters from an upper section of the extraction tower through the pump 6, the raw oil enters from a middle section of the extraction tower through the pump 7, and the secondary solvent enters from a lower section of the extraction tower through the pump 8. An extract flowing out from a bottom of the extraction tower is subjected to solvent recovery to obtain a secondary extract oil, and a raffinate flowing out from a top of the extraction tower and the solubilizer (from the pump 5) and a part of the primary extraction solvent enter the heat exchanger 14 through the mixer 13 to conduct cooling, and then enter the filter 15 to conduct filtration to obtain a wax paste and a filtrate. The wax paste is subjected to solvent recovery to obtain a wax, and the filtrate is subjected to solvent recovery to obtain a low-pour point, high-aromatic, and environmental-friendly rubber oil. An extraction section between an upper feed port (primary extraction solvent inlet) and a middle feed port (raw oil inlet) of the extraction tower is called a first extraction section, an extraction section between the raw oil inlet and a lower feed port (secondary solvent inlet) of the extraction tower is called a second extraction section.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present disclosure will be described in detail below with reference to specific examples to further illustrate the present disclosure.

Example 1

[0023] A small extraction tower in the laboratory was used, and a process was shown in the figure. The extraction tower has an inner diameter of 33 mm and is filled with a wire mesh filler. A first extraction section has a height of 2 m, and a second extraction section has a height of 1 m. A primary extraction solvent was NMP and a secondary solvent was heptane. A fourth vacuum side stream extract oil produced by an oil refinery of China was used as a raw oil, and the extract oil had a pour point of 38 C. A weight ratio of the NMP, raw oil and heptane was 2.5:1:0.5. A temperature of the second extraction section from bottom to top was 50 C. to 55 C., a temperature of the first extraction section from bottom to top was 55 C. to 70 C., a raffinate was obtained at a top of the tower, and an extract was obtained at a bottom of the tower. Benzene and NMP were added to the raffinate, where the benzene was added at 100% (volume) of a raw oil flow, and the NMP was added at 100% of the benzene. A resulting mixture was mixed in a mixer, and then entered into a heat exchanger and cooled to 15 C. A cooled mixture was filtered through a filter to obtain a wax paste and a filtrate. The wax paste was subjected to solvent recovery to obtain a wax, with a yield of 12% of the raw oil. The filtrate was subjected to solvent recovery to obtain an environmental-friendly rubber oil, with a yield of 55%, a PCA content of 2.9%, a benzo[a]pyrene content of 0.2 g/g, and a total content of eight carcinogens of 2.1 g/g. The contents of eight carcinogen monomers are all less than 1 g/g, the aromatic carbon rate C.sub.A is 25.0%, and the pour point is 4 C., thus meeting requirements of the low-pour point, high-aromatic, and environmental-friendly rubber oil. The study found that wax crystals had large particles and their filtration was relatively smooth without clogging the filter.

Example 2

[0024] A small extraction tower in the laboratory was used, and a process was shown in the figure. The extraction tower has an inner diameter of 33 mm and is filled with a wire mesh filler. A first extraction section has a height of 2 m, and a second extraction section has a height of 1 m. A primary extraction solvent was NMP and a secondary solvent was a C6-C10 mixed alkane. A fourth vacuum side stream extract oil produced by an oil refinery of China was used as a raw oil, and the extract oil had a pour point of 38 C. A weight ratio of the NMP, raw oil, and the secondary solvent was 2.5:1:0.3. A temperature of the second extraction section from bottom to top was 40 C. to 55 C., a temperature of the first extraction section from bottom to top was 55 C. to 80 C., a raffinate was obtained at a top of the tower, and an extract was obtained at a bottom of the tower. Toluene and NMP were added to the raffinate, where the toluene was added at 300% of a raw oil flow, and the NMP was added at 200% of the raw oil flow. A resulting mixture was mixed in a mixer, and then entered into a heat exchanger and cooled to 10 C. A cooled mixture was filtered through a filter to obtain a wax paste and a filtrate. The wax paste was subjected to solvent recovery to obtain a wax, with a yield of 10% of the raw oil. The filtrate was subjected to solvent recovery to obtain an environmental-friendly rubber oil, with a yield of 56%, a PCA content of 2.4%, a benzo[a]pyrene content of 0.2 g/g, and a total content of eight carcinogens of 2.1 g/g. The contents of eight carcinogen monomers are all less than 1 g/g, the aromatic carbon rate C.sub.A is 25.0%, and the pour point is 8 C., thus meeting requirements of the low-pour point, high-aromatic, and environmental-friendly rubber oil. The study found that wax crystals had large particles and their filtration was relatively smooth without clogging the filter.

Example 3

[0025] A small extraction tower in the laboratory was used, and a process was shown in the figure. The extraction tower has an inner diameter of 33 mm and is filled with a wire mesh filler. A first extraction section has a height of 2 m, and a second extraction section has a height of 1 m. A primary extraction solvent was NMP and a secondary solvent was heptane. A fourth vacuum side stream extract oil produced by an oil refinery of China was used as a raw oil, and the extract oil had a pour point of 38 C. A weight ratio of the NMP, the raw oil, and the heptane was 2.0:1:0.4. A temperature of the second extraction section from bottom to top was 50 C. to 55 C., a temperature of the first extraction section was from bottom to top 55 C. to 70 C., a raffinate was obtained at a top of the tower, and an extract was obtained at a bottom of the tower. Xylene and NMP were added in the raffinate, where the xylene was added at 150% of a raw oil flow, and the NMP was added at 150% of the raw oil flow. A resulting mixture was mixed in a mixer, and then entered into a heat exchanger and cooled to 10 C. A cooled mixture was filtered through a filter to obtain a wax paste and a filtrate. The wax paste was subjected to solvent recovery to obtain a wax, with a yield of 6% of the raw oil. The filtrate was subjected to solvent recovery to obtain an environmental-friendly rubber oil, with a yield of 58%, a PCA content of 2.4%, a benzo[a]pyrene content of 0.2 g/g, and a total content of eight carcinogens of 2.1 g/g. The contents of eight carcinogen monomers are all less than 1 g/g, the aromatic carbon rate C.sub.A is 25.0%, and the pour point is 18 C., thus meeting requirements of the low-pour point, high-aromatic, and environmental-friendly rubber oil. The study found that wax crystals had large particles and their filtration was relatively smooth without clogging the filter.

Example 4

[0026] A small extraction tower in the laboratory was used, and a process was shown in the figure. The extraction tower has an inner diameter of 33 mm and is filled with a wire mesh filler. A first extraction section has a height of 2 m, and a second extraction section has a height of 1 m. A primary extraction solvent was NMP and a secondary solvent was petroleum ether. A fourth vacuum side stream extract oil produced by an oil refinery of China was used as a raw oil, and the extract oil had a pour point of 38 C. A weight ratio of the NMP, the raw oil and the petroleum ether was 2.0:1:0.4 (by weight). A temperature of the second extraction section from bottom to top was 50 C. to 55 C., a temperature of the first extraction section from bottom to top was 55 C. to 70 C., a raffinate was obtained at a top of the tower, and an extract was obtained at a bottom of the tower. solubilizer and NMP were added to the raffinate, where the solubilizer was a mixture of benzene and toluene and added at 150% of a raw oil flow, and the NMP was added at 150% of the raw oil flow. A resulting mixture was mixed in a mixer, and then entered a heat exchanger and cooled to 10 C. A cooled mixture was filtered through a filter to obtain a wax paste and a filtrate. The wax paste was subjected to solvent recovery to obtain a wax, with a yield of 6% of the raw oil. The filtrate was subjected to solvent recovery to obtain an environmental-friendly rubber oil, with a yield of 58%, a PCA content of 2.4%, a benzo[a]pyrene content of 0.2 g/g, and a total content of eight carcinogens of 2.1 g/g. The contents of eight carcinogen monomers are all less than 1 g/g, the aromatic carbon rate C.sub.A is 25.0%, and the pour point is 18 C., thus meeting requirements of the low-pour point, high-aromatic, and environmental-friendly rubber oil. The study found that wax crystals had large particles and their filtration was relatively smooth without clogging the filter.

Example 5

[0027] A small extraction tower in the laboratory was used, and a process was shown in the figure. The extraction tower has an inner diameter of 33 mm and is filled with a wire mesh filler. A first extraction section has a height of 2 m, and a second extraction section has a height of 1 m. A primary extraction solvent was NMP and a secondary solvent was a C12 alkane. A fourth vacuum side stream extract oil produced by an oil refinery of China was used as a raw oil, and the extract oil had a pour point of 38 C. A weight ratio of the NMP, the raw oil and C12 was 2.0:1:0.4. A temperature of the second extraction section from bottom to top was 60 C. to 70 C., a temperature of the first extraction section from bottom to top was at 70 C. to 80 C., a raffinate was obtained at a top of the tower, and an extract was obtained at a bottom of the tower. solubilizer and NMP were added to the raffinate, where the solubilizer was a mixture of benzene, toluene, and xylene in a ratio of 1:1:1 and added at 200% of a raw oil flow, and the NMP was added at 150% of the raw oil flow. A resulting mixture was mixed in a mixer, and then entered into a heat exchanger and cooled to 0 C. A cooled mixture was filtered through a filter to obtain a wax paste and a filtrate. The wax paste was subjected to solvent recovery to obtain a wax, with a yield of 10% of the raw oil. The filtrate was subjected to solvent recovery to obtain an environmental-friendly rubber oil, with a yield of 56%, a PCA content of 2.8%, a benzo[a]pyrene content of 0.3 g/g, and a total content of eight carcinogens of 4.2 g/g. The contents of eight carcinogen monomers are all less than 1 g/g, the aromatic carbon rate C.sub.A is 24.5%, and the pour point is 10 C., thus meeting requirements of the low-pour point, high-aromatic, and environmental-friendly rubber oil. The study found that wax crystals had large particles and their filtration was relatively smooth without clogging the filter.

[0028] It can be seen from the above examples that the method of the present disclosure could be used to prepare the low-pour point, highly-aromatic, and environmental-friendly rubber oil. Certainly, the present disclosure may further include other various examples. A person skilled in the art could make various corresponding modifications and variations according to the present disclosure without departing from the spirit and essence of the present disclosure, but all these corresponding modifications and variations shall fall within the scope defined by the appended claims in the present disclosure.