JP5481270B2 - Method for reducing sulfur compounds in hydrocarbon oils - Google Patents

Description

  The present invention relates to a method for reducing sulfur content in hydrocarbon oils by a solvent extraction method.

There is a hydrodesulfurization method as a method for reducing the sulfur content in hydrocarbon oil. In the hydrodesulfurization method, the reaction is performed in the presence of a catalyst in a high-temperature and high-pressure hydrogen gas atmosphere, so the apparatus is large-scale and the operation cost is high. In hydrodesulfurization, hydrogen gas is not economical because hydrogen gas is consumed in aromatic ring and olefin hydrogenation reactions other than desulfurization reaction. Furthermore, a toxic amount of toxic hydrogen sulfide corresponding to the number of sulfur atoms to be desulfurized is by-produced.
Moreover, there exists an adsorbent method as a method of reducing the sulfur content in hydrocarbon oil. In this method, if the amount of the compound adsorbed on the adsorbent exceeds a certain amount, the desulfurization activity is drastically reduced, so that the operation management is not easy. In addition, when recovering the desulfurization activity of the adsorbent whose desulfurization activity has decreased, the adsorbent is adsorbed by heating the adsorbent by desorbing the sulfur compound adsorbed on the adsorbent using a solvent with strong dissolving power. An operation such as distilling off the sulfur compound adsorbed on the agent must be added. And utilization of the sulfur compound isolate | separated from hydrocarbon oil is hardly considered.

  A solvent extraction method is also widely known as a method for reducing sulfur compounds in hydrocarbon oils. As extraction solvents, liquid sulfur dioxide, aniline, nitrobenzene, chlorex, phenol, furfural, methylpyrrolidone, sulfolane, ethylene glycol, etc. are known, but have high vapor pressure, strong toxicity, and corrosiveness. It has drawbacks such as high boiling point, high freezing point, and odor. In particular, in the desulfurization of hydrocarbon oil having a boiling point of 140 to 350 ° C., there is a sufficient difference in boiling point from the hydrocarbon oil and there is no extraction solvent that is easy to handle. For example, furfural which is the extraction solvent most often used for industrial use has a boiling point of 162 ° C., and therefore the boiling point overlaps with the hydrocarbon oil. Therefore, it is not easy to recover the hydrocarbon oil extracted to furfural only by distillation.

  On the other hand, as an extraction solvent, acetone, dimethyl sulfoxide, acetonitrile, nitromethane, trimethyl phosphate, methanol, hexamethylphosphoric acid amide, acetic acid, N-methylpyrrolidinone, pyridine, and the like, and naphtha by a solvent extraction method using a mixture of these and water, Methods for recovering organic sulfur compounds from gasoline, kerosene, and straight-run light diesel oil have been proposed (Patent Documents 1 to 3). However, the extraction efficiency with these extraction solvents is low.

Japanese Patent Laid-Open No. 7-197036 Japanese Patent Laid-Open No. 10-168464 JP 2001-247876 A

    The problem to be solved by the present invention is a method for easily and efficiently separating a sulfur compound from a hydrocarbon oil containing a sulfur compound without using a high-temperature and high-pressure apparatus and without using an expensive catalyst or adsorbent. Is to provide.

The method for reducing the sulfur content in a hydrocarbon oil containing a sulfur compound of the present invention is characterized in that the hydrocarbon oil is contacted with one or more extraction solvents selected from hydrofluoroethers and hydrofluorocarbons. .
Furthermore, the present invention provides the contact mixture of the hydrocarbon oil and the extraction solvent separated into a hydrocarbon oil-rich phase and a phase rich in the extraction solvent by stationary separation and / or centrifugation, and separated. In this method, the extraction solvent is volatilized from the phase rich in extraction solvent to recover the sulfur compound as a non-volatile content.

  The present invention does not require a high-temperature and high-pressure apparatus from a hydrocarbon oil containing a sulfur compound, easily and efficiently separates a sulfur compound without using an expensive catalyst or adsorbent, and further separates from a hydrocarbon oil. The sulfur compound thus produced can be recovered without being gasified into hydrogen sulfide or sulfur dioxide.

  The hydrocarbon oil containing the sulfur compound is not particularly limited, but carbon is 83 to 87 wt%, hydrogen is 11 to 14 wt%, sulfur is 5 wt% or less, nitrogen is 0.4 wt% or less, and oxygen is 0.5 wt%. % Boiling point obtained from a crude oil having an elemental composition of less than or equal to 0.5% and less than or equal to 0.5% by weight of metal through a purification process such as a distillation process, hydrodesulfurization process, hydrocracking process, catalytic reforming process, catalytic cracking process Is preferably in the range of 140 to 350 ° C, more preferably hydrocarbon oil having a boiling range of 145 to 300 ° C. When the boiling point is less than 140 ° C., the difference in boiling point between the hydrocarbon oil and the extraction solvent is small, and the sulfur compound extracted from the hydrocarbon oil to the extraction solvent and the extraction solvent are separated by a distillation method. Is not preferable because it is difficult. Moreover, it is not preferable that the boiling point exceeds 350 ° C. because the viscosity is high and handling is difficult. Specifically, a kerosene fraction, a light oil fraction, a heavy oil fraction and the like are suitable.

  As the extraction solvent, one or more selected from hydrofluoroether and hydrofluorocarbon are used. This extraction solvent preferably has a boiling point in the range of 30 ° C to 140 ° C, more preferably in the range of 35 to 135 ° C. A boiling point of less than 30 ° C. is not preferable because it is highly volatile at room temperature and difficult to handle. Further, when the boiling point exceeds 140 ° C., the extraction solvent is distilled off by a distillation method, and the operation cost when recovering the sulfur compound extracted from the hydrocarbon oil is large. Also, the extraction solvent, the sulfur compound, Since the boiling point difference between the two is small, it is not preferable because they are difficult to separate by distillation.

  Further, the extraction solvent preferably has a saturated hydrocarbon solubility in the extraction solvent at 25 ° C. of less than 20 g / 100 g, more preferably less than 10 g / 100 g, and the fragrance in the extraction solvent at 25 ° C. The solubility of the group hydrocarbon is preferably 40 g / 100 g or more, more preferably 50 g / 100 g or more. Here, the solubility is the maximum addition amount that keeps the liquid mixture uniform when adding hydrocarbon oil to 100 g of the extraction solvent.

This is because the hydrocarbon composition of crude oil contains a large amount of paraffin and monocyclic naphthene (cycloparaffin) in the light fraction, and the proportion of aromatic compounds increases as it becomes heavier. When the solubility of the saturated hydrocarbon is 20 g / 100 g or more, the recovery rate of the hydrocarbon oil with a reduced sulfur content is lowered, which is not preferable.
On the other hand, sulfur compounds in crude oil are mostly mercaptans and sulfides in light fractions, and thiophenes that are aromatic compounds increase as they become heavier. Therefore, when the solubility of the aromatic hydrocarbon at 25 ° C. is less than 40 g / 100 g, the amount of the sulfur compound separated from the hydrocarbon oil decreases, which is not preferable.

Specific examples of such hydrofluoroethers include 1,2,2,2-tetrafluoroethyl-heptafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl. Ether, nonafluorobutyl methyl ether, nonafluorobutyl ethyl ether, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4- (trifluoromethyl) -pentane 1,1,1,2,3,3-hexafluoro-2-heptafluoropropyloxy-3- (1,2,2,2-tetrafluoroethoxy) -propane, 1,1,1,2,3 , 3-hexafluoro-4- (1,1,2,3,3,3-hexafluoropropoxy) -pentane.
Specific examples of the hydrofluorocarbon include 1,1,1,3,3-pentafluorobutane, 1,1,1,2,2,3,4,5,5,5-decafluoropentane, Examples include 1,2,2,3,3,4,5-octafluorocyclopentane, 1,1,2,2,3,3,4-heptafluorocyclopentane, and the like.

These hydrofluoroethers and hydrofluorocarbons may be used alone or in combination of two or more.
Table 1 shows the boiling points of hydrofluoroether and hydrofluorocarbon, and the solubility of saturated hydrocarbon (n-tridecane) and aromatic hydrocarbon (ethylbenzene) in the extraction solvent at 25 ° C.

In the present invention, the hydrocarbon oil and the extraction solvent are brought into contact with each other. This contact is not particularly limited by any method, and may be performed in a batch using a stirring mixer, for example, as in a static mixer. It may be carried out continuously using a static mixer or an extraction tower having a plurality of extraction layers (for example, 20 stages) in the vertical direction.
In this case, it is preferable that the extraction solvent with respect to hydrocarbon oil shall be 0.1-100 by weight ratio, and 0.2-50 are more preferable. If it is less than 0.1, the sulfur compound cannot be sufficiently extracted, and if it exceeds 100, the recovery of the extraction solvent is costly.
The contact temperature is preferably 0 to 140 ° C., more preferably 20 to 120 ° C., and the contact time is preferably 0.05 to 50 hours, more preferably 0.5 to 5 hours.

  After contacting with the hydrocarbon oil and the extraction solvent, it is allowed to stand to separate, or separated into a phase rich in hydrocarbon oil (raffinate) and a phase rich in extraction solvent (extract) by centrifugation or the like, and the raffinate From each of the extracts, the extraction solvent is volatilized by distillation or the like and recovered. The recovered extraction solvent is reused for contact with the hydrocarbon oil. In addition, a sulfur compound is collect | recovered from an extract with an aromatic compound, and a sulfur compound is isolate | separated and collect | recovered by the solvent extraction method etc. The aromatic compound can be used as it is or can be returned to the hydrocarbon oil, and the sulfur compound can be used as a raw material for pharmaceuticals, agricultural chemicals, dyes, resins and the like.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is limited to these and is not interpreted.
Table 2 shows properties of petroleum fractions used in Examples and Comparative Examples.

[Example 1]
Petroleum fraction 1 (10 g, 13 mL) and 1,1,1,3,3-pentafluorobutane (10 g, 7 mL) were placed in a container and stirred at 35 ° C. for 60 minutes. Then, it left still at room temperature for 12 hours, and isolate | separated into the raffinate and the extract. The raffinate was dispensed into a beaker and 1,1,1,3,3-pentafluorobutane was distilled off at 40 ° C., and the sulfur content was measured according to JIS K2541. The sulfur content was 2480 ppm, and the desulfurization rate was 28%.
In addition, the separated extract was collected in a beaker, and 1,1,1,3,3-pentafluorobutane was distilled off at 40 ° C., and then the sulfur content was measured according to the method defined in JIS K2541 (measurement of sulfur content The method was the same below). The sulfur content was 5,850 ppm.

[Example 2]
Example 1 except that 10 g (7 mL) of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether was used instead of 1,1,1,3,3-pentafluorobutane The same operation was performed. The sulfur content was 2,680 ppm and the desulfurization rate was 22%.
Further, the separated extract was collected in a beaker, and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether was distilled off at 40 ° C., and then the sulfur content was measured. The sulfur content was 13,500 ppm.

Example 3
1,1,1,2,3,3-hexafluoro-4- (1,1,2,3,3,3-hexafluoropropoxy) instead of 1,1,1,3,3-pentafluorobutane -The same operation as in Example 1 was carried out except that 10 g (7 mL) of pentane was used. The sulfur content was 2,580 ppm and the desulfurization rate was 25%.

Example 4
Petroleum fraction 2 (10 g, 13 mL) and 1,1,1,3,3-pentafluorobutane (10 g, 7 mL) were placed in a container and stirred at 35 ° C. for 60 minutes. Then, it left still at room temperature for 12 hours, and isolate | separated into the raffinate and the extract. The raffinate was fractionated into a beaker and 1,1,1,3,3-pentafluorobutane was distilled off at 40 ° C., and then the sulfur content was measured. The sulfur content was 9 ppm and the desulfurization rate was 25%.

Example 5
Example 4 except that 10 g (7 mL) of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether was used instead of 1,1,1,3,3-pentafluorobutane The same operation was performed. The sulfur content was 9 ppm and the desulfurization rate was 25%.

Example 6
1,1,1,2,3,3-hexafluoro-4- (1,1,2,3,3,3-hexafluoropropoxy) instead of 1,1,1,3,3-pentafluorobutane -The same operation as in Example 4 was performed except that 10 g (7 mL) of pentane was used. The sulfur content was 9 ppm and the desulfurization rate was 25%.

[Comparative Example 1]
The same operation as in Example 1 was performed except that 10 g (13 mL) of methanol was used instead of 1,1,1,3,3-pentafluorobutane. The sulfur content was 2,880 ppm and the desulfurization rate was 16%.

[Comparative Example 2]
The same operation as in Example 4 was performed except that 10 g (13 mL) of methanol was used instead of 1,1,1,3,3-pentafluorobutane. The sulfur content was 11 ppm and the desulfurization rate was 8%.

[Comparative Example 3]
The same operation as in Example 4 was performed except that 10 g (13 mL) of ethanol was used instead of 1,1,1,3,3-pentafluorobutane, but raffinate and extract were allowed to stand at room temperature for 12 hours. Phase separation did not occur.

[Comparative Example 4]
The same operation as in Example 4 was performed except that 10 g (13 mL) of acetone was used instead of 1,1,1,3,3-pentafluorobutane, but raffinate and extract were allowed to stand at room temperature for 12 hours. Phase separation did not occur.

[Comparative Example 5]
The same operation as in Example 4 was performed except that 10 g (6 mL) of perfluoroheptane was used instead of 1,1,1,3,3-pentafluorobutane. The sulfur content was 12 ppm, and the desulfurization rate was 0%.

  The present invention can be used for reducing sulfur compounds in hydrocarbon oils containing sulfur compounds, particularly kerosene fractions and gas oil fractions.

Claims (2)

Hydrocarbon oil having a boiling point of 140 to 350 ° C. containing a sulfur compound is converted into 1,1,1,3,3-pentafluorobutane, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoro. Contact with one or more extraction solvents selected from ethyl ether and 1,1,1,2,3,3-hexafluoro-4- (1,1,2,3,3,3-hexafluoropropoxy) -pentane A method for reducing sulfur compounds in hydrocarbon oils. The contact mixture of the hydrocarbon oil and the extraction solvent according to claim 1 is separated into a phase rich in hydrocarbon oil and a phase rich in extraction solvent by stationary separation and / or centrifugation, and the separated extraction solvent is separated into the separated extraction solvent. A method for reducing sulfur compounds in hydrocarbon oils, comprising volatilizing an extraction solvent from a rich phase and recovering sulfur compounds as nonvolatile components.