JPH1180752A - Desulfurization of petroleum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the desulfurization efficiency in the desulfurization of petroleum by ultraviolet irradiation without being influenced by aromatic compounds such as naphthalene in the petroleum in the photochemical reaction. SOLUTION: Petroleum oil selected from gasoline, kerosene, light oil, heavy oil and crude oil is irradiated with ultraviolet rays under the introduction of an oxygen-containing gas in the presence of one or more polar organic solvents selected from acetonitrile, dimethylformamide and diethylene glycol or the above polar organic solvents mixed with water to effect photochemical reaction. After the reaction, the system is separated by leaving standing to transfer the sulfur component to the polar organic solvent and obtain desulfurized petroleum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for desulfurizing petroleums using ultraviolet rays.

[0002]

2. Description of the Related Art Hydrodesulfurization, oxidative desulfurization (hydrogen peroxide desulfurization, biodesulfurization) and the like are known as conventional methods for desulfurizing petroleum of this kind. In recent years, the present inventor, Komazawa et al., Has proposed a method of irradiating ultraviolet rays to desulfurize petroleums. This method involves irradiating ultraviolet light while supplying oxygen-containing gas to gas oil in the presence of water, and oxidizing sulfur compounds contained in gas oil by a photochemical reaction in the gas oil phase. It becomes water-soluble and moves from the light oil phase to the water phase, so that it can be separated and desulfurized.

[0003]

However, in the above method, when a photochemical reaction is caused by irradiating ultraviolet rays while supplying an oxygen-containing gas to the light oil, aromatic compounds such as naphthalene contained in the light oil are used. Absorbs the excitation energy and causes a photoreaction inhibition that inhibits the desired desulfurization reaction, so that the reaction rate is reduced and the desulfurization efficiency is reduced. In particular, the photochemical reaction of dibenzothiophene (DBT), which is a difficult-to-desulfurize component, is significantly suppressed by coexistence with an aromatic compound such as naphthalene.

[0004] The present invention has been made in view of the above circumstances, and even if petroleum containing a sulfur compound which is difficult to desulfurize,
An object of the present invention is to provide a method for increasing the reaction rate and obtaining high desulfurization efficiency without suppressing the reaction due to the coexistence of an aromatic compound such as naphthalene.

[0005]

The invention according to claim 1 is
A method for desulfurizing petroleums, comprising irradiating petroleums with ultraviolet rays in the presence of a polar organic solvent while supplying an oxygen-containing gas. The invention according to claim 2 is the petroleum desulfurization method according to claim 1, wherein the polar organic solvent is one or more of acetonitrile, dimethylformamide, and diethylene glycol. The invention according to claim 3 is the petroleum desulfurization method according to claim 1, wherein water is added to the polar organic solvent.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of an apparatus for performing the petroleum desulfurization method of the present invention. This apparatus is a cylindrical quartz glass internal irradiation type reaction tube, and has a reaction tube main body 1 and an L provided on a shoulder portion of the reaction tube main body 1.
A gas injection port 2 in the shape of a U-shaped tube, a sample injection port 3 provided on a shoulder opposite to the gas injection port 2, and a reaction tube main body 1 provided in the center of the reaction tube main body 1 in a vertical direction. A cylindrical outer jacket 4 having a small diameter, a light emitting unit 5 provided inside the outer jacket 4, a 300 W high-pressure mercury lamp 6 provided inside the light emitting unit 5,
And a magnetic stirrer 7 provided on the inner bottom of the reaction tube main body 1. The above gas inlet 2
Is connected to a thin tube extending to near the bottom of the reaction tube main body 1, and the gas blown from the gas blowing port 2 is supplied to the inside of the reaction tube main body 1 through this tube. A portion of the outer jacket 4 protruding above the reaction tube body 1 has a facing surface 2 for supplying cooling water to the outside of the tube.
It has two L-shaped tubules. The light emitting section 5 having a smaller diameter than the outer jacket is inserted into the outer jacket 4, and a plug is plugged at the top. Further, a filter tube 8 made of Pyrex or uranyl glass for adjusting the irradiation wavelength is inserted into a liquid tank between the outer jacket 4 and the light emitting section 5. A Pyrex filter tube blocks ultraviolet light of wavelength less than 280 nm, and a uranyl glass filter tube blocks light of wavelength less than 320 nm.

Next, an example of a method for desulfurizing petroleum using the above-described apparatus will be described below. A mixture of petroleum and a polar organic solvent is put into the reaction tube main body 1 from the sample injection port 3 so that the volume ratio between them is about 1: 1 to 1: 7. Next, oxygen is supplied from the gas blowing port 2 at 200 to 800 ml / min.
Feed at a flow rate of Instead of this oxygen, an oxygen-containing gas such as air may be supplied. In this case, the oxygen concentration of this oxygen-containing gas is set to 20 to 40 mol%, and the supply flow rate is such that the supply amount of oxygen is the saturation amount of the whole solution. What should I do? While supplying the oxygen or the oxygen-containing gas, the mixture is stirred by the magnetic stirrer 7 or the oxygen-containing gas bubbling. Ultraviolet light having a wavelength of 250 to 320 nm is irradiated for 2 to 24 hours to perform a photochemical reaction. All operations are performed under atmospheric pressure, and the temperature during the reaction is maintained at about 20 to 80 ° C.

The petroleum used in the present invention is light oil or heavy oil (Arabian light). In addition, any petroleum including gasoline, kerosene and crude oil may be used. The polar organic solvent used in the present invention is one that is effective for aromatic extraction and does not contain sulfur in the functional group. For example, acetonitrile, diethylene glycol and dimethylformamide are effective. Here, when a sulfur-containing one such as dimethyl sulfoxide or sulfolane is used as the polar organic solvent, the solvent itself absorbs ultraviolet rays in the process of irradiating ultraviolet rays, and further causes a side reaction. Occurs. Therefore, desulfurization is preferably performed using a polar organic solvent that does not contain sulfur and has a low absorption in the ultraviolet region. on the other hand,
When water is present in the polar organic solvent, the dissolution of the polar organic solvent in petroleum such as light oil can be suppressed. For this reason, component separation is facilitated, and water may be added to the polar organic solvent to form a mixed solvent, which may be used. here,
The volume percentage of water in the mixed solvent of the polar organic solvent and water is any point in the range of 0 to 100%, preferably any point of 0 to 30%. When a petroleum reaction is carried out using this mixed solvent, the mixture of the petroleum and the mixed solvent is adjusted so that the volume ratio between the two becomes about 1: 1 to 1: 7. Further, the mixing of the petroleum, the polar organic solvent or the polar organic solvent to which water is added and the oxygen-containing gas must be performed well, and the mixing method may be either mechanical stirring or air stirring. good.

After the photochemical reaction, the reaction solution is allowed to stand, and separated into an oil phase and a solvent phase. After separation, purification is performed for each of the oil phase and the solvent phase. The oil phase is washed with water and distilled to remove the dissolved solvent. The solvent phase is subjected to distillation or extraction to separate components. In the case of performing distillation, the solvent first flows out due to the difference in boiling point, then the oil component flows out, and finally the sulfur compound remains as a residue. On the other hand, in the case of performing extraction, an oil component is extracted using n-paraffin, and further, distillation is performed to separate into a solvent and a sulfur compound. The removed sulfur compound is used effectively as it is, or is stirred while blowing air in the presence of water, irradiated with ultraviolet rays, reacted to form sulfate ions, and then subjected to alkali treatment.

[0010] According to the method using the above-mentioned apparatus, sulfur compounds in petroleum are oxidized by a photochemical reaction with oxygen in a polar organic solvent phase, and are soluble in a polar organic solvent and petroleum. Since it becomes hardly soluble sulfoxide or sulfone, desulfurization from the oil phase becomes possible. Here, the hardly desulfurizable sulfur compound contained in petroleum, for example, dibenzothiophene, is selectively eluted into the solvent phase during mixing and stirring with the polar organic solvent or the polar organic solvent to which water is added. For this reason, naphthalenes in petroleum, which had suppressed the reaction in a conventional reaction system using only water as a solvent, did not suppress the reaction in a polar organic solvent, and did not react in a solvent phase. It is possible to proceed. Therefore, the desulfurization efficiency increases. In addition, since there is no formation of an emulsion in the component separation, the processing time can be reduced as compared with a reaction system using only water. Further, the oxidized sulfur compounds (sulfoxide and sulfone) after the separation and purification are further oxidized to sulfate ions by the desulfurization method of the present invention, and are converted to sodium sulfate by alkali treatment, so that they can be directly discarded.
Therefore, there is no need to use a new process for disposal, leading to cost reduction.

FIG. 2 is a flowchart showing an example of the industrial-scale desulfurization process of the present invention. In this example, the reaction is carried out using acetonitrile as a polar organic solvent and adding water thereto. First, water is mixed with acetonitrile, light oil is added to the mixture, and ultraviolet light is irradiated while blowing air into the mixture to perform desulfurization. Subsequently, the mixture is allowed to stand, and the gas oil phase and the acetonitrile phase are separated. The gas oil phase in the supernatant is washed with water and distilled to separate the dissolved acetonitrile to take out the desulfurized gas oil. The acetonitrile phase is extracted with n-hexane to separate dissolved aromatic components. The hexane phase is further distilled to separate light oil.
The acetonitrile phase is also subjected to distillation to separate acetonitrile and oxidized sulfur compounds.

The respective components obtained are used effectively, or the sulfur compounds finally taken out from the acetonitrile phase are further subjected to a photochemical reaction using the desulfurization method of the present invention to be oxidized to sulfate ions, Subsequently, it is possible to carry out an alkali treatment and to discard.

[0013]

【Example】

(Example 1) The following were used for desulfurization. Reaction tube: Eiko's internal irradiation type reaction tube: EHB-W-
300 type light source: High pressure mercury lamp 300W (average life 2000 hours) Light oil: Commercial light oil 100ml light oil and acetonitrile 30
0 ml is introduced from the sample inlet 3 and stirred while blowing air at a flow rate of 500 ml / min from the gas inlet 2, and 250 to 32 through the filter tube 8 from the light emitting part 5.
Irradiation with 0 nm ultraviolet light was performed. At regular intervals, 3 ml of a sample was taken out, the sample taken out was allowed to stand and separated into a gas oil phase and an acetonitrile phase, and then the sulfur compound content in the gas oil phase was analyzed by a fluorescent X-ray method and a microcoulometric titration method. The operation was performed at room temperature under atmospheric pressure, except that the internal temperature of the reaction tube main body 1 was maintained at about 50 ° C. when the ultraviolet irradiation was performed. As a result, the weight percent concentration of sulfur in light oil is
The initial concentration of 0.2% by weight was 0.05% by weight after 2 hours and 0.02% by weight after 5 hours.

(Example 2) 100 ml of crude oil (Arabian light) and 300 ml of a mixed solvent of acetonitrile / water containing 10% by weight of water were introduced into the reaction tube main body 1 at a sample injection port 3.
And the same operation as in Example 1 was performed. as a result,
The weight percent concentration of sulfur in the crude oil was 1.8 at the initial concentration.
The weight% was 1.4% by weight after 2 hours and 0.9% by weight after 5 hours.

(Example 3) Light oil 10 was added to the reaction tube main body 1.
0 ml and 300 ml of diethylene glycol were introduced through the sample inlet 3, and the same operation as in Example 1 was performed. As a result, the weight percent concentration of sulfur in light oil was 0.2% by weight of the initial concentration, 0.07% by weight after 2 hours, and 0.04% by weight after 5 hours.

(Example 4) A total of 400 ml of light oil and acetonitrile was put into the reaction tube main body 1 from the sample injection port 3 and stirred while blowing air at a flow rate of 500 ml / min from the gas injection port 2. Ultraviolet rays of 250 to 320 nm were irradiated through the filter tube 8.
Thereafter, the same operation as in Example 1 was performed. Here, the volume ratio of acetonitrile / light oil was changed to 1, 3, and 7,
The change with time of the weight percent concentration of sulfur in each gas oil was measured. The operation was performed at room temperature under atmospheric pressure, except that the internal temperature of the reaction tube main body 1 was maintained at about 50 ° C. when the ultraviolet irradiation was performed. The result is shown in FIG. The weight percent concentration of sulfur in light oil is 0.2% by weight
However, when the volume ratio is 1, after 2 hours, it is reduced to 0.12% by weight.
After an hour, it was 0.095% by weight. When the volume ratio is 3,
0.05% by weight after 2 hours, 0.03% after 5 hours
% By weight. When the volume ratio is 7, the volume ratio is 0.2 after 2 hours.
After 5 hours, the content became 0.005% by weight. In the gas oil / acetonitrile reaction system, the result was that the larger the volume ratio of acetonitrile, the higher the reaction efficiency and the higher the desulfurization efficiency.

(Example 5) 400 ml of light oil and acetonitrile / water were put into the reaction tube main body 1 through the sample inlet 3 and air was blown through the gas inlet 2 at 500 ml / mi.
The mixture was stirred while blowing at a flow rate of n, and was irradiated with ultraviolet rays of 250 to 320 nm from the light emitting section 5 through the filter tube 8. Thereafter, the same operation as in Example 1 was performed. In addition, since it is possible to suppress the solvent from being dissolved in the light oil by using water, in this embodiment, the volume percentage of water in the acetonitrile / water mixed solvent is set to 0 to 10%.
The reaction was carried out while changing the amount to 0%. The result is shown in FIG. The vertical axis shows the weight percent concentration of sulfur contained in light oil as a parameter, and the horizontal axis shows the irradiation time of ultraviolet rays. After the irradiation time of 6 hours, the volume percentage of water in the mixed solvent of acetonitrile / water is 0.1 or 0.1.
As it increases to 0,20,50,100%, the weight percent of sulfur becomes 0.025,0.03,0.06,
It increased to 0.13 and 0.17% by weight. Therefore, the result was obtained that the desulfurization efficiency could be increased as the volume percentage of water in acetonitrile was reduced to 0 or closer to 0. Also, considering that it is possible to suppress the solvent from being dissolved in light oil by using water, the volume percentage of water is 10 to 20%.
It is most practical to use a mixed solvent of water / acetonitrile. FIG. 5 shows the relationship between the weight percent concentration of sulfur in light oil and the volume percent of water contained in the solvent depending on the presence or absence of ultraviolet irradiation for 2 hours. The vertical axis represents the weight percent concentration of sulfur contained in light oil, and the horizontal axis represents the volume percentage of water in the mixed solvent of acetonitrile / water. The volume ratio of acetonitrile phase / light oil phase is 3
Met. The reaction efficiency is increased by the irradiation of ultraviolet rays, and when the volume percentage of water is 20%, the sulfur concentration without irradiation with ultraviolet rays is 0.17% by weight, whereas the sulfur concentration is 0.09% by weight when irradiated. there were.

Comparative Example 1 Light oil 10 was added to the reaction tube body 1.
0 ml and 300 ml of pure water were introduced from the sample injection port 3 and stirred while blowing air at a flow rate of 500 ml / min from the gas injection port 2, and ultraviolet light of 250 to 320 nm was irradiated from the light emitting section 5 through the filter tube 8. A sample (3 ml) was taken out at regular intervals, and the sulfur compound content of the gas oil was analyzed by a fluorescent X-ray method. The operation was performed at room temperature under the atmospheric pressure, except that the internal temperature of the reaction tube main body 1 was kept at about 50 ° C. during the irradiation with ultraviolet rays. After a water / light oil emulsion was formed and the separation operation required a longer time than the organic solvent system and was sufficiently separated, the light oil phase was taken out and the sulfur compound content was identified by a fluorescent X-ray method. As a result, the weight percent concentration of sulfur in light oil is 0.24% by weight of the initial concentration,
0.18% by weight after 12 hours and 0.2% after 24 hours.
It was 17% by weight.

Comparative Example 2 Light oil 10 was added to the reaction tube body 1.
0 ml and 300 ml of a 30% by weight aqueous hydrogen peroxide solution were introduced through the sample injection port 3, and air was blown through the gas injection port 2.
The mixture was stirred while blowing at a flow rate of 0 ml / min, and ultraviolet light of 250 to 320 nm was irradiated from the light emitting unit 5 through the filter tube 8. The operation was performed at room temperature under the atmospheric pressure, except that the internal temperature of the reaction tube main body 1 was kept at about 50 ° C. during the irradiation with ultraviolet rays. A 50 ml sample is taken out at regular intervals, the light oil phase and the aqueous hydrogen peroxide solution are allowed to stand for separation, and the light oil phase is washed three times with pure water of the same amount as the light oil to remove residual hydrogen peroxide. Thereafter, the sulfur compound content was identified by a fluorescent X-ray method. As a result, the weight percent concentration of sulfur in the gas oil was 0.2% by weight at the initial concentration, 0.08% by weight after 12 hours, and 0.04% by weight after 24 hours.

[0020]

As described above, according to the desulfurization method of the present invention, by using a polar organic solvent, sulfur compounds contained in petroleum are eluted into the polar organic solvent and the reaction proceeds. The efficiency of desulfurization is improved without being affected by the reaction of the aromatic compound such as naphthalene contained therein due to the inhibition of the photoreaction. In addition, by using one or more of acetonitrile, dimethylformamide, and diethylene glycol as the polar organic solvent, adverse effects such as ultraviolet absorption and side reactions can be removed, and desulfurization can be efficiently promoted. Further, by mixing water in the organic solvent, the dissolution of the solvent in petroleum such as light oil can be suppressed. Therefore, since the treatment after the reaction is facilitated, desulfurized petroleum can be efficiently extracted. As an example of an industrial-scale process, the desulfurization efficiency is most increased by performing the reaction using a mixed solvent of acetonitrile / water having a volume percentage of water of 10 to 20%. As described above, since the desulfurization efficiency is high and the by-products can be easily treated when discarded, they are practically superior to the conventional desulfurization methods.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an apparatus used to carry out the desulfurization method of the present invention.

FIG. 2 is a flowchart of the desulfurization process of the present invention.

FIG. 3 is a graph showing a change over time in a sulfur concentration in Example 4.

FIG. 4 is a graph showing a change in sulfur concentration over time in Example 5.

FIG. 5 is a diagram showing a change in sulfur concentration according to a change in volume percentage of water in Example 5.

Claims (3)

[Claims] 1. A method for desulfurizing petroleums, comprising irradiating petroleums with ultraviolet rays in the presence of a polar organic solvent while supplying an oxygen-containing gas. 2. The method according to claim 1, wherein the polar organic solvent is acetonitrile,
2. The method for desulfurizing petroleums according to claim 1, wherein one or more of dimethylformamide and diethylene glycol are used. 3. The method according to claim 1, wherein water is added to the polar organic solvent.