JP4854075B2 - Method for producing ultra-low sulfur gas oil base and ultra-low sulfur gas oil composition comprising the ultra-low sulfur gas oil base - Google Patents

Description

  The present invention relates to a method for producing an ultra-low sulfur gas oil base material having a sulfur content reduced to 1 mass ppm or less and an ultra-low sulfur gas oil composition.

  In recent years, the quality regulation value of light oil tends to be stricter worldwide in order to improve the air environment. In particular, the sulfur content in diesel oil has an impact on the durability of post-treatment devices such as oxidation catalysts, nitrogen oxide (NOx) reduction catalysts, and continuously regenerating diesel exhaust particulate removal filters that are expected as countermeasures for diesel vehicle exhaust gases. As a result, there is a demand for reducing the sulfur content of diesel oil. Therefore, the lower the sulfur content in light oil, the lower the generation of sulfate in the exhaust gas, the deterioration of the nitrogen oxide reduction catalyst, and the reduction in the generation of particulate matter on the aftertreatment catalyst. Therefore, it can be expected that nitrogen oxides and particulate matter are prevented from being discharged.

  Under such circumstances, development of an ultra-deep desulfurization technology that significantly removes sulfur content in light oil is being promoted. As a technology for reducing the sulfur content in light oil, usually, the operating conditions for hydrodesulfurization are made conditions that facilitate desulfurization, for example, raising the reaction temperature or lowering the liquid space velocity (LHSV). Conceivable. However, when the reaction temperature is raised, carbonaceous matter is deposited on the catalyst, and the activity of the catalyst is rapidly reduced. When LHSV is lowered, the desulfurization ability is improved, but the refining capacity is lowered, so the scale of the equipment is reduced. There is a need to expand. Furthermore, if the operating conditions are severe, the aromatic hydrogenation reaction proceeds excessively, and a large amount of hydrogen is consumed, resulting in an increase in production cost.

Further, the hydrorefined oil having a sulfur content of 5 to 10 mass ppm is subjected to deep hydrotreating in the presence of a hydrogenation catalyst to obtain a deep hydrorefined gas oil having a sulfur content of 5 mass ppm or less. Gas oil composition using refined light oil and unrefined oil and / or hydrorefined oil as raw materials, and sulfur content of 5 mass ppm or less and total aromatic content of 3 to 12 vol% or 10 vol% or less in the presence of a hydrorefining catalyst A method for manufacturing a product is disclosed (Patent Documents 1 and 2). However, in this method, in the deep hydrogenation treatment, the reaction is performed in the presence of high-pressure hydrogen of 2 to 10 MPa, or a low LHSV of 0.1 to 2 hr ⁻¹ is required. From the viewpoint of economical production, there is a problem because the hydrogen consumption is considerably large because the group is almost hydrogenated. Moreover, since the total aromatic content is reduced to 12% by volume or less, the density is lowered, the calorific value is reduced, the fuel consumption is deteriorated and the output is reduced, and further, the seal rubber used in the fuel injection system There is also concern about fuel leakage (leakage) due to the influence on the members.

On the other hand, the present applicant has previously proposed a method for reducing the sulfur content in light oil to 10 mass ppm or less without substantially reducing the aromatic content by adsorptive desulfurization (Patent Document 3). However, this adsorptive desulfurization has a low ability to take in sulfur, and when the operation is performed for a long period of time, it is necessary to frequently perform a regeneration treatment, which is not economical.
Disclosed is a method of desulfurizing a stream selected from petroleum or chemical streams containing heterocycles of fused rings under conditions favorable for aromatic saturation by a reaction zone containing a hydrodesulfurization catalyst and a reaction zone containing a hydrogen sulfide absorbent material. (Patent Document 4). However, this method is not preferable because hydrogen consumption accompanying aromatic saturation is remarkably high, and the production cost is increased.
JP 2004-269683 A Japanese Patent Laid-Open No. 2004-269685 International Publication No. 03/097771 Special table 2003-508580 gazette

  The present invention solves the above problems, and does not significantly increase the consumption of hydrogen under relatively mild conditions, and does not significantly reduce the aromatic content, and has an ultra-low sulfur gas oil base having a sulfur content of 1 mass ppm or less. Provides a method of manufacturing the material, has a high calorific value, excellent fuel economy and output, does not affect the seal rubber member used in the fuel injection system, and does not cause fuel leakage, 1 mass ppm of sulfur It is an object to provide the following ultra-low sulfur gas oil composition.

  The present inventor has conducted extensive research to solve the above-mentioned problems. As a result, in the desulfurization treatment using a desulfurization agent having a sulfur sorption function (sometimes simply referred to as sorption / removal sulfur), The present inventors have found that the sulfur content is influenced by the properties of the low sulfur gas oil fraction that is the raw material for the detachable sulfur, particularly the content of sulfur and polycyclic aromatics. That is, the present invention is a method for producing an ultra-low sulfur gas oil base as follows, or an ultra-low sulfur gas oil composition comprising an ultra-low sulfur gas oil base produced by such a method.

In the present invention, a low sulfur gas oil fraction having a sulfur content of 2 to 50 mass ppm and a polycyclic aromatic content of 4% by volume or less is contacted with a porous desulfurization agent having a sulfur sorption function in the presence of hydrogen. The ultra-low sulfur gas oil base material is obtained by desulfurizing and obtaining an ultra-low sulfur gas oil base material having a sulfur content of 1 mass ppm or less, and the content of polycyclic aromatics in the ultra-low sulfur gas oil base material is It is preferable that it is 3 volume% or less, and the ratio which occupies for the total sulfur content of the alkyl dibenzothiophenes in the said low sulfur gas oil fraction is 70 mass% or more.
Furthermore, the porous desulfurization agent having the sulfur sorption function contains zinc and another metal, and the other metal is at least one metal selected from copper, nickel, cobalt and iron, in particular, The porous desulfurization agent having a sulfur sorption function preferably contains zinc and nickel.
Further, the present invention is an ultra-low sulfur gas oil composition having a sulfur content of 1 mass ppm or less including an ultra-low sulfur gas oil base material produced by such a method, and in particular, the polycyclic aromatic content is 3 It is preferable that it is below volume%.

According to the method for producing an ultra-low sulfur gas oil base material of the present invention, an ultra-low sulfur gas oil base material having a sulfur content of 1 ppm by mass or less over a long period of time under a relatively mild condition without significantly reducing the aromatic content. In addition, the consumption of hydrogen can be reduced, and the production cost can be kept low.
Moreover, since the ultra-low sulfur gas oil composition of the present invention has a sulfur content of 1 ppm by mass or less, it can reduce the amount of sulfur oxide emissions in the exhaust gas, and suppress the deterioration of the nitrogen oxide reduction catalyst. The generation of particulate matter on the post-treatment catalyst can be reduced to reduce the environmental burden such as the suppression of nitrogen oxides and particulate matter emissions, and the aromatics remain at a moderate level. The amount is high, the fuel consumption and driving output of an automobile is excellent, the seal rubber member used in the fuel injection system is not affected, and the fuel leakage does not occur.

[Desulfurization process with desulfurization agent with sulfur sorption function]
In the method for producing an ultra-low sulfur gas oil base material according to the present invention, a method of contacting a low sulfur gas oil fraction with a porous desulfurization agent having a sulfur sorption function in the presence of hydrogen (removable sulfur) is used. The porous desulfurization agent having sulfur sorption function used in the present invention is to fix sulfur atoms in organic sulfur compounds (especially alkyldibenzothiophenes) to the desulfurization agent, and other than sulfur atoms in organic sulfur compounds. Is a porous desulfurization agent having a function of desorbing from the desulfurization agent by cleaving a carbon-sulfur bond in the organic sulfur compound. When this hydrocarbon residue is eliminated, hydrogen present in the system is added to carbon whose bond with sulfur has been cleaved. Therefore, a hydrocarbon compound obtained by removing sulfur atoms from the organic sulfur compound is obtained as a product. However, hydrocarbon compounds from which sulfur atoms have been removed may give products that have undergone reactions such as hydrogenation, isomerization, and decomposition. On the other hand, since sulfur is fixed to the desulfurization agent, unlike hydrorefining, sulfur compounds such as hydrogen sulfide are not generated as products.

The porous desulfurization agent is not particularly limited as long as it has a sorption function for organic sulfur compounds, but the metal contained in the porous desulfurization agent can remove only hydrogen sulfide only with zinc or the like, and copper, nickel The organic sulfur compound cannot be sufficiently desulfurized by using only one kind of other metals. In order to increase the capacity of sulfur incorporation into the desulfurizing agent, a metal selected from zinc as the first metal and copper, nickel, cobalt and iron as the second metal is preferable. Particularly preferably, the first metal is zinc and the second metal is a combination of nickel. A preferable desulfurizing agent contains metal components such as nickel and zinc in a total amount of 50 to 85% by mass, particularly 60 to 80% by mass of the metal components. These metal components are usually contained in the desulfurizing agent in the form of oxides or sulfides. In order to improve the desulfurization performance or to use it industrially, it is preferable to mold by adding other components. Alternatively, the molded and fired desulfurizing agent may be further impregnated and supported with a metal component and fired. The desulfurizing agent is preferably used after being reduced in a hydrogen atmosphere. The specific surface area of the desulfurizing agent is preferably 30 to 200 m ² / g, especially 50 to 150 m ² / g, still more 50 to 100 m ² / g.

  The ratio (mass) of the second metal content to the first metal is 50% or less, preferably 35% or less, particularly 2 to 20%. When the ratio (mass) of the content of the second metal to the content of the first metal exceeds 50%, the life of the porous desulfurizing agent is remarkably shortened, which is not preferable. The content of the first metal with respect to the total amount of the desulfurizing agent is preferably 30% by mass or more, more preferably 50% by mass or more, and particularly preferably 60 to 80% by mass. The content of the second metal with respect to the total amount of the desulfurizing agent is preferably 33% by mass or less, more preferably 20% by mass or less, and particularly preferably 1 to 10% by mass. When the content of the first metal is less than 30% by mass or the content of the second metal exceeds 33% by mass, the life of the porous desulfurizing agent is shortened, which is not preferable.

  Further, the desulfurization agent used in the present invention preferably has an alkali metal content including sodium of 1.0% by mass or less, more preferably 0.5% by mass or less, and more preferably It is 0.2 mass% or less. If the alkali metal is contained in an amount exceeding 1.0 mass% with respect to the total amount of the desulfurizing agent, the desulfurization performance is remarkably lowered, which is not preferable.

  In the case of a porous desulfurization agent containing zinc and nickel, the organic sulfur compound is decomposed on nickel, and sulfur atoms are first taken into nickel. Sulfur atoms incorporated into nickel move to zinc in the presence of hydrogen. Since this sulfur atom replaces the oxygen atom in the zinc oxide, the zinc, which was almost in the state of oxide at first, becomes a sulfide as the reaction time elapses. Not all zinc atoms are exposed on the surface of the desulfurization agent, but oxygen in zinc oxide that is not exposed on the surface is also replaced by sulfur in order, so that sulfur is taken in until zinc is completely sulfided. be able to. That is, as compared with the case of adsorptive desulfurization in which the organic sulfur compound is adsorbed only on the surface of the desulfurizing agent, the storage and desorption sulfur has a very high sulfur uptake capability and a long life.

  The above-described sorption / removal sulfur treatment using the porous desulfurizing agent continuously supplies hydrogen and raw material oil to the porous desulfurization agent having a sulfur sorption function packed in the fixed bed flow type reactor. The format is preferred. As specific desulfurization treatment conditions, the temperature is preferably from 100 to 500 ° C, more preferably from 200 to 400 ° C, particularly from 250 to 350 ° C. When the reaction temperature is less than 100 ° C., desulfurization hardly proceeds. When the reaction temperature exceeds 500 ° C., the metal component in the porous desulfurization agent is sintered, and the desulfurization activity is greatly reduced. The hydrogen pressure during the desulfurization treatment is preferably 0.5 to 10 MPa, more preferably 1 to 5 MPa, and particularly preferably 2 to 3 MPa. If the hydrogen pressure is less than 0.5 MPa, polycyclic aromatics may increase due to the dehydrogenation reaction, and desulfurization will not proceed easily. When the hydrogen pressure exceeds 10 MPa, not only polycyclic aromatics but also monocyclic aromatics are considerably hydrogenated, resulting in a very large hydrogen consumption.

In the fixed bed flow type, when the collection / removal sulfur treatment is performed by contacting the porous desulfurizing agent and the low sulfur gas oil fraction, LHSV is preferably in the range of ¹ to 50 hr ⁻¹ , more preferably in the range of 2 to 40 hr ⁻¹ , especially Is preferably selected from the range of 3 to 10 hr ⁻¹ . When LHSV is less than ¹ hr ⁻¹ , the reactor for collecting and removing sulfur becomes too large. When the LHSV exceeds 50 hr ⁻¹ , sufficient time cannot be obtained for collecting / removing sulfur. The hydrogen / oil supply ratio is preferably selected from the range of 10 to 1,000 NL / L, more preferably 50 to 600 NL / L, and particularly preferably 100 to 500 NL / L. When the hydrogen / oil supply ratio is less than 10 NL / L, polycyclic aromatics are hardly reduced, and desulfurization is difficult to proceed. When the hydrogen / oil supply ratio exceeds 1,000 NL / L, the capacity of the compressor that supplies hydrogen becomes too large.

  The purity of the coexisting hydrogen during the detachable sulfur treatment with the porous desulfurizing agent is preferably 50% by volume or more, more preferably 80% by volume or more, and particularly preferably 95% by volume or more. When the hydrogen purity is less than 50% by volume, the hydrogen compressor supplying hydrogen is undesirably large. In the desulfurization treatment with the porous desulfurization agent, sulfur compounds such as hydrogen sulfide and carbonyl sulfide as impurities in the coexisting hydrogen should be contained as little as possible because they reduce the sorption capacity of the porous desulfurization agent. Preferably, the concentration of the sulfur compound in the hydrogen is 1% by volume or less, further 0.1% by volume or less, particularly 0.01% by volume or less.

  As described above, the sorption / removal sulfur treatment using a desulfurization agent having a sulfur sorption function in the present invention does not generate sulfur compounds such as hydrogen sulfide as a product, unlike the hydrodesulfurization treatment using a hydrodesulfurization catalyst. Therefore, since the hydrogen sulfide concentration in the hydrogen after the reaction does not increase, it can be used as coexisting hydrogen for removing and adding hydrogen sulfide without removing the hydrogen sulfide, It can also be used as hydrogen in a hydrodesulfurization treatment with a hydrodesulfurization catalyst that is preferable as a preceding step.

[Low sulfur gas oil fraction]
The low-sulfur gas oil fraction subjected to the collection / removal sulfur has a polycyclic aromatic content of 4% by volume or less, preferably 3% by volume or less, and particularly preferably 2% by volume or less. This polycyclic aromatic component is measured by the method specified in JPI-5S-49-97, and is the total content of the bicyclic aromatic hydrocarbon compound and the tricyclic aromatic hydrocarbon compound. The tricyclic aromatic content (content of tricyclic aromatic hydrocarbon compound) is preferably 1% by volume or less, and more preferably 0.7% by volume or less. The polycyclic naphthene content (the total content of the bicyclic or tricyclic cyclic saturated hydrocarbon compounds) is preferably 20% by volume or less, and more preferably 15% by volume or less. When the polycyclic aromatic content in the low-sulfur gas oil fraction subjected to collection / removal sulfur exceeds 4 vol%, the tricyclic aromatic content exceeds 1 vol%, or the polycyclic naphthene content exceeds 20 vol% This is not preferable because desulfurization of the organic sulfur compound is difficult to proceed in the detaching and attaching sulfur process. If the polycyclic aromatics contained in the low-sulfur gas oil fraction subjected to the collecting / removing sulfur process exceeds 4% by volume or the tricyclic aromatics exceeds 1% by volume, it is necessary to reduce these in advance. is there. The method is not particularly limited, but a method of selecting a raw material having a low polycyclic aromatic content, a method of hydrogenation by contacting with a hydrogenation catalyst in the presence of hydrogen, or a solvent that can extract aromatics such as sulfolane is used. The method of extracting a ring aromatic is mentioned.
The sulfur content of the low sulfur gas oil fraction is 2 to 50 mass ppm, preferably 2 to 30 mass ppm, and particularly preferably 2 to 10 mass ppm.

  Further, in the storage / detachment sulfur process, depending on the reaction conditions, the polycyclic aromatics are hydrogenated to form monocyclic aromatics or polycyclic naphthenes. In other words, polycyclic aromatics can be reduced while collecting / removing sulfur, and desulfurization interference by polycyclic aromatics can be avoided. In the method for producing an ultra-low sulfur gas oil base material of the present invention, the polycyclic aromatic component of the obtained ultra-low sulfur gas oil base material is 3% by volume or less, preferably 2% by volume or less, more preferably 1% by volume or less. Especially preferably, it is 0.5 volume% or less, and it is so preferable that it is small. However, under conditions where polycyclic aromatics are hydrogenated, monocyclic aromatics may also be hydrogenated. However, excessive hydrogenation of monocyclic aromatics results in extremely high hydrogen consumption, When the aromatic content is lowered and used in a diesel vehicle or the like, it is not preferable from the viewpoint of suppressing the influence on the seal rubber member used in the fuel injection system. In addition, although the aromatic content does not change greatly by polycyclic aromatic hydrogenation, the hydrogenation of monocyclic aromatics changes the aromatic content according to the hydrogenated amount. Therefore, in the method for producing an ultra-low sulfur gas oil base material of the present invention, the monocyclic aromatic content of the obtained ultra-low sulfur gas oil base material is preferably 3% by volume or more, more preferably 5% by volume or more. In particular, it is 10 to 20% by volume. It is preferable to suppress the amount of monocyclic aromatics to be reduced to 50% or less, more preferably 30% or less, and particularly 10% or less in the collecting / removing sulfur process.

  As a method for obtaining a low-sulfur gas oil fraction to be subjected to the collection / removal sulfur process, it is preferable to subject the gas oil fraction to hydrodesulfurization treatment using a hydrodesulfurization catalyst as described later. In this hydrodesulfurization treatment, alkyl dibenzothiophenes are the most likely sulfur compounds among organic sulfur compounds, while in the desorption and desulfurization, alkyl dibenzothiophenes are desulfurized under milder conditions than hydrodesulfurization. Can do. Therefore, the proportion of the alkyldibenzothiophene sulfur compound in the total sulfur content of the low-sulfur gas oil fraction used for the collection and removal sulfur process is 70% by mass or more, further 80% by mass or more, particularly 90% by mass or more as the sulfur content. Is preferred.

  In addition, the alkyl dibenzothiophene sulfur compound referred to here is alkyl dibenzothiophene such as 2-methyldibenzothiophene, 2-ethyldibenzothiophene, 2,3-dimethyldibenzothiophene, 2,3,4-trimethyldibenzothiophene. It is a sulfur compound with a group. Furthermore, among the alkyldibenzothiophenes, alkyldibenzothiophenes having alkyl groups at the 4-position and 6-position of the dibenzothiophene skeleton are sulfur compounds that are particularly liable to remain in hydrodesulfurization treatment using hydrodesulfurization catalyst for light oil fractions. Therefore, the ratio of the alkyl dibenzothiophene sulfur compound having an alkyl group at the 4-position and the 6-position of the dibenzothiophene skeleton in the total sulfur content of the low-sulfur gas oil fraction is 50 mass% or more, further 70 mass as the sulfur content. % Or more, and particularly preferably 90% by mass or more. Examples of alkyl dibenzothiophene sulfur compounds having alkyl groups at the 4-position and 6-position of the dibenzothiophene skeleton include 4,6-dimethyldibenzothiophene, 4,6-diethyldibenzothiophene, 4,6,7-trimethyldibenzothiophene, and the like. Can be mentioned.

[Hydrodesulphurization with hydrodesulfurization catalyst]
In oil refining, gas oil fractions obtained by distilling crude oil usually contain 5,000 to 20,000 ppm by mass of sulfur, but without any treatment, the porous material has a sulfur sorption function. When desulfurization treatment is performed with a desulfurizing agent, the life of the porous desulfurizing agent is remarkably shortened and cannot be practically used. For this reason, when producing an ultra-low sulfur light oil base material having a sulfur content of 1 mass ppm or less, the desulfurization treatment is performed so that the sulfur content is 2 to 50 mass ppm before the desulfurization treatment with the porous desulfurization agent. However, the method for obtaining a low sulfur gas oil fraction having a sulfur content of 2 to 50 ppm by mass may be carried out by any method as long as the sulfur content falls within this range, but hydrodesulfurization treatment with a hydrodesulfurization catalyst is preferred. Is the method. This hydrodesulfurization treatment can also reduce the polycyclic aromatic content.

  As the hydrodesulfurization catalyst used in this hydrodesulfurization treatment, a catalyst containing a Group 6 element and a Group 9 and / or Group 10 element is preferably used. As the Group 6 element of the periodic table, molybdenum, tungsten, cobalt as the Group 9 element, and nickel as the Group 10 element are particularly preferable. These Group 6 elements and Group 9 and / or Group 10 elements are preferably used by being supported on an inorganic porous oxide carrier. As the inorganic porous oxide carrier, oxides of elements of Groups 2, 4, 13, and 14 of the periodic table can be used. Among these, silica, alumina, magnesia, zirconia, boria, calcia and the like are suitable, and these may be used alone or in combination of two or more. In particular, alumina (having each crystal structure such as γ, δ, η, and χ), silica-alumina, silica, alumina-magnesia, silica-magnesia, and alumina-silica-magnesia are preferable. Here, the periodic table is based on IUPAC, 1990 recommendation.

The inorganic porous oxide carrier can be easily prepared by a method in which an inorganic hydrated oxide is produced by a coprecipitation method, a kneading method, or the like, molded, dried and fired.
The loading of the metal component or the like is preferably performed by a commonly used spray impregnation method or dipping method, and a pore filling method of impregnating a solution corresponding to the water absorption rate of the inorganic porous oxide carrier is particularly preferable. In order to control the metal loading state, an organic compound or an organic salt may be allowed to coexist in the metal loading liquid. After impregnating the solution containing the metal component and the like, drying is carried out in a temperature range of 50 to 180 ° C., preferably 80 to 150 ° C. for 10 minutes to 24 hours. May be repeated. A hydrotreatment catalyst precursor is produced by impregnating a desired amount of a desired metal component and then calcining a dried product obtained by drying. This calcination treatment is preferably performed at a temperature range of 400 to 600 ° C., particularly 450 to 580 ° C., the temperature rising time to the calcination temperature is 10 to 240 minutes, and the holding time at the calcination temperature is 1 to 240 minutes. Is preferred.

  The hydrodesulfurization catalyst precursor exhibits an active site as a hydrodesulfurization catalyst by sulfiding. Usually, the sulfiding treatment is performed after filling the hydrotreating catalyst precursor into a reactor used for the hydrodesulfurization treatment. This sulfiding treatment is carried out by gradually raising the temperature while passing the sulfiding agent through the reactor filled with the hydrotreating catalyst precursor. The final sulfiding treatment temperature is 450 ° C. or less, preferably 100 to 400 ° C. It is. Sulfur compounds are added to petroleum distillates, petroleum distillates or desulfurized petroleum distillates containing sulfur compounds such as straight-run gas oil fractions as sulfiding agents in a hydrogen atmosphere at normal or higher hydrogen partial pressure. It is carried out using added one or hydrogen sulfide. When a sulfur compound is added to a petroleum distillate or the like and used, this sulfur compound is not particularly limited as long as it can be decomposed and converted into hydrogen sulfide under sulfurization treatment conditions, Carbon disulfide, thiophenes, dimethyl sulfide, dimethyl disulfide and various polysulfides. After filling the hydrotreating catalyst precursor into the reaction apparatus and before starting the sulfiding treatment, a drying process for removing water adhering to the hydrotreating catalyst precursor may be performed. This drying treatment is carried out at normal temperature to 220 ° C., preferably 100 to 200 ° C., in a hydrogen or inert gas atmosphere with a gas flowing at normal pressure or higher.

There are no particular restrictions on the type of reaction in the hydrodesulfurization treatment using the hydrodesulfurization catalyst, such as batch type, flow type, fixed bed type, fluidized bed type, etc., but the hydrogenation filled in the fixed bed flow type reaction device. A mode in which hydrogen and raw material oil are continuously supplied and brought into contact with the treatment catalyst is preferable. Preferable reaction conditions for the hydrodesulfurization treatment are a reaction temperature of 200 to 450 ° C., particularly 250 to 400 ° C., a hydrogen pressure of 2 to 10 MPa, particularly 3 to 8 MPa, a hydrogen / oil supply ratio of 100 to 1000 NL / L, Particularly, it is 100 to 500 NL / L, and LHSV is 0.1 to 5 hr ⁻¹ , particularly 0.5 to 2 hr ⁻¹ . Even in the hydrodesulfurization treatment using the hydrodesulfurization catalyst to obtain the above-mentioned low sulfur gas oil fraction, polycyclic aromatics are hydrogenated to some extent at the same time as desulfurization, so the amount of polycyclic aromatics is reduced to 4% by volume. A method of setting reaction conditions so as to be as follows may be used. Hydrodesulfurization is usually carried out under severer reaction conditions than detachable sulfur. The ratio of the hydrogen pressure in the recovery and attachment sulfur process to the hydrogen pressure in the hydrodesulfurization treatment is preferably 0.1 to 1, more preferably 0.2 to 0.8, and particularly 0.3 to 0.7. The ratio of LHSV in the collecting / removing sulfur process with respect to LHSV in the hydrodesulfurization treatment is preferably 2 to 50, more preferably 3 to 20, particularly 4 to 10.

  Hydrogen sulfide produced by desulfurization is dissolved in the low sulfur gas oil produced by hydrodesulfurization treatment using a hydrodesulfurization catalyst, and the sulfur sorption capacity of the porous desulfurization agent in the subsequent desulfurization treatment using the porous desulfurization agent Preferably, hydrogen sulfide is removed as much as possible before the desulfurization treatment with the porous desulfurization agent so as not to damage the heat. A method for removing hydrogen sulfide is not particularly limited, but gas containing no hydrogen sulfide, stripping by steam injection, rectification, removal by an adsorbent, or the like can be used alone or in combination. The content of hydrogen sulfide in the low-sulfur gas oil fraction subjected to the collection / removal sulfur process is preferably 5 ppm by mass or less, more preferably 1 ppm by mass or less, particularly 0.5 ppm by mass or less as the sulfur content.

[Light oil fraction]
The gas oil fraction used as a raw material for producing the low sulfur gas oil fraction used in the method for producing the ultra-low sulfur gas oil base material of the present invention preferably has a sulfur content of 0.5% by mass or more, The sulfur content is 0.5 to 5% by mass, particularly 1 to 2% by mass, the nitrogen content is 50 ppm by mass or more, particularly 80 to 500 ppm by mass, and the density (15 ° C.) is 0.80 to 0. .90 g / cm ³ , 50 volume% distillation temperature is 250-320 ° C., especially 260-310 ° C., 70 volume% distillation temperature is 280-340 ° C., particularly 290-330 ° C., The 90% by volume distillation temperature is 310-370 ° C, in particular 320-360 ° C, and the 95% by volume distillation temperature is 320-390 ° C, in particular 330-380 ° C.

  As this light oil fraction, it is preferable to use a straight-run light oil fraction obtained by distilling crude oil. A straight-run gas oil fraction may be used alone, or a mixed light-oil fraction obtained by mixing a cracked light oil fraction such as pyrolysis oil or catalytic cracked oil with a straight-run light oil fraction may be used. In this case, it is preferable to mix 5 to 45% by volume, particularly 15 to 35% by volume of the cracked gas oil fraction, and 95 to 55% by volume, particularly 85 to 65% by volume of the straight gas oil fraction. Furthermore, if it is a fraction corresponding to light oil, other process oils can be mixed with the light oil fraction as a raw material. The straight-run gas oil fraction is obtained by atmospheric distillation of crude oil, and approximately 10% by volume distillation temperature is 200 to 290 ° C, 50% by volume distillation temperature is 260 to 320 ° C, and 90% by volume distillation temperature is 300%. ~ 370 ° C.

  Pyrolysis oil is a light fraction oil obtained by applying a heat to a heavy oil fraction and undergoing a cracking reaction mainly composed of radical reactions. For example, a delayed coking method, a visbreaking method or a fluid coking method is used. This refers to the fraction obtained. Although these fractions may use the whole fraction obtained as a pyrolysis oil, it is suitable to use the fraction whose distillation temperature exists in the range of 150-520 degreeC.

Examples of the catalytic cracking oil include middle fractions and heavy fractions, particularly fractions obtained by catalytic cracking of a vacuum gas oil fraction or atmospheric distillation residue with a zeolite catalyst, etc. A cracked gas oil fraction produced as a by-product in a fluid catalytic cracker for the purpose of gasoline production is preferred. In general, a light catalytic cracked oil having a relatively low boiling point and a heavy catalytic cracked oil having a relatively high boiling point are separately collected from this fraction. In the present invention, any of these fractions can be used, but it is preferable to use the former light catalytic cracking oil, so-called light cycle oil (LCO). The LCO generally has a 10 vol% distillation temperature of 200 to 250 ° C, a 50 vol% distillation temperature of 250 to 290 ° C, and a 90 vol% distillation temperature of 300 to 355 ° C. In addition, heavy catalytic cracking oil, so-called heavy cycle oil (HCO), has a 10 vol% distillation temperature of 280 to 340 ° C, a 50 vol% distillation temperature of 390 to 420 ° C, and a 90 vol% distillation temperature of 450 ° C or higher. It is in.
Since LCO contains a large amount of polycyclic aromatics, if the proportion of LCO in the gas oil fraction used as a raw material is large, the low sulfur gas oil fraction obtained by hydrodesulfurization has a large amount of polycyclic aromatics. It will be included. Therefore, the ratio of LCO in the gas oil fraction as a raw material is preferably 50% by volume or less, particularly 30% by volume or less, and further 20% by volume or less.

[Super low sulfur gas oil base]
In the present invention, the ultra-low sulfur gas oil base material is desulfurized by contacting a low sulfur gas oil fraction having a specific sulfur content and aromatic content with a porous desulfurization agent having a sulfur sorption function in the presence of hydrogen. Can be obtained. The sulfur content of the ultra-low sulfur gas oil base is 1 mass ppm or less, preferably 0.8 mass ppm or less, more preferably 0.5 mass ppm or less, and the smaller the better. For this reason, the low sulfur gas oil fraction to be used in the collecting / removing sulfur process has a sulfur content of 2 to 50 ppm by mass, preferably 2 to 30 ppm by mass, and particularly 2 to 10 ppm by mass.

[Ultra-low sulfur gas oil composition]
The ultra-low sulfur gas oil composition of the present invention includes an ultra-low sulfur gas oil base material and has a sulfur content of 1 mass ppm or less. The ultra-low sulfur gas oil base is preferably contained in an amount of 50% by volume or more, particularly 80% by volume or more, but the ultra-low sulfur gas oil base may be used as it is as an ultra-low sulfur gas oil composition. In addition, the ultra-low sulfur gas oil composition of the present invention can have other base materials provided that physical properties such as sulfur content, aromatic content, distillation properties, density (15 ° C.), and true calorific value satisfy the conditions described later. You may mix. Other base materials include straight-run kerosene, pyrolysis kerosene, catalytic cracking kerosene, hydrodesulfurized oil obtained by hydrodesulfurizing them with a hydrodesulfurization catalyst, and further desulfurized to a sulfur content of 10 ppm by mass or less. Examples include ultra-low sulfur kerosene, hydrocracked kerosene and hydrocracked diesel oil obtained by hydrocracking vacuum gas oil, synthetic kerosene and synthetic gas oil obtained by chemically synthesizing natural gas, asphalt, and the like.

  The ultra-low sulfur gas oil composition of the present invention has a sulfur content of 1 mass ppm or less. This sulfur content is measured by the method prescribed in ASTM D 5453 (ultraviolet fluorescence method).

  The aromatic content is preferably 10 to 25% by volume, more preferably 10 to 20% by volume, and particularly preferably 13 to 18% by volume. If the aromatic content is less than 10% by volume, the calorific value is lowered and the fuel consumption is lowered. If the aromatic content is 25% by volume or more, the amount of particulate matter discharged from the engine increases, which is not preferable. Among the aromatic components, the polycyclic aromatic component is preferably 3% by volume or less, more preferably 2% by volume or less, further 1% by volume or less, and particularly preferably 0.5% by volume or less. If the polycyclic aromatic exceeds 3% by volume, the amount of particulate matter discharged from the engine increases, which is not preferable.

  The 50 vol% distillation temperature in the distillation properties is preferably 250 to 320 ° C, particularly 260 to 310 ° C, the 70 vol% distillation temperature is preferably 280 to 340 ° C, particularly 290 to 330 ° C, 90% The volume% distillation temperature is preferably 310 to 370 ° C, particularly 320 to 360 ° C, and the 95 volume% distillation temperature is preferably 320 to 390 ° C, particularly 330 to 380 ° C. If the 95% by volume distillation temperature exceeds 390 ° C., the amount of particulate matter discharged from the engine increases, which is not preferable. This distillation property is measured by a method defined in JIS K 2254.

Density is preferably 0.80~0.87g / cm ³ at 15 ° C., more preferably ^{0.82~0.86g / cm 3, 0.83~0.85g / cm} 3 is particularly preferred. If the density at 15 ° C. is less than 0.80 g / cm ³ , the calorific value is lowered and fuel consumption and acceleration are deteriorated, which is not preferable. When the density at 15 ° C. exceeds 0.87 g / cm ³ , the concentration of particulate matter in the exhaust gas increases, which is not preferable. The density at 15 ° C. is measured by the method defined in JIS K 2249.

  The true calorific value is preferably 34.5 MJ / L or more, and more preferably 35 MJ / L or more. A true calorific value of less than 34.5 MJ / L is not preferable because the output is reduced. This true calorific value is measured by the method defined in JIS K 2279.

The kinematic viscosity at 30 ° C. is preferably 1.5 to 5.0 mm ² / s, and more preferably 2.5 to 5.0 mm ² / s. If the kinematic viscosity at 30 ° C. is less than 1.5 mm ² / s, the fuel injection amount of the diesel vehicle may decrease and the output may decrease, and the lubricity in each part of the fuel injection pump mounted on the engine It is damaged and is not preferred. If the kinematic viscosity at 30 ° C. exceeds 5.0 mm ² / s, the resistance inside the fuel injection system increases, the injection system becomes unstable, and the concentration of NOx and particulate matter in the exhaust gas becomes high, which is not preferable. The kinematic viscosity at 30 ° C. is measured by the method defined in JIS K 2283.

  As additives to light oil, known fuel additives such as low-temperature fluidity improvers, wear resistance improvers, cetane number improvers, antioxidants, metal deactivators, and corrosion inhibitors may be added. Good. As the low temperature fluidity improver, an ethylene copolymer or the like can be used. In particular, a vinyl ester of a saturated fatty acid such as vinyl acetate, vinyl propionate or vinyl butyrate is preferably used. As the wear resistance improver, for example, a long chain fatty acid (having 12 to 24 carbon atoms) or a fatty acid ester thereof is preferably used. The wear resistance is sufficiently improved by the addition amount of 10 to 500 ppm, preferably 50 to 100 ppm.

(Example)
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these Examples.

(Preparation of low sulfur gas oil fraction)
First, a light oil fraction D serving as a raw material oil for preparing a low sulfur gas oil fraction used in the present invention was prepared as follows. 75% by volume of straight-run gas oil A obtained by distillation of Middle Eastern crude oil, light contact obtained by catalytic cracking after hydrodesulfurization of vacuum gas oil fraction obtained by distillation of Middle Eastern crude oil A light oil fraction D was obtained by mixing 20% by volume of pyrolysis oil C obtained by pyrolysis treatment of 5% by volume of cracked oil B and heavy oil mainly composed of vacuum residual oil. Table 1 shows the properties of straight-run gas oil A, light catalytic cracking oil B, pyrolysis oil C and gas oil fraction D.

Volume of hydrodesulfurization catalyst CoMo / alumina (cobalt content 3 wt%, molybdenum content 13 wt%) and NiMo / alumina (nickel content 3 wt%, molybdenum content 12 wt%) prepared by the loading method The reaction tube was filled to a ratio of 1: 3. As a pretreatment, a light oil containing 1% by weight of dimethyl disulfide was passed through the reaction tube at 300 ° C. while flowing hydrogen at 5 MPa to perform a sulfiding treatment.
Thereafter, a light oil fraction D is passed through the reaction tube and reacted under the conditions of a reaction temperature of 345 ° C., a hydrogen partial pressure of 7.0 MPa, an LHSV of 1.2 hr ⁻¹ , and a hydrogen / oil supply ratio of 440 NL / L. It was. Hydrogen sulfide was stripped off from the effluent reaction product to obtain a low sulfur gas oil fraction E. Table 2 shows the properties of the low sulfur gas oil fraction E.

  In this example, the properties shown in Tables 1 and 2 were measured according to the following method. Density is JIS K 2249, sulfur content is ASTM D 5453 (ultraviolet fluorescence method), nitrogen content is JIS K 2609, distillation property is JIS K 2254, kinematic viscosity is JIS K 2283, color is JIS K 2580 ASTM color test method, The true calorific value was measured according to JIS K 2279. The aromatic content was measured based on JPI-5S-49-97.

Nickel zinc composite oxide was prepared by the following coprecipitation method as a porous desulfurization agent with sulfur sorption function. A solution in which 106 g of sodium carbonate was dissolved in water was heated to 60 ° C., and a solution in which 214 g of zinc nitrate hexahydrate was dissolved in water and 23 g of nickel nitrate hexahydrate was added dropwise. The resulting precipitate was filtered and washed with water. Then, after drying at 120 degreeC for 16 hours, it baked at 350 degreeC for 3 hours, and obtained nickel zinc composite oxide (desulfurization agent Z). The desulfurizing agent Z had a nickel content of 6.9% by mass, a zinc content of 71.0% by mass, a sodium content of 0.01% by mass, and a specific surface area of 56 m ² / g.

This nickel zinc composite oxide was filled in a reaction tube. Hydrogen gas was allowed to flow through this at a temperature of 300 ° C. for 6 hours to perform a reduction treatment. Thereafter, the low sulfur gas oil fraction E and hydrogen are passed through the reaction tube, and the reaction is performed under the conditions of a reaction temperature of 300 ° C., a hydrogen pressure of 3.0 MPa, LHSV of 5.0 hr ⁻¹ , and a hydrogen / oil supply ratio of 400 NL / L. After 500 hours from the start, an ultra-low sulfur gas oil fraction F was obtained. Properties of the obtained ultra-low sulfur gas oil fraction F are shown in Table 2.

  As is clear from this result, the gas oil fraction was separated from the hydrodesulfurization catalyst containing Group 6 element and Group 9 element and Group 6 element in the periodic table in the presence of hydrogen at high pressure. After the step of obtaining a low sulfur gas oil fraction having a sulfur content of 2 to 50 mass ppm and a polycyclic aromatic content of 4% by volume or less by contacting with a hydrodesulfurization catalyst containing a Group 10 element, the obtained low sulfur gas oil An ultra-low sulfur gas oil fraction having a sulfur content of 1 mass ppm or less can be obtained by contacting the fraction with a porous desulfurization agent having a sulfur sorption function in the presence of hydrogen to perform desulfurization treatment.

  The experiment conducted in Example 1 was further reacted under exactly the same conditions to obtain a low sulfur gas oil fraction G 5000 hours after the start of oil passage. Table 2 shows the properties of the obtained low sulfur gas oil fraction G. As is apparent from this result, an ultra-low sulfur gas oil fraction having a sulfur content of 1 mass ppm or less can be obtained over a long period of time.

Comparative Example 1

The reaction mixture was filled with the nickel-zinc composite oxide prepared in Example 1 (nickel content: 6.9% by mass, zinc content: 71.0% by mass), and hydrogen gas was charged at a temperature of 300 ° C. for 6 hours. It was distributed and reduced. Thereafter, a low sulfur gas oil fraction E and hydrogen were passed through the reaction tube under the conditions of a reaction temperature of 300 ° C., a hydrogen pressure of 1.0 MPa, an LHSV of 5.0 hr ⁻¹ , and a hydrogen / oil supply ratio of 400 NL / L. A light oil fraction H was obtained 500 hours after the start of oil passage. Table 2 shows the properties of the obtained light oil fraction H.

Comparative Example 2

A catalyst formed by mixing zinc oxide and alumina at a ratio of 95: 5 (weight ratio) was filled in a reaction tube, and hydrogen gas was passed through the tube at a temperature of 300 ° C. for 6 hours for reduction treatment. Thereafter, a low sulfur gas oil fraction E and hydrogen were passed through the reaction tube under the conditions of a reaction temperature of 300 ° C., a hydrogen pressure of 1.0 MPa, an LHSV of 5.0 hr ⁻¹ , and a hydrogen / oil supply ratio of 400 NL / L. A light oil fraction I was obtained 100 hours after the start of oil passing. Table 2 shows the properties of the light oil fraction I obtained.

The reaction mixture was filled with the nickel-zinc composite oxide prepared in Example 1 (nickel content: 6.9% by mass, zinc content: 71.0% by mass), and hydrogen gas was charged at a temperature of 300 ° C. for 6 hours. It was distributed and reduced. Thereafter, 4,6-dimethyldibenzothiophene (manufactured by ACROS, purity 95% or more) as a sulfur content was added to this reaction tube at 6 mass ppm and polycyclic aromatic solvent P-220 (manufactured by Japan Energy, 2-ring aroma content) The n-dodecane solution adjusted to contain 1% by volume as a polycyclic aromatic component (91 wt%, sulfur content 0.1 mass ppm or less) was passed with hydrogen, reaction temperature 300 ° C., hydrogen pressure 1.0 MPa. , LHSV was 40.0 hr ⁻¹ , and the hydrogen / oil supply ratio was 200 NL / L. The sulfur content of the product oil obtained 50 hours after the start of oil passing was 0.9 mass ppm.

Comparative Example 3

  The reaction was carried out under exactly the same conditions as in Example 3, except that the polycyclic aromatic content of P-220 was changed to 5% by volume in Example 3. The sulfur content of the product oil obtained 50 hours after the start of oil passing was 2.4 mass ppm.

Comparative Example 4

  In Example 3, instead of P-220, phenanthrene (a Wako Pure Chemical special grade reagent was purified to have a sulfur content of 0.2 mass ppm) was added to adjust the polycyclic aromatic content to 1.1% by volume. The reaction was carried out under exactly the same conditions as in Example 3. The sulfur content of the product oil obtained 50 hours after the start of oil passing was 2.5 ppm by mass.

Claims (4)

A low sulfur gas oil fraction having a sulfur content of 2 to 50 ppm by mass and a polycyclic aromatic content of 4% by volume or less contains zinc and other metals in the presence of hydrogen , and other metals are copper, nickel A porous desulfurization agent having a sulfur sorption function which is at least one metal selected from cobalt and iron , a reaction temperature of 100 to 500 ° C., a hydrogen pressure of 0.5 to 10 MPa, LHSV of ^{1 to} 50 hr ⁻¹ , hydrogen / A method for producing an ultra-low sulfur gas oil base material, characterized in that an ultra-low sulfur gas oil base material having a sulfur content of 1 mass ppm or less is obtained by contact with an oil supply ratio of 10 to 1,000 NL / L and desulfurization treatment.   The method for producing an ultra-low sulfur gas oil base material according to claim 1, wherein the content of the polycyclic aromatic in the ultra-low sulfur gas oil base material is 3% by volume or less.   The method for producing an ultra-low sulfur gas oil base material according to claim 1 or 2, wherein the proportion of alkyl dibenzothiophenes in the low sulfur gas oil fraction in the total sulfur content is 70% by mass or more. The method for producing an ultra-low sulfur gas oil base material according to claim 1 , wherein the porous desulfurization agent having a sulfur sorption function contains zinc and nickel.