JP4658491B2 - Production method of environment-friendly diesel oil - Google Patents

Description

The present invention relates to a method for producing environmentally friendly diesel fuel corresponding to the environmental protection, more particularly with addressing environmental protection by reducing the sulfur content, and environmental secured amount of heat generated per sufficient unit volume a process for the production of light oil.

  In recent years, from the viewpoint of environmental protection, diesel vehicles have been required to significantly reduce emissions of environmental pollutants such as PM (particulate matter), NOx (nitrogen oxide) and HC (hydrocarbon) in exhaust gas. Yes. For this reason, development of diesel vehicles using post-treatment systems such as diesel engine improvements and oxidation catalysts, NOx reduction catalysts, DPFs (diesel particulate filters), and the like is being promoted. In order to effectively demonstrate the capabilities of these exhaust gas aftertreatment systems and maintain durability, light oil used as fuel is required to be reduced in sulfur content. This is because the catalyst used in the exhaust gas aftertreatment system that is installed to reduce PM and NOx contained in the exhaust gas of diesel automobiles is poisoned by sulfur oxides generated by the combustion of sulfur in light oil, and the catalyst This is because the function of According to the Central Environmental Council “Future vehicle emission reduction measures (7th report)” (July 29, 2003), the allowable limit of sulfur in diesel oil will be 10 ppm from 2007 It has become.

  In a diesel vehicle, if the amount of PM generated by burning light oil is large, the load on the DPF increases. Regarding the relationship between PM production and light oil properties, the amount of PM produced increases as the aromatic content in light oil increases, but the increase in monocyclic aromatics does not significantly affect the amount of PM produced, and more than two rings It is thought that the polycyclic aromatic component of is greatly related to the production of PM (Non-patent Document 1). On the other hand, in order to reduce carbon dioxide emission, which is considered to be a cause of global warming, there is a demand for improvement in automobile fuel consumption.

  By the way, as a means for recovering the function of the exhaust gas post-treatment catalyst that has been poisoned, a method is generally employed in which light oil itself, which is a fuel, is supplied onto the catalyst and reacted. Therefore, if diesel oil with a lower sulfur content is used, the frequency of sulfur poisoning recovery control of the catalyst can be reduced and the fuel consumed can be reduced, improving fuel efficiency and consequently reducing carbon dioxide emissions. It becomes possible. According to the latest research (Non-Patent Document 2), if the catalyst poisoning recovery control frequency of the exhaust gas aftertreatment system is adjusted according to the sulfur content of the light oil used as fuel, the sulfur content in the light oil is 10 ppm, The fuel consumption can be improved by 3.9% compared to the case of 50 ppm. Therefore, it is conceivable that fuel efficiency can be further improved by further reducing the sulfur content contained in the light oil from 10 ppm.

Supervised by Toshiaki Kabe, Satoshi Kawada, Toru Takatsuka, Makoto Makoto, Atsushi Ishihara, “Hydrogenation Purification-Science & Technology-”, ICP, Tokyo (2000) Shigeki Uchiyama, Petroleum Industry Revitalization Center 17th Technology Development Research Results Presentation Presentation, Tokyo (June 4, 2003)

  According to the Fischer-Tropsch method, it is possible to synthesize hydrocarbons containing normal paraffin as a main component and containing almost no sulfur from synthesis gas consisting of hydrogen and carbon monoxide obtained by reforming natural gas. It is known that it can be done. In recent years, attention has been focused on producing a synthetic light oil containing substantially no sulfur content from the synthesized hydrocarbon as a raw material (for example, Patent Documents 1 to 7, Non-Patent Document 3). However, such a synthetic light oil has a sufficiently low sulfur content, but has a disadvantage that it has a lower density and a lower calorific value per unit volume than a conventional petroleum light oil.

Japanese National Patent Publication No. 11-513729 Japanese National Patent Publication No. 11-513730 JP-T-2001-511207 Special table 2001-522382 gazette Special table 2002-507635 gazette Japanese translation of PCT publication No. 2002-526636 Japanese translation of PCT publication No. 2002-526637 Masahiko Shibuya, Petroleum Society 10th Catalysis Symposium Proceedings, pp. 8-14, Tokyo (October 3, 2001)

  A gas oil fraction cracked and produced by hydrotreating a petroleum-based vacuum gas oil fraction under the reaction conditions of a hydrogen pressure of 10 to 25 MPa and a reaction temperature of 350 to 450 ° C. in the presence of a catalyst is a hydrocracked gas oil and be called. Although the hydrocracked gas oil having a sulfur content of about 10 ppm by mass can be obtained relatively easily because the reaction is performed at the high hydrogen pressure as described above, there is a problem that the amount of hydrogen consumed is large and the energy consumed in the process is large. There was a point. In addition, since the hydrogenation reaction of the aromatic component proceeds excessively, the obtained hydrocracked gas oil has a problem that the density is low and the calorific value per unit volume is small.

The object of the present invention is to solve the above-mentioned problems of the prior art, the sulfur content and the polycyclic aromatic content are sufficiently low, and the true calorific value per unit volume equivalent to that of light oil that is commercially available in the past. method for producing environmentally friendly diesel fuel to ensure a certain to provide.

  The inventors of the present invention succeeded in obtaining a gas oil having an extremely low sulfur content by hydrotreating a petroleum fraction under predetermined hydrogenation conditions.

According to the embodiment of the present invention, the density is 0.795 g / cm ³ or more, the sulfur content is 5 mass ppm or less, the monocyclic aromatic content is 5 to 18% by volume, and the polycyclic aromatic content is 2% by volume or less. And a method for producing an environmentally friendly light oil having a true calorific value per unit volume of 34500 J / cm ³ or more,
A hydrocarbon oil having a sulfur content of 0.5% by mass or more, a density of 0.80 to 0.90 g / cm ³ , and a 90% by volume distillation temperature of 370 ° C. or less is used as a raw material oil, a hydrogen pressure of 3 to 10 MPa, a reaction A first step of obtaining a reaction mixture by contacting with a hydrotreating catalyst under reaction conditions of a temperature of 280 to 450 ° C;
A second step of gas-liquid separation of the reaction mixture obtained in the first step to obtain a crudely refined oil;
A third step of contacting the crude refined oil obtained in the second step with a hydrotreating catalyst under reaction conditions of a hydrogen pressure of 3 to 10 MPa and a reaction temperature of 280 to 450 ° C .;
Provided is a method for producing environmentally friendly diesel oil in which the total pressure in the first step is higher than the total pressure in the third step.

  The present invention provides an environmentally-friendly light oil that has a sulfur content as low as 5 ppm by mass or less and further as 1 ppm by mass or less and that secures a true calorific value per unit volume equivalent to that of conventionally marketed diesel oil. As a result, both the reduction of environmental pollutant emissions and the reduction of carbon dioxide emissions from diesel vehicles have been realized.

[Environmentally friendly diesel]
The environment-friendly light oil produced by the production method of the present invention has a density of 0.795 g / cm ³ or more, a sulfur content of 5 mass ppm or less, a monocyclic aromatic content of 5 to 18% by volume, and a polycyclic aromatic content. It is 2% by volume or less and the true calorific value per unit volume is 34500 J / cm ³ or more.

The density of the environment-friendly light oil is preferably 0.800 to 0.850 g / cm ³ , more preferably 0.805 to 0.845 g / cm ³ , and particularly 0.810 to 0.840 g / cm ³ . The density in this specification refers to the density in 15 degreeC measured by JISK2249. If the density of the environment-friendly light oil is less than 0.795 g / cm ³ , the true calorific value per unit volume is lowered, and the fuel consumption per unit volume of the environment-friendly light oil is deteriorated. When the density is 0.850 g / cm ³ or more, the production cost of environment-friendly light oil increases . Sulfur environmentally friendly diesel fuel is preferably at most 1 mass ppm. When the sulfur content is 5 ppm by mass or more, it is necessary to increase the frequency of sulfur poisoning recovery control of the catalyst of the exhaust gas aftertreatment device of a diesel vehicle, which is not preferable because fuel efficiency is deteriorated. The 1-ring aromatic component in this specification refers to the 1-ring aromatic component measured by JPI-5S-49-97 "Petroleum product-hydrocarbon type test method-high performance liquid chromatograph method" . 1 ring aromatic content of environmentally friendly diesel fuel is a 5 to 18% by volume, preferably 8 to 18% by volume, in particular 10 to 16% by volume. When the aromatic content of one ring is less than 5% by volume, the true calorific value per unit volume is lowered, and the fuel consumption per unit volume of the environmentally friendly light oil is deteriorated. The polyaromatic component in the present specification means a bicyclic aromatic component and a tricyclic or higher aromatic component measured by JPI-5S-49-97 “Petroleum products—hydrocarbon type test method—high performance liquid chromatographic method”. It refers to the sum of. Polycyclic aromatic content of environmentally friendly diesel fuel is less than 2% by volume, preferably 1.5 volume%, particularly less than 1% by volume. If the polycyclic aromatic content exceeds 2% by volume, the amount of PM produced increases and the load on the DPF increases, such being undesirable. The total aromatic content in the present specification means a 1-ring aromatic content, a 2-ring aromatic content and a 2-ring aromatic content measured by JPI-5S-49-97 “Petroleum products—Hydrocarbon type test method—High performance liquid chromatographic method”. Refers to the total aromatic content of 3 or more rings . Total aromatic content of environmentally friendly gas oil, preferably 5-20% by volume, more 8-20 volume%, in particular 10 to 18% by volume. When the total aromatic content is less than 5% by volume, the true calorific value per unit volume is lowered, and the fuel consumption per unit volume of the environmentally friendly light oil is deteriorated. Moreover, if the total aromatic content is lowered, the swelling characteristics of rubber used as a fuel system sealant for diesel automobiles is deteriorated, which is not preferable. When the total aromatic content exceeds 20% by volume, it becomes difficult to control the sulfur content to 5 mass ppm or less, which is not preferable. The true calorific value per unit volume in the specification of the present application refers to that obtained by JIS K 2279 . Net calorific value per unit volume of the environmentally friendly diesel fuel is a 34500J / cm ³ or more, preferably in the range of 34500~36500J / cm ^3. From the viewpoint of fuel consumption, the higher the true calorific value per unit volume, the better. However, when it exceeds 36500 J / cm ³ , it becomes difficult to ensure practical characteristics as fuel, for example, combustibility and low-temperature fluidity.

The environmentally friendly light oil produced by the production method of the present invention preferably has a kinematic viscosity at 30 ° C. of 1.7 mm ² / s or more, more preferably 2.0 mm ² / s or more, and particularly 2.7 mm ² / s. That's it. If the kinematic viscosity is lower than 1.7 mm ² / s, the lubricity on the sliding surface of the fuel injection pump or nozzle of the diesel vehicle is deteriorated, which causes seizure and the like, which is not preferable . Environmentally friendly diesel fuel, preferably, filter plugging point is -5 ° C. or less, more -12 ° C. or less, in particular is -19 ° C. or less. If the clogging point is too low, the passage through the fuel filter of a diesel vehicle becomes worse at low temperatures, which is not preferable . Environmentally friendly diesel fuel is preferably is -2.5 ° C. or less pour point, further -7.5 ° C. or less, in particular is -20 ° C. or less. A high pour point is not preferable because it tends to solidify at low temperatures . Environmentally friendly diesel fuel is preferably cloud point is -5 ° C. or less. If the cloud point is high, the passing property of the fuel filter of a diesel vehicle is deteriorated at low temperatures, which is not preferable . Environmentally friendly diesel fuel is preferably cetane index of 45 or more, more than 50, in particular 55 or more. If the cetane index is low, the ignitability is deteriorated and the startability at low temperatures is deteriorated . Environmentally friendly diesel fuel is preferably 10% carbon residue, 0.10 wt% or less, further 0.05% or less, particularly equal to or less than 0.02 mass%. If the residual carbon content is high, unburned substances are likely to be generated, which is not preferable. The kinematic viscosity, clogging point, pour point, cloud point, cetane index and 10% residual carbon content in the present specification are JIS K 2283, JIS K 2288, JIS K 2269, JIS K 2269, and JIS K 2280, respectively. And those defined in JIS K 2270 . Environmentally friendly diesel fuel, 90 volume% distillation temperature is preferably 360 ° C. or less, more three hundred to three hundred fifty-five ° C., particularly preferably from 310 to 340 ° C.. If the 90% by volume distillation temperature is high, the combustibility deteriorates, which is not preferable. If the 90% by volume distillation temperature is low, the true calorific value per unit volume is lowered, and the fuel efficiency per unit volume of environment-friendly diesel oil is deteriorated.

The environment-friendly light oil produced by the production method of the present invention has a 50% by volume distillation temperature of preferably 240 to 310 ° C, more preferably 245 to 305 ° C, particularly 250 to 300 ° C. If the 50% by volume distillation temperature is too high, the flammability will deteriorate, and if the 50% by volume distillation temperature is too low, the true calorific value per unit volume will decrease and the fuel efficiency per unit volume of environmentally friendly light oil will deteriorate. It is not preferable . Environmentally friendly diesel fuel, 10 volume% distillation temperature is preferably 180 to 260 ° C., further one hundred and ninety-five to two hundred and fifty-five ° C., in particular two hundred and five to two hundred and fifty ° C.. If the 10% by volume distillation temperature is too high, the yield of environmentally friendly light oil is reduced and the production cost is increased, and if the 10% by volume distillation temperature is too low, the flash point of the environmentally friendly light oil becomes high, which is not preferable. In addition, the distillation properties such as 90% by volume distillation temperature, 50% by volume distillation temperature, 10% by volume distillation temperature and the like in the present specification refer to those specified by JIS K 2254.

[Method for producing environmentally friendly diesel oil]
According to the method for producing environment-friendly light oil of the present invention, the environment-friendly light oil as described above can be produced.

[Raw oil]
The raw material oil in the production method of the environment-friendly light oil of the present invention has a density of 0.80 to 0.90 g / cm ³ , a sulfur content of 0.5% by mass or more, and a 90 vol% distillation temperature of 370 ° C. or less. Hydrogen oil.

Density of feedstock, preferably 0.81~0.89g / cm ^3, particularly preferably from 0.82~0.88g / cm ^3. Usually, the sulfur content of raw material oil is 0.5-5 mass%, especially 1-3 mass%. Further, the nitrogen content of the raw material oil is usually 50 ppm by mass or more, particularly 80 to 500 ppm by mass. As long as the above-described conditions are satisfied, there is no particular limitation on the origin of the hydrocarbon oil, but the raw oil containing the straight-run gas oil fraction alone or the straight-run gas oil fraction as a main component, for example, the raw material containing 80% by volume or more It is preferable to use oil. In addition, process oils obtained from various petroleum refining processes may be used by mixing with straight-run gas oil fractions.

  The straight-run gas oil fraction is obtained by atmospheric distillation of crude oil. Usually, approximately 10% by volume distillation temperature is 180 to 280 ° C, 50% by volume distillation temperature is 240 to 320 ° C, and 90% volume distillation temperature. Is 300-370 degreeC.

  Examples of the process oil that can be mixed with the straight-run gas oil fraction to obtain a raw material oil include pyrolysis oil, catalytic cracking oil, direct desulfurization gas oil, and indirect desulfurization gas oil. Pyrolysis oil is a light fraction oil obtained by applying heat to a heavy oil fraction and mainly using a radical reaction. For example, it can be obtained by the delayed coking method, visbreaking method or fluid coking method. Refers to the fraction to be made. 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 150-360 degreeC. Catalytic cracked oil is a fraction obtained when catalytically cracking middle distillate and heavy distillate, especially vacuum gas oil distillate, atmospheric distillation residue, etc. with zeolitic catalyst, especially for the production of high octane gasoline This is a cracked gas oil fraction by-produced in the fluidized catalytic cracker. 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 220 to 250 ° C, a 50 vol% distillation temperature of 260 to 290 ° C, and a 90 vol% distillation temperature of 310 to 355 ° C. In addition, heavy catalytic cracked oil, so-called heavy cycle oil (HCO), typically has a 10 vol% distillation temperature of 280-340 ° C, a 50 vol% distillation temperature of 390-420 ° C, and a 90 vol% distillation temperature of 450. Since the temperature is higher than ℃, the HCO is further fractionated to mix the light fraction into the raw material oil so that the 90 vol% distillation temperature of the raw material oil used in the production method of the environment-friendly light oil of the present invention is 370 ° C or lower. In addition, it is preferable to limit the amount mixed with the raw material oil. The direct desulfurized gas oil is a light oil fraction produced as a by-product when hydrotreating the atmospheric residue and / or the vacuum residue with a direct desulfurizer. Indirect desulfurized gas oil is a gas oil fraction that is produced as a by-product when a vacuum gas oil fraction is hydrotreated with an indirect desulfurization apparatus. Even when direct desulfurized gas oil or indirect desulfurized gas oil is used as part of the feedstock, an appropriate fractionation is performed so that the 90 vol% distillation temperature of the feedstock used in the method for producing the environment-friendly diesel oil of the present invention is 370 ° C or lower. It is preferable that the amount mixed with the raw material oil is limited and used.

[Hydrogenation treatment]
The reaction apparatus used for the hydrotreating in the method for producing environmentally-friendly light oil of the present invention is not particularly limited in the reaction type such as batch type, flow type, fixed bed type, fluidized bed type, etc. A form in which hydrogen and raw material oil are continuously supplied and brought into contact with the filled hydroprocessing catalyst is preferable. The hydrogenation treatment in the method for producing environment-friendly light oil of the present invention is performed at a reaction temperature of 280 to 450 ° C., preferably 300 to 420 ° C., particularly 320 to 400 ° C., and a hydrogen pressure of 3 to 10 MPa, preferably 4 to 9 MPa. In particular, it is carried out under reaction conditions of 4.5 to 8.5 MPa. If the reaction temperature is less than 280 ° C., it becomes difficult to make the sulfur content of the environmentally friendly light oil 5 ppm by mass or less, and if it exceeds 450 ° C., the decomposition reaction is remarkably caused, resulting in a decrease in light oil yield and coking. When the hydrogen pressure is lower than 3 MPa, it is difficult to make the sulfur content of the environmentally friendly light oil 5 ppm by mass or less, and when it exceeds 10 MPa, the calorific value per unit volume of the environmentally friendly light oil becomes small, which is not preferable. The hydrogenation treatment in the method for producing environmentally-friendly light oil of the present invention preferably has a liquid hourly space velocity (LHSV) of 0.1 to 5 h ⁻¹ , more preferably 0.3 to 3 h ⁻¹ , particularly 0.5 to 0.5. It is preferable to carry out under the reaction conditions of 2h- ¹ . The LHSV is less than 0.1 h ^-1, the reactor becomes too large for the manufacture of a certain amount of environmental light oil, when LHSV exceeds ^{5h -1,} the sulfur content of the environmental gas oil below 5 ppm by mass This is not preferable. Moreover, the hydrogenation treatment in the method for producing an environmentally-friendly light oil of the present invention is preferably performed under reaction conditions of a hydrogen / oil ratio of 100 to 2000 NL / L, more preferably 100 to 1000 NL / L, and particularly 150 to 800 NL / L. Do. If the hydrogen / oil ratio is less than 100 NL / L, it becomes difficult to reduce the sulfur content of the environmentally friendly light oil to 5 ppm by mass or less, and if it exceeds 2000 NL / L, the cost for supplying hydrogen increases and is economical. Production of environmentally friendly light oil becomes difficult, which is not preferable. When hydrotreating in a fixed bed flow type reactor, the hydrotreating catalyst may be filled into a single catalyst bed or divided into two or more catalyst beds. When the hydrotreatment catalyst is divided into two or more catalyst beds and charged with the hydrotreating catalyst, it is preferable to supply quench hydrogen between the catalyst beds. In the case of supplying quench hydrogen between the catalyst beds, the ratio of the total amount of hydrogen and quench hydrogen supplied together with the raw material oil to the reactor inlet and the supply amount of the raw material oil is 100 to 2000 NL / L, further 100 It is preferable to set it to -1000NL / L, especially 150-800NL / L.

[Hydroprocessing catalyst]
The hydrotreating catalyst used in the method for producing environmentally friendly light oil of the present invention is a porous body containing, as active metal elements, one or more elements selected from molybdenum and tungsten and one or more elements selected from cobalt or nickel. A known cobalt-molybdenum-based hydrogenation catalyst, nickel-molybdenum-based hydrogenation catalyst, nickel-cobalt-molybdenum-based hydrogenation catalyst, nickel-tungsten-based hydrogenation catalyst, or the like can be used. Preferably, the total content of molybdenum and tungsten is 5 to 50% by mass, and the total content of cobalt and nickel is 1 to 15% by mass. Further, it may contain an element such as phosphorus, boron or fluorine. Further, hydrogenation containing a chelating organic compound such as ethylenediaminetetraacetic acid (EDTA), trans-1,2-cyclohexanediamine-N, N, N ′, N′-tetraacetic acid, nitrilotriacetic acid, citric acid, etc. A treatment catalyst is also preferably used. These chelating organic compounds are more preferably contained in the hydrotreating catalyst in the form of a complex with cobalt or nickel. The hydrotreating catalyst used in the method for producing environment-friendly light oil of the present invention preferably has a mesopore central pore diameter of 4 to 20 nm, more preferably 4 to 15 nm. Furthermore, preferably, a specific surface area is 30-800 m < ² > / g, More preferably, it is 50-600 m < ² > / g. The hydrotreating catalyst used in the method for producing environmentally friendly light oil of the present invention is preferably not a powder but a molded body. Although there is no restriction | limiting in particular in the shape of a molded object, and a shaping | molding method, A spherical shape or a columnar shape is preferable. In the case of a spherical shape, the diameter is preferably 0.5 to 20 mm. The cross-sectional shape in the case of a columnar shape is not particularly limited, but a circular shape, a three-leaf shape, and a four-leaf shape are preferable cross-sectional shapes. The dimensions of the molded body in the case of a columnar shape are preferably about 0.25 to 400 mm ² in cross-sectional area and about 0.5 to 20 mm in length. Although there is no restriction | limiting in particular in the manufacturing method of a hydroprocessing catalyst, It is preferable to manufacture by including additional elements, such as the above-mentioned active metal element and phosphorus, in a porous inorganic oxide support | carrier. Examples of porous inorganic oxides include oxides such as alumina, silica, titania, magnesia, zirconia, silica-alumina, silica-titania, silica-zirconia, silica-magnesia, silica-alumina-titania, silica-alumina-zirconia, etc. Of these, a composite oxide, Y-type zeolite, stabilized Y-type zeolite, β-zeolite, mordenite-type zeolite, or one or more selected from zeolites such as MCM-22 is preferable. Moreover, in the manufacturing method of the environmentally friendly light oil of the present invention, two or more hydroprocessing catalysts may be combined and stacked in the reaction apparatus. In 4-position or 6-position of dibenzothiophene (DBT) such as 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) contained in the light oil fraction It is known that there exists a sulfur compound having a steric hindrance to a sulfur atom having an alkyl substituent, and is called a non-desulfurization sulfur compound (T. Kabe, A. Ishihara, W. Quinn, “Hydrosulfurization and Hydrodenitrogenation ", Kodansha (1999)). When the light oil fraction is hydrotreated, the difficult-to-desulfurize sulfur compound remains selectively. On the other hand, in the desulfurization of such a hard-to-desulfurize sulfur compound, a steric hindrance due to a substituent is caused by hydrogenating the benzene ring in the DBT skeleton rather than a reaction route (direct desulfurization route) in which sulfur atoms in the DBT skeleton are directly desulfurized. It is known that a catalyst using a hydrotreating catalyst that can easily take a reaction route (hydrodesulfurization route) that desulfurizes after relaxing the catalyst is more advantageous, and a cobalt-molybdenum-based hydrotreating catalyst and nickel-molybdenum. It is known that the latter is easier to take a hydrodesulfurization route when compared with a hydrotreating catalyst (Takashi Hamada, Ryo Mabuchi, Isao Mochida, Journal of Petroleum Institute, 37, 368-375 (1994). Year)). Therefore, when two or more types of hydrotreating catalysts are combined and used in a reactor, a catalyst having a smaller proportion of nickel in the total content of cobalt and nickel contained in the hydrotreating catalyst. It is preferable to arrange the one having a larger proportion of nickel in the total content of cobalt and nickel on the side closer to the reactor outlet, closer to the reactor inlet to which the raw material oil is supplied.

[Sulfurization treatment of hydrotreating catalyst]
The hydrotreating catalyst used in the method for producing environmentally friendly light oil of the present invention is usually activated by sulfiding. Usually, the sulfiding treatment is performed after the hydrotreating catalyst precursor is charged into the reaction apparatus used in the method for producing the environment-friendly light oil of the present invention. This sulfuration treatment is performed at about 75 to 400 ° C., preferably about 100 to 350 ° C., under a hydrogen atmosphere of normal pressure or higher, and a petroleum distillate containing a sulfur compound and a sulfur-containing compound added thereto. Alternatively, hydrogen sulfide is used. The sulfur-containing compound in the case of adding a sulfur-containing compound to petroleum distillate is not particularly limited as long as it can be decomposed and converted into hydrogen sulfide under the sulfidizing treatment conditions. Carbon sulfide, 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 150 ° C. or lower, under a hydrogen or inert gas atmosphere, with the gas flowing at normal pressure or higher.

[Hydrogenation including gas-liquid separation process]
As a preferred embodiment of the method for producing environmentally friendly light oil of the present invention, a first step of performing crude purification by hydrotreating raw material oil, a second step of performing gas-liquid separation of the reaction mixture obtained in the first step, There is a method for producing an environmentally-friendly light oil including a third step of performing a hydrogenation treatment in which the sulfur content of the crude refined oil obtained in the second step is reduced to 5 mass ppm or less. When raw material oil is hydrotreated, desulfurization reaction and denitrogenation reaction proceed to produce hydrogen sulfide and ammonia. However, hydrogen sulfide and ammonia poison the hydrotreating catalyst and inhibit the desulfurization reaction. Therefore, the reaction mixture obtained in the first step is gas-liquid separated in the second step to remove hydrogen sulfide and ammonia, and the obtained crude refined oil is further hydrotreated in the third step. It is preferable because desulfurization can proceed efficiently, environmentally friendly light oil can be produced under milder conditions, and production of environmentally friendly light oil can be increased.

  The first step and the third step may be performed using different reactors, or the first step and the third step may be performed in the same reactor. In the case where the first step and the third step are performed using different reactors, the first step is provided between the reactor for the first step and the reactor for the third step. Gas-liquid separation device for performing gas-liquid separation of the reaction mixture obtained from the reactor for the gas, and a device for supplying the crude refined oil obtained from the gas-liquid separation device to the reactor for the third step together with hydrogen The hydrogenation treatment is preferably performed using a series of apparatuses. As the gas-liquid separator, a known separator such as a high-pressure separator, a stripper, a flasher, or a distillation tower is preferably used, and two or more separators may be used in combination. For example, it is particularly preferable to carry out gas-liquid separation of crude refined oil obtained by gas-liquid separation in a high-pressure separation tank using a stripper because hydrogen sulfide and ammonia can be effectively removed. The gas stream supplied for the stripping process by the stripper is preferably hydrogen, an inert gas or steam. As the inert gas, any gas that does not cause a chemical reaction with a crude oil such as nitrogen, helium, argon, and carbon dioxide can be used. On the other hand, in the case where the first step and the third step are carried out in the same reactor, the apparatus and method disclosed in Table No. 2000-42130 and International Patent Publication No. 2002-31088. Is preferably used. In the present invention, the ratio of the amount of hydrogen sulfide supplied per unit time to the second step from the first step, the amount of hydrogen sulfide supplied per unit time to the third step relative to the amount of ammonia, and the amount of ammonia in the present invention, The residual ratio of hydrogen sulfide and the residual ratio of ammonia are referred to as the residual ratio, and these residual ratios are preferably 0 to 50%. If the residual ratio is higher than 50%, the reaction inhibition reducing effect in the third step by gas-liquid separation is reduced, which is not preferable. The lower these residual ratios, the higher the reaction inhibition reduction effect in the third step. However, if the residual ratio is brought close to 0%, the energy consumption in the production of environmentally friendly light oil increases and the economic efficiency is impaired. The residual ratio is more preferably 1 to 40%, and particularly preferably 3 to 20%.

In the preferred embodiment, the hydrogenation is performed regardless of whether the first step and the third step are performed in the same reactor, or whether the first step and the third step are performed using different reactors. The treatment catalyst and reaction conditions are preferably selected as follows. The ratio of the hydroprocessing catalyst used in the first step to the total amount of the hydroprocessing catalyst used in the first step and the third step is preferably 20 to 80% by volume, particularly 30 to 70% by volume. is there. If this ratio is less than 20% by volume, sulfur compounds other than the hard-to-desulfurize sulfur compound are supplied to the third step, and the hydrotreating catalyst used in the third step cannot exhibit sufficient desulfurization performance. If it exceeds 80% by volume, the reaction zone advantageous for the desulfurization reaction in which the coexisting concentration of hydrogen sulfide and ammonia is reduced is not preferable. The hydrotreating catalyst used in the first step and the third step may be the same, but it is preferable to use different hydrotreating catalysts. In the case where different hydrotreating catalysts are used in the first step and the third step, the first one having a smaller ratio of nickel to the total content of cobalt and nickel contained in the hydrotreating catalyst. In this step, it is preferable to use a material having a larger ratio of nickel in the total content of cobalt and nickel in the third step.

  Each of the hydrotreating catalysts used in the first step and the third step may be a single hydrotreating catalyst, or two or more types of catalysts may be combined and stacked. When two or more types of catalysts are combined and stacked and used, the one with a smaller ratio of nickel to the total content of cobalt and nickel contained in the hydrotreating catalyst is used as a raw material oil or a crude refining It is preferable to arrange | position the thing with a larger ratio of the nickel which occupies for the total content of cobalt and nickel in the side near the reactor inlet to which oil is supplied, in the side nearer to the reactor outlet. The reaction temperature in the first step and the third step is selected from the range of 280 to 450 ° C, preferably 300 to 420 ° C, particularly 320 to 400 ° C. The hydrogen pressure in the first step and the third step is preferably selected from the range of 3 to 10 MPa, preferably 4 to 9 MPa, particularly 4.5 to 8.5 MPa. The reaction temperatures of the first step and the third step are not necessarily the same, and may be selected independently from the above range for each step. The total pressure in the first step is preferably higher than the total pressure in the third step, and is particularly preferably about 0.01 to 1 MPa higher than the total pressure in the third step. If the total pressure is the same as or lower than the total pressure in the third step, the fluid flow becomes unsatisfactory.

The total liquid space velocity, which is the ratio of the feed amount on the volume basis of the feedstock to the total volume of the hydrotreating catalyst used in the first step and the third step, is preferably 0.1 to 5 h ⁻¹ , in particular 0.3 to 3h- ¹ . The hydrogen / oil ratio in the first step is preferably 50 to 2000 NL / L, more preferably 100 to 1000 NL / L, and particularly preferably 150 to 800 NL / L. The hydrogen / oil ratio in the third step is preferably 20 to 1000 NL / L, further 40 to 800 NL / L, particularly 50 to 500 NL / L. Since the amount of hydrogen consumed in the third step is less than the amount of hydrogen consumed in the first step, the hydrogen / oil ratio in the third step may be lower than the hydrogen / oil ratio in the first step. Good. When hydrotreating in a fixed bed flow type reactor, each of the hydrotreating catalysts used in the first step and the third step may be packed in a single catalyst bed, or two or more The catalyst bed may be divided and filled. When the hydrotreatment catalyst is divided into two or more catalyst beds and charged with the hydrotreating catalyst, it is preferable to supply quench hydrogen between the catalyst beds. When quench hydrogen is supplied between the catalyst beds, the ratio of the total amount of hydrogen and quench hydrogen supplied to the reactor inlet together with the raw material oil or the crude refined oil and the supply amount of the raw material oil or the crude refined oil is For one step, preferably 50-2000 NL / L, more preferably 100-1000 NL / L, especially 150-800 NL / L, for the third step, preferably 20-1000 NL / L, further 40 It is preferable to set it to -800NL / L, especially 50-500NL / L. Moreover, in this aspect, DBT without an alkyl substituent contained in the roughly refined oil supplied to the third step is preferably 10 ppm by mass or less, more preferably 5 ppm by mass or less, especially as a sulfur content. It is preferable that it is 1 mass ppm or less. If DBT is desulfurized to a very low concentration, the hardly-desulfurizable sulfur compound will remain selectively in the crude refined oil, and the difficult-to-desulfurize sulfur compound will become efficient under the reaction conditions of the third step. It is preferable because it is well desulfurized. Furthermore, in this aspect, the sulfur content contained in the roughly refined oil supplied to the third step is preferably 2000 ppm by mass or less, more preferably 1000 ppm by mass or less, and particularly 50 to 500 ppm by mass. preferable. Usually, in the crude refined oil desulfurized to such a sulfur level, the hardly-desulfurizable sulfur compound remains selectively, and the hardly-desulfurizable sulfur compound is efficiently used under the reaction conditions of the third step. It is preferable because it is well desulfurized.

  The temperature of the liquid phase in the second step is not particularly limited, but is preferably selected from the range of 30 to 450 ° C., more preferably 200 to 420 ° C., particularly 220 to 400 ° C., and the outlet reaction in the first step. It is particularly preferred that the temperature is the same as the temperature or lower in the range of 100 ° C. or less. If the temperature of the liquid phase in the second step is too low, the energy required for heating the crude refined oil or hydrogen supplied to the third step increases, which is not preferable. There is no particular limitation on the temperature of hydrogen or inert gas supplied to the stripper when the stripping treatment is performed in the second step, but it is preferably a temperature higher than room temperature, and the outlet of the first step is from 100 ° C. A reaction temperature range is particularly preferred. When the stripping process is performed in the second step, the flow rate of hydrogen or inert gas supplied to the stripper is 0.01 to 2 times the flow rate of hydrogen supplied to the first step, and further 0 It is preferable to select from a range of 1 to 1 times.

[Combination]
In the method for producing environmentally-friendly light oil of the present invention, the light oil fraction obtained by the above-described production method is used as it is as an environmentally-friendly light oil or as a base material for mixing with other base materials to prepare an environmentally-friendly light oil product. be able to. Other light oil bases include, for example, kerosene produced by refining crude oil, synthetic light oil derived by the Fischer-Tropsch process, hydrocracked light oil, or semi-finished products, intermediate products, etc. Materials. Moreover, vegetable oil methyl ester etc. can be mix | blended as another light oil base material. When preparing compounded to environmentally friendly diesel gas oil fraction obtained with other gas oil bases in the production method of the present invention, can be blended at an appropriate ratio so that the desired quality of the gas oil The blending ratio of the other light oil base is preferably 20% by mass or less, particularly 5 to 15% by mass.

  Further, in the method for producing environmentally friendly light oil of the present invention, as additives, low-temperature fluidity improver, wear resistance improver, cetane improver, antioxidant, metal deactivator, corrosion inhibitor, etc. Known fuel additives may be added. As the low temperature fluidity improver, an ethylene copolymer or the like can be used, and 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, a long chain (for example, having 12 to 24 carbon atoms) fatty acid or 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.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by this Example .

[Reference example]
[Hydroprocessing catalyst A]
The hydrotreating catalyst A prepared by supporting molybdenum, nickel, and phosphorus on a pellet-shaped carrier having a trefoil shape of γ-alumina as a main component and having a nominal size of 1/20 inch, has 12 molybdenum in the catalyst. Contains 3.3% by mass of nickel, 3.3% by mass of nickel, 2% by mass of phosphorus, the pore volume analyzed by the nitrogen adsorption method is 0.43 mL / g, the specific surface area is 183 m ² / g, and the median pore diameter is 7.8 nm. there were.

[Hydrogenation treatment]
100 mL of the hydrotreating catalyst A was charged into a fixed bed flow reactor, and the temperature was raised from room temperature to 150 ° C. in 2 hours while flowing hydrogen at a hydrogen pressure of 5.0 MPa and 40 L / h. Thereafter, the hydrotreating catalyst A was subjected to sulfurization treatment by the following procedure. Sulfurizing agent (commercial light oil mixed with 1% carbon disulfide) was passed for 2 hours under conditions of hydrogen pressure 5.0 MPa, hydrogen / oil ratio 200 NL / L, LHSV 2.0 h ⁻¹ , 150 ° C. did. Thereafter, the supply of the sulfiding agent and hydrogen was continued under constant conditions other than temperature, the temperature was raised to 230 ° C. at 20 ° C./h, and the temperature was kept constant at 230 ° C. for 4 hours. Thereafter, the temperature was further increased to 300 ° C. at 17.5 ° C./h, and the temperature was kept constant at 300 ° C. for 7 hours. Thereafter, a hydrotreating reaction was performed under the conditions of a gas oil fraction A having properties shown in Table 1 as a raw material oil, a hydrogen pressure of 6.5 MPa, a hydrogen / oil ratio of 350 NL / L, LHSV of 1.0 h ⁻¹ , and a reaction temperature of 352 ° C. Went. Table 2 shows the property analysis results of the resulting product oil (light oil A).

[Example]
[Hydroprocessing catalyst B]
50 g of ion-exchanged water, 31.8 g of molybdenum trioxide (manufactured by Taiyo Mining Co., Ltd.), 45.6% cobalt carbonate (manufactured by Kansai Catalysts Chemical Co., Ltd.) 10.7 g, 45.0% nickel carbonate (Nippon Chemical Industrial Co., Ltd.) 3.6 g and 85% phosphoric acid (Kanto Chemical Co., Ltd.) 4.9 g were added and dissolved at 80 ° C. with stirring. Furthermore, after naturally cooling to 60 ° C., 24 g of citric acid (manufactured by Kanto Chemical Co., Inc.) was added, dissolved while stirring, and naturally cooled to 40 ° C., and then 35% hydrogen peroxide (manufactured by Kanto Chemical Co., Ltd.). ) 8 g was added and allowed to cool to room temperature with stirring to prepare a support liquid. 120 g of the carrier A used in the reference example was impregnated with this supporting liquid by a pore filling method. The impregnated material was dried at 130 ° C. overnight and then calcined in the air at 550 ° C. for 30 minutes in a ventilated rotary kiln to prepare a hydrotreating catalyst B. The composition analysis result of the hydrotreating catalyst B was 12.6% by mass of molybdenum, 2.9% by mass of cobalt, 1.0% by mass of nickel, and 0.8% by mass of phosphorus. When the mesopore structure of the hydrotreating catalyst B was analyzed by a nitrogen adsorption method, the pore volume was 0.42 mL / g, the specific surface area was 201 m ² / g, and the median pore diameter was 7.3 nm.

[Hydroprocessing catalyst C]
Silica alumina powder and pseudo boehmite powder are mixed at a blending ratio of 80% by mass of silica alumina and 20% by mass of alumina on a dry carrier basis, and a nitric acid aqueous solution is added and kneaded, and the nominal size is 1/20 inch. After extrusion through a three-leaf die, the carrier B was prepared by drying and firing at 600 ° C. for 1 hour in an air stream. As the silica-alumina powder, a powder having a silica / alumina molar ratio of 4.4, an average particle size of 8.8 μm, and a loss on ignition of 15.3% by mass was used. 9.0 g of ammonia water (28%) manufactured by Kanto Chemical Co., Inc. was added to about 20 mL of ion exchange water and stirred. To this, 14.0 g of ethylenediaminetetraacetic acid (EDTA, Kanto Chemical Co., Ltd. deer special grade) was added and stirred to dissolve EDTA. To this solution was added 29.51 g of nickel nitrate hexahydrate (Kanto Chemical Co., Ltd. deer special grade) and stirred to obtain a blue-green uniform solution. To this solution, 47.26 mL of ammonium metatungstate aqueous solution (MW-2, W concentration 693 g / L, manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) was added to obtain about 130 mL of a uniform support liquid. 120 g of carrier B was impregnated with this supporting liquid by a pore filling method. The impregnated product was dried at 130 ° C. for 24 hours to obtain a hydrotreating catalyst C. The composition analysis result of the hydrotreating catalyst C was 17.4% by mass of tungsten, 3.1% by mass of nickel, 3.1% by mass of carbon, and 2.8% by mass of nitrogen. When the mesopore structure of the hydrotreating catalyst C was analyzed by a nitrogen adsorption method, the pore volume was 0.12 mL / g, the specific surface area was 63 m ² / g, and the median pore diameter was 6.3 nm.

[Hydrogenation using a reactor equipped with a gas-liquid separation mechanism]
A schematic flow of the reactor used is shown in FIG. This reactor comprises two reactors, reactor 1 and reactor 2, with a high pressure separation tank 3 and a stripper 4 between them, and the reactor 2 is connected to a high pressure separation tank 5, a mist separation tank 6 and a stripper 7. They are connected by piping 16-42. Hydrogen supply to the reactors 1 and 2 is performed from the pipe 14 and the pipes 29 and 30, respectively. The raw material oil is sent to the reactor 1 through the pipes 13 and 15. Hydrogen gas can be supplied to the stripper 4 from the pipe 23 and brought into gas-liquid contact with the liquid staying in the stripper 4. From the high-pressure separation tank 3 and the stripper 4, the gas (off-gas) containing hydrogen sulfide and ammonia generated by the hydrotreatment reaction can be removed from the reaction system through the pipe 21 and the pipe 24, respectively. The liquid taken out from the stripper 4 is supplied to the reactor 2 through the pipes 26 to 28 and 31. The reaction mixture hydrotreated in the reactor 2 is gas-liquid separated in the high-pressure separation tank 5 and the mist separation tank 6, and the liquid component is sent to the stripper 7 and stripped, and then taken out as product oil.

Reactor 1 is filled with 50 mL of hydrotreating catalyst B, and reactor 2 is filled with 50 mL of hydrotreating catalyst C, and on-off valves 8 and 10 are closed and on-off valve 9 is opened, and hydrogen pressure is 5.0 MPa, 40 L. The temperature was raised from room temperature to 120 ° C. in 2 hours while flowing hydrogen at / h. Thereafter, the sulfiding treatment of the hydrotreating catalysts B and C was performed according to the following procedure. Sulfurizing agent (commercial light oil mixed with 1% carbon disulfide) hydrogen pressure 5.0MPa, hydrogen / oil ratio 200NL / L, total liquid space velocity with respect to total catalyst charge in reactor 1 and reactor 2 Oil was passed for 2 hours under the conditions of 2.0 h ⁻¹ and 120 ° C. Thereafter, the supply of the sulfiding agent and hydrogen was continued under the conditions other than the temperature, the temperature was raised to 230 ° C. at 27.5 ° C./h, and the temperature was kept constant at 230 ° C. for 4 hours. Thereafter, the temperature was further increased to 300 ° C. at 42.5 ° C./h, and the temperature was kept constant at 300 ° C. for 7 hours. Thereafter, a hydrotreating reaction was carried out using a light oil fraction B having properties shown in Table 1 as a feedstock. Open / close valves 8, 10 and 11 are opened, and open / close valve 9 is closed, hydrogen pressure of reactor 1 is 5.1 MPa, hydrogen pressure of reactor 2 is 5.0 MPa, hydrogen / feed oil for reactor 1 and reactor 2 respectively. Reactor 1, Reactor 2 with a feed ratio of 200 NL / L, a total liquid space velocity of 1.5 h ^{−1 with} respect to the total catalyst charge in reactor 1 and reactor 2 and a hydrogen supply of 30 L / h from pipe 23 to stripper 4 The reaction was carried out at a temperature of 345 ° C. in both the high-pressure separation tank 3 and the stripper 4. Table 2 shows the property analysis results of the resulting product oil (light oil B). Further, when the open / close valve 11 was closed and the open / close valve 12 was opened, the sampled intermediate product oil was stripped with nitrogen gas, and the sulfur content of the intermediate product oil was analyzed.

[Comparative Example 1]
[Hydroprocessing catalyst D]
On a dry carrier basis, composed of 7% by mass of mordenite and 93% by mass of alumina, 150 g of a cylindrical carrier having a diameter of 1.4 mm, 46.5 g of ammonium molybdate, 41.8 g of nickel nitrate hexahydrate, 19 of phosphoric acid solution 19 An impregnation solution containing 0.6 g was impregnated with molybdenum, nickel and phosphorus. This was dried overnight at 130 ° C., and then calcined at 500 ° C. for 30 minutes using a rotary kiln, and hydrotreated with 12% by mass of molybdenum, 4% by mass of nickel and 2.5% by mass of phosphorus in the catalyst. Catalyst D was prepared. As a mordenite raw material, a powder having a silica / alumina molar ratio of 210 and a zeolite pore major axis of 0.70 nm was used.

[Manufacture of light oil from Fischer-Tropsch synthetic oil]
The fixed bed flow reactor was charged with 100 mL of the hydrogenation catalyst D, and the temperature was raised from room temperature to 120 ° C. in 2 hours while flowing hydrogen at a hydrogen pressure of 9 MPa and 40 L / h. Thereafter, the hydrotreating catalyst D was subjected to sulfurization treatment by the following procedure. A sulfurizing agent (commercial light oil mixed with 1% carbon disulfide) was passed for 2 hours under conditions of hydrogen pressure 5.0 MPa, hydrogen / oil ratio 200 NL / L, LHSV 2.0 h ⁻¹ , 120 ° C. did. Thereafter, the supply of the sulfiding agent and hydrogen was continued under the conditions other than the temperature, the temperature was raised to 230 ° C. at 27.5 ° C./h, and the temperature was kept constant at 230 ° C. for 4 hours. Thereafter, the temperature was further increased to 300 ° C. at 42.5 ° C./h, and the temperature was kept constant at 300 ° C. for 7 hours. Then, hydrogenolysis and isomerization reaction are performed using normal paraffin raw materials described later under the reaction conditions of hydrogen pressure 9 MPa, hydrogen / raw oil supply ratio 1500 NL / L, LHSV = 0.5 h ⁻¹ , reaction temperature 370 ° C. Then, fractionation was carried out from the resulting product oil so as to obtain a 50 vol% distillation temperature almost equal to that of the light oil B obtained in the Example, whereby a light oil C was obtained. SX-60M manufactured by SMDS (Shell Middle Distillate Synthesis) was used as the normal paraffin raw material. This is a density of 0.82 g / mL in terms of 15 ° C., an initial distillation point of 343 ° C., a 10% by volume distillation temperature of 401 ° C., a 90% by volume distillation temperature of 524 ° C., and an end point of 581 ° C., according to the Fischer-Tropsch method. It is synthesized.

[Comparative Example 2]
The light oil (light oil D) currently on the market was obtained. The properties are shown in Table 2.

From Table 2, the light oil A of the reference example and the light oil B of the example have a sulfur content of 1 mass ppm or less, which is extremely lower than the light oil D of the commercially available light oil, and has a true calorific value per unit volume equivalent to the light oil D. ing. Further, it can be seen that the true calorific value per unit volume is remarkably superior to the light oil C derived from the Fischer-Tropsch synthetic oil having a sulfur content of 1 mass ppm or less.

The following methods were used as measurement methods in the reference examples, examples, and comparative examples.

[Measurement method of pore characteristics]
For measurement of pore characteristics by the nitrogen gas adsorption method, an ASAP2400 type measuring instrument manufactured by Micromeritics was used.

[Method for measuring sulfur content]
The sulfur content of the light oil fraction was measured using a ZSX101e type fluorescent X-ray analyzer manufactured by Rigaku Corporation.

The environmentally-friendly light oil produced by the production method of the present invention has a sulfur content of 5 ppm by mass or less, further 1 ppm by mass or less, and a true calorific value per unit volume equivalent to that of conventionally marketed diesel oil. As a result, it is possible to simultaneously reduce both the emission of environmental pollutants and the reduction of carbon dioxide emissions from diesel vehicles, thereby contributing to the protection of the global environment.

It is explanatory drawing which shows the schematic flow of the reaction apparatus provided with the gas-liquid separation apparatus between the reactors used in the Example .

1 and 2: Reactor, 3: High pressure separation tank, 4: Stripper, 5: High pressure separation tank, 6: Mist separation tank, 7: Stripper, 8-12: Open / close valve, 13-42: Piping

Claims (4)

The density is 0.795 g / cm ³ or more, the sulfur content is 5 mass ppm or less, the monocyclic aromatic content is 5 to 18% by volume, the polycyclic aromatic content is 2% by volume or less, and the true heat generation per unit volume. A method for producing an environmentally friendly light oil having an amount of 34500 J / cm ³ or more,
A hydrocarbon oil having a sulfur content of 0.5% by mass or more, a density of 0.80 to 0.90 g / cm ³ , and a 90% by volume distillation temperature of 370 ° C. or less is used as a raw material oil, a hydrogen pressure of 3 to 10 MPa, a reaction A first step of obtaining a reaction mixture by contacting with a hydrotreating catalyst under reaction conditions of a temperature of 280 to 450 ° C;
A second step of gas-liquid separation of the reaction mixture obtained in the first step to obtain a crudely refined oil;
A third step of contacting the crude refined oil obtained in the second step with a hydrotreating catalyst under reaction conditions of a hydrogen pressure of 3 to 10 MPa and a reaction temperature of 280 to 450 ° C .;
A method for producing environmentally friendly diesel oil, wherein the total pressure in the first step is higher than the total pressure in the third step.   In the first step and the third step, different hydrotreating catalysts are used, and the first step is performed with a smaller proportion of nickel in the total content of cobalt and nickel contained in the hydrotreating catalyst. Furthermore, the manufacturing method of the environment-friendly light oil of Claim 1 which uses what has a larger ratio of nickel to the total content of cobalt and nickel for a 2nd process. The method for producing environmentally friendly diesel oil according to claim 1 or 2, wherein a total content of molybdenum and tungsten contained in the hydrotreating catalyst in the third step is 5 to 50% by mass.
  The method for producing an environmentally friendly light oil according to any one of claims 1 to 3, wherein the hydrotreating catalyst in the third step contains a chelating organic compound.

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