JP2005255995A - Preparation process of petroleum fraction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preparation process of petroleum fractions, wherein the amount of sulfur in diesel oil fractions can be greatly reduced compared to the conventional level while the facilities and operation conditions for the conventional diesel oil desulfurization apparatus are maintained. <P>SOLUTION: The preparation process of the petroleum fractions comprises a first step of obtaining the primary generated oil containing nitrogens in an amount of 60% or less to a nitrogen content in a raw oil by adjusting reaction conditions in the presence of the primary catalyst containing a carrier having mainly an alumina and an active metal selected from a nickel-molybdenum, a nickel-tungsten, and a nickel-cobalt-molybdenum, supported on the carrier, to hydrotreat the raw oil containing mainly the diesel oil fractions, and a second step of obtaining the secondary generated oil by adjusting reaction conditions in the presence of the secondary catalyst containing a carrier having mainly an alumina, and a cobalt molybdenum, an active metal supported on the carrier, to hydrotreat the primary generated oil. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a petroleum fraction, and more particularly to a method for producing a petroleum fraction in which a feedstock containing a light oil fraction as a main component is hydrodesulfurized.

  In recent years, awareness of environmental issues including air pollution is increasing. For example, exhaust gas from diesel vehicles using light oil as fuel contains fine particles called particulates in addition to chemical substances such as sulfur oxide (SOx) and nitrogen oxide (NOx). There are concerns about the impact on the human body. From such a point of view, the demand for purifying exhaust gas from a diesel vehicle has become increasingly severe. Therefore, in order to remove particulates from the exhaust gas, it has been proposed to install a particulate filter such as DPF or a device having a function of removing particulates after the automobile engine. Application to is being considered. Further, as a method for removing NOx in exhaust gas, a method using a NOx reduction and removal catalyst is being developed.

  However, due to the influence of SOx or the like generated by the combustion of sulfur content in light oil, the above-mentioned device for removing particulates cannot sufficiently exhibit its performance, and the above-mentioned catalyst has a reduced NOx reduction and removal activity. . In particular, a long-distance transportation truck equipped with a diesel engine has a longer mileage than a normal gasoline vehicle, and the above-described reduction in device performance and reduction in catalyst activity are significant. Therefore, in order to sufficiently suppress such a decrease in apparatus performance and a decrease in catalyst activity, it is necessary to sufficiently remove SOx in diesel vehicle exhaust gas.

  Various methods for removing SOx in diesel vehicle exhaust gas have been proposed. Among them, a method for reducing the sulfur content (sulfur compounds) in light oil that is the source of SOx is the most effective means. It is considered as one. Gas oil (unrefined gas oil) fraction immediately after crude oil distillation or heavy oil cracking reaction usually contains 1 to 3% by mass of sulfur, and hydrodesulfurization is one of the methods for reducing this sulfur content. A method using a catalyst may be mentioned.

  It is known that most of the sulfur content (sulfur compounds) contained in the crude gas oil fraction is thiophene, benzothiophene and dibenzothiophene and their derivatives. Among these, dibenzothiophene compounds having a plurality of methyl groups represented by 4,6-dimethyldibenzothiophene as substituents are particularly poor in hydrodesulfurization reactivity compared to other sulfur compounds. Therefore, when it is necessary to further reduce the sulfur compound in the unrefined gas oil fraction as compared with other sulfur compounds, if the gas oil fraction contains a large amount of dibenzothiophene compound, sulfur It may be difficult to reduce the compound as desired. Therefore, in order to remove more of such sulfur compounds, it is considered that the catalyst and the catalyst system need to be further devised.

  As a catalyst used for hydrodesulfurization of a light oil fraction, a catalyst in which an active metal obtained by combining a group 6 metal and a group 8 metal on a porous carrier such as alumina is generally used. Exemplary active metal combinations include cobalt-molybdenum, nickel-molybdenum, or nickel-tungsten. Various studies and proposals have been made regarding active metals used for hydrodesulfurization of gas oil fractions, taking into consideration the reaction characteristics of the catalyst and the degree of desulfurization. Among them, not only a metal is used alone, but also a method for using a combination of plural kinds of metals has been proposed.

For example, Patent Document 1 intends to provide a method for deep desulfurization of a light oil fraction under mild conditions, and hydrodesulfurizes the light oil fraction in the presence of a catalyst supporting nickel and molybdenum, followed by cobalt and Hydrodesulfurization in the presence of a catalyst supporting molybdenum, or hydrodesulfurization first in the presence of a catalyst supporting cobalt and molybdenum, and then hydrodesulfurization in the presence of a catalyst supporting nickel and molybdenum A method for deep desulfurization of light oil is disclosed.
Japanese Patent Laid-Open No. 4-183786

  However, the present inventors have examined in detail a conventional hydrodesulfurization method for gas oil fractions such as those disclosed in Patent Document 1 above. It has been found that the hydrodesulfurization method makes no mention of under what reaction atmosphere the catalyst used exhibits excellent hydrodesulfurization activity. In particular, it has become clear that Patent Document 1 does not describe hydrodesulfurization that reduces the sulfur content in the gas oil fraction to 10 ppm by mass or less. Moreover, the Example currently disclosed by patent document 1 is a result using a batch-type reaction apparatus, and it is unknown whether it can apply to the flow-type reaction apparatus employ | adopted as an actual light oil desulfurization apparatus.

  In the future, it is expected that regulations for reducing the sulfur compound content in light oil will become stricter. For example, when the sulfur content in the gas oil fraction needs to be 10 ppm by mass or less, in order to produce such a low sulfur gas oil, the operating conditions and / or the reaction tower such as increasing the hydrogen pressure are used. Adjustment of equipment conditions, such as increasing the volume, is considered essential. However, since it is difficult to satisfy the above-described operating conditions and equipment conditions with the current equipment, it is estimated that the equipment needs to be remodeled or newly installed. Furthermore, even if the sulfur content in light oil can be reduced to 10 ppm by mass or less with the current equipment, the operating cost will increase significantly, and the throughput (throughput) will decrease significantly. it is conceivable that.

  Therefore, in order to minimize the modification of equipment from the current diesel oil desulfurization equipment, and to further reduce the sulfur content in the diesel oil fraction under conditions as close as possible to the current operating conditions, an appropriate catalyst system The present inventors believe that it is necessary to construct

  The present invention has been made in view of the above circumstances, and maintains the equipment and operating conditions of a conventional gas oil desulfurization apparatus, and further can reduce the sulfur content in the gas oil fraction more sufficiently than in the past. An object is to provide a manufacturing method.

  As a result of intensive studies to achieve the above object, the present inventors have found that the nitrogen compounds contained in the unrefined gas oil fraction affect the hydrodesulfurization activity of specific active metals. Has been found to be effective in removing the nitrogen compounds, and the present invention has been completed.

  That is, the method for producing a petroleum fraction of the present invention is selected from the group consisting of a carrier mainly composed of alumina and nickel-molybdenum, nickel-tungsten and nickel-cobalt-molybdenum supported on the carrier. A feedstock containing a light oil fraction as a main component by adjusting the first reaction conditions including reaction pressure, LHSV, reaction temperature and hydrogen / oil ratio in the presence of a first catalyst comprising at least one active metal. A first step of obtaining a first product oil containing 60% or less of nitrogen with respect to the nitrogen content in the feedstock, a carrier mainly composed of alumina, and on the carrier Hydrogenation of the first product oil in the presence of a second catalyst comprising a supported active metal, cobalt-molybdenum, by adjusting second reaction conditions including reaction pressure, LHSV, reaction temperature and hydrogen / oil ratio. Process Characterized in that it comprises a second step of obtaining a second product oil by.

  Although the factor by which the method for producing a petroleum fraction of the present invention achieves the above-mentioned object has not been clarified in detail, the present inventors consider the factor as follows. However, the factors are not limited to these.

  Among the sulfur compounds contained in the feedstock containing the gas oil fraction as the main component (hereinafter referred to as “light oil feedstock”) as the main component, as the difficult desulfurization component that is difficult to remove (desulfurization), And dibenzothiophene compounds having an alkyl substituent (hereinafter referred to as “alkyl-substituted dibenzothiophene compounds”). The desulfurization route from this alkyl-substituted dibenzothiophene compound includes (1) a route for directly extracting a sulfur atom (hereinafter referred to as route (1)) and (2) desulfurization after hydrogenation of the aromatic ring present at the dibenzothiophene site. It is considered that there are two main reaction pathways (hereinafter referred to as pathway (2)).

  When components other than these difficult desulfurization sulfur compounds that undergo a desulfurization reaction relatively easily are desulfurized (path (1)), the sulfur content in the resulting light oil is reduced to about 0.05% by mass or less. Is possible. However, when the sulfur content in light oil is reduced to, for example, 10 ppm by mass or less, the target sulfur content cannot be achieved only by desulfurization from a sulfur compound that can be easily desulfurized. It is presumed that desulfurization of is necessary.

  When desulfurization treatment is performed from an alkyl-substituted dibenzothiophene compound that is a difficult desulfurization component, a method in which the desulfurization reaction proceeds after removing the steric hindrance by hydrogenating the aromatic ring (route (2)) is an effective method. One. In order to allow the desulfurization reaction of this route (2) to proceed efficiently and reliably, the present inventors have at least one activity selected from the group consisting of nickel-molybdenum, nickel-tungsten and nickel-cobalt-molybdenum. We believe that it is better to use a catalyst comprising a metal (hereinafter referred to as “nickel-molybdenum catalyst or the like”). Since these nickel-molybdenum catalysts and the like have high hydrogenation activity, it is presumed that they are effective for hydrodesulfurization reaction through the route (2) and hydrodenitrogenation reaction that proceeds similarly via hydrogenation. The

  However, nickel-molybdenum catalysts and the like are relatively easily poisoned by hydrogen sulfide generated as the hydrodesulfurization reaction proceeds. As a result, the catalytic activity of hydrodesulfurization reaction and hydrodenitrogenation reaction is low. It is considered to have a property of decreasing over time.

  On the other hand, on the catalyst having cobalt-molybdenum as an active metal (hereinafter referred to as “cobalt-molybdenum catalyst”), it is presumed that the desulfurization reaction of the route (1) mainly proceeds more selectively. This cobalt-molybdenum catalyst is considered to be susceptible to poisoning by organic nitrogen compounds. However, the cobalt-molybdenum catalyst has high resistance to hydrogen sulfide, and has a feature that hydrogen consumption can be suppressed as compared with a nickel-molybdenum catalyst or the like.

  As a result of diligent research on hydrodesulfurization activity of light oil under various conditions, the present inventors filled a nickel-molybdenum catalyst or the like on the inlet side of the light oil feedstock in the reaction tower, and cobalt-molybdenum in the subsequent stage. By filling the catalyst, the sulfur content in the product oil (second product oil) can be obtained under the same reaction conditions as compared with the case where each catalyst is used alone or when the order of filling is reversed. It has been found that the concentration can be sufficiently reduced (for example, 10 ppm by mass or less). The mechanism is considered as follows.

  That is, the catalyst is charged as described above. First, in the first reaction step, the diesel oil feedstock is brought into contact with a nickel-molybdenum catalyst or the like as the first catalyst, thereby hydrodesulfurizing the diesel oil feedstock ( Route (2)) and the hydrodenitrogenation reaction proceed more selectively. At this time, the organic nitrogen contained in the first product oil is adjusted by adjusting the reaction conditions so that the nitrogen content in the first product oil is 60% or less with respect to the nitrogen content in the raw material oil. Since the compound can be sufficiently reduced, it is presumed that the influence of poisoning by the organic nitrogen compound on the cobalt-molybdenum catalyst charged in the subsequent stage can be reduced. In addition, since the nickel-molybdenum catalyst and the like are filled in the raw material oil inlet side of the reaction tower with relatively little hydrogen sulfide generated by hydrodesulfurization, it is possible to sufficiently suppress a decrease in reaction activity due to poisoning. .

  Next, in the second reaction step, it is estimated that the reaction of the route (1) proceeds selectively in the desulfurization reaction of the first product oil by bringing the first product oil into contact with the cobalt-molybdenum catalyst that is the second catalyst. Is done. At this time, since the cobalt-molybdenum catalyst packed at the outlet side of the reaction tower has high resistance to hydrogen sulfide, it is assumed that the reaction activity of the cobalt-molybdenum catalyst is maintained sufficiently high even when contacted with hydrogen sulfide. .

  That is, on the inlet side of the reaction tower, the hydrodesulfurization reaction is in a relatively early stage, so the hydrogen sulfide concentration is relatively low and the organic nitrogen compound concentration is relatively high. On the other hand, it is considered that the concentration of hydrogen sulfide in the product oil increases and the concentration of organic nitrogen compound decreases as it goes to the outlet of the reaction tower.

  Further, the present inventors have found that the influence of poisoning on the cobalt-molybdenum catalyst by the organic nitrogen compound is greater for the desulfurization reaction of the above-mentioned route (1) than for the desulfurization reaction of the route (2). It was found that the effect was greater than that of the nickel-molybdenum catalyst. Also from this fact, when nickel-molybdenum catalyst or the like is charged on the inlet side of the reaction tower and cobalt-molybdenum catalyst is charged in the subsequent stage, the influence of nitrogen poisoning on the desulfurization reaction of the route (1) in the cobalt-molybdenum catalyst. It is considered that not only the activity reduction of the desulfurization reaction of the route (1) is sufficiently suppressed, but also a higher desulfurization activity can be obtained than when each catalyst is used alone. Furthermore, it is presumed that an increase in hydrogen consumption can be suppressed by suppressing a decrease in the activity of the desulfurization reaction in the route (1) that does not consume hydrogen.

  Therefore, the light oil fraction that is the second produced oil obtained by the method for producing a petroleum fraction of the present invention can have a sulfur content (sulfur compound) content of 10 ppm by mass or less.

  In addition, by adjusting the first reaction conditions so that the nitrogen content (nitrogen content ratio) in the first product oil is 100 ppm by mass or less, the sulfur content in the light oil feedstock can be more effectively and reliably reduced. Since it can reduce, it is preferable.

  In the method for producing a petroleum fraction according to the present invention, hydrogen sulfide generated on the reaction tower inlet side, that is, on the nickel-molybdenum catalyst or the like is reduced as described above. Even if the gas-liquid obtained through the steps is not separated, the activity of the desulfurization reaction in the second step tends to be sufficiently suppressed. By carrying out like this, the energy loss which generate | occur | produces when isolate | separating a gas-liquid can be suppressed, and it exists in the tendency which leads to the reduction of operating cost.

  The ratio of the first space volume filled with the nickel-molybdenum catalyst as the first catalyst and the second space volume filled with the cobalt-molybdenum catalyst as the second catalyst is 5:95 to 60: 40 is preferable. By doing so, it becomes easy to adjust the LHSV within an appropriate range, and therefore, the desulfurization reaction can proceed more effectively.

The method of manufacturing a petroleum fraction of the present invention, the desulfurization activity k ₂ of desulfurization activity k ₁ and the second catalyst of the first catalyst is a compound represented by the following formula (1);
0.875 <(k ₁ / k ₂ ) <1.15 (1)
It is preferable to adjust the first reaction condition and / or the second reaction condition so as to satisfy the above condition. Here, “desulfurization activity” refers to the desulfurization reaction rate, and can be calculated from the reaction conditions using a usual method using the desulfurization reaction rate equation (Arrhenius equation). By adjusting (k ₁ / k ₂ ) within this numerical range, the desulfurization activity can be further improved, and the sulfur content in the gas oil fraction can be sufficiently reduced as compared with the conventional case.

  Moreover, it is preferable that the support | carrier with which the 1st catalyst was equipped, and the support | carrier with which the 2nd catalyst was equipped are the porous support | carriers which respectively contain 60 mass% or more of alumina. Thereby, it exists in the tendency which can suppress the fall of catalyst activity further. Furthermore, from the viewpoint of further improving hydrodenitrogenation activity, it is preferable to use a carrier having acid properties as the carrier provided in the first catalyst.

In the method for producing a petroleum fraction of the present invention, the first reaction condition and the second reaction condition are a reaction pressure of 2 to 10 MPa, LHSV 0.1 to 2.0 h ⁻¹ , a reaction temperature of 300 to 410 ° C., and a hydrogen / oil ratio, respectively. It is preferable to adjust within the range of 100 to 500 NL / L. By adjusting the nuclear reaction conditions within this numerical range, even when the composition of the raw material oil is changed, a light oil containing a desired sulfur content can be obtained more easily.

  In the method for producing a petroleum fraction of the present invention, when the active metal is nickel-cobalt-molybdenum, the sulfur content in the product oil and the hydrogen consumption can be reduced in a balanced manner, and a light oil having a desired quality is obtained. It is preferable because it can be obtained and energy consumption in the light oil production process can be further suppressed. Moreover, since the amount of hydrogen produced in the hydrogen production apparatus can be reduced by reducing the amount of hydrogen consumed, the amount of carbon dioxide generated as a result of the production of hydrogen in the apparatus can also be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the petroleum fraction which can maintain the equipment and operating conditions of the conventional light oil desulfurization apparatus, and can fully reduce the sulfur content in a light oil fraction more than before can be provided. .

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The method for producing a petroleum fraction of the present embodiment is a kind selected from the group consisting of a carrier mainly composed of alumina and nickel-molybdenum, nickel-tungsten and nickel-cobalt-molybdenum supported on the carrier. In the presence of the first catalyst comprising the above active metal, the first reaction conditions including reaction pressure, LHSV (liquid space velocity), reaction temperature and hydrogen / oil ratio are adjusted, and the light oil fraction is the main component. A first step of obtaining a first product oil containing 60% or less of nitrogen with respect to a nitrogen content in the raw material oil by hydrotreating the raw material oil to be contained; a carrier mainly composed of alumina; In the presence of a second catalyst comprising cobalt-molybdenum, an active metal supported on the support, the second reaction conditions including reaction pressure, LHSV, reaction temperature, and hydrogen / oil ratio are adjusted, 1 production oil It is intended to include a second step of obtaining a second product oil by hydrotreating.

Here, “LHSV (liquid hourly spacevelocity)” refers to the volumetric flow rate of the raw material oil in the standard state (25 ° C., 101.325 kPa) per volume of the catalyst layer filled with the catalyst. The unit “h ⁻¹ ” indicates the reciprocal of time (hour). In addition, among “NL / L” which is a unit usually used for the hydrogen / oil ratio, “NL” which is a unit of hydrogen capacity indicates a hydrogen capacity (L) in a normal state (0 ° C., 101325 Pa). Furthermore, reaction temperature shows the average temperature of a catalyst layer.

(Raw oil)
The feedstock oil used in the present embodiment contains a light oil fraction as a main component. Here, the “light oil fraction” means a straight-run gas oil fraction having a boiling range of 220 to 380 ° C. obtained from an atmospheric distillation apparatus in petroleum refining, a fluid catalytic cracking apparatus, a residual oil direct desulfurization apparatus, and a vacuum gas oil. It means one or more diesel oil fractions selected from the group consisting of cracked gas oil fractions having the same boiling point range as described above, obtained from desulfurization equipment, thermal cracking equipment and vacuum gas oil hydrocracking equipment. Examples of the petroleum fraction other than the light oil fraction contained in the feedstock oil include a kerosene fraction. In addition, the mixing ratio of kerosene fractions other than the light oil fraction is preferably 80% by mass or less with respect to the total amount of the raw material oil from the viewpoint of preventing catalyst poisoning.

(First step)
In the first step according to the method for producing a petroleum fraction of the present embodiment, the above-described feedstock (light oil feedstock) includes a carrier mainly composed of alumina, and nickel-molybdenum and nickel supported on the carrier. -It is supplied to a reaction tower packed with a first catalyst comprising one or more active metals selected from the group consisting of tungsten and nickel-cobalt-molybdenum.

  The alumina (aluminum oxide) contained in the first catalyst support is preferably γ-alumina. γ-alumina is produced via an alumina intermediate using a known method such as a method of neutralizing or hydrolyzing an aluminum salt and aluminate, or a method of hydrolyzing aluminum amalgam or aluminum alcoholate. The In addition to the above-described method, a commercially available alumina intermediate or boehmite powder may be used.

  The content ratio of alumina in the carrier is preferably 60% by mass or more. When the content ratio of alumina in the support is less than 60% by mass, the catalyst activity tends to decrease due to coke formation, unlike the desired one such as an extremely increased acid property of the support. Further, from the viewpoint of further improving the hydrodenitrogenation performance of the first catalyst, it is preferable that the carrier used for the first catalyst has an appropriate acid property. In order to obtain a carrier having such an acid property, the content ratio of alumina in the carrier is 90% by mass or more, and at least one element selected from Si, Ti, Zr, Mg, Ca and B is used as the other element (component). It is preferable to contain in the range of 1-10 mass% in terms of oxide with respect to the total amount of the carrier. These elements are more preferably contained in the range of 1.2 to 9% by mass in terms of oxides, and more preferably 1.5 to 8% by mass. Of the above elements, Si, Ti, or Zr is more preferable, and Si or Ti is particularly preferable. Moreover, these elements may combine 2 or more types, In that case, it is preferable to combine Si and Ti.

  Although the mechanism of the effect manifestation by the above elements has not been elucidated, the above elements form a complex oxide state with alumina, and promote the cleavage of the carbon-sulfur bond synergistically with the active metal supported at the molar ratio. It is thought that. The present inventors currently estimate that the desulfurization activity is improved due to this.

  If the above elements are less than 1% by mass in terms of oxides, the desulfurization activity tends to decrease, and if it exceeds 10% by mass, the acid properties of the carrier become excessively strong. Reactions tend to occur. Moreover, when the content of alumina is within the above range, the nitrogen content in the first product oil should be 60% or less with respect to the nitrogen content in the light oil feedstock with a smaller first catalyst amount. Can do. By reducing the amount of the first catalyst, a catalyst having a second catalyst, cobalt-molybdenum as an active metal (cobalt-molybdenum catalyst), can be charged more in the reaction tower, so that the hydrogen consumption is excessively increased. The desulfurization ability of the entire reaction tower can be further improved without increasing the number.

The average pore diameter of the first catalyst is preferably 3 to 10 nm, and more preferably 5 to 9 nm. If the average pore diameter is smaller than 3 nm, the diffusion of molecules to be reacted tends to be insufficient, and if the average pore diameter exceeds 10 nm, the surface area of the first catalyst is decreased, leading to a decrease in catalytic activity. It is in. The pore volume of the first catalyst is preferably 0.3 mL / g or more. When the pore volume is smaller than 0.3 mL / g, it becomes difficult to impregnate the first catalyst with the active metal, and it tends to be difficult to obtain the desired first catalyst. Furthermore, the specific surface area of the first catalyst is preferably 200 m ² / g or more. When the specific surface area of the first catalyst is less than 200 m ² / g, the active metal supporting area decreases, which tends to decrease the catalytic activity. The pore volume and specific surface area of these catalysts can be measured and calculated by a method called the BET method based on nitrogen adsorption.

  As a method for supporting nickel-molybdenum, which is an active metal, on the first catalyst, a method used for producing a normal desulfurization catalyst can be employed. As the cobalt source, an organic or inorganic cobalt salt such as cobalt nitrate, cobalt chloride or cobalt acetate can be used. As the nickel source, an organic or inorganic cobalt salt such as nickel nitrate, nickel chloride or nickel acetate can be used. As the molybdenum source, ammonium molybdate or molybdenum oxide can be used, and as the tungsten source, ammonium tungstate can be used. For each metal, organic salts or inorganic salts other than those listed here may be used. Furthermore, an organic compound may coexist in the impregnation liquid containing the active metal. In addition to these active metals, phosphorus may be supported on the first catalyst.

  On the other hand, the carrier preparation method for any carrier component other than alumina such as an oxide of an element selected from Si, Ti, Zr, Mg, Ca and B described above may be a normal carrier preparation method. It is not limited. For example, a method of adding oxides, hydroxides, nitrates, sulfates or other salt compounds of these elements in a solid or solution state at any stage of preparing alumina. Alternatively, the above-described salt compound may be impregnated and supported in a solution state after first firing only alumina, but it is preferable to add the above-described salt compound at any stage before firing the alumina.

  The supported amount of active metal in the first catalyst of the present embodiment is not particularly limited, and a supported amount comparable to that in a normal desulfurization catalyst can be employed. However, when the amount of active metal supported is extremely small, the catalytic activity tends to be insufficient. When the amount is extremely large, aggregation of the active metal occurs during the production or use of the catalyst, and the desired catalytic activity is obtained. It tends to be difficult to obtain. Therefore, usually, when the first catalyst is a nickel-molybdenum catalyst or a nickel-tungsten catalyst, the supported amount of nickel is preferably 2 to 8% by mass with respect to the total amount of the first catalyst. In the case of a nickel-cobalt-molybdenum catalyst, the supported amount of nickel is preferably 0.1 to 8% by mass and the supported amount of cobalt is 2 to 8% by mass with respect to the total amount of the first catalyst.

  The first catalyst in the present embodiment may be presulfided by the same method as a general hydrodesulfurization catalyst before being used for actual hydrodesulfurization of light oil. This preliminary sulfidation can be performed, for example, using straight-run gas oil alone or by adding a sulfurizing agent to straight-run gas oil under a hydrogen pressurization condition at 200 ° C. or higher according to a predetermined procedure. . The first catalyst that has undergone the preliminary sulfidation treatment is in a state in which the active metal on the catalyst is sulfided, and can exhibit a desired catalytic activity (desulfurization activity). As the sulfurizing agent, sulfur compounds such as dimethyl disulfide and polysulfide are used. It is also possible to use a catalyst that has been subjected to a sulfurization treatment or a catalyst that has been subjected to an activation treatment with a sulfur-containing, oxygen-containing or nitrogen-containing organic solvent.

  In the first step, a gas oil feedstock is hydrotreated on the first catalyst described above to obtain a first product oil. At that time, under the first reaction conditions including reaction pressure, LHSV, reaction temperature and hydrogen / oil ratio, the nitrogen content in the first product oil is 60% or less with respect to the nitrogen content in the light oil feedstock. (Hereinafter, the ratio of the nitrogen content in the first produced oil to the nitrogen content in the light oil feedstock is referred to as “nitrogen residual ratio”).

  When the nitrogen residual ratio is 60% or less, the poisoning of the second catalyst by the nitrogen compound can be sufficiently reduced, so that the sulfur content in the resulting second product oil can be sufficiently reduced. Become. From such a viewpoint, the nitrogen content in the first product oil is preferably 100 ppm by mass or less, more preferably 50 ppm by mass or less, still more preferably 40 ppm by mass or less, and 30 ppm by mass or less. Is particularly preferred.

  In order to adjust the first reaction conditions so that the nitrogen residual rate is 60% or less, first, the amount of packed first catalyst (packing space volume) into the reaction tower was calculated and determined by the following procedure, for example. After that, the amount of the first catalyst is charged into the actual reaction tower. Here, a catalyst (nickel-molybdenum catalyst) carrying nickel-molybdenum as an active metal will be described, but the same calculation can be made even when a first catalyst is obtained by carrying other active metals.

For example, a hydrodenitrogenation reaction of straight run gas oil having a sulfur content of 1.3% by mass and a nitrogen content (nitrogen compound) of 200 ppm by mass in the presence of a predetermined amount of nickel-molybdenum catalyst, hydrogen partial pressure of 4.9 MPa, hydrogen / Oil ratio 200 NL / L, LHSV (liquid hourly space velocity) 1.0 to 2.0 h ⁻¹ , reaction temperature 340 to 370 ° C. Here, this hydrodenitrogenation reaction is represented by the following formula (2);
k = A × exp (−E / RT) (2)
It is possible to follow the Arrhenius equation expressed by In the formula (2), k is a rate constant, A is a frequency factor, E is an activation energy, R is a gas constant, and T is a reaction temperature.

  More specifically, the gas oil feedstock is hydrotreated while the first reaction conditions are variously changed within the above numerical range. Then, the nitrogen content in the obtained first product oil is measured, and the rate constant and the activation energy in the hydrodenitrogenation reaction are calculated. By substituting the calculated rate constant and activation energy into the Arrhenius equation, and determining the liquid speed so that the nitrogen residual ratio is 60% or less, the filling space volume of the nickel-molybdenum catalyst corresponding to this liquid speed Can be calculated.

  In the method for producing petroleum fractions, the first reaction condition is adjusted so that the nitrogen residual ratio is 60% or less. The gas oil feedstock and the first produced oil are collected, and the nitrogen content and the first There is a method of measuring the nitrogen content in the produced oil, calculating the nitrogen residual rate based on the measurement result, and preparing the first reaction condition. At this time, the reaction order and activation energy of the hydrodenitrogenation calculated as described above and the Arrhenius equation can also be used, whereby the degree of deterioration of the first catalyst can be grasped. . The nitrogen content or nitrogen content can be measured based on, for example, a sulfur content test method defined in JIS-K-2541, a nitrogen content test method defined in JIS-K-2609, or the like. .

The first reaction conditions in the first step are preferably a reaction temperature of 300 to 410 ° C., a hydrogen partial pressure of 2 to 10 MPa, an LHSV of 0.1 to 2 h ⁻¹ , a hydrogen / oil ratio of 100 to 500 NL / L, and a reaction temperature of 300 ° C. It is more preferable that it is ˜390 ° C., hydrogen partial pressure 3 to 8 MPa, LHSV 0.3 to 1.8 h ⁻¹ , and hydrogen / oil ratio 150 to 300 NL / L. The first reaction conditions can be adjusted and set in accordance with individual apparatuses and feedstocks within such numerical ranges. In order to further advance the hydrodesulfurization reaction, it is only necessary to increase the hydrogen partial pressure and lower the LHSV. However, these adjustments of the first reaction condition tend to increase the operating cost. The first reaction condition may be adjusted and set in consideration of the above.

  When a nickel-molybdenum catalyst or the like is used as the first catalyst, the hydrodenitrogenation reaction proceeds when the contact time between the first catalyst and the light oil feedstock (first product oil) increases, but the nickel-molybdenum catalyst. Etc. themselves are relatively strongly affected by poisoning by hydrogen sulfide, so that the catalyst life tends to be shortened. Moreover, since the amount of hydrogen consumption increases, the operating cost tends to increase. Therefore, the first reaction condition may be adjusted and set in consideration of the catalyst life and the operating cost.

(Second step)
In the second step of the present embodiment, the first product oil obtained by the first step described above includes a support mainly composed of alumina, and cobalt-molybdenum that is an active metal supported on the support. The second catalyst is supplied to the reaction tower.

  The average pore diameter, pore volume and specific surface area of the second catalyst are preferably in the same numerical range as the first catalyst from the same viewpoint as the first catalyst. Further, the support used for the second catalyst, the method for supporting the active metal and the amount supported thereof are preferably the same as those for the first catalyst described above, and after the preliminary sulfidation, the method is used for the method for producing the petroleum fraction of the present embodiment. May be. Furthermore, the second reaction condition in the second step is preferably within the same numerical range as the first reaction condition from the same viewpoint as the first reaction condition described above.

  The second product oil obtained through the second step of the present embodiment includes a petroleum fraction that is lighter than the gas oil produced as a by-product in the first step and the second step. A light oil fraction is recovered by fractionation and removal.

  In the method for producing a petroleum fraction of the present embodiment, the hydrogenation treatment in the first step and the hydrogenation treatment in the second step described above may be performed in separate reaction towers, or performed in one reaction tower. It may be broken. Further, from the viewpoint of ease of operation management and prevention of catalyst deterioration, it is preferable to provide a plurality of catalyst beds (catalyst layers) in the reaction tower and provide a quench zone for introducing hydrogen gas between the catalyst beds. This makes it possible to remove reaction heat and replenish consumed hydrogen.

  The reaction tower of the desulfurization apparatus used in the present embodiment may be a trickle flow format or an upflow format, but a trickle flow format is generally adopted.

  In the desulfurization apparatus used in the present embodiment, a high-pressure or low-pressure gas-liquid separation apparatus that separates the first product oil and the gas component is installed at the rear stage of the reaction tower. In the present embodiment, since the hydrogen sulfide content in the first product oil and gas component supplied to the second catalyst is relatively small, the reaction tower (catalyst bed) and the second catalyst filled with the first catalyst Even if the gas-liquid separation device described above is not provided between the packed reaction tower (catalyst bed), defects such as deterioration of the second catalyst tend to be suppressed.

The amount (packing space volume) of the first catalyst and the second catalyst used in this embodiment in the reaction tower is not particularly limited, but the first space volume filled with the first catalyst, The ratio with the second space volume filled with the catalyst is preferably 5:95 to 60:40. As a result, the liquid space velocity per unit volume of the catalyst obtained by combining the first step and the second step becomes 0.1 h ^{−1 to 3} h ⁻¹ , and the desulfurization reaction tends to proceed more effectively. . When the first space volume is lower than the above ratio, the second catalyst tends to be poisoned with nitrogen. When the first space volume is higher than the above ratio, the first catalyst itself tends to be poisoned with hydrogen sulfide. . From such a viewpoint, the ratio of the first space volume to the second space volume is more preferably 10:90 to 40:60, and still more preferably 10:90 to 30:70. Here, “packing space volume” or “space volume” refers to a volume corresponding to a region filled with the catalyst in the reaction column, and the inner diameter of the reaction column, the height of the catalyst packed in the reaction column. Calculated from the above.

Further, when the desulfurization activity of the first catalyst alone is k ₁ and the desulfurization activity of the second catalyst alone is k ₂ , the following formula (1);
0.875 <(k ₁ / k ₂ ) <1.15 (1)
It is preferable that the first reaction condition and / or the second reaction condition is adjusted so that the above condition is satisfied. The desulfurization activity of k ₁ and k ₂ specifically indicates the desulfurization reaction rate, and can be calculated from the reaction conditions using a usual method using the reaction rate equation (Arrhenius equation) of the desulfurization reaction. When (k ₁ / k ₂ ) is 0.875 or less, the desired desulfurization activity tends not to be obtained, and when (k ₁ / k ₂ ) is 1.15 or more, the desired desulfurization activity is also obtained. Tend not to be obtained.

  In the method for producing a petroleum fraction of the present embodiment described above, the sulfur content contained in the second product oil can be reduced to 50 mass ppm or less by adjusting the first reaction condition and the second reaction condition. It can also be made into ppm or less. In addition, content of the sulfur content (sulfur compound) in 2nd production | generation oil etc. can be measured based on the method as described in JIS-K-2541 "sulfur content test method" or ASTM-D5453, for example. .

  As mentioned above, although preferred embodiment of the manufacturing method of the petroleum fraction which concerns on this invention was described, this invention is not limited to the said embodiment.

  For example, in another embodiment of the method for producing petroleum fractions according to the present invention, when the first catalyst and the second catalyst are packed in separate reaction towers, the above-described gas-liquid separation equipment is used for the reaction. You may provide between towers. Thereby, since hydrogen sulfide supplied to the second catalyst can be further reduced, the catalyst life tends to be extended.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(Example 1)
25 mL of catalyst A (nickel-molybdenum catalyst) as a first catalyst was stacked in a reaction tube 1 having an inner diameter of 25 mm, and 75 mL of catalyst B (cobalt-molybdenum catalyst) as a second catalyst was stacked and filled in a reaction tube 2. These reaction tubes 1 and 2 are connected in series, and using straight-run gas oil containing 3% by mass of dimethyl disulfide as a sulfur content, the catalyst layer average temperature is 320 ° C., the hydrogen partial pressure is 5 MPa, LHSV1h ⁻¹ , hydrogen / The catalyst was presulfided for 12 hours under an oil ratio of 200 NL / L. After the preliminary sulfidation was completed, a Middle East straight gas oil GO1 (10% distillation point 285 ° C., 90% distillation point 350 ° C., sulfur content 1.31 mass%, nitrogen content 150 mass ppm) was subjected to a hydrogen partial pressure of 5 MPa. , LHSV1h ^-1 combined with the first catalyst and the second catalyst (reaction tubes 1 and 2), and supplied to the reaction tubes 1 and 2 under the reaction conditions of hydrogen / oil ratio of 200 NL / L to perform hydrogenation treatment It was. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 510 ppm by mass and the nitrogen content was 31 ppm by mass (that is, the nitrogen residual rate was 20 0.7%). The sulfur content in the second product oil at the outlet of the reaction tube 2 was 8.1 mass ppm, and the chemical hydrogen consumption at this time was 336 scf / bbl. Here, “chemical hydrogen consumption” refers to the amount of hydrogen consumed by a reaction such as hydrodesulfurization reaction or hydrodenitrogenation reaction on a catalyst, excluding hydrogen dissolved in moisture. . This “chemical hydrogen consumption” is usually calculated from the difference between the amount of hydrogen supplied to the reaction tube (catalyst layer) and the amount of hydrogen coming out of the reaction tube. Table 1 shows the physical properties of the catalysts A and B and the catalyst C described later.

In addition, all the content rates of the above-mentioned supported metals including phosphorus are expressed in terms of metal oxides (CoO, NiO, MoO ₃ , P ₂ O ₅ ), and the balance is γ-alumina of the support. In Table 1, “inorganic oxide” means silicon oxide (SiO ₂ ; silica), titanium oxide (TiO ₂ ; titania), magnesium oxide (MgO; magnesia), zirconium oxide (ZrO ₂ ; zirconia), pentoxide. It shows at least one oxide selected from diphosphorus (P ₂ O ₅ ), calcium oxide (CaO; calcia) and diboron trioxide (B ₂ O ₃ ).

(Example 2)
The reaction tube 1 having an inner diameter of 25 mm was filled with 12.5 mL of the catalyst A described above as a first catalyst and 87.5 mL of the catalyst B described above as a second catalyst in the reaction tube 2. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the Middle East straight-run gas oil GO1 is reacted under a reaction condition of a partial pressure of hydrogen of 5 MPa, LHSV1h ⁻¹ combined with the first catalyst and the second catalyst, and a hydrogen / oil ratio of 200 NL / L. Hydrogenation was carried out by feeding into the pipes 1 and 2. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of the direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. .3%). The sulfur content in the second product oil at the outlet of the reaction tube 2 was 9.4 ppm by mass, and the chemical hydrogen consumption at this time was 315 scf / bbl.

(Example 3)
The reaction tube 1 having an inner diameter of 25 mm was filled with 75 mL of the catalyst A as a first catalyst and 25 mL of the catalyst B as a second catalyst in the reaction tube 2. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the Middle East straight-run gas oil GO1 is reacted under a reaction condition of a partial pressure of hydrogen of 5 MPa, LHSV1h ⁻¹ combined with the first catalyst and the second catalyst, and a hydrogen / oil ratio of 200 NL / L. Hydrogenation was carried out by feeding into the pipes 1 and 2. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of DC light oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 29.7 mass ppm and the nitrogen content was 7.1 mass ppm (that is, The nitrogen residual ratio was 4.7%. The sulfur content in the second product oil at the outlet of the reaction tube 2 was 10.0 mass ppm, and the chemical hydrogen consumption at this time was 378 scf / bbl.

Example 4
The reaction tube 1 having an inner diameter of 25 mm was filled with 25 mL of the above-mentioned catalyst C (nickel-cobalt-molybdenum catalyst) as the first catalyst and 75 mL of the above-mentioned catalyst B as the second catalyst in the reaction tube 2. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the Middle East straight-run gas oil GO1 is reacted under a reaction condition of a partial pressure of hydrogen of 5 MPa, LHSV1h ⁻¹ combined with the first catalyst and the second catalyst, and a hydrogen / oil ratio of 200 NL / L. Hydrogenation was carried out by feeding into the pipes 1 and 2. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 530.0 mass ppm and the nitrogen content was 40.0 mass ppm (that is, The nitrogen residual rate was 26.7%). The sulfur content in the second product oil at the outlet of the reaction tube 2 was 8.6 mass ppm, and the chemical hydrogen consumption at this time was 306 scf / bbl.

(Example 5)
The reaction tube 1 having an inner diameter of 25 mm was filled with 25 mL of the catalyst A as a first catalyst and 75 mL of the catalyst B as a second catalyst in the reaction tube 2. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation was completed, a Middle Eastern straight oil gas GO2 (10% distillation point 301 ° C., 90% distillation point 355 ° C., sulfur content 1.35 mass%, nitrogen content 210 mass ppm) was subjected to a hydrogen partial pressure of 5 MPa. The hydrogenation treatment is performed by supplying the reaction mixture into the reaction tubes 1 and 2 under the reaction conditions of LHSV 0.7h ⁻¹ including the first catalyst and the second catalyst (reaction tubes 1 and 2) and the hydrogen / oil ratio of 200 NL / L Went. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of DC light oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 510 ppm by mass and the nitrogen content was 63 ppm by mass (that is, the nitrogen residual rate was 30 0.0%). The sulfur content in the second product oil at the outlet of the reaction tube 2 was 9.3 ppm by mass, and the chemical hydrogen consumption at this time was 368 scf / bbl.

(Example 6)
The reaction tube 1 having an inner diameter of 25 mm was filled with 25 mL of the above-mentioned catalyst C as the first catalyst and 75 mL of the above-mentioned catalyst B as the second catalyst in the reaction tube 2. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the above-mentioned Middle Eastern straight-run gas oil GO2 is combined with a partial pressure of hydrogen of 5 MPa, LHSV 0.7h ⁻¹ in which the first catalyst and the second catalyst (reaction tubes 1 and 2) are combined, and a hydrogen / oil ratio of 200 NL. Under the reaction conditions of / L, hydrogenation was performed by supplying the reaction tubes 1 and 2 into the reaction tubes 1 and 2. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 530 mass ppm and the nitrogen content was 75 mass ppm (that is, the nitrogen residual ratio was 35 0.7%). The sulfur content in the second product oil at the outlet of the reaction tube 2 was 9.5 ppm by mass, and the chemical hydrogen consumption at this time was 339 scf / bbl.

(Comparative Example 1)
50 mL of the above catalyst A was stacked and filled in each of reaction tubes 1 and 2 having an inner diameter of 25 mm. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the reaction tube 1 under the reaction conditions of the above-described Middle Eastern straight-run gas oil GO1 with a partial pressure of hydrogen of 5 MPa, LHSV1h ^-1 combined with the reaction tubes 1 and 2 and a hydrogen / oil ratio of 200 NL / L. No. 2 was supplied for hydrogenation treatment. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 80.1 mass ppm and the nitrogen content was 4.5 mass ppm (ie The nitrogen residual rate was 3.0%. The sulfur content in the second product oil at the outlet of the reaction tube 2 was 11.9 mass ppm, and the chemical hydrogen consumption at this time was 403 scf / bbl.

(Comparative Example 2)
50 mL of the above-mentioned catalyst B was stacked and filled in each of reaction tubes 1 and 2 having an inner diameter of 25 mm. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the reaction tube 1 under the reaction conditions of the above-described Middle Eastern straight-run gas oil GO1 with a partial pressure of hydrogen of 5 MPa, LHSV1h ^-1 combined with the reaction tubes 1 and 2 and a hydrogen / oil ratio of 200 NL / L. No. 2 was supplied for hydrogenation treatment. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 94.0 ppm by mass and the nitrogen content was 15.0 ppm by mass (ie The nitrogen residual ratio was 10.0%. The sulfur content in the second product oil at the outlet of the reaction tube 2 was 13.8 mass ppm, and the chemical hydrogen consumption at this time was 328 scf / bbl.

(Comparative Example 3)
The above-mentioned catalyst B was stacked in a reaction tube 1 having an inner diameter of 25 mm, and 50 mL of the above-mentioned catalyst A was stacked and filled in a reactor 2. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the reaction tube 1 under the reaction conditions of the above-described Middle Eastern straight-run gas oil GO1 with a partial pressure of hydrogen of 5 MPa, LHSV1h ^-1 combined with the reaction tubes 1 and 2 and a hydrogen / oil ratio of 200 NL / L. No. 2 was supplied for hydrogenation treatment. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. As a result, the sulfur content was 94.0 ppm by mass and the nitrogen content was 15.0 ppm by mass (ie The nitrogen residual ratio was 10.0%. The sulfur content in the second product oil at the outlet of the reaction tube 2 was 10.6 mass ppm, and the chemical hydrogen consumption at this time was 360 scf / bbl.

(Comparative Example 4)
The reaction tube 1 having an inner diameter of 25 mm was filled with 25 mL of the above-mentioned catalyst B as the first catalyst and 75 mL of the above-mentioned catalyst B as the second catalyst in the reaction tube 2. These reaction tubes 1 and 2 were connected in series, and the catalyst was presulfided for 12 hours in the same manner as in Example 1. After the preliminary sulfidation is completed, the above-mentioned Middle Eastern straight-run gas oil GO2 is combined with a partial pressure of hydrogen of 5 MPa, LHSV 0.7h ⁻¹ in which the first catalyst and the second catalyst (reaction tubes 1 and 2) are combined, and a hydrogen / oil ratio of 200 NL. Under the reaction conditions of / L, hydrogenation was performed by supplying the reaction tubes 1 and 2 into the reaction tubes 1 and 2. The reaction tube heater was adjusted so that the average temperature of the catalyst layers of the reaction tubes 1 and 2 was 360 ° C. Next, on the 14th day after the start of the supply of the direct current diesel oil, the properties of the first product oil at the outlet of the reaction tube 1 were analyzed and measured. 8%). The sulfur content in the second product oil at the outlet of the reaction tube 2 was 13.8 mass ppm, and the chemical hydrogen consumption at this time was 341 scf / bbl.

The above results are summarized in Table 2.

Claims (9)

A first catalyst comprising: a support mainly composed of alumina; and one or more active metals selected from the group consisting of nickel-molybdenum, nickel-tungsten, and nickel-cobalt-molybdenum supported on the support. In the raw material oil by adjusting the first reaction conditions including reaction pressure, LHSV, reaction temperature and hydrogen / oil ratio in the presence of A first step of obtaining a first product oil containing 60% or less of nitrogen with respect to the nitrogen content of
In the presence of a second catalyst comprising a support mainly composed of alumina and cobalt-molybdenum, which is an active metal supported on the support, a reaction pressure, an LHSV, a reaction temperature, and a hydrogen / oil ratio are included. A second step of adjusting the reaction conditions and obtaining a second product oil by hydrotreating the first product oil;
A method for producing an oil fraction, comprising:   The method for producing a petroleum fraction according to claim 1, wherein the first reaction conditions are adjusted so that the nitrogen content in the first product oil is 100 mass ppm or less.   The method for producing a petroleum fraction according to claim 1 or 2, wherein the gas-liquid obtained through the first step is not separated before the second step.   The ratio between the first space volume filled with the first catalyst and the second space volume filled with the second catalyst is 5:95 to 60:40. 4. The method for producing an oil fraction according to any one of 3 above. The desulfurization activity _{k 1} and desulfurization activity _{k 2} of the second catalyst of the first catalyst is a compound represented by the following formula (1);
0.875 <(k ₁ / k ₂ ) <1.15 (1)
The method for producing a petroleum fraction according to any one of claims 1 to 4, wherein the first reaction condition and / or the second reaction condition is adjusted so as to satisfy the following condition.   The said support | carrier with which the said 1st catalyst was equipped, and the said support | carrier with which the said 2nd catalyst was equipped respectively are the porous support | carriers which contain 60 mass% or more of aluminas, Any one of Claims 1-5 characterized by the above-mentioned. A method for producing an oil fraction according to claim 1.   The method for producing a petroleum fraction according to any one of claims 1 to 6, wherein a carrier having an acid property is used as the carrier provided in the first catalyst. The first reaction condition and the second reaction condition are within the ranges of reaction pressure 2 to 10 MPa, LHSV 0.1 to 2.0 h ⁻¹ , reaction temperature 300 to 410 ° C., and hydrogen / oil ratio 100 to 500 NL / L, respectively. It adjusts, The manufacturing method of the petroleum fraction as described in any one of Claims 1-7 characterized by the above-mentioned. The method for producing a petroleum fraction according to any one of claims 1 to 8, wherein the active metal is nickel-cobalt-molybdenum.