JP7583538B2 - Catalyst system, method for hydrocracking feedstock oil containing heavy gas oil fraction using the same, and hydrocracking apparatus - Google Patents

Description

The present invention relates to a catalyst system, a method for hydrocracking feedstock containing heavy gas oil fractions using the catalyst system, and a hydrocracking apparatus.

Heavy gas oil fractions such as automatic gas oil (AGO) and vacuum gas oil (VGO) are obtained by distilling crude oil under atmospheric pressure or under reduced pressure. After undergoing refining processes such as hydrocracking, these fractions are used for a variety of purposes such as kerosene, automobile fuel, and lubricant base oil. Various methods have been investigated for hydrocracking (see, for example, Patent Document 1).

Patent Document 1 discloses a method for producing lubricating base oil, which includes a first step of catalytically cracking a feedstock oil containing aromatic hydrocarbons with a hydrocracking catalyst containing zeolite to produce a catalytically cracked oil, and a second step of contacting the feedstock oil with a hydrocracking catalyst containing an amorphous solid acid.

JP 2017-66227 A

However, since the above-mentioned heavy diesel fractions are used for important purposes such as kerosene, base stock for automobile fuels (gasoline base stock), and lubricant base oil after hydrocracking, there is a demand for more inexpensive and stable production and supply of fractions suitable for these uses. Therefore, it is necessary to study the type of catalyst used for hydrocracking, reaction conditions, and various other aspects to improve the yield of the desired fractions or to improve hydrocracking activity.

The present invention focuses on middle distillates with boiling points between 120°C and 360°C, which are used heavily in the above-mentioned applications and are mainly treated as kerosene and diesel, among the heavy diesel fractions already mentioned above, and aims to provide a catalyst system that can increase the yield of the middle distillate and maintain excellent hydrocracking activity when hydrocracking heavy diesel fractions, thereby enabling a stable supply of middle distillates at lower cost, i.e., a catalyst system that achieves both a high yield of middle distillates and hydrocracking activity, and further a method and apparatus for hydrocracking feedstock containing heavy diesel fractions using the catalyst system.

As a result of extensive research into solving the above problems, the inventors have discovered that the problems can be solved by the invention described below. That is, the present invention provides a catalyst system having the following configuration, as well as a method and apparatus for hydrocracking feedstock oil containing a heavy gas oil fraction using the catalyst system.

1. A catalyst system for hydrocracking a feedstock containing a heavy gas oil fraction, comprising: a packed bed A composed of a catalyst A having a zeolite ratio of 12% or more; and a packed bed B composed of a catalyst B having a zeolite ratio of less than 12%, the packed bed A being packed so as to come into contact with the heavy gas oil fraction first, and the ratio (R _A /R _B ) of the ratio (R _A ) of the packed bed A to the ratio (R B ) of _the packed bed B being 20/80 to 95/5.
2. A method for hydrocracking a feedstock containing a heavy gas oil fraction, using the catalyst system described in 1 above.
3. A hydrocracking unit for feedstock containing a heavy gas oil fraction, comprising the catalyst system described in 1 above.

The present invention provides a catalyst system that achieves both a high yield rate of middle distillates and high hydrocracking activity, as well as a method and apparatus for hydrocracking feedstock containing heavy gas oil fractions using the catalyst system.

The catalyst system, hydrocracking method, and hydrocracking apparatus according to an embodiment of the present invention (hereinafter, sometimes simply referred to as the present embodiment) will be specifically described below. Note that in this specification, the numerical values associated with "less than," "more than," and "to" in describing numerical ranges are numerical values that can be arbitrarily combined, and the numerical values in the examples are numerical values that can be used as upper or lower limits.

[Catalyst system]
The catalyst system of this embodiment is a catalyst system for hydrocracking a feedstock oil containing a heavy gas oil fraction, in which a packed bed A composed of a catalyst A having a zeolite ratio of 12% or more and a packed bed B composed of a catalyst B having a zeolite ratio of less than 12% are packed so that the packed bed A comes into contact with the heavy gas oil fraction first and the ratio (R _A /R _B ) of the ratio ( _R A ) of the packed bed A to the ratio (R _B ) of the packed bed B is 20/80 to 95/5.

Catalyst A having a zeolite ratio of 12% or more is characterized by a higher hydrocracking activity but insufficient middle distillate selectivity, while catalyst B having a zeolite ratio of less than 12% is characterized by a higher middle distillate selectivity but insufficient hydrocracking activity. In the catalyst system of this embodiment, catalyst A and catalyst B having such characteristics are used in combination at the above ratio (R _A /R _B ), and the packed beds of each catalyst are arranged so that the feedstock oil containing a heavy gas oil fraction is passed through the packed bed B of catalyst B after the packed bed A of catalyst A, thereby making it possible to improve the merits of each catalyst while compensating for the disadvantages of each catalyst, and as a result, it is possible to achieve both a high middle distillate yield and hydrocracking activity. In this specification, middle distillates refer to fractions having a boiling point of 120°C to 360°C as described above, and include fractions usually called light oil and kerosene.

The inventors have found that middle distillate selectivity tends to depend on the performance of the packed bed of the catalyst with which the feedstock containing a heavy gas oil fraction comes into contact later, and by arranging packed bed B of catalyst B, which has higher middle distillate selectivity, so that the feedstock comes into contact later than packed bed A of catalyst A, it has become possible to fully obtain the advantage of higher middle distillate selectivity of catalyst B, while compensating for the disadvantage of lower hydrocracking activity of catalyst B with catalyst A, which has the advantage of higher hydrocracking activity, thereby achieving both a high middle distillate yield and hydrocracking activity. In addition, the inventors have also found that by setting the ratio of packed bed A of catalyst A to the above ratio (R _A /R _B ) of 20/80 to 95/5, i.e., 20% or more, the properties of the middle distillate yield can be maintained at a high level, and by setting it to 95% or less, a high level of hydrocracking activity can be obtained. In this way, by achieving both a high yield of middle distillates and high hydrocracking activity, it has become possible to carry out hydrocracking of heavy gas oil fractions more cheaply and stably (over the long term).

[Catalyst A]
Catalyst A is a catalyst characterized by having a zeolite ratio of 12% or more, and is a catalyst having superior hydrocracking activity compared to catalyst B described below. In this specification, the zeolite ratio means the content of zeolite in the catalyst carrier.

Catalyst A is preferably a catalyst in which an active metal is supported on a carrier containing, for example, ultra-stable Y-type zeolite (also called "USY zeolite"), metal-supported USY zeolite, or other zeolite, and a porous inorganic oxide such as alumina, silica-alumina, silica, alumina-boria, alumina-zirconia, or alumina-titania, with a zeolite ratio of 12% or more.

(Zeolite)
The zeolite is more preferably a metal-supported USY zeolite, and for example, a preferred example of the metal-supported USY zeolite is USY zeolite supported with at least one metal selected from Groups 3 to 16 of the periodic table. In particular, iron-supported USY zeolite, which supports iron as the metal, is preferred.

The USY zeolite and the metal-supported USY zeolite can be produced, for example, by the following method.
As the raw material for USY zeolite, Y zeolite having a ratio (molar ratio) of silica to alumina, i.e., SiO ₂ /Al ₂ O ₃ of 4.5 or more, preferably 5.0 or more, and Na ₂ O of 2.4 mass % or less, preferably 1.8 mass % or less is used.
First, the above-mentioned Y-type zeolite is subjected to a steaming treatment to obtain USY zeolite. Here, the conditions for the steaming treatment may be appropriately selected according to various circumstances, but it is preferable to perform the treatment in the presence of steam at a temperature of 510° C. to 810° C. The steam may be introduced from the outside, or physically adsorbed water or crystal water contained in the Y-type zeolite may be used. In addition, a mineral acid is added to the USY zeolite obtained by the steaming treatment, and the mixture is mixed and stirred to dealuminate the zeolite structural framework, and the aluminum that has fallen off is washed and removed by the steaming and mineral acid treatment.

Various types of mineral acids can be used here, but hydrochloric acid, nitric acid, sulfuric acid, etc. are commonly used. In addition, inorganic acids such as phosphoric acid, perchloric acid, peroxodisulfonic acid, dithioic acid, sulfamic acid, nitrososulfonic acid, etc., and organic acids such as formic acid, trichloroacetic acid, trifluoroacetic acid, etc. can also be used.
The amount of these mineral acids used may be about 0.5 to 20 moles, preferably 3 to 16 moles, per kg of USY zeolite. The mineral acid concentration is 0.5 to 50 mass % solution, preferably 1 to 20 mass % solution. The treatment temperature is room temperature to 100°C, preferably 50 to 100°C. The treatment time is 0.1 to 12 hours.

Next, a metal salt solution is added to this system to support the metal on the USY zeolite. Examples of the support method include a mixing and stirring treatment, a dipping method, and an impregnation method, with the mixing and stirring treatment being preferred. The metal is preferably at least one metal from Groups 3 to 16 of the periodic table. Specifically, preferred examples include yttria and lanthanum from Group 3 of the periodic table, zirconium and titanium from Group 4, vanadium, niobium and thallium from Group 5, chromium, molybdenum and tungsten from Group 6, manganese and rhenium from Group 7, iron, ruthenium and osmium from Group 8, cobalt, rhodium and iridium from Group 9, nickel, palladium and platinum from Group 10, copper from Group 11, zinc and cadmium from Group 12, aluminum and gallium from Group 13, tin from Group 14, phosphorus and antimony from Group 15, and selenium from Group 16. Among these,
At least one metal selected from the group consisting of Groups 4, 7, 8, 9 and 10 is more preferred, with titanium, manganese, iron, cobalt, nickel, palladium and platinum being even more preferred, and iron being particularly preferred.

As salts of various metals, sulfates and nitrates are preferred. When performing metal salt solution treatment, the temperature varies depending on the situation and cannot be unequivocally defined, but the treatment temperature is usually about 30°C to 100°C, preferably 50°C to 80°C, and the treatment time is usually about 0.1 hours to 12 hours, preferably 0.5 hours to 5 hours.

These metals are preferably supported at the same time as dealumination from the zeolite structural framework, and are appropriately selected and carried out at a pH of 2.0 or less, preferably 1.5 or less. The iron salt may be ferrous sulfate, ferric sulfate, etc., with ferric sulfate being preferred. The iron sulfate may be added as is, but is preferably added as a solution. The solvent used in this case may be any solvent capable of dissolving the iron salt, with water, alcohol, ether, ketone, etc. being preferred. The concentration of the iron sulfate added is usually 0.02 to 10.0 mol/L, preferably 0.05 to 5.0 mol/L.

When a mineral acid and an iron sulfate are added to treat a crystalline aluminosilicate, the slurry ratio, i.e., treatment solution volume (liters)/aluminosilicate mass (kg), is conveniently in the range of 1 to 50, and particularly preferably 5 to 30.
The iron-loaded crystalline aluminosilicate obtained by the above treatment is further washed with water and dried, if necessary.
In the manner described above, USY zeolite and metal-supported USY zeolite can be produced.

(Porous inorganic oxide)
Preferred examples of the porous inorganic oxide to be combined with zeolite include alumina, silica-alumina, silica, alumina-boria, alumina-zirconia, and alumina-titania, and among these, alumina as the main component is preferred. In the present specification, the term "main component" refers to a content of 50% by mass or more, preferably 70% by mass, and more preferably 80% by mass, based on the porous inorganic oxide (100% by mass). .

As the alumina, boehmite gel, alumina sol, and alumina produced from these are preferably used. Alumina is preferable because it can support the active metal in a highly dispersed manner, and the alumina described below is particularly preferable because it makes it easier to optimize the pore distribution of the catalyst.

A particularly preferred alumina is one that is produced through a process in which an alumina hydrate (boehmite gel) is obtained as an intermediate by a neutralization reaction of an aqueous solution containing an aluminum salt, and the relative peak height of the boehmite crystals in X-ray diffraction analysis (XRD) of the alumina hydrate is 65 to 85. If the relative peak height is 65 or more, the average pore diameter of the alumina will not become excessively small, improving the desulfurization activity of the catalyst for heavy diesel oil fractions, and if it is 85 or less, the average pore diameter of the alumina will not become excessively large, improving the cracking activity of the catalyst.

In the present invention, the relative peak height of the boehmite crystals of alumina hydrate is calculated by measuring the peak heights (peak heights) of the standard material and the sample material alumina (boehmite) at 2θ: 10° to 20° using an X-ray diffraction device, and using the formula (1) described below. Specifically, it is a value measured by the following method.

(Method of measuring relative peak height)
Using an X-ray diffractometer, the alumina (boehmite) peak heights of the standard material and the sample material were measured, and the relative peak height was calculated according to the following formula (1).
Relative peak height = (B/A) x 100 (1)
In the formula, A represents the peak height of a standard material (manufactured by Sasol, product name: Catapal D), and B represents the measured peak height of a sample material.
The conditions for the X-ray diffraction measurement are as follows.
・Measuring device: Rigaku (RINT-2100)
Measurement conditions:
Target: Cu
Filter: Ni
Voltage: 30kV
Current: 14mA
Scan speed: 1°/min,
Full scale: 1000cps,
Smoothing score: 19
Scan angle (2θ): 10° to 20°
・How to measure peak high:
In the broken line profile, tangents were drawn to the background on both sides of the peak, and then a perpendicular line was drawn from the peak top to determine the height from the background to the peak top, and these values were taken as the peak heights. Note that the measuring device is not limited to the above model, and an equivalent device may be used.

Alumina that satisfies the above conditions can be produced, for example, by the following method: (1) reacting an aqueous solution containing an aluminum salt with a neutralizing agent to obtain alumina hydrate (boehmite) with a pH of 6 to 11, and then (2) subjecting the alumina hydrate to a washing step, aging step, drying step, and kneading step.

In the above method, aluminum sulfate, aluminum nitrate, aluminum chloride, etc. can be used as the aluminum salt, and sodium aluminate, potassium aluminate, caustic soda, ammonia, etc. can be used as the neutralizing agent.
The pH of the alumina hydrate is preferably slightly alkaline, specifically, pH 7 to 10, from the viewpoint of facilitating the production of a hydrate having a desired particle size.

In the washing step (2), washing is performed sufficiently, and when aluminum sulfate is used as the aluminum salt, washing is preferably performed so that the amount of sulfate radicals (SO ₄ ²⁻ ) remaining in the alumina hydrate is 1 mass% or less, and further 0.7 mass% or less. The temperature of the aging step is preferably 80 to 160° C., and more preferably 90 to 100° C., and the kneading time is preferably 1 to 24 hours, and more preferably 2 to 12 hours.
As the above-mentioned method for producing alumina, it is preferable to adopt the method described in Japanese Patent No. 3755826.

(Zeolite ratio)
The zeolite ratio of catalyst A is 12% or more, that is, when the carrier of catalyst A contains the above-mentioned zeolite and a porous inorganic oxide, the content of the zeolite is 12% or more, preferably 14% or more, more preferably 15% or more, and even more preferably 18% or more. There is no particular upper limit, but from the viewpoint of improving the middle distillate yield and hydrocracking activity, it may be about 45% or less, preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less.
The support of catalyst A is preferably composed of the above-mentioned zeolite and porous inorganic oxide, i.e., the sum of the two components is preferably 100% by mass, but may contain other components, such as clay minerals and phosphorus, to the extent that the improvement in the middle distillate yield and hydrocracking activity is not hindered. In this case, the content of the other components is usually about 30% by mass or less, and preferably 25% by mass or less. When the content of the other components is within the above range, the effect of using the components can be easily obtained, and the improvement in the middle distillate yield and hydrocracking activity can also be achieved.

The carrier of catalyst A is prepared by, for example, forming a slurry of zeolite such as the above-mentioned USY zeolite or metal-supported USY zeolite with water, and also forming a slurry of a gel or sol-like porous inorganic oxide with water, and thoroughly mixing these with a kneader, etc. From the viewpoint of more efficiently producing the carrier, the water content in each slurry state is preferably 30 to 80 mass %, more preferably 40 to 70 mass %, for the crystalline aluminosilicate slurry, and preferably 50 to 90 mass %, more preferably 55 to 85 mass %, for the porous inorganic oxide slurry.
The zeolite and the porous inorganic oxide are mixed and kneaded, and then molded into a shape having a diameter of 1/12 inch to 1/32 inch and a length of 1.5 mm to 6 mm, and then molded into a cylindrical, trilobal, or quadrilobal shape. The molded product is then dried at 30 to 200°C for 0.1 to 24 hours, and then calcined at 300 to 750°C (preferably 450 to 700°C) for 1 to 10 hours (preferably 2 to 7 hours), to obtain a carrier for catalyst A.

(active metals)
The active metal used in the hydrocracking catalyst is preferably at least one metal selected from the group 6, 8, 9 and 10 of the periodic table.
Here, molybdenum and tungsten are preferable as metals belonging to Group 6 of the periodic table, and nickel and cobalt are preferable as metals belonging to Groups 8 to 10. As a combination of two types of metals, it is preferable to use a combination of a metal of Group 6 with a metal of Groups 8 to 10, and specifically, nickel-molybdenum, cobalt-molybdenum, nickel-tungsten, cobalt-tungsten, etc. are preferable, among which cobalt-molybdenum and nickel-molybdenum are preferable, and nickel-molybdenum is particularly preferable.

The supported amounts of the metals as the active components are not particularly limited and may be appropriately selected depending on various conditions such as the properties of the feed oil, the desired hydrocracking activity, and the yield of middle distillates. Generally, the amount of the Group 6 metal is 0.5 to 30 mass %, preferably 5 to 20 mass %, of the total catalyst, and the amount of the Group 8 to 10 metal is 0.1 to 20 mass %, preferably 1 to 10 mass %, of the total catalyst.
There is no particular limitation on the method for supporting the above metal components on the carrier, and any known method such as impregnation, kneading, coprecipitation, etc. can be used.
The above-mentioned metal components supported on the carrier are usually dried at 30 to 200° C. for 0.1 to 24 hours, and then calcined at 250 to 700° C. (preferably 300 to 650° C.) for 1 to 10 hours (preferably 2 to 7 hours) to complete the catalyst.

[Catalyst B]
Catalyst B is a catalyst characterized by having a zeolite ratio of less than 12%, and is a catalyst superior to Catalyst A in middle distillate selectivity.
Preferred examples of catalyst B include catalysts in which an active metal is supported on a support containing a zeolite, such as ultra-stable Y-type zeolite (also referred to as "USY zeolite") or metal-supported USY zeolite, and a porous inorganic oxide, such as alumina, silica-alumina, silica, alumina-boria, alumina-zirconia, or alumina-titania, with the zeolite ratio being less than 12%.

The zeolite, porous inorganic oxide, and active metal in catalyst B are the same as those described for the zeolite, porous inorganic oxide, and active metal in catalyst A. The properties of catalyst B are the same as those described for the properties of catalyst A, but catalysts A and B differ in the ratio of zeolite contained in the carrier.
In this way, by using two types of catalysts with different zeolite ratios in combination, as described above, it is possible to utilize the advantages of each catalyst and at the same time complement each other's disadvantages, resulting in a high middle distillate yield and hydrocracking activity.

The zeolite ratio of catalyst B must be less than 12% as described above, and is preferably 11% or less from the viewpoint of improving the middle distillate yield and hydrocracking activity. There is no particular lower limit, and the zeolite ratio is usually 1% or more, preferably 3% or more, and more preferably 5% or more.
The support of catalyst B may be prepared by blending zeolite and a porous inorganic oxide so that the zeolite ratio is less than 12%, and thoroughly mixing the resulting slurry in a kneader or the like, and may be prepared according to the method described as the method for producing the support of catalyst A. In addition, the active metal may be supported according to the method described as the method for producing catalyst A.

[Ratio of Packing Layer A to Packing Layer B]
In the catalyst system of this embodiment, the packed bed A composed of the catalyst A and the packed bed B composed of the catalyst B must be packed so that the ratio (R _A /R B ) of the ratio of packed bed A (R _A ) to the ratio of packed bed B (R _{B ) is 20/80 to 95/5. If the ratio (R A /R B ) is} less than 20/80, i.e., the ratio of packed bed A (R _A ) is _less than 20 and the ratio of packed bed B (R _B ) is more than 80, excellent hydrocracking activity cannot be obtained. On the other hand, if the ratio (R _A /R _B ) is more than 95/5, i.e., the ratio of packed bed A (R _A ) is more than 95 and the ratio of packed bed B (R _B ) is less than 5, excellent middle distillate selectivity cannot be obtained.
From the viewpoint of improving the middle distillate yield and hydrocracking activity, the ratio is preferably 25/75 or more, more preferably 35/65 or more, even more preferably 45/55 or more, still more preferably 55/45 or more, and the upper limit is preferably 90/10 or less, more preferably 85/15 or less, even more preferably 80/20 or less, and still more preferably 75/25 or less.

[Arrangement of Packing Bed A and Packing Bed B]
In the catalyst system of this embodiment, it is necessary that the packed bed A is packed so as to come into contact with the feed oil containing the heavy gas oil fraction first, that is, the packed bed B is packed next to the packed bed A. Therefore, in the catalyst system of this embodiment, the feed oil containing the heavy gas oil fraction is passed through the packed bed A and then through the packed bed B. If the packed beds are not packed in this manner, it is not possible to utilize the respective advantages of the catalyst A and the catalyst B while at the same time compensating for each other's disadvantages, and a high middle distillate yield and hydrocracking activity cannot be obtained.

In the catalyst system of this embodiment, there are no limitations on the manner in which packed beds A and B are packed, so long as packed bed A is first in contact with the heavy light oil fraction that serves as the feedstock, but from the standpoint of saving space, it is preferable that they are provided in order in one reactor.

[Desulfurization/Denitrification Catalyst Layer]
The catalyst system of the present embodiment may have a layer filled with a desulfurization and denitrification catalyst, that is, a desulfurization and denitrification catalyst layer, as necessary.
The desulfurization and denitrification catalyst is not particularly limited as long as it is a catalyst that generally has desulfurization activity and denitrification activity, and commercially available products can be used. For example, a hydrogenation catalyst in which cobalt-molybdenum, nickel-molybdenum, or the like is supported as an active metal on an inorganic composite oxide support made of aluminum, silicon, phosphorus (e.g., diphosphorus pentasulfide, etc.) can be used.

When a desulfurization/denitrification catalyst is used, the desulfurization/denitrification catalyst bed is preferably provided so as to come into contact with the heavy gas oil fraction serving as the feedstock oil prior to the packed bed A. This improves the yield of middle distillates and hydrocracking activity, and also improves the life span of catalysts A and B, making it possible to supply the heavy gas oil fraction more cheaply and stably.
In this case, the desulfurization and denitrification catalyst bed is preferably provided in a reactor separate from the packed bed A and the packed bed B from the viewpoint of maintenance and the like.

(Feedstock oil)
The feedstock oil of the catalyst system of this embodiment includes a heavy gas oil fraction. Examples of the heavy gas oil fraction include heavy gas oil (AGO), vacuum gas oil (VGO), and mixed oils thereof obtained by atmospheric distillation and vacuum distillation of crude oil. In addition, an uncracked fraction (UCO) produced after hydrocracking any of heavy gas oil (AGO), vacuum gas oil (VGO), and mixed oils thereof can also be used as the feedstock oil.

The properties of these feedstock oils are not particularly limited as long as they contain the above-mentioned heavy gas oil fraction, but for example, the density (15 ° C.) is usually 0.800 g / cm ³ or more and 1.000 g / cm ³ or less, preferably 0.820 g / cm ³ or more and 0.950 g / cm ³ or less, more preferably 0.850 g / cm ³ or more and 0.900 g / cm ³ or less, the sulfur content is usually 1.0 mass% or more and 2.9 mass% or less, preferably 1.5 mass% or more and 2.8 mass% or less, and the nitrogen content is usually 100 mass ppm or more and 1000 mass ppm or less, preferably 300 mass ppm or more and 750 mass ppm or less. If it is within the preferred range, the catalyst system of this embodiment is easy to function, and the middle distillate yield and hydrocracking activity are easily improved.
In addition, the distillation properties of the feedstock oil (JIS K2254:1998 (Petroleum products - Distillation test method)) are usually, respectively, 240°C or more and 290°C or less, 340°C or more and 380°C or less, 410°C or more and 450°C or less, 475°C or more and 510°C or less, and 530°C or more and 570°C or less, in terms of the initial boiling point, 10% by volume distillation temperature, 50% by volume distillation temperature, 90% by volume distillation temperature, and end point.
In the catalyst system of this embodiment, any oil having these properties and including middle distillates can be used as the feedstock oil, without being limited to the above-mentioned fractions.

The feedstock oil used in the catalyst system of this embodiment is not particularly limited as long as it contains a heavy diesel fraction, and fractions having the above properties or fractions containing intermediate distillates can also be used, but the content of heavy diesel fraction contained in the feedstock oil is preferably 70 mass% or more, more preferably 85 mass% or more, even more preferably 95 mass% or more, and even more preferably 100 mass%, i.e., it is even more preferable that the feedstock oil is a heavy diesel fraction.

(Hydrocracking conditions)
The conditions in the catalyst system of this embodiment are as follows. By carrying out hydrocracking under the following conditions, it is possible to improve the middle distillate yield and hydrocracking activity.
At the inlet of the feed oil in hydrocracking, i.e., upstream of the packed bed A of the catalyst A, the hydrogen pressure is usually 9.0 MPa to 19.0 MPa, preferably 10.0 MPa to 16.0 MPa, more preferably 10.5 MPa to 13.0 MPa, the LHSV is usually 0.1 h ^-1 to 9.0 h ^-1 , preferably 0.3 h ^-1 to 5.0 h ^-1 , more preferably 0.5 h ^-1 to 3.0 h ^-1 , the reaction temperature is usually 310°C to 450°C, preferably 330°C to 420°C, more preferably 350°C to 400°C, and the hydrogen/feed oil ratio is usually 300 Nm ³ /kL to 2000 Nm ³ /kL, preferably 500 Nm ³ /kL to 1800 Nm ³ /kL, more preferably 650 Nm ³ The viscosity is preferably from 800 ^{Nm 3 /} kL to 1300 Nm ³ /kL, and more preferably from 900 Nm ³ /kL to 1100 Nm ³ /kL.

When a desulfurization/denitrification catalyst layer is provided, the nitrogen content at the outlet of the desulfurization/denitrification catalyst layer is usually adjusted to 1 mass ppm or more and 20 mass ppm or less, preferably 3 mass ppm or more and 17 mass ppm or less, and more preferably 5 mass ppm or more and 15 mass ppm or less. Note that the nitrogen content is an adjustment target, and does not necessarily have to be within the above range at all times.

When the catalyst system of this embodiment is used to hydrocrack feedstock, the temperature at the outlet of the catalyst system (also called hydrocracking temperature (WAT: Weight Average Temperature)) is adjusted so that the middle distillate yield at the outlet of the catalyst system is usually in the range of 55% by mass to 70% by mass, preferably 60% by mass to 65% by mass. In this case, the hydrocracking temperature (WAT) is usually set to a low temperature of 360°C to less than 378°C, 365°C to 375°C, or 368°C to 373°C. In other words, the catalyst system of this embodiment achieves both a high middle distillate yield and hydrocracking activity, and is therefore capable of maintaining such low temperatures.

[Hydrogenolysis method]
The hydrocracking method of the present embodiment is a method for hydrocracking a feedstock oil containing a heavy gas oil fraction, using the catalyst system of the present embodiment described above.
The catalyst system of this embodiment employed in the hydrocracking method of this embodiment is as described above. Similarly, the catalyst system may have a desulfurization/deoxidization catalyst layer.

The feedstock oil containing a heavy gas oil fraction used in the hydrocracking method of this embodiment is the same as the feedstock oil containing a heavy gas oil fraction described as being used in the catalyst system of this embodiment, and the hydrocracking conditions are also the same as the hydrocracking conditions described as being used in the catalyst system of this embodiment.

[Hydrocracker]
The hydrocracker of this embodiment is equipped with the catalyst system of this embodiment described above.
The catalyst system of this embodiment employed in the hydrocracking method of this embodiment is as described above, and may also have a desulfurization/denitrification catalyst layer. Also, it is preferable that the packed bed A of catalyst A and the packed bed B of catalyst B are packed in a single reactor, and the desulfurization/denitrification catalyst layer may be provided in a reactor other than the single reactor.

The feedstock oil that can be hydrocracked in the hydrocracking unit of this embodiment is the same as the feedstock oil containing the heavy gas oil fraction described as being used in the catalyst system of this embodiment, and the hydrocracking conditions are also the same as the hydrocracking conditions described as being used in the catalyst system of this embodiment.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[Evaluation method]
1. Middle Distillate Yield The middle distillate yield in the examples and comparative examples was evaluated according to the following criteria. The higher the middle distillate yield, the higher the catalyst performance. D is a failure.
A: The yield of the middle distillate was 46.0 mass% or more.
B: The yield of the middle distillate was 45.8% by mass or more and less than 46.0% by mass.
C: The yield of the middle distillate was 45.5% by mass or more and less than 45.8% by mass.
D: The yield of the middle distillate was less than 45.5 mass%.
2. Hydrocracking activity In the examples and comparative examples, the hydrocracking temperature (WAT: Weight Average Temperature) was adjusted so that the hydrocracking rate at the outlet of the second reaction tower packed with packed bed A of catalyst A and packed bed B of catalyst B was 62 mass%. The hydrocracking temperature (WAT) was evaluated according to the following criteria. The lower the WAT, the higher the hydrocracking activity of the catalyst. D is a failure.
A: The WAT was less than 370°C.
B: WAT was 370°C or higher and less than 373°C.
C: WAT was 373°C or higher and less than 378°C.
D: WAT was 378°C or higher.

( Comparative Example 3 )
The feedstock oil used was a mixed oil containing heavy gas oil (AGO), vacuum gas oil (VGO) and uncracked oil (UCO) in a volume ratio of 4:3:3 and having the properties shown in Table 1. A first reaction tower packed with a desulfurization and denitrification catalyst and having a desulfurization and denitrification catalyst layer, and a second reaction tower packed with a packed bed A of catalyst A and a packed bed B of catalyst B in a ratio of 50/50 were prepared, and a bench facility of a hydrocracking unit was produced in which these reaction towers were connected so that the mixed oil was passed through the first reaction tower and the second reaction tower in that order, and so that the packed bed A was passed first.
As operating conditions, LHSV = 1.0 h ^-1 , hydrogen partial pressure 11.0 MPa, nitrogen content at the outlet of the first reaction tower was adjusted to 5 to 15 mass ppm, and the hydrocracking temperature (WAT: Weight Average Temperature) of the packed bed A of catalyst A and the packed bed B of catalyst B was adjusted so that the hydrocracking rate was 62 mass%. The yields of naphtha fraction (boiling point 120 ° C. or less), middle fraction (boiling point 120 to 360 ° C.), and uncracked oil fraction (boiling point 360 ° C. or more) were measured by gas chromatographic distillation for the hydrocracked feed oil at the outlet of the second reaction tower. The intermediate fraction yield and the temperature (WAT) of the hydrocracking catalyst layer are shown in Table 2. The evaluation of the intermediate fraction yield and hydrocracking activity is also shown in Table 2.

Example 2
Hydrocracking was carried out in the same manner as in Comparative Example 3 , except that the ratio of packed bed A to packed bed B in the second reaction tower was 70/30. The middle distillate yield and hydrocracking rate are shown in Table 2.

(Comparative Examples 1 and 2)
Hydrocracking was carried out in the same manner as in Comparative Example 3 , except that the ratio of packed bed A and packed bed B in the second reaction tower was set as shown in Table 2. The middle distillate yield and hydrocracking rate are shown in Table 2.

From the results of the examples, it was confirmed that by setting the ratio of packed bed A to packed bed B in the range of 20/80 to 95/5, it is possible to achieve both a middle distillate yield and a high hydrocracking activity in a well-balanced manner.
On the other hand, in Comparative Example 1, in which only the packed bed A was used, the hydrocracking activity was high due to the characteristics of the catalyst A, but the yield of the middle distillate was poor. In Comparative Example 2, in which only the packed bed B was used, the yield of the middle distillate was high due to the characteristics of the catalyst B, but the hydrocracking activity was poor.

Claims (9)

A catalyst system for hydrocracking a feedstock oil containing a heavy gas oil fraction, comprising: a packed bed A composed of a catalyst A having a zeolite ratio of 12 mass% or more in a catalyst carrier; and a packed bed B composed of a catalyst B having a zeolite ratio of less than 12 mass%, the packed bed A being arranged such that a volume ratio ( _RA ) of the packed bed A to a volume ratio ( _RB ) of the packed bed B is ( _RA /RB ₎ a ratio of the packed bed A to the heavy light oil fraction is 55/45 to 95/5 ; the zeolite in the carrier of the catalyst A and the catalyst B is a metal-supported USY zeolite supporting at least one metal selected from Groups 3 to 16 of the Periodic Table; the catalyst A and the catalyst B each have a Group 6 metal and a Group 8 to 10 metal as active metals, the amount of the Group 6 metal supported is 0.5 to 30 mass% of the entire catalyst, and the amount of the Group 8 to 10 metal supported is 0.1 to 20 mass% of the entire catalyst. The catalyst system according to claim 1, further comprising a desulfurization/denitrification catalyst layer provided in contact with the heavy gas oil fraction prior to the packed bed A. The catalyst system according to claim 1 or 2, wherein at least the packed bed A and the packed bed B are provided in one reactor. The catalyst system according to claim 3, wherein the desulfurization nitrogen catalyst layer is provided in a reactor separate from the first reactor. The catalyst system according to any one of claims 1 to 4, wherein the ratio (R _A /R _B ) is from 55/45 to 75/25. The catalyst system according to any one of claims 1 to 5, wherein the feedstock oil is at least one selected from heavy gas oil (AGO) and vacuum gas oil (VGO). The catalyst system according to claim 6, wherein the feedstock further comprises uncracked oil (UCO). A method for hydrocracking a feedstock containing a heavy gas oil fraction, using the catalyst system according to any one of claims 1 to 7. A hydrocracking unit for feedstock containing a heavy gas oil fraction, comprising the catalyst system according to any one of claims 1 to 7.