A method for producing light oil products from heavy oil

Abstract

The present invention provides a method for producing light oil products from heavy oil, which includes: after mixing the heavy raw material with hydrogen, it enters a hydrocracking reactor and sequentially flows through a protective layer and a catalyst layer for hydrocracking reaction. The protective layer includes at least two kinds of protectants, and the catalyst layer includes at least three kinds of catalysts. The total acid amount of the catalysts in the catalyst layer is 100 - 500 μmol / g, the strong acid amount is 30 - 150 μmol / g, the medium strong acid amount is 50 - 300 μmol / g, and the medium strong acid amount is more than the strong acid amount. In the catalyst layer, the sum of the medium strong acid amount and the strong acid amount of at least one catalyst is less than 50% of the total acid amount; it also includes that the sum of the medium strong acid amount and the strong acid amount of at least one catalyst in the catalyst layer is greater than 50% of the total acid amount. The present invention can highly selectively and low-convert heavy oil products into light oil products, effectively reduce the gas product yield, improve the yields of kerosene and naphtha, especially the naphtha yield is greatly increased, and effectively improve the economic benefits of the processing unit.

Description

Technical Field

[0001] The present invention relates to a method for producing light oil products from heavy oil, belonging to the technical field of hydrocracking. Background Art

[0002] As a non-renewable resource, the utilization of petroleum resources is tending to develop towards heavy and inferior quality. On the other hand, with the improvement of clean oil product standards, the requirements for the quality and cleanliness of petroleum fuel products are becoming increasingly strict. Therefore, it is urgent to lighten heavy crude oil and other oil products and efficiently convert them into clean oil products.

[0003] Hydrocracking technology is one of the important technologies for producing high-quality clean refined oil products, with unique advantages such as strong raw material adaptability, flexible processing schemes, and good product quality. The product has high cleanliness, and impurities such as sulfur and nitrogen meet the national VI fuel oil standard. The aviation kerosene has high quality and can be directly used as military aviation fuel. The heavy naphtha has a high aromatic potential and is a high-quality raw material for catalytic chemical production of aromatics or high-octane gasoline. At the same time, it can also co-produce clean diesel blending components that meet the national VI standard. Hydrocracking technology has gradually developed into a key secondary processing technology for modern refining and chemical enterprises to produce clean oil products and high-quality chemical raw materials.

[0004] The hydrocracking catalysts in industrial applications mainly include alumina, molecular sieves, active metals, and silica-alumina oxides. Among them, alumina, molecular sieves, and silica-alumina oxides form the carrier. The main function of the carrier is to provide suitable acidic sites during the hydrocracking reaction process to promote the bond breaking of heavy oil molecules, and at the same time provide a large specific surface area. The active metals mainly provide the hydrogenation function.

[0005] The existing hydrocracking technologies mainly focus on the development of efficient hydrocracking carriers and catalysts.

[0006] CN111318313A discloses a hydrocracking catalyst carrier, its preparation method and application. The carrier contains Y zeolite and SAPO-34 zeolite. Based on the carrier, the weight content of Y zeolite is 2wt% - 35wt%, and the content of SAPO-34 zeolite is 2wt% - 25wt%. The catalyst prepared from this carrier has high reaction activity, middle oil selectivity, and excellent product properties during the hydrocracking reaction process. However, this technology does not optimize the acidity of the SAPO-34 zeolite, and the carbon deposition rate of SAPO-34 is relatively high, which is not conducive to meeting the requirements of the long-term stability of the catalyst in industrial applications.

[0007] WO2020119754A1 discloses a hydrocracking catalyst, its preparation method and application. The catalyst in the patent includes a carrier, silica supported on the carrier and an active component. The carrier contains Y zeolite and SAPO-34 zeolite. The method for preparing the hydrocracking catalyst includes optimizing the acidity of the SAPO-34 zeolite, but only silane is used as a regulator in the synthesis material, resulting in a high cost, which is not conducive to reducing the catalyst cost and popularizing industrialization.

[0008] CN105709844A discloses a hydrocracking catalyst carrier and its preparation method. The catalyst carrier uses modified Y zeolite and β zeolite as cracking centers together. The Y zeolite used is a large crystal, high-silica Y zeolite with a concentrated effective pore size distribution. The hydrocracking catalyst prepared therefrom is used in the hydrocracking process for producing high-quality middle distillate oil products, and has the characteristics of high activity and good selectivity, but the selectivity of the catalyst for jet fuel is not high.

[0009] CN104667969B The present invention discloses a hydrocracking catalyst and its preparation method. The catalyst includes a carrier of β zeolite, Y zeolite and alumina. The hydrocracking catalyst has the characteristics of appropriate silicon-aluminum ratio, large specific surface area, appropriate acidity, reasonable pore structure and low non-framework aluminum content. The prepared catalyst can be used for producing low-freezing-point diesel oil and improving the properties of chemical raw materials, but the selectivity of the catalyst for middle distillate is relatively low.

[0010] Although there are many reports on the carrier of hydrocracking catalysts and the catalyst preparation process in the prior art, in the process of using heavy oil to produce base oil by the existing hydrocracking technology, there are technical problems such as low conversion efficiency and low yield of light oil products. As an important chemical raw material, the yield of naphtha is usually less than 50%. How to effectively improve the yield of light oil products and maximize the production of naphtha products is a technical problem that needs to be solved by the hydrocracking technology. Summary of the Invention

[0011] The present invention provides a method for producing light oil products from heavy oil, which can convert heavy raw materials into clean light oil products, effectively improve the liquid yield of light oil products, especially the high yield of naphtha, and overcome the problem of low naphtha yield in the production of existing hydrocracking catalysts.

[0012] The method for producing light oil products from heavy oil in the present invention includes: after mixing the heavy raw material with hydrogen, entering a hydrocracking reactor and flowing through a protection layer and a catalyst layer in sequence for hydrocracking reaction;

[0013] In the method as described above, the protection layer includes at least two kinds of protectants, and the catalyst layer includes at least three kinds of catalysts.

[0014] For the method as described above, the pore volume of the protective layer protecting agent is 0.4 - 0.8 ml / g, and the specific surface area is 100 - 300 m 2 / g;

[0015] and / or, the pore volume of the catalyst in the catalyst layer is 0.1 - 0.6 ml / g, and the specific surface area is 100 - 400 m 2 / g.

[0016] For the method as described above, the total acid amount of the catalyst in the catalyst layer is 100 - 500 μmol / g; and / or, the strong acid amount of the catalyst in the catalyst layer is 30 - 150 μmol / g; and / or, the medium strong acid amount of the catalyst in the catalyst layer is 50 - 300 μmol / g; and / or, the medium strong acid amount of the catalyst in the catalyst layer is more than the strong acid amount.

[0017] For the method as described above, the sum of the medium strong acid amount and the strong acid amount of at least one catalyst in the catalyst layer is less than 50% of the total acid amount; it also includes that the sum of the medium strong acid amount and the strong acid amount of at least one catalyst in the catalyst layer is greater than 50% of the total acid amount; and / or, the proportion of the sum of the strong acid amount and the medium strong acid amount of the catalyst in the catalyst layer to the total acid amount of the catalyst is 40 - 90%.

[0018] For the method as described above, the percentage content of the main active metal in the protecting agent in the protective layer is further preferably 0 - 10%; and / or, the percentage content of the main active metal in the catalyst in the catalyst layer is further preferably 15 - 40%.

[0019] For the method as described above, the pore volume of the protective layer protecting agent is 0.4 - 0.8 ml / g, and the specific surface area is 100 - 300 m 2 / g, the percentage content of the main active metal in the protecting agent in the protective layer to the mass of the protecting agent is 0 - 15%, and further, the percentage content of the main active metal in the protecting agent to the mass of the protecting agent is 0 - 10%; and / or, the pore volume of the catalyst in the catalyst layer is 0.1 - 0.6 ml / g, and the specific surface area is 100 - 400 m 2 / g, the percentage content of the main active metal in the catalyst in the catalyst layer to the mass of the catalyst is 10 - 50%, and further, the percentage content of the main active metal in the catalyst to the mass of the catalyst is 10 - 40%.

[0020] For the method as described above, the pore volume of the protective agent in the protective layer shows a decreasing trend along the material flow direction in the hydrocracking reactor, and the specific surface area of the protective agent shows an increasing trend along the material flow direction in the hydrocracking reactor; and / or, the pore volume and specific surface area of the catalyst in the catalyst layer show a decreasing trend along the material flow direction in the hydrocracking reactor; and / or, the total acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrocracking reactor; the proportion of the sum of the acid amounts of strong acids and medium strong acids in the total acid amount shows an increasing trend along the material flow direction in the hydrocracking reactor; and / or the content of the main active metal in the catalyst shows an increasing trend along the material flow direction in the hydrocracking reactor.

[0021] For the method as described above, the volume of the protective layer accounts for 2-20% of the sum of the volume of the protective layer and the volume of the catalyst layer;

[0022] For the method as described above, the conditions for the hydrocracking reaction are: the reaction pressure is 6-15 MPa, the reaction temperature is 300-400 °C, the volume space velocity is 0.5-2.0 h -1 , and the hydrogen-oil volume ratio is (100-1000):1.

[0023] For the method as described above, the heavy feedstock is selected from one or several of coker gas oil (CGO), vacuum gas oil (VGO), under-wax oil, and diesel oil. Among them, the sulfur content of the heavy feedstock is not more than 1500 μg / g, the nitrogen content is not more than 20 μg / g, and the final boiling point is not higher than 580 °C.

[0024] For the method as described above, after mixing the heavy feedstock with hydrogen, it enters the hydrocracking reactor and flows through the protective layer and the catalyst layer in sequence for the hydrocracking reaction. The liquid yield of the produced light oil products is not less than 90%. Among them, the light oil products include kerosene and naphtha, and the liquid yield of naphtha is not less than 55%.

[0025] By using the method for producing light oil products from heavy oil of the present invention, the overall liquid yield level of the device can be improved, the yield of low-value gas products can be reduced, and at the same time, the product distribution can be effectively improved to produce more high-value light oil products (kerosene and naphtha). Especially, naphtha, as a high-quality ethylene cracking feedstock, has a greatly increased naphtha yield, which can effectively improve the economic benefits of the processing device. Detailed implementation mode

[0026] To enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below. The specific embodiments listed below only describe the principles and features of the present invention, and the examples given are only used to explain the present invention, not to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] Hydrocracking technology has become one of the key core technologies for producing high-quality light oil products. The focus of hydrocracking technology lies in the research and development of catalysts. Hydrocracking catalysts mainly consist of a carrier and a main active metal. The main active metal can be a metal of Group VIB or Group VIII, specifically metal oxides or metal sulfides, etc. Its carrier is generally alumina. Due to the limitations of the pore size and surface acidity of alumina, a catalyst using only alumina as the carrier cannot achieve deep polycyclic aromatic hydrocarbon saturation and the removal of heterocyclic nitrogen compounds.

[0028] Therefore, according to the research of the inventors, for the further research and development of catalysts, in addition to the need to improve the pore structure of the carrier and adjust the interaction between the carrier and the metal, it is also necessary to optimize the surface acidic structure of the hydrocracking catalyst. Increasing the acid amount of the catalyst is beneficial to enhancing the cracking of liquid products, but an increase in the proportion of weak acid amount in the catalyst is not conducive to the improvement of the cracking activity of the oil product. What really plays a leading role is the strong acid amount and medium strong acid amount in the catalyst. According to different preparation processes, there may be two types of acid centers on the hydrocracking catalyst, namely Bronsted acid centers and Lewis acid centers. The total acid amount of the catalyst is the sum of the acid amounts of Bronsted acid and Lewis acid. Bronsted acid centers can provide protons, while Lewis acid centers can accept unpaired electrons. The prior art mainly optimizes the acidity at the catalyst particle scale, resulting in poor catalytic selectivity of the catalyst and low yield of light oil products. There is little research on achieving the purpose of improving the hydrocracking effect by coordinating the acidic characteristics of the catalyst through a grading process.

[0029] In view of this, the embodiments of the present invention provide a grading method for a hydrocracking catalyst, including:

[0030] Along the material flow direction of the hydrogenation reactor, a protective agent (protective layer) and a catalyst (catalyst layer) are filled in sequence; the protective layer includes a protective agent, and the pore volume of the protective agent in the protective layer shows a decreasing trend along the material flow direction in the hydrogenation reactor; the catalyst layer includes a catalyst, and the total acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor; the proportion of the sum of the acid amounts of strong acids and medium strong acids in the total acid amount shows an increasing trend along the material flow direction in the hydrogenation reactor; the content of the main active metal in the catalyst shows an increasing trend along the material flow direction in the hydrogenation reactor.

[0031] Through the above grading method, the cracking performance of the overall catalytic system formed by the protective layer and the catalyst layer in the hydrogenation reactor can be improved, and the liquid yield of light oil products can be increased while taking into account, so as to enhance the overall operation economy of the hydrogenation reactor / unit.

[0032] The inventor believes through research and analysis that in the above grading method, based on the use functions of the protective agent and the catalyst, a reasonable grading filling is carried out. The protective agent can be used to preliminarily remove impurities from the materials (such as the oil product to be treated) entering the hydrogenation reactor, such as removing mechanical impurities and at least part of metals, etc. The catalyst layer further carries out deep hydrocracking on the materials. Among them, the content of the main active metal in the catalyst shows an increasing trend along the material flow direction, so that the hydrogenation activity of the catalyst shows an increasing trend along the material flow direction, which can slowly increase the hydrogenation activity of the catalyst and control the temperature rise of the bed layer in the hydrogenation reactor, which is beneficial to the progress of the hydrogenation reaction; at the same time, the total acid amount of the catalyst layer shows an increasing trend along the material flow direction, and the proportion of the sum of the acid amounts of strong acids and medium strong acids in the total acid amount of the catalyst shows an increasing trend along the material flow direction, so that the cracking activity of the catalyst increases slowly, ensuring the ring-opening cracking activity of the deep oil products, so as to be conducive to generating more high-quality light oil products, especially the naphtha yield is greatly improved. Therefore, through the above grading method, the overall catalytic performance of the catalytic system formed by the protective agent and the catalyst can be efficiently exerted, the deep cracking activity of the catalytic system can be improved, and the liquid yield of light oil products can be increased while taking into account.

[0033] Specifically, the hydrogenation reactor can be placed vertically, and the material flow direction in the hydrogenation reactor can be the direction from top to bottom of the hydrogenation reactor (that is, the direction from the upper part / top of the hydrogenation reactor to the lower part / bottom of the hydrogenation reactor).

[0034] The above-mentioned decreasing trend can include gradual decrease or gradient decrease (or stepwise decrease), that is, the pore volume of the protective agent in the protective layer can gradually decrease or gradient decrease along the material flow direction in the hydrogenation reactor.

[0035] Specifically, the protective layer may include at least two protective sub-layers distributed in sequence along the material flow direction in the hydrogenation reactor. The pore volume of the protective agent in each protective sub-layer may remain unchanged or show a decreasing trend along the material flow direction. In some specific embodiments, among two adjacent protective sub-layers, the pore volume of the protective agent in the upstream one is greater than that in the downstream one. The upstream-to-downstream direction is the material flow direction in the hydrogenation reactor, that is, the pore volume of the protective agent in the sub-layer closer to the catalyst layer is smaller. Thus, the pore volume of the protective agent in the protective layer decreases in a gradient along the material flow direction in the hydrogenation reactor.

[0036] In some specific embodiments, the above-mentioned protective layer includes two protective sub-layers, which are respectively a first protective sub-layer and a second protective sub-layer distributed in sequence along the material flow direction of the hydrogenation reactor. That is, the first protective sub-layer, the second protective sub-layer, and the catalyst layer are distributed in sequence along the material flow direction in the hydrogenation reactor, and the pore volume of the protective agent in the first protective sub-layer is greater than that in the second protective sub-layer.

[0037] Specifically, the pore volume of the above-mentioned protective agent may be not less than 0.5 ml / g, and further may be not less than 0.6 ml / g. Exemplarily, the pore volume of the above-mentioned protective agent is, for example, 0.6 ml / g, 0.7 ml / g, 0.8 ml / g, 0.9 ml / g, 1 ml / g, or a range composed of any two of them.

[0038] It can be understood that when the protective layer includes at least two protective sub-layers (such as the first protective sub-layer and the second protective sub-layer), the pore volume of the protective agent in each sub-layer is not less than 0.5 ml / g, and further may be not less than 0.6 ml / g.

[0039] Specifically, the difference in the pore volume of the protective agent between two adjacent protective sub-layers (such as the difference in the pore volume of the protective agent between the first protective sub-layer and the second protective sub-layer) may be, for example, 0.1 - 0.5 ml / g, such as 0.1 ml / g, 0.2 ml / g, 0.3 ml / g, 0.4 ml / g, 0.5 ml / g, or a range composed of any two of them, but is not limited thereto.

[0040] Exemplarily, the pore volume of the above-mentioned first protective sub-layer is greater than 0.6 ml / g, for example, 0.65 ml / g - 1.0 ml / g, and the pore volume of the second protective sub-layer is less than 0.6 ml / g, for example, 0.5 ml / g - 0.59 ml / g.

[0041] Generally, the specific surface area of the protective agent in the protective layer shows an increasing trend along the material flow direction in the hydrogenation reactor. The increasing trend may include gradual increase or gradient increase (or stepped increase, stepped addition), that is, the specific surface area of the protective agent in the protective layer may gradually increase or increase in a gradient along the material flow direction in the hydrogenation reactor.

[0042] In at least two of the above-mentioned protective sub-layers, the specific surface area of the protective agent in each protective sub-layer may remain unchanged or show an increasing trend along the material flow direction. In some specific embodiments, in two adjacent protective sub-layers, the specific surface area of the protective agent in the upstream one is smaller than that in the downstream one. That is, the specific surface area of the protective agent in the protective sub-layer closer to the catalyst layer is larger, so that the specific surface area of the protective agent in the protective layer increases in a gradient along the material flow direction in the hydrogenation reactor.

[0043] For example, the specific surface area of the protective agent in the first protective sub-layer is smaller than that in the second protective sub-layer.

[0044] Specifically, the specific surface area of the above-mentioned protective agent may be 100 - 200 m 2 / g, such as 100 m 2 / g, 110 m 2 / g, 120 m 2 / g, 130 m 2 / g, 140 m 2 / g, 150 m 2 / g, 160 m 2 / g, 170 m 2 / g, 180 m 2 / g, 190 m 2 / g, 200 m 2 / g or the range composed of any two of them.

[0045] It can be understood that when the protective layer includes at least two protective sub-layers (such as the first protective sub-layer and the second protective sub-layer), the specific surface area of the protective agent in each sub-layer can be 100 - 200 m 2 / g respectively.

[0046] Specifically, the difference in the specific surface area of the protective agent in two adjacent protective sub-layers (such as the difference between the specific surface area of the protective agent in the first protective sub-layer and that in the second protective sub-layer) can be, for example, 10 - 50 m 2 / g, such as 10 m 2 / g, 12 m 2 / g, 15 m 2 / g, 18 m 2 / g, 20 m 2 / g, 20 m 2 / g, 25 m 2 / g, 30 m 2 / g, 35 m 2 / g, 40 m 2 / g, 45 m 2 / g, 50 m 2 / g or a range composed of any two of them, but not limited thereto.

[0047] Exemplarily, the specific surface area of the above-mentioned first protective sub-layer is not greater than 150 m 2 / g, for example, it is 100 - 150 m 2 / g, the specific surface area of the second protective sub-layer is greater than 150 m 2 / g, for example, it is 150 - 200 m 2 / g.

[0048] Specifically, the above-mentioned protective agent may include a first carrier and a first active metal. Among them, the first active metal may include one or several of nickel, cobalt, molybdenum, and tungsten, and the first carrier may include an amorphous porous material.

[0049] In some embodiments, the amorphous porous material may include alumina, amorphous silica-alumina, titanium dioxide, zirconium dioxide, silicon dioxide, Al 2 O 3 -SiO 2 composite oxide, Al 2 O 3 -TiO 2 composite oxide, Al 2 O 3 -ZrO 2 composite oxide, ZrO 2 -TiO 2 composite oxide, TiO 2 -SiO 2 one or several of the composite oxides.

[0050] Specifically, the mass percentage of the main active metal in the protective agent accounts for 0 - 10% of the mass of the protective agent. For example, it is 0% (i.e., the protective agent does not contain the main active metal), 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a range composed of any two of them.

[0051] Generally, when the protective agent contains the main active metal (i.e., the mass percentage of the main active metal therein is not 0), the protective layer also has certain desulfurization, denitrification, and demetallization functions, which is beneficial to further improving the hydrocracking efficiency.

[0052] When the protective layer includes at least two protective sub-layers, the types of carriers, the types of main active metals, and the mass percentage contents of the main active metals in these protective sub-layers may be the same or different.

[0053] In some embodiments, the mass percentage content of the main active metal of the protective agent in the protective layer remains unchanged or shows an increasing trend along the material flow direction in the hydrogenation reactor. The increasing trend may include gradual increase or gradient increase, that is, the mass percentage content of the first active metal of the protective agent in the protective layer may remain unchanged, gradually increase, or increase in a gradient along the material flow direction in the hydrogenation reactor.

[0054] Specifically, when the protective layer includes at least two protective sub-layers, the mass percentage content of the main active metal in each protective sub-layer may remain unchanged or show an increasing trend along the material flow direction.

[0055] Exemplarily, the mass percentage content of the main active metal in each protective sub-layer is substantially the same (i.e., unchanged) along the material flow direction, and the mass percentage contents of the first active metal in any two adjacent ones of these protective sub-layers are substantially the same, thereby making the mass percentage content of the main active metal of the protective agent in the protective layer remain unchanged along the material flow direction in the hydrogenation reactor; or, among these protective sub-layers, the mass percentage content of the main active metal in the protective sub-layer closer to the catalyst layer is higher, thereby making the mass percentage content of the main active metal of the protective agent in the protective layer show an increasing trend.

[0056] Exemplarily, the protective agent in the first protective sub-layer does not contain the first active metal (i.e., the mass percentage content of the first active metal therein is 0), and the mass percentage content of the second active metal of the protective agent in the second protective sub-layer is 0 or greater than 0, for example, 5-10%, but not limited thereto.

[0057] In the above grading method, the total acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor. The increase in the increasing trend may specifically be a gradual increase or a gradient increase.

[0058] Specifically, the catalyst layer may include at least two catalytic sub-layers distributed in sequence along the material flow direction in the hydrogenation reactor. The total acid amount of the catalyst in each catalytic sub-layer may remain unchanged, or show an increasing trend, and the distribution of the total acid amount of the catalyst in these catalytic sub-layers satisfies that the total acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor.

[0059] For example, the above catalyst layer includes three catalytic sub-layers, namely the first catalytic sub-layer, the second catalytic sub-layer and the third catalytic sub-layer. The protective layer, the first catalytic sub-layer, the second catalytic sub-layer and the third catalytic sub-layer are sequentially distributed along the material flow direction. The total acid amount of the catalyst in the first catalytic sub-layer is lower than that of the catalyst in the second catalytic sub-layer, and the total acid amount of the catalyst in the second catalytic sub-layer is lower than that of the catalyst in the third catalytic sub-layer. Thus, the total acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction.

[0060] In the above grading method, the strong acid amount and medium strong acid amount in the catalyst layer account for an increasing trend of the total acid amount of the catalyst along the material flow direction. The increase in the above increasing trend can specifically be a gradual increase or a gradient increase.

[0061] Specifically, the catalyst layer may include at least two catalytic sub-layers sequentially distributed along the material flow direction in the hydrogenation reactor. The sum of the strong acid amount and medium strong acid amount of the catalyst in each catalytic sub-layer may remain unchanged, or show an increasing trend, and the distribution of the sum of the strong acid amount and medium strong acid amount of the catalyst in these catalytic sub-layers accounting for the total acid amount of the catalyst satisfies that the sum of the strong acid amount and medium strong acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor.

[0062] For example, the above catalyst layer includes three catalytic sub-layers, namely the first catalytic sub-layer, the second catalytic sub-layer and the third catalytic sub-layer. The protective layer, the first catalytic sub-layer, the second catalytic sub-layer and the third catalytic sub-layer are sequentially distributed along the material flow direction. The sum of the strong acid amount and medium strong acid amount of the catalyst in the first catalytic sub-layer accounting for the total acid amount of the catalyst is lower than that of the second catalytic sub-layer, and the sum of the strong acid amount and medium strong acid amount of the catalyst in the second catalytic sub-layer is lower than that of the third catalytic sub-layer. Thus, the sum of the strong acid amount and medium strong acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction.

[0063] The acid types in the catalyst are divided into Acids and Lewis acids. According to the research of the inventors, by moderately adjusting the number and strength of the acid centers of the catalyst, the cracking activity of the catalyst can be further adjusted. However, the acid amount of the catalyst also affects the liquid yield. Excessive acid amount and too strong acidity of the catalyst will both exacerbate the cracking reaction, resulting in a decrease in the liquid yield and an increase in the production of gas products. Insufficient acid amount of the catalyst will lead to low conversion rate of the raw material and low yield of light oil products. Considering these factors comprehensively, in order to achieve the effects of improving the conversion rate of the catalyst and the liquid yield of light oil products, in some preferred embodiments, the total acid amount of the above catalyst can be controlled to be 100-500 μmol / g, such as 100 μmol / g, 120 μmol / g, 140 μmol / g, 160 mol / g, 180 μmol / g, 200 μmol / g, 220 μmol / g, 240 μmol / g, 250 μmol / g, 260 μmol / g, 280 μmol / g, 300 μmol / g, 320 μmol / g, 340 μmol / g, 350 μmol / g, 360 μmol / g, 380 μmol / g, 400 μmol / g, 420 μmol / g, 440 μmol / g, 450 μmol / g, 460 μmol / g, 480 μmol / g, 490 μmol / g, 500 μmol / g or the range composed of any two of them.

[0064] It can be understood that when the catalyst layer includes at least two catalytic sub-layers (such as the above-mentioned first catalytic sub-layer, second catalytic sub-layer and third catalytic sub-layer), the total acid amount of the catalyst in each catalytic sub-layer is 100-500 μmol / g respectively, and it satisfies that the total acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor.

[0065] Specifically, the difference in the total acid amount of the catalysts in two adjacent catalytic sub-layers can be 10 - 300 μmol / g, such as 10 μmol / g, 20 μmol / g, 30 μmol / g, 40 μmol / g, 50 μmol / g, 60 μmol / g, 70 μmol / g, 80 μmol / g, 90 μmol / g, 100 μmol / g, 110 μmol / g, 120 μmol / g, 130 μmol / g, 140 μmol / g, 150 μmol / g, 160 μmol / g, 170 μmol / g, 180 μmol / g, 190 μmol / g, 200 μmol / g, 210 μmol / g, 220 μmol / g, 230 μmol / g, 240 μmol / g, 250 μmol / g, 260 μmol / g, 270 μmol / g, 280 μmol / g, 290 μmol / g, 300 μmol / g or the range composed of any two of them. Exemplarily, the difference in the total acid amount of the catalysts in the first catalytic sub-layer and the second catalytic sub-layer can be 10 - 300 mmol / g, and the difference in the total acid amount of the catalysts in the second catalytic sub-layer and the third catalytic sub-layer can be 50 - 200 μmol / g.

[0066] Through further research, the sum of the strong acid amount and the medium strong acid amount of the catalysts in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor, and the specific increase can be a gradual increase or a gradient increase.

[0067] In some preferred embodiments, the proportion of the sum of the strong acid amount and the medium strong acid amount of the catalysts in the total acid amount of the catalysts can be 70 - 90%, such as 40%, 43%, 45%, 48%, 50%, 55%, 60%, 65%, 70%, 73%, 75%, 78%, 80%, 83%, 85%, 90% or the range composed of any two of them.

[0068] It can be understood that when the catalyst layer includes at least two catalytic sub-layers (such as the first catalytic sub-layer, the second catalytic sub-layer, and the third catalytic sub-layer above), the proportion of the sum of the strong acid amount and the medium strong acid amount of the catalysts in each catalytic sub-layer in the total acid amount of the catalysts is 40 - 90%, and it satisfies that the proportion of the sum of the strong acid amount and the medium strong acid amount of the catalysts in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor.

[0069] Specifically, the difference in the proportion of the sum of the strong acid amount and the medium strong acid amount of the catalysts in two adjacent catalytic sub-layers can be 2 - 10%, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or the range composed of any two of them.

[0070] The sum of the medium-strong acid amount and the strong acid amount of at least one catalyst in the catalyst layer is less than 50% of the total acid amount; it also includes that the sum of the medium-strong acid amount and the strong acid amount of at least one catalyst in the catalyst layer is greater than 50% of the total acid amount.

[0071] Through research, it is found that although a too high medium-strong acid amount in the catalyst can promote the improvement of hydrocracking activity, it is not conducive to the long-term operation of the catalyst, and it will also lead to a decrease in liquid yield and the generation of more low-value gas products. Through experimental research, it is determined that the medium-strong acid amount of the catalyst is 30 - 150 μmol / g, such as 30 μmol / g, 40 μmol / g, 50 μmol / g, 60 μmol / g, 70 μmol / g, 80 μmol / g, 90 μmol / g, 100 μmol / g, 110 μmol / g, 120 μmol / g, 130 μmol / g, 140 μmol / g, 150 μmol / g or the range composed of any two of them.

[0072] Specifically, the difference in the strong acid amount between adjacent two catalytic sub-layers can be 20 - 100 μmol / g, such as 20 μmol / g, 30 μmol / g, 40 μmol / g, 50 μmol / g, 60 μmol / g, 70 μmol / g, 80 μmol / g, 90 μmol / g, 100 μmol / g or the range composed of any two of them.

[0073] The medium-strong acid in the catalyst can moderately control the cracking activity of the catalyst and improve the product distribution. The medium-strong acid amount in the catalyst is 50 - 300 μmol / g, such as 50 μmol / g, 60 μmol / g, 70 μmol / g, 80 μmol / g, 90 μmol / g, 100 μmol / g, 110 μmol / g, 120 μmol / g, 130 μmol / g, 140 μmol / g, 150 μmol / g, 160 μmol / g, 170 μmol / g, 180 μmol / g, 190 μmol / g, 200 μmol / g, 210 μmol / g, 220 μmol / g, 230 μmol / g, 240 μmol / g, 250 μmol / g, 260 μmol / g, 270 μmol / g, 280 μmol / g, 290 μmol / g, 300 μmol / g or the range composed of any two of them.

[0074] An excess of strong acid amount over medium strong acid amount in the catalyst bed can effectively control the cracking depth, avoid generating excessive gas products, and prevent the economic benefits of the unit from deteriorating. The medium strong acid amount in the catalyst bed is 20 - 150 μmol / g higher than the strong acid amount, such as 20 μmol / g, 30 μmol / g, 40 μmol / g, 50 μmol / g, 60 μmol / g, 70 μmol / g, 80 μmol / g, 90 μmol / g, 100 μmol / g, 110 μmol / g, 120 μmol / g, 130 μmol / g, 140 μmol / g, 150 μmol / g, or the range composed of any two of them.

[0075] Specifically, the acids in the catalyst can be classified into weak acids, medium strong acids, and strong acids according to acid strength. The weak acid amount of the catalyst is the amount of weak acid, and the total acid amount of the catalyst is the sum of the amounts of weak acid, medium strong acid, and strong acid in the catalyst. The acid amount and acid strength of the catalyst in the present invention can be measured by conventional methods in the art. For example, the ammonia temperature-programmed desorption (NH 3 -TPD) characterization method is used to measure the acid amount and acid strength of the catalyst. Through the above method, it can be obtained that the amount of ammonia desorbed between 100 °C and 230 °C corresponds to the amount of weak acid, the amount of ammonia desorbed between 230 °C and 370 °C corresponds to the amount of medium strong acid, and the amount of ammonia desorbed above 370 °C corresponds to the amount of strong acid. The specific operation method generally can include: purging the catalyst sample with helium at 500 °C for 1 hour and then cooling to 60 °C, introducing ammonia saturated vapor, and performing pulsed adsorption five times to reach equilibrium; heating to 100 °C and purging for 2 hours, and then performing temperature-programmed ammonia desorption at a heating rate of 10 °C / minute until heating to 650 °C; the desorbed ammonia is absorbed by hydrochloric acid solution, and then the excess hydrochloric acid is titrated with sodium hydroxide solution. The amounts of hydrochloric acid consumed to absorb ammonia are respectively defined as the amounts of weak acid, medium strong acid, strong acid, and total acid of the catalyst.

[0076] In addition, the mass percentage content of the main active metal in the catalyst in the above catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor. The specific increasing trend can include gradually increasing or increasing in a gradient.

[0077] When the above catalyst layer includes at least two catalytic sub-layers, the mass percentage content of the main active metal in the catalyst of each catalytic sub-layer can remain unchanged or show an increasing trend along the material flow direction. In some specific embodiments, in two adjacent catalytic sub-layers, the mass percentage content of the main active metal in the catalyst in the upstream one is less than that in the catalyst in the downstream one. That is, the mass percentage content of the main active metal in the catalyst in the catalytic sub-layer farther away from the protective layer is greater, thereby making the mass percentage content of the main active metal in the catalyst in the catalytic layer gradually increase or increase in a gradient along the material flow direction in the hydrogenation reactor.

[0078] For example, the mass percentage of the main active metal of the catalyst in the first catalyst sub-layer is less than that of the catalyst in the second catalyst sub-layer, and the mass percentage of the main active metal of the catalyst in the second catalyst sub-layer is less than that of the catalyst in the third catalyst sub-layer. Thus, the mass percentage of the main active metal of the catalyst in the catalyst layer gradually increases or increases in a gradient along the material flow direction.

[0079] Specifically, the mass percentage of the main active metal in the above-mentioned catalyst can be 20-40% (i.e., the mass of the main active metal accounts for 20-40% of the total mass of the catalyst). For example, 20%, 25%, 30%, 35%, 40% or the range composed of any two of them. The main active metal includes one or more of Co, Mo, Ni, and W.

[0080] It can be understood that when the catalyst layer includes at least two catalyst sub-layers (such as the first catalyst sub-layer, the second catalyst sub-layer, and the third catalyst sub-layer mentioned above), the mass percentage of the main active metal of the catalyst in each catalyst sub-layer is 20-40% respectively, and it satisfies that the mass percentage of the main active metal of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrogenation reactor.

[0081] Specifically, the difference in the mass percentage of the main active metal of the catalyst between two adjacent catalyst sub-layers (such as between the first catalyst sub-layer and the second catalyst sub-layer, or between the second catalyst sub-layer and the third catalyst sub-layer, etc.) can be 5-15%. For example, 5%, 6%, 7%, 8%, 9%, 18%, 10%, 11%, 12%, 13%, 14%, 15% or the range composed of any two of them.

[0082] The pore volume of the above-mentioned catalyst is 0.2-0.6 ml / g. For example, 0.2 ml / g, 0.3 ml / g, 0.4 ml / g, 0.5 ml / g, 0.6 ml / g or the range composed of any two of them. It can be understood that when the catalyst layer includes at least two catalyst sub-layers (such as the first catalyst sub-layer, the second catalyst sub-layer, and the third catalyst sub-layer mentioned above), the pore volume of the catalyst in each catalyst sub-layer can be 0.2-0.6 ml / g respectively, and the pore volumes of the catalysts in these catalyst sub-layers can be the same or different.

[0083] In addition, the specific surface area of the above-mentioned catalyst is 100-400 m 2 / g. For example, 100 m 2 / g, 120 m 2 / g, 140 m 2 / g, 160 m 2 / g, 180 m 2 / g, 200 m2 / g, 220 m 2 / g, 240 m 2 / g, 260 m 2 / g, 280 m 2 / g, 300 m 2 / g, 320 m 2 / g, 340 m 2 / g, 360 m 2 / g, 380 m 2 / g, 400 m 2 / g, or a range composed of any two of them.

[0084] In addition, the above catalyst further includes a carrier, and the carrier may include an inorganic porous material, and the inorganic porous material may specifically be an amorphous porous material.

[0085] In some embodiments, the amorphous porous material may include alumina, amorphous silicon-aluminum (ASA), titanium dioxide, zirconium dioxide, silicon dioxide, Al 2 O 3 -SiO 2 、Al 2 O 3 -TiO 2 composite oxide, Al 2 O 3 -ZrO 2 composite oxide, ZrO 2 -TiO 2 composite oxide, TiO 2 -SiO 2 one or more of composite oxides.

[0086] In addition, the mass percentage content of the amorphous porous material in the catalyst may be 5-27% (that is, the mass of the amorphous porous material accounts for 5-27% of the total mass of the catalyst), for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27% or a range composed of any two of them, and the mass percentage content of the molecular sieve in the catalyst is 50-70% (that is, the mass of the molecular sieve accounts for 50-70% of the total mass of the catalyst), for example, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70% or a range composed of any two of them.

[0087] In addition, the above catalyst may further include an acidic promoter, and the mass percentage of the acidic promoter in the catalyst may be 0.5-3% (i.e., the mass of the acidic promoter accounts for 0.5-3% of the total mass of the catalyst), such as 0.5%, 0.6%, 0.7%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3% or the range composed of any two of them.

[0088] Specifically, the acidic promoter may include one or more of phosphoric acid, boric acid, hydrofluoric acid, nitric acid, citric acid, tartaric acid, and malic acid.

[0089] When the catalyst layer includes at least two catalytic sub-layers, the types of the main active metals of the catalysts in these catalytic sub-layers, the mass percentage of the main active metals, the types of the carriers (inorganic materials / molecular sieves) and their mass percentages, the types of the acidic promoters, the mass percentage of the acidic promoters, etc. may be the same or different.

[0090] In addition, the volume of the above protective layer may account for 2-20% of the sum of the volume of the protective layer and the volume of the catalyst layer, such as 2%, 3%, 4%, 5%, 7%, 10%, 12%, 15%, 18%, 20% or the range composed of any two of them, and the volume of the catalyst layer may account for 80-98% of the sum of the volume of the protective layer and the volume of the catalyst layer, such as 80%, 82%, 85%, 88%, 90%, 93%, 95%, 98% or the range composed of any two of them.

[0091] Generally, in the above protective layer and catalyst layer, the volume ratio of the protective layer is basically equal to the ratio of its length (or thickness) in the material flow direction, and the volume ratio of the catalyst layer is basically equal to the ratio of its length (or thickness) in the material flow direction. That is, the length (thickness) of the protective layer in the material flow direction is L 1 , and the length (thickness) of the catalyst layer in the material flow direction is L 2 , L 1 / (L 1 +L 2 ) is equal to the ratio of the volume of the above protective layer to the sum of the volume of the protective layer and the volume of the catalyst layer, that is, L 1 / (L 1 +L 2 ) is 2-20%, and L 2 / (L 1 +L 2 ) is equal to the ratio of the volume of the above catalyst layer to the sum of the volume of the protective layer and the volume of the catalyst layer, that is, L 2 / (L 1 +L 2 ) is 80-98%.

[0092] When the protective layer includes at least two protective sub - layers, the volume of the above - mentioned protective layer refers to the sum of the volumes of these protective sub - layers, and the length (thickness) of the above - mentioned protective layer refers to the sum of the lengths (thicknesses) of these protective sub - layers; when the catalyst layer includes at least two catalytic sub - layers, the volume of the above - mentioned catalyst layer refers to the sum of the volumes of these catalytic sub - layers, and the length (thickness) of the above - mentioned catalyst layer refers to the sum of the lengths (thicknesses) of these catalytic sub - layers.

[0093] When the protective layer includes at least two protective sub - layers, the proportion of the volume of each of these protective sub - layers in the sum of the volume of the protective layer and the volume of the catalyst layer can be the same or different. Exemplarily, when the protective layer includes a first protective sub - layer and a second protective sub - layer, the proportion of the volume of the first protective sub - layer in the sum of the volume of the protective layer and the volume of the catalyst layer is a 1 , and the proportion of the volume of the second protective sub - layer in the sum of the volume of the protective layer and the volume of the catalyst layer is a 2 , a 1 can be greater than, equal to, or less than a 2 , exemplarily, a 1 , a 2 can be 2 - 15% respectively, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or the range composed of any two of them.

[0094] When the catalyst layer includes at least two catalytic sub - layers, the proportion of the volume of each of these catalytic sub - layers in the sum of the volume of the protective layer and the volume of the catalyst layer can be the same or different. Exemplarily, when the catalyst layer includes a first catalytic sub - layer, a second catalytic sub - layer and a third catalytic sub - layer, the proportion of the volume of the first catalytic sub - layer in the sum of the volume of the protective layer and the volume of the catalyst layer is b 1 , and the proportion of the volume of the second catalytic sub - layer in the sum of the volume of the protective layer and the volume of the catalyst layer is b 2 , and the proportion of the volume of the third catalytic sub - layer in the sum of the volume of the protective layer and the volume of the catalyst layer is b 3 , b 1 can be greater than, equal to, or less than b 2 , b 2 can be greater than, equal to, or less than b 3 , b 1 can be greater than, equal to, or less than b 3 , exemplarily, b 1 , b 2 , b 3 can be 15 - 45% respectively, such as 15%, 20%, 25%, 30%, 35%, 40%, 45% or the range composed of any two of them.

[0095] The hydrogenation reactor of the embodiments of the present invention can be a conventional structure in the art. Each protective sub-layer and each catalytic sub-layer therein are respectively a bed layer of the hydrogenation reactor, that is, the hydrogenation reactor can have a multi-layer bed layer composed of at least two protective sub-layers and at least two catalytic sub-layers. Any two adjacent bed layers can be separated by structures such as trays and distribution trays for distributing packing (such as protective agents or catalysts, etc.) into the hydrogenation reactor to form a bed layer.

[0096] The oil hydrocracking method provided by the embodiments of the present invention includes: introducing the oil to be treated into the hydrogenation reactor to contact with the protective agent and the catalyst for hydrocracking. Among them, the protective agent and the catalyst in the hydrogenation reactor are loaded according to the above grading method, and the flow direction of the oil to be treated in the hydrogenation reactor is the material flow direction in the hydrogenation reactor, that is, after the oil to be treated enters the hydrogenation reactor, it first flows through the protective layer and then through the catalyst layer.

[0097] Generally, the above hydrocracking reaction is carried out in the presence of hydrogen. Specifically, the oil to be treated can be mixed with hydrogen and then introduced into the hydrogenation reactor to contact with the protective agent and the catalyst in turn for hydrocracking. During the hydrocracking process, reactions such as desulfurization, denitrification, aromatic saturation, ring opening by cracking, and cracking of long-chain alkanes are carried out to realize the lightening of the oil to be treated and treatments such as desulfurization and denitrification, and can also take into account the improvement of the liquid yield of light products, especially the yield of naphtha.

[0098] In some embodiments, the conditions for the above hydrotreating can be: the reaction pressure is 6 - 15 MPa, such as 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa or the range composed of any two of them; the reaction temperature is 300 - 400 °C, such as 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C or the range composed of any two of them; the volume space velocity is 0.5 - 2.0 h -1 , such as 0.5 h -1 , 0.8 h -1 , 1 h -1 , 1.2 h -1 , 1.5 h -1 , 1.8 h -1 , 2 h -1 or the range composed of any two of them; the hydrogen-oil volume ratio is (100 - 1000):1, such as 100:1, 200:1, 300:1, 400:1, 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1 or the range composed of any two of them.

[0099] In some embodiments, the sulfur mass in the oil to be processed is not greater than 1000 μg / g, such as 10 μg / g, 30 μg / g, 50 μg / g, 80 μg / g, 100 μg / g, 150 μg / g, 200 μg / g, 250 μg / g, 300 μg / g, 350 μg / g, 400 μg / g, 450 μg / g, 500 μg / g, 600 μg / g, 700 μg / g, 800 μg / g, 900 μg / g, 1000 μg / g, or the range composed of any two of them. The nitrogen mass in the oil to be processed is not greater than 20 μg / g, such as 1 μg / g, 2 μg / g, 3 μg / g, 4 μg / g, 5 μg / g, 6 μg / g, 7 μg / g, 8 μg / g, 9 μg / g, 10 μg / g, 11 μg / g, 12 μg / g, 13 μg / g, 14 μg / g, 15 μg / g, 16 μg / g, 17 μg / g, 18 μg / g, 19 μg / g, 20 μg / g, or the range composed of any two of them.

[0100] The above-mentioned oil to be processed may include wax oil, specifically, it may include one or several mixtures of coker gas oil (CGO), vacuum gas oil (VGO), coker diesel, oil under wax, and diesel. The hydrocracking method of the embodiments of the present invention can improve the desulfurization, denitrification, and light oil yield of these oils to be processed, especially the high naphtha yield.

[0101] The above-mentioned coker gas oil (CGO), vacuum gas oil (VGO), coker diesel, oil under wax, and diesel may or may not be pretreated by hydrogenation, as long as the sulfur content is not greater than 1500 μg / g, the nitrogen content is not greater than 20 μg / g, and the final boiling point is not higher than 580 °C.

[0102] Too high final boiling point of the processing raw material will significantly increase the efficiency of converting heavy oil into light oil products, and it is necessary to increase the reaction temperature and reduce the reaction space velocity. Adjusting these process conditions is not conducive to the long-term operation of the device and improving the processing capacity of the device.

[0103] To make the purpose, technical solution, and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0104] In the following Examples 1 to 3 and Comparative Examples 1 to 3, vacuum gas oil (VGO) was used as the feedstock (oil to be treated), and after being mixed with hydrogen, it entered the hydrogenation reactor and flowed through the protective layer and the catalyst layer in sequence for hydrogenation reaction treatment. The properties of the feedstock are shown in Table 1.

[0105] Table 1 Properties of the Feedstock

[0106]

[0107] In the following Examples 1 to 3 and Comparative Examples 1 to 2, the feedstock flowed from top to bottom in the hydrogenation reactor (i.e., the material flow direction in the hydrogenation reactor was from top to bottom); in the hydrogenation reactor, the protective layer included a first protective sub-layer (upper protective layer) and a second protective sub-layer (lower protective layer), and the catalyst layer included a first catalytic sub-layer (upper catalyst layer), a second catalytic sub-layer (middle catalyst layer), and a third catalytic sub-layer (lower catalyst layer). The upper protective layer, lower protective layer, upper catalyst layer, middle catalyst layer, and lower catalyst layer were distributed in sequence along the material flow direction;

[0108] For each protective sub-layer and each catalytic sub-layer in each example and comparative example, the pore volume, specific surface area, carrier, type and content of the main active metal, filling ratio (the ratio of the volume of each protective sub-layer to the sum of the volumes of the protective layer and the catalyst layer), and the type and content of the main active metal, type and content of the amorphous porous material, type and content of the molecular sieve, acidic promoter and its content, sum of the total acid amount, strong acid amount and medium strong acid amount as a proportion of the total acid amount of the catalyst, pore volume, filling ratio (the ratio of the volume of each catalytic sub-layer to the sum of the volumes of the protective layer and the catalyst layer) are shown in Table 2; among them, the contents are all mass percentages.

[0109] Among them, in Comparative Example 1, a single type of protective agent was used (i.e., different types of protective agents were used for the upper protective layer and the lower protective layer), and the total acid amount of the catalyst layer remained unchanged along the material flow direction (i.e., the total acid amounts of the catalysts in the upper catalyst layer, middle catalyst layer, and lower catalyst layer were the same), and the proportion of the sum of the strong acid amount and the medium strong acid amount in the total acid amount of the catalyst was the same (i.e., the proportions of the sum of the strong acid amount and the medium strong acid amount in the total acid amount of the catalyst in the upper catalyst layer, middle catalyst layer, and lower catalyst layer were the same);

[0110] Among them, in Comparative Example 2, a single type of protective agent was used (i.e., the same protective agent was used for the upper protective layer and the lower protective layer), and the total acid amount of the catalyst layer decreased along the material flow direction (i.e., the total acid amounts of the catalysts in the upper catalyst layer, the middle catalyst layer, and the lower catalyst layer decreased in sequence), and the proportion of the sum of the strong acid amount and the medium strong acid amount in the total acid amount of the catalyst was the same (i.e., the proportion of the sum of the strong acid amount and the medium strong acid amount in the total acid amount of the catalyst in the upper catalyst layer, the middle catalyst layer, and the lower catalyst layer decreased in sequence).

[0111] In addition, the hydrotreating conditions in the hydrotreating reactors of each example and comparative example were the same, specifically: the reaction temperature was 380 °C, the reaction pressure was 15 MPa, the liquid hourly space velocity was 1.2 h -1 , and the hydrogen-oil volume ratio was 500:1.

[0112] In addition, the hydrocracking product results of each example and comparative example are shown in Table 3 (including sulfur content, nitrogen content, kerosene liquid yield, and naphtha liquid yield).

[0113] Table 2 Catalyst grading in the hydrotreating reactor

[0114]

[0115]

[0116] Table 3 Product properties of hydrocracking

[0117] Analysis project Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Sulfur, μg / g 3 4 3 4 12 Nitrogen, μg / g 1 1 1 2 5 Kerosene yield, wt% 32 36 37 41 31 Naphtha yield, wt% 59 57 58 43 35 Total liquid yield, wt% 97.5 96.2 97.4 86.1 95.4 Gas yield, wt% 2.5 3.8 2.6 13.9 5.6

[0118] It can be seen that compared with Comparative Examples 1-2, the sulfur and nitrogen contents of the products in Examples 1-3 are lower. The present invention can significantly improve the total liquid yield of the unit, reduce the gas product yield, increase the yield of light oil products (kerosene and naphtha), especially the naphtha yield is relatively high. Petroleum oil is a high-quality raw material for ethylene cracking. Increasing the naphtha yield can effectively improve the economic benefits of the unit. At the same time, as a low-value-added product, the low gas yield can further improve the economic benefits of the unit.

[0119] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing light oil products from heavy oil, characterized in that, it includes: After the heavy raw material is mixed with hydrogen, it enters the hydrocracking reactor and flows through the protective layer and the catalyst layer in sequence for hydrocracking reaction; Among them, the sulfur content of the heavy raw material is not more than 1500 μg / g, the nitrogen content is not more than 20 μg / g, and the final boiling point is not higher than 580 °C; Among them, the protective layer includes at least two kinds of protectants, and the catalyst layer includes at least three kinds of catalysts; The total acid amount of the catalyst in the catalyst layer is 100-500 μmol / g; The strong acid amount of the catalyst in the catalyst layer is 30-150 μmol / g; The medium strong acid amount of the catalyst in the catalyst layer is 50-300 μmol / g; The medium strong acid amount of the catalyst in the catalyst layer is more than the strong acid amount; Among the catalysts in the catalyst layer, the sum of the medium strong acid amount and the strong acid amount of at least one catalyst is less than 50% of the total acid amount; among the catalysts in the catalyst layer, the sum of the medium strong acid amount and the strong acid amount of at least one catalyst is greater than 50% of the total acid amount; The proportion of the sum of the strong acid amount and the medium strong acid amount of the catalyst in the catalyst layer to the total acid amount of the catalyst is 40-90%; The pore volume of the protectant in the protective layer shows a decreasing trend along the material flow direction in the hydrocracking reactor, and the specific surface area of the protectant shows an increasing trend along the material flow direction in the hydrocracking reactor; The pore volume and specific surface area of the catalyst in the catalyst layer show a decreasing trend along the material flow direction in the hydrocracking reactor; The total acid amount of the catalyst in the catalyst layer shows an increasing trend along the material flow direction in the hydrocracking reactor; the proportion of the sum of the acid amounts of strong acid and medium strong acid to the total acid amount shows an increasing trend along the material flow direction in the hydrocracking reactor; The content of the main active metal in the catalyst shows an increasing trend along the material flow direction in the hydrocracking reactor.

2. The method for producing light oil products from heavy oil according to claim 1, characterized in that: The pore volume of the protective agent in the protective layer is 0.4 - 0.8 mL / g, the specific surface area is 100 - 300 m 2 / g, and the percentage of the main active metal content in the protective agent in the mass of the protective agent is 0 - 15%; The pore volume of the catalyst in the catalyst layer is 0.1 to 0.6 mL / g, the specific surface area is 100 to 400 m 2 / g, and the percentage of the main active metal content in the mass of the catalyst is 10 to 50%.

3. The method for producing light oil products from heavy oil according to claim 1, characterized in that: The percentage content of the main active metal in the protectant accounting for the mass of the protectant is 0-10%; The percentage content of the main active metal in the catalyst accounting for the mass of the catalyst is 15-40%.

4. The method for producing light oil products from heavy oil according to claim 1, characterized in that: The main active metal in the protectant is selected from one or more of Co, Mo, Ni, and W; The main active metal in the catalyst is selected from one or more of Co, Mo, Ni, and W.

5. The method for producing light oil products from heavy oil according to claim 1, characterized in that: The heavy raw material is selected from one or more of coker gas oil, vacuum gas oil, wax bottom oil, and diesel oil.

6. The method for producing light oil products from heavy oil according to claim 1, characterized in that: The volume of the protective layer accounts for 2-20% of the sum of the volume of the protective layer and the volume of the catalyst layer.

7. The method for producing light oil products from heavy oil according to any one of claims 1-6, characterized in that: The liquid yield of the produced light oil products is not less than 90%, wherein the light oil products include kerosene and naphtha, and the liquid yield of naphtha is not less than 55%.

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