A diesel hydrocracking catalyst and its preparation method and application

Abstract

The present disclosure relates to a diesel hydrocracking catalyst, its preparation method, and application. The catalyst comprises a carrier and an active metal component supported on the carrier; the active metal component comprises a Group VIII metal element and a Group VIB metal element; the carrier comprises a composite molecular sieve and a heat-resistant inorganic oxide matrix, the composite molecular sieve comprising a first molecular sieve and a second molecular sieve, the first molecular sieve being a Y molecular sieve and the second molecular sieve being a molecular sieve having a BX value greater than 1; wherein the BX value of a particular molecular sieve to be tested is defined as the ratio of the amount of benzene adsorbed by the molecular sieve to the amount of butylbenzene adsorbed by the molecular sieve to be tested. The catalyst disclosed herein improves the dealkylation and side chain cracking performance of polycyclic aromatic hydrocarbon ring-opening products, and increases the yield and selectivity of light aromatic hydrocarbons (BTX).

Description

Technical Field

[0001] The present disclosure relates to the field of catalysts, and in particular, to a diesel hydrocracking catalyst, a preparation method thereof, and applications thereof. Background Art

[0002] In recent years, with increasingly stringent fuel oil quality standards, restrictions on the hydrocarbon composition and structure of gasoline and diesel products have gradually increased, particularly for aromatics, weakening the fuel oil market's appetite for aromatics. However, annually, refineries produce large quantities of PAH-rich byproducts, such as catalytic cracking diesel, catalytic cracking slurry, and heavy aromatics. The disposal of these materials limits the efficient utilization of petroleum resources and restricts refinery processing capacity and economic profitability. On the other hand, with the economic development and rising living standards of developing countries, the market for chemical materials such as low-carbon olefins and light aromatics continues to see significant growth. From a molecular perspective, PAH byproducts from refining and chemical processing represent a vast reservoir of aromatics, promising to become inexpensive chemical feedstocks.

[0003] Domestic and foreign researchers have also conducted extensive research and developed related process technologies in the field of hydrocracking of polycyclic aromatic hydrocarbons or materials rich in polycyclic aromatic hydrocarbons to produce light aromatic hydrocarbons. The hydrocracking of polycyclic aromatic hydrocarbons to produce light aromatic hydrocarbons is a complex reaction process, which includes a series of parallel sequential reactions such as hydrogenation saturation, isomerization, ring opening, and cracking, and there are mutual constraints and contradictions between the reactions. Precise control of the reaction process is the key to improving the yield and selectivity of light aromatic hydrocarbons such as BTX. The hydrocracking of polycyclic aromatic hydrocarbons is a heterogeneous catalytic process. If the diffusion, adsorption / desorption properties of reactants, reaction intermediates and product molecules can be effectively controlled from the reaction time and reaction space scales, the ring opening reaction of polycyclic aromatic hydrocarbons and the dealkylation or side chain cracking reaction of the ring opening products can be directionally strengthened, the goal of improving the yield and selectivity of BTX can be achieved.

[0004] Chinese patent document 201510897878.4 discloses a high-aromatic diesel hydrocracking catalyst, its preparation method, and its application. The catalyst also features a composite molecular sieve and discloses a method for preparing a small-grain modified Y molecular sieve. The composite molecular sieve is composed of a small-grain Y molecular sieve and a SAPO-11 molecular sieve. The small-grain Y molecular sieve improves the accessibility of acidic sites and the dispersion of metal components, while the SAPO-11 regulates the reaction of different hydrocarbon types, thereby improving the gasoline yield and octane number during the hydrocracking of catalytically cracked diesel.

[0005] Chinese patent document 201310512696.1 discloses a catalyst for converting sulfur-containing polycyclic aromatic hydrocarbons into monocyclic aromatic hydrocarbons and its preparation method. The catalyst composition is a mixture of 30-65% FAU zeolite and ZSM-12 molecular sieve, 33.5-69.8% binder, 0.1-0.5% of at least one metal selected from Pt, Pd or Ir, and 0.1-1% of at least one metal selected from La, Ce or Sn. This catalyst can, to a certain extent, solve the problems of low conversion depth of polycyclic aromatic hydrocarbons, low yield and selectivity of monocyclic aromatic hydrocarbons, and rapid catalyst deactivation rate.

[0006] Chinese patent document 201911336168.9 discloses a Y-type molecular sieve and its preparation. The outer surface of the Y-type molecular sieve presents rhombic nanocrystals, and the surface nanocrystal size is 30-800nm. The Y molecular sieve can be used in the hydrocracking process to improve the performance of the catalyst.

[0007] Although the catalysts provided in the above patent documents can produce light aromatics by hydrocracking polycyclic aromatic hydrocarbons or materials rich in polycyclic aromatic hydrocarbons, they are still not ideal in achieving high yield and high selectivity of light aromatic hydrocarbons BTX. Summary of the Invention

[0008] The purpose of the present disclosure is to provide a diesel hydrocracking catalyst and its application to improve the dealkylation and side chain cracking performance of polycyclic aromatic hydrocarbon ring-opening products and improve the yield and selectivity of light aromatic hydrocarbons BTX.

[0009] To achieve the above-mentioned objectives, the present disclosure provides, in a first aspect, a diesel hydrocracking catalyst, comprising a carrier and an active metal component supported on the carrier; the active metal component comprises a Group VIII metal element and a Group VIB metal element; the carrier comprises a composite molecular sieve and a heat-resistant inorganic oxide matrix, the composite molecular sieve comprising a first molecular sieve and a second molecular sieve, the first molecular sieve being a Y molecular sieve and the second molecular sieve being a molecular sieve having a BX value greater than 1; wherein the BX value of a certain molecular sieve to be tested is defined as the ratio of the amount of benzene adsorbed by the molecular sieve to be tested to the amount of butylbenzene adsorbed by the molecular sieve to be tested.

[0010] Optionally, the BX value of the second molecular sieve is 1.5-10, preferably, the BX value of the second molecular sieve is 1.5-5; Optionally, the pore volume of the second molecular sieve is 0.4-0.7 cm 3 / g, acid density is 0.8-2.5μmol / m 2 .

[0011] Optionally, the weight ratio of the first molecular sieve to the second molecular sieve in the composite molecular sieve is 1:1-9:1, preferably 3:2-9:1.

[0012] Optionally, the content of the composite molecular sieve in the hydrocracking catalyst is 45-65% by weight, the content of the heat-resistant inorganic oxide matrix is ​​10-25% by weight, and the content of the active metal component is 5-35% by weight.

[0013] Optionally, based on the total weight of the catalyst, the catalyst contains 1.5-6 wt% of Group VIII metal elements and 10-35 wt% of Group VIB metal elements in terms of oxides.

[0014] Optionally, the first molecular sieve is selected from at least one of HY molecular sieve, rare earth Y molecular sieve REY, rare earth HY molecular sieve REHY, ultrastable Y molecular sieve USY, partially amorphized USY, rare earth ultrastable Y molecular sieve REUSY, titanium-containing Y molecular sieve, phosphorus-containing Y and ultrastable HY type molecular sieves and dealuminated Y type molecular sieve; preferably, the first molecular sieve is selected from at least one of HY molecular sieve, rare earth Y molecular sieve, rare earth HY molecular sieve, ultrastable Y molecular sieve, rare earth ultrastable Y molecular sieve, partially amorphized Y molecular sieve, titanium-containing Y molecular sieve and phosphorus-containing Y type molecular sieve; the second molecular sieve is selected from at least one of PKU-16 molecular sieve, SCM-15 molecular sieve, ITQ-4 molecular sieve, JU-64 molecular sieve, Beryllophosphate-H molecular sieve and UCSB-10GaZn molecular sieve; the heat-resistant inorganic oxide matrix is ​​selected from at least one of alumina, silica and silica-alumina.

[0015] A second aspect of the present disclosure provides a method for preparing a hydrocracking catalyst, the method comprising:

[0016] S1. Mixing a first molecular sieve, a second molecular sieve, a heat-resistant inorganic oxide matrix, and an auxiliary agent, kneading and extruding to obtain an extruded strip; performing a first drying and a first calcination on the extruded strip to obtain a carrier; the auxiliary agent is selected from at least one of an inorganic binder and an extrusion aid;

[0017] S2. impregnating the support with an aqueous solution containing a compound of a Group VIII metal and a compound of a Group VIB metal to obtain an impregnated support; and subjecting the impregnated support to a second drying and activation treatment;

[0018] Wherein, the weight ratio of the first molecular sieve, the second molecular sieve and the heat-resistant inorganic oxide matrix is ​​1-16:1-16:1-16.

[0019] In step S1, the conditions for the first drying treatment include: a drying temperature of 80-300°C, preferably 100-200°C; a drying time of 1-12 hours, preferably 2-8 hours; the conditions for the first calcination include: a calcination temperature of 350-850°C, preferably 450-650°C; a calcination time of 1-12 hours, preferably 2-6 hours; in step S2, the conditions for the impregnation include: an impregnation temperature of 20-150°C, and an impregnation time of 1-6 hours; the conditions for the second drying include: a temperature of 100-300°C, preferably 100-200°C; a time of 2-8 hours; the conditions for the activation treatment include: a temperature of 250-650°C, preferably 300-500°C; a time of 1-12 hours, preferably 2-6 hours.

[0020] A third aspect of the present disclosure provides a method for hydrocracking diesel to produce more light aromatics, the method comprising: contacting diesel and hydrogen with the above-mentioned hydrocracking catalyst to carry out a hydrocracking reaction, wherein the hydrocracking reaction is carried out using a fixed bed single-stage series and diesel circulation process.

[0021] Optionally, the single-stage series process includes a hydrofining reaction zone and a hydrocracking reaction zone; further optionally, the temperature of the hydrofining reaction zone is 250-420°C, the reaction pressure is 4.0-10.0 MPa, the hydrogen-to-oil volume ratio is 200-1500, and the volume space velocity is 0.5-2.5h -1 , the diesel circulation ratio is 0-0.6; the temperature of the hydrocracking reaction is 300-450°C, the reaction pressure is 4.0-10.0MPa, the hydrogen-oil volume ratio is 200-1500, and the volume space velocity is 0.5-2.5h -1 , the diesel circulation ratio is 0-0.6.

[0022] Through the above technical solution, the catalyst disclosed in the present invention can significantly improve the dealkylation and side chain cracking performance of polycyclic aromatic hydrocarbon ring-opening products, and improve the yield and selectivity of light aromatic hydrocarbons BTX.

[0023] Other features and advantages of the present disclosure will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0024] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0025] In a first aspect, the present disclosure provides a diesel hydrocracking catalyst, comprising a carrier and an active metal component supported on the carrier; the active metal component comprises a Group VIII metal element and a Group VIB metal element; the carrier comprises a composite molecular sieve and a heat-resistant inorganic oxide matrix, the composite molecular sieve comprising a first molecular sieve and a second molecular sieve, the first molecular sieve being a Y molecular sieve and the second molecular sieve being a molecular sieve having a BX value greater than 1; wherein the BX value of a molecular sieve to be tested is defined as the ratio of the amount of benzene adsorbed by the molecular sieve to be tested to the amount of butylbenzene adsorbed by the molecular sieve to be tested.

[0026] The BX value disclosed in the present disclosure is obtained by an adsorption molar ratio test method, specifically as follows: first accurately measure benzene and butylbenzene (100 ml, room temperature), then add a certain amount of molecular sieve material (5 g), and under inert gas (N2) protection, 1 atmosphere, and constant temperature, sealed and stirred at 360°C for 10 hours, then filtered, and the filtrate is re-converted to volume. After cooling to room temperature, the solution volume is measured again with a graduated cylinder to obtain the adsorption volume difference ΔV. 测试分子筛_丁基苯 , ΔV 测试分子筛_苯 The calculation formula of BX value is:

[0027] BX=ΔV 测试分子筛_苯 / ΔV 测试分子筛_丁基苯 ; where ΔV 测试分子筛_丁基苯 Greater than 0.

[0028] After extensive experimentation, the inventors of the present disclosure discovered that improving the compatibility of the catalytic material or catalyst pore structure and size with the reactants, reaction intermediates, or product molecules is an effective means of enhancing the diffusion and adsorption properties of polycyclic aromatic hydrocarbons and their hydrogenation reaction intermediates on the catalyst, thereby helping to achieve the goal of increasing BTX yield and selectivity. Therefore, the present disclosure uses the BX value to achieve rational screening of molecular sieves, the acidic component of the catalyst, to enhance the compatibility of the molecular sieve pore structure with the reactants, reaction intermediates, and product molecules during the hydrocracking of polycyclic aromatic hydrocarbons, thereby strengthening the cracking reaction of the alkyl side chains of the polycyclic aromatic hydrocarbon hydrogenation ring-opening products. This method can be used in the hydrocracking of diesel, especially low-quality diesel rich in polycyclic aromatic hydrocarbons, to produce BTX.

[0029] According to the present disclosure, the BX value of the second molecular sieve may be 1.5-10, preferably, the BX value of the second molecular sieve may be 1.5-5; alternatively, the pore volume of the second molecular sieve may be 0.4-0.7 cm 3 / g, the acid density can be 0.8-2.5μmol / m 2 .

[0030] According to the present disclosure, the weight ratio of the first molecular sieve to the second molecular sieve in the composite molecular sieve may be 1:1-9:1, preferably 3:2-9:1.

[0031] According to the present disclosure, the content of the composite molecular sieve in the hydrocracking catalyst may be 45-65 wt %, the content of the heat-resistant inorganic oxide matrix may be 10-25 wt %, and the content of the active metal component may be 5-35 wt %.

[0032] According to the present disclosure, the catalyst may contain 1.5-6 wt% of Group VIII metal elements and 10-35 wt% of Group VIB metal elements in terms of oxides, based on the total weight of the catalyst.

[0033] According to the present disclosure, the first molecular sieve can be selected from at least one of HY molecular sieve, rare earth Y molecular sieve REY, rare earth HY molecular sieve REHY, ultrastable Y molecular sieve USY, partially amorphized USY, rare earth ultrastable Y molecular sieve REUSY, titanium-containing Y molecular sieve, phosphorus-containing Y and ultrastable HY type molecular sieves and dealuminated Y type molecular sieve; preferably, the first molecular sieve can be selected from at least one of HY molecular sieve, rare earth Y molecular sieve, rare earth HY molecular sieve, ultrastable Y molecular sieve, rare earth ultrastable Y molecular sieve, partially amorphized Y molecular sieve, titanium-containing Y molecular sieve and phosphorus-containing Y type molecular sieve; the second molecular sieve can be selected from at least one of PKU-16 molecular sieve, SCM-15 molecular sieve, ITQ-4 molecular sieve, JU-64 molecular sieve, Beryllophosphate-H molecular sieve and UCSB-10GaZn molecular sieve; the heat-resistant inorganic oxide matrix can be selected from at least one of alumina, silica and silica-alumina.

[0034] The alumina described in the present disclosure is selected from one or more transition phase alumina selected from γ, η, θ, δ and χ, and can also be one or more transition phase alumina selected from γ, η, θ, δ and χ containing one or more additive components selected from silicon, titanium, magnesium, boron, zirconium, thorium, niobium and rare earth, preferably γ-alumina and γ-alumina containing one or more additive components selected from silicon, phosphorus, titanium, magnesium, boron, zirconium, thorium, niobium and rare earth. They can be commercially available products or obtained by any existing method. The silica-alumina preferably has a pseudo-boehmite structure, and can also be a commercially available product or prepared by any existing technology. For example, the Siral series of commercial silica-alumina produced by Condea Company of Germany has a pseudo-boehmite structure and can be used in the present disclosure.

[0035] The catalyst provided in the present disclosure can be carried out in any reaction vessel sufficient to allow the raw oil to contact the catalyst under hydrogenation reaction conditions, for example, the reaction is carried out in a fixed bed reactor, a moving bed reactor or an ebullating bed reactor. It is also possible to directly process other types of hydrocarbon oil raw materials to carry out hydrogenation treatment. The hydrocarbon oil raw material can also be various heavy mineral oils or synthetic oils or their mixed distillate oils, such as one or more selected from crude oil, distillate oil, solvent refined oil, wax paste, wax oil, Fischer-Tropsch synthetic oil, coal liquefaction oil, light deasphalted oil and heavy deasphalted oil. The catalyst disclosed in the present disclosure is particularly suitable for the hydro-reforming or hydrocracking process of diesel, especially low-quality diesel rich in polycyclic aromatic hydrocarbons.

[0036] A second aspect of the present disclosure provides a method for preparing a hydrocracking catalyst, the method comprising:

[0037] S1. Mixing a first molecular sieve, a second molecular sieve, a heat-resistant inorganic oxide matrix, and an auxiliary agent, kneading and extruding to obtain an extruded strip; performing a first drying and a first calcination on the extruded strip to obtain a carrier; the auxiliary agent is selected from at least one of an inorganic binder and an extrusion aid;

[0038] S2. impregnating the support with an aqueous solution containing a compound of a Group VIII metal and a compound of a Group VIB metal to obtain an impregnated support; and subjecting the impregnated support to a second drying and activation treatment;

[0039] Wherein, the weight ratio of the first molecular sieve, the second molecular sieve and the heat-resistant inorganic oxide matrix is ​​1-16:1-16:1-16.

[0040] In step S1, the conditions for the first drying treatment include: a drying temperature of 80-300°C, preferably 100-200°C; a drying time of 1-12 hours, preferably 2-8 hours; the conditions for the first calcination include: a calcination temperature of 350-850°C, preferably 450-650°C; a calcination time of 1-12 hours, preferably 2-6 hours; in step S2, the conditions for the impregnation include: an impregnation temperature of 20-150°C, and an impregnation time of 1-6 hours; the conditions for the second drying include: a temperature of 100-300°C, preferably 100-200°C; a time of 2-8 hours; the conditions for the activation treatment include: a temperature of 250-650°C, preferably 300-500°C; a time of 1-12 hours, preferably 2-6 hours.

[0041] A third aspect of the present disclosure provides a method for hydrocracking diesel to produce more light aromatics, the method comprising: contacting diesel and hydrogen with the above-mentioned hydrocracking catalyst to carry out a hydrocracking reaction, wherein the hydrocracking reaction is carried out using a fixed bed single-stage series and diesel circulation process.

[0042] In a preferred embodiment of the present disclosure, the single-stage series process includes a hydrofining reaction zone and a hydrocracking reaction zone; further preferably, the temperature of the hydrofining reaction zone is 250-420°C, the reaction pressure is 4.0-10.0 MPa, the hydrogen-to-oil volume ratio is 200-1500, and the volume space velocity is 0.5-2.5h -1 , the diesel circulation ratio is 0-0.6; the temperature of the hydrocracking reaction can be 300-450°C, the reaction pressure can be 4.0-10.0MPa, the hydrogen-oil volume ratio can be 200-1500, and the volume space velocity can be 0.5-2.5h -1 , the diesel circulation ratio can be 0-0.6.

[0043] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0044] Example 1

[0045] Weigh 57.1 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70%, 37.6 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, and 156.1 g of PKU-16 molecular sieve with a dry basis of 82%, add appropriate amounts of additives including inorganic binders and extrusion aids, mix well, and extrude into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder, dry at 120°C for 3 hours, and calcine at 600°C for 4 hours to obtain carrier Z1.

[0046] 100 g of support Z1 was impregnated for 3 hours with 78 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 192.3 g / L MoO3, 25.6 g / L NiO, and 12.8 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain Catalyst C1. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0047] Example 2

[0048] Weigh 57.1 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70%, 150.6 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, and 39.0 g of PKU-16 molecular sieve with a dry basis of 82%, and add appropriate amounts of additives including inorganic binders and extrusion aids, etc., mix them evenly, and extrude them into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder. Dry them at 120°C for 3 hours and calcine them at 600°C for 4 hours to obtain carrier Z2.

[0049] 100 g of support Z2 was impregnated for 3 hours with 78 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 192.3 g / L MoO3, 25.6 g / L NiO, and 12.8 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain Catalyst C2. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0050] Example 3

[0051] Weigh 57.1 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70%, 150.6 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, and 39.0 g of PKU-16 molecular sieve with a dry basis of 82%, add appropriate amounts of additives including organic binders and extrusion aids, mix well, and extrude into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder, dry at 120°C for 3 hours, and calcine at 600°C for 4 hours to obtain carrier Z3.

[0052] 100 g of support Z3 was impregnated for 3 hours with 90 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 166.7 g / L MoO3, 22.2 g / L NiO, and 11.1 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain Catalyst C3. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0053] Example 4

[0054] 100 g of support Z2 was impregnated for 3 hours with 78 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 96.2 g / L MoO3, 12.8 g / L NiO, and 6.4 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain catalyst C4. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0055] Example 5

[0056] 100 g of support Z2 was impregnated for 3 hours with 78 ml of a mixed solution of molybdenum trioxide, basic cobalt carbonate, phosphoric acid, and citric acid containing 192.3 g / L MoO3, 25.6 g / L CoO, and 12.8 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain Catalyst C5. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0057] Example 6

[0058] 100 g of support Z2 was impregnated for 3 hours with 78 ml of a mixed solution of ammonium metatungstate, basic nickel carbonate, and phosphoric acid containing 282.1 g / L WO3, 38.5 g / L NiO, and 25.6 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain catalyst C6. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0059] Example 7

[0060] Weigh 57.1 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70%, 150.6 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, and 38.6 g of SCM-15 molecular sieve with a dry basis of 83%, add appropriate amounts of additives including inorganic binders and extrusion aids, mix well, and extrude into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder, dry at 120°C for 3 hours, and calcine at 600°C for 4 hours to obtain carrier Z7.

[0061] 100 g of carrier Z7 was impregnated for 3 hours with 75 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 200.0 g / L MoO3, 26.7 g / L NiO, and 13.3 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain catalyst C7. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0062] Example 8

[0063] Weigh 42.9 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70%, 131.8 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, 33.7 g of SCM-15 molecular sieve with a dry basis of 83%, and 39.5 g of amorphous silica-alumina material (Siral40 from Condea, Germany) with a dry basis of 76%, add appropriate amounts of additives including inorganic binders and extrusion aids, mix well, and extrude into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder, dry at 120°C for 3 hours, and calcine at 600°C for 4 hours to obtain carrier Z8.

[0064] 100 g of support Z8 was impregnated for 3 hours with 75 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 200.0 g / L MoO3, 26.7 g / L NiO, and 13.3 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain catalyst C8. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0065] Example 9

[0066] Weigh 228.6 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70%, 37.6 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, and 9.6 g of SCM-15 molecular sieve with a dry basis of 83%, add appropriate amounts of additives including inorganic binders and extrusion aids, mix well, and extrude into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder, dry at 120°C for 3 hours, and calcine at 600°C for 4 hours to obtain carrier Z9.

[0067] 100 g of carrier Z9 was impregnated for 3 hours with 75 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 200.0 g / L MoO3, 26.7 g / L NiO, and 13.3 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain catalyst C9. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0068] Example 10

[0069] Weigh 142.9 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70%, 58.8 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, and 60.2 g of SCM-15 molecular sieve with a dry basis of 81%, add appropriate amounts of additives including inorganic binders and extrusion aids, and mix them evenly. Extrude them into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder, dry them at 120°C for 3 hours, and calcine them at 600°C for 4 hours to obtain carrier Z10.

[0070] 100 g of support Z10 was impregnated for 3 hours with 80 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 187.5 g / L MoO3, 25.0 g / L NiO, and 12.5 g / L P2O5, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain Catalyst C10. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0071] Comparative Example 1

[0072] Weigh 57.1 g of pseudo-boehmite (Catalyst Changling Branch) with a dry basis of 70% and 188.2 g of Y-type molecular sieve (Catalyst Changling Branch, unit cell constant 24.60A) with a dry basis of 85%, add appropriate amounts of additives including inorganic binders and extrusion aids, mix well, and extrude into butterfly-shaped carrier strips with an circumscribed circle diameter of 1.6 mm on an extruder. Dry at 120°C for 3 hours and calcine at 600°C for 4 hours to obtain carrier DZ.

[0073] 100 g of carrier DZ was impregnated for 3 hours with 78 ml of a mixed solution of molybdenum trioxide, basic nickel carbonate, phosphoric acid, and citric acid containing 192.3 g / L MoO₃, 25.6 g / L NiO, and 12.8 g / L P₂O₅, respectively. The catalyst was then dried at 120°C for 2 hours and calcined at 450°C for 3 hours to obtain catalyst DC. The theoretical composition after calcination, based on the catalyst, is shown in Table 2.

[0074] Table 1

[0075] Molecular sieve number <![CDATA[Pore volume / (cm 3 / g)]]> <![CDATA[Acid density / (mmol / m 2 )]]> BX value PKU-16 0.532 1.812 1.857 SCM-15 0.624 1.988 1.734 Y 0.510 1.522 1.309

[0076] Table 2

[0077]

[0078] Test Case

[0079] The performance of catalysts C1, C2, C3, C7 and DC1 was tested using the following method: 3 The performance of the catalyst was evaluated on a 30 ml fixed bed device using catalytic cracking diesel with a sulfur content of 10,500 ppm, a nitrogen content of 657 ppm, and a total aromatic content of 84.6%. The upper part of the bed was filled with an industrial refined catalyst, and the lower part was filled with a catalyst. The amount of catalyst was 15 ml. The catalyst was pre-sulfurized before adding the crude oil. The sulfurization conditions were: sulfurization at 110°C for 2 hours and sulfurization at 300°C for 4 hours. The sulfurized oil was kerosene containing 6% by weight of carbon disulfide. The reaction conditions of the hydrorefining reaction zone were: reaction temperature of 350°C, hydrogen partial pressure of 6.5 MPa, liquid hourly space velocity of 1.5 h -1 , hydrogen-oil volume ratio 800, hydrocracking reaction zone reaction conditions: reaction temperature 390 ° C, hydrogen partial pressure 6.5 MPa, modifier liquid hourly space velocity 1.2h -1 , hydrogen to oil volume ratio is 1000. The test results are listed in Table 3.

[0080] Table 3

[0081] catalyst C1 C2 C3 C7 D1 BTX yield Benchmark*0.95 Baseline*1.18 Baseline*1.08 Baseline*1.25 Benchmark BTX selectivity Baseline*1.49 Baseline*1.38 Baseline*1.32 Baseline*1.22 Benchmark

[0082] The test results in Table 3 indicate that the catalyst provided by the present disclosure has higher LCO conversion, BTX yield and selectivity, and helps to improve the selectivity and yield of the target product BTX when used for producing light aromatics from aromatics-rich materials such as LCO hydrocracking.

[0083] The preferred embodiments of the present disclosure are described in detail above. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0084] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0085] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A diesel hydrocracking catalyst, characterized in that: The catalyst comprises a carrier and an active metal component supported on the carrier; the active metal component comprises a metal element of Group VIII and a metal element of Group VIB; the carrier comprises a composite molecular sieve and a heat-resistant inorganic oxide matrix, the composite molecular sieve comprises a first molecular sieve and a second molecular sieve, the first molecular sieve is a Y molecular sieve, the second molecular sieve has a BX value of 1.5-10, and the pore volume of the second molecular sieve is 0.4-0.7 cm 3 / g, acid density is 0.8-2.5μmol / m 2 ; The BX value of a certain molecular sieve to be tested is defined as the molar ratio of the amount of benzene adsorbed by the molecular sieve to be tested to the amount of butylbenzene adsorbed by the molecular sieve to be tested. The second molecular sieve is at least one selected from PKU-16 molecular sieve, SCM-15 molecular sieve, ITQ-4 molecular sieve, JU-64 molecular sieve, Beryllophosphate-H molecular sieve, and UCSB-10GaZn molecular sieve.

2. The hydrocracking catalyst according to claim 1, wherein The BX value of the second molecular sieve is 1.5-5.

3. The hydrocracking catalyst according to claim 1, wherein The weight ratio of the first molecular sieve to the second molecular sieve in the composite molecular sieve is 1:1-9:

1.

4. The hydrocracking catalyst according to claim 3, wherein The weight ratio of the first molecular sieve to the second molecular sieve in the composite molecular sieve is 3:2-9:

1.

5. The hydrocracking catalyst according to claim 1, wherein The content of the composite molecular sieve in the hydrocracking catalyst is 45-65% by weight, the content of the heat-resistant inorganic oxide matrix is ​​10-25% by weight, the content of the active metal component is 5-35% by weight, and the sum of all components is 100%.

6. The hydrocracking catalyst according to claim 1, wherein Based on the total weight of the catalyst, the catalyst contains 1.5-6 wt% of Group VIII metal elements and 10-35 wt% of Group VIB metal elements in terms of oxides.

7. The hydrocracking catalyst according to claim 1, wherein The first molecular sieve is at least one selected from HY molecular sieve, rare earth Y molecular sieve REY, rare earth HY molecular sieve REHY, ultrastable Y molecular sieve USY, partially amorphized USY, rare earth ultrastable Y molecular sieve REUSY, titanium-containing Y molecular sieve, phosphorus-containing Y and ultrastable and HY type molecular sieves and dealuminated Y type molecular sieve; The heat-resistant inorganic oxide matrix is ​​selected from at least one of alumina, silica, and silica-alumina.

8. The hydrocracking catalyst according to claim 7, wherein The first molecular sieve is at least one selected from HY molecular sieve, rare earth Y molecular sieve, rare earth HY molecular sieve, ultrastable Y molecular sieve, rare earth ultrastable Y molecular sieve, partially amorphized Y molecular sieve, titanium-containing Y molecular sieve and phosphorus-containing Y molecular sieve.

9. A method for preparing the hydrocracking catalyst according to claim 1, characterized in that: The method includes: S1. Mixing a first molecular sieve, a second molecular sieve, a heat-resistant inorganic oxide matrix, and an auxiliary agent, kneading and extruding to obtain an extruded strip; performing a first drying and a first calcination on the extruded strip to obtain a carrier; the auxiliary agent is selected from at least one of an inorganic binder and an extrusion aid; S2. impregnating the support with an aqueous solution containing a compound of a Group VIII metal and a compound of a Group VIB metal to obtain an impregnated support; and subjecting the impregnated support to a second drying and activation treatment; Wherein, the weight ratio of the first molecular sieve, the second molecular sieve and the heat-resistant inorganic oxide matrix is ​​1-16:1-16:1-16.

10. The method according to claim 9, wherein: In step S1, the conditions for the first drying treatment include: a drying temperature of 80-300°C; a drying time of 1-12 hours; the conditions for the first calcination include: a calcination temperature of 350-850°C; a calcination time of 1-12 hours; In step S2, the conditions for the impregnation include: an impregnation temperature of 20-150°C and an impregnation time of 1-6 hours; the conditions for the second drying include: a temperature of 100-300°C and a time of 2-8 hours; the conditions for the activation treatment include: a temperature of 250-650°C and a time of 1-12 hours.

11. The method according to claim 10, wherein: In step S1, the conditions for the first drying treatment include: a drying temperature of 100-200°C; a drying time of 2-8 hours; the conditions for the first calcination include: a calcination temperature of 450-650°C; a calcination time of 2-6 hours; The conditions for the second drying include: a temperature of 100-200° C.; the conditions for the activation treatment include: a temperature of 300-500° C.; and a time of 2-6 hours.

12. A method for producing more light aromatics by hydrocracking of diesel, characterized in that: The method comprises: contacting diesel and hydrogen with the hydrocracking catalyst according to any one of claims 1 to 8 to carry out a hydrocracking reaction, wherein the hydrocracking reaction is carried out using a fixed bed single-stage series connection and diesel circulation process.

13. The method according to claim 12, wherein: The single-stage series process includes a hydrofining reaction zone and a hydrocracking reaction zone.

14. The method according to claim 13, wherein The temperature of the hydrorefining reaction zone is 250-420°C, the reaction pressure is 4.0-10.0 MPa, the hydrogen-to-oil volume ratio is 200-1500, and the volume space velocity is 0.5-2.5h -1 , the diesel circulation ratio is 0-0.6; the temperature of the hydrocracking reaction is 300-450°C, the reaction pressure is 4.0-10.0MPa, the hydrogen-oil volume ratio is 200-1500, and the volume space velocity is 0.5-2.5h -1 , the diesel circulation ratio is 0-0.6.

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