Catalyst with aluminum-rich ZSM-5 zeolite as carrier as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst with aluminum-rich ZSM-5 zeolite as a carrier as well as a preparation method and application of the catalyst. The catalyst with the aluminum-rich ZSM-5 type zeolite as the carrier comprises the aluminum-rich ZSM-5 type zeolite carrier and metal components loaded on the carrier, the metal components comprise VIB group metal oxides and optional VIII group metal components, and the silicon-aluminum molecular ratio of the aluminum-rich ZSM-5 type zeolite carrier is 5-18. The catalyst is used for catalyzing hydrocracking reaction of diesel oil, has the advantages of light aromatic hydrocarbon selectivity, high purity and the like, and can realize efficient chemical utilization of the catalytic diesel oil.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and specifically relates to a catalyst with aluminum-rich ZSM-5 zeolite as a carrier, and a preparation method and application thereof. Background Art

[0002] In recent years, refining enterprises have experienced a huge surplus of inferior aromatic-rich oil products, mainly catalytic diesel, or catalytic diesel for short. Catalytic diesel is one of the main products of the catalytic cracking process, with an annual national output of about 50 million tons. Although their boiling point is in the diesel fraction, due to the presence of a large number of polycyclic aromatic hydrocarbons, it is not economical to process them into diesel, and some enterprises can only use them as fuel oil. Hydrocracking technology is one of the important means of secondary processing of crude oil and lightening of heavy oil. Due to its strong adaptability to raw materials, flexible operation and product solutions, and good product quality, it has become an important way to produce high-quality light oil products and solve the source of chemical raw materials.

[0003] In the existing process, light oil-type hydrocracking catalysts use gasoline or naphtha as target products, and there are problems such as low aromatic yield and purity, and too high diesel yield. Relevant research institutions have developed a technology that can catalyze diesel into a high-octane gasoline blending component. For example, the technology disclosed in Chinese patent CN101724454A and Chinese patent CN102839018A, the aromatic content of the obtained heavy naphtha fraction is between 50-65%, which can be used as a high-octane gasoline blending component, and the catalyst used contains 20-75wt% of Y-type zeolite. However, due to the open pores of Y-type zeolite, it does not have the shape-selective effect of cracking non-aromatics, and the resulting products C8, C9 and C 10 The aromatic content of the fraction is relatively low, and the non-aromatic content is relatively high. Since it cannot meet the indicators of reforming oil, there are obvious difficulties in its entry into the aromatics complex as a raw material for the production of benzene and paraxylene.

[0004] ZSM-5 has a significant shape-selective function. Under certain operating conditions, the raw material is mixed with hydrogen and passed through the catalyst bed. The normal alkanes and short side-chain isoalkanes in the raw material undergo hydrocracking reactions to generate low molecular hydrocarbons, while other components remain essentially unchanged, ultimately achieving the purpose of lowering the pour point (or freezing point). ZSM-5 molecular sieves allow normal alkanes and short side-chain isoalkanes to enter its pores, while excluding highly branched isoalkanes, cycloalkanes and aromatics. Patent CN1219571A discloses a small-grain ZSM-5 catalytic dewaxing catalyst, with a ZSM-5 grain size of 0.1-0.5μm, a silicon-aluminum molecular ratio of 50-120, a low yield of C1-C4 hydrocarbons, and a liquid yield of more than 80%.

[0005] The development of high-performance hydrocracking catalysts is a key issue in maximizing the conversion of catalytic diesel into light aromatics that meet the quality indicators of the aromatics complex and producing high-quality light hydrocarbons that can be used as olefin feedstocks, directly providing feedstocks for chemical plants such as aromatics and olefins. Therefore, it is necessary to develop hydrocracking catalysts that have both shape-selective effects and stronger non-aromatic cracking capabilities, and efficiently produce high-quality light aromatics and light hydrocarbons from catalytic diesel. Light aromatics can be used to produce benzene and xylene, and light hydrocarbons can be used as ethylene feedstocks. Moreover, non-sulfurized hydrocracking catalysts have strong sulfur resistance and do not require a complicated start-up sulfurization process. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a catalyst with aluminum-rich ZSM-5 zeolite as a carrier, and the aluminum-rich ZSM-5 zeolite used provides abundant B acid centers, which can contact with polycyclic aromatic hydrocarbons to produce cracking reactions. The present invention provides a catalyst with aluminum-rich ZSM-5 zeolite as a carrier for use in the hydrocracking reaction of polycyclic aromatic hydrocarbon-rich feedstock oil, which well solves the problem of low selectivity and purity of light aromatic hydrocarbons obtained by catalytic diesel hydrocracking reaction, and realizes efficient chemical utilization of catalytic diesel.

[0007] One of the objects of the present invention is to provide a catalyst with an aluminum-rich ZSM-5 zeolite as a carrier, comprising: an aluminum-rich ZSM-5 zeolite carrier, and a metal component loaded on the carrier, wherein the metal component comprises a Group VIB metal oxide and an optional Group VIII metal component, and the silicon-aluminum molecular ratio of the aluminum-rich ZSM-5 zeolite carrier is between 5 and 18.

[0008] According to the present invention, the catalyst further comprises a binder, and the binder can be selected from catalyst binders commonly used in the prior art to provide good mechanical properties and textural properties. Preferably, the binder is selected from at least one of alumina and silica. The alumina can be obtained from pseudo-boehmite, and the silica can be obtained from porous silica gel powder and ammonia-type silica sol. The binder can be incorporated into the catalyst in any suitable manner, for example, by mixing, extruding, curing, drying and calcining with an aluminum-rich ZSM-5 zeolite carrier to obtain a catalyst carrier.

[0009] According to the present invention, based on the total amount of the aluminum-rich ZSM-5 zeolite carrier and the binder as 100 parts by weight, the aluminum-rich ZSM-5 zeolite carrier is 5 to 80 parts, preferably 10 to 70 parts, and more preferably 15 to 60 parts; the Group VIB metal oxide is 1 to 20 parts, preferably 2 to 18 parts, and more preferably 3 to 15 parts; the Group VIII metal component is 0 to 10 parts, preferably 0.2 to 8 parts, and more preferably 0.5 to 6 parts, calculated as the Group VIII metal.

[0010] According to the present invention, in the catalyst with aluminum-rich ZSM-5 zeolite as a carrier:

[0011] The content of framework aluminum in the aluminum-rich ZSM-5 zeolite carrier accounts for more than 92% of the total aluminum, preferably more than 95%; the average length of the particles of the aluminum-rich ZSM-5 zeolite carrier in at least one dimension is less than 20 nm;

[0012] The VIB group metal oxide is selected from at least one of metal molybdenum oxide and metal tungsten oxide; the VIB group metal oxide can continuously exert hydrogenation effect in a sulfur-containing atmosphere;

[0013] The Group VIII metal component is selected from at least one of a nickel-containing component and a cobalt-containing component; the Group VIII metal component exists in the catalyst in the form of a metal oxide or a metal element, which can improve the hydrogenation capacity of the VIB Group metal oxide; the nickel-containing component and the cobalt-containing component can be chemically combined with one or more other components in the final catalyst composition as a simple substance or an oxide, or exist in the catalyst as a metal element.

[0014] The catalyst of the present invention may also include conventional components of catalysts in the art, such as diatomaceous earth, activated clay, etc., and the amount used may be a common amount.

[0015] The second object of the present invention is to provide a method for preparing a catalyst with the above-mentioned aluminum-rich ZSM-5 zeolite as a carrier, comprising: loading components including Group VIB metal oxides and optional Group VIII metal components on a carrier including aluminum-rich ZSM-5 zeolite, and obtaining the catalyst through calcination and reduction.

[0016] The preparation method of the catalyst provided by the present invention is not limited to the above preparation method, and can be prepared by any method commonly used in the field of catalysts. For example, the preparation of the catalyst of the present invention may include the steps of molding a catalyst carrier including the aluminum-rich ZSM-5 zeolite and loading a metal component, and then calcining and reducing to obtain a catalyst. Among them, the carrier molding can be carried out by combining the zeolite with a commonly used binder, etc., using methods commonly used in the art such as extrusion, rolling or oil column molding; the metal component can be prepared by methods commonly used in the art such as co-precipitation, co-gelation, kneading, ion exchange or impregnation of a metal precursor compound and a catalyst carrier.

[0017] According to the present invention, the method for preparing the catalyst with aluminum-rich ZSM-5 zeolite as a carrier comprises the following steps:

[0018] Step 1) forming the components including the aluminum-rich ZSM-5 zeolite, drying and calcining to obtain a catalyst carrier;

[0019] Step 2) preparing a soluble Group VIB metal compound and a soluble Group VIII metal compound into a metal compound aqueous solution;

[0020] Step 3) The catalyst carrier obtained in step 1) is immersed in the aqueous solution of the metal compound obtained in step 2), and then taken out, dried, calcined and reduced to obtain the catalyst.

[0021] According to the present invention, the preparation method of the catalyst with the aluminum-rich ZSM-5 zeolite as the carrier, in step 1): the aluminum-rich ZSM-5 zeolite is first mixed with a binder and then molded, and the mixed molding process can adopt the molding equipment and molding process conditions commonly used in the art; the drying treatment after molding is not particularly limited, and the drying equipment and drying conditions commonly used in the art can be adopted, for example, the drying temperature is 50 to 180°C, preferably 60 to 150°C; the calcination treatment after drying is not particularly limited, and the calcination equipment and calcination conditions commonly used in the art can be adopted, for example, the calcination temperature is 520 to 600°C, preferably 530 to 580°C; the calcination time is 1 to 8h, preferably 2 to 6h.

[0022] According to the present invention, in the preparation method of the catalyst with aluminum-rich ZSM-5 zeolite as a carrier, in step 2), the soluble Group VIB metal compound is selected from at least one of soluble molybdenum compounds and soluble tungsten compounds, preferably at least one of ammonium tungstate and ammonium molybdate; the soluble Group VIII metal compound is selected from at least one of soluble nickel compounds and soluble cobalt compounds, preferably at least one of nickel nitrate, nickel sulfate, nickel halide, nickel oxalate, nickel acetate, cobalt nitrate, cobalt chloride, and cobalt oxalate; the concentration of the formed metal compound solution is not particularly limited, as long as the added metal compound is completely dissolved. Specifically, the total concentration of the metal compound in the metal compound aqueous solution is 3 to 45 wt%, preferably 5 to 40 wt%. A suitable amount of ammonia water can be added to the metal compound aqueous solution to obtain a homogeneous solution.

[0023] According to the present invention, in the preparation method of the catalyst with aluminum-rich ZSM-5 zeolite as the carrier, in the step 3), the impregnation can adopt the impregnation process commonly used in the art, such as equal volume impregnation; the drying treatment of the carrier after impregnation is not particularly limited, and the drying equipment and drying conditions commonly used in the art can be adopted, for example, the drying temperature is 50 to 150°C, preferably 60 to 120°C; the calcination treatment after drying is not particularly limited, and the calcination equipment and calcination conditions commonly used in the art can be adopted, for example, the calcination temperature is 450 to 600°C, Preferably, the temperature is 480-580°C; the calcination time is 0.5-8h, preferably 1-6h; the calcined catalyst precursor is reduced to obtain the catalyst, and the reduction process can adopt the reduction conditions commonly used in the art, for example, the reduction of the catalyst precursor is completed in a hydrogen atmosphere. Specifically, the reduction conditions are: the reduction heating rate is 1-20°C / h, preferably 5-10°C / h; the reduction end temperature is 300-450°C, preferably 320-420°C; the end temperature is maintained for 1-24h, preferably 2-16h.

[0024] According to the present invention, the aluminum-rich ZSM-5 zeolite is obtained by the following preparation method:

[0025] a) dissolving sodium hydroxide and an alumina source in water, and then sequentially adding a silica source and a template agent, and stirring to obtain a glue solution;

[0026] b) pre-crystallizing and hydrothermally crystallizing the colloid obtained in step a) and then cooling it to obtain a high-crystallinity ZSM-5 slurry;

[0027] c) continuing to add an alumina source and water to the high crystallinity ZSM-5 slurry obtained in step b);

[0028] d) repeating the pre-crystallization and hydrothermal crystallization of step b) to perform secondary crystallization;

[0029] e) filtering, washing, drying and calcining the product obtained after the secondary crystallization to obtain the aluminum-rich ZSM-5 zeolite.

[0030] According to the present invention, in the method for preparing the aluminum-rich ZSM-5 zeolite:

[0031] The alumina source is selected from at least one of sodium aluminate, aluminum hydroxide and aluminum sulfate;

[0032] The silicon dioxide source is selected from at least one of silica gel, silica sol and white carbon black;

[0033] The template agent is selected from organic amines, preferably at least one selected from tetrapropylammonium hydroxide, tetrapropylammonium bromide and n-propylamine.

[0034] According to the present invention, in the method for preparing the aluminum-rich ZSM-5 zeolite:

[0035] In the step a), the molar ratio of the silica source, the template, the alumina source, the sodium hydroxide and the water is (20-50): (2-10): 1: (0.01-0.20): (120-500), wherein the silica source is calculated as SiO2 and the alumina source is calculated as Al2O3;

[0036] The pre-crystallization conditions in step b) and step d) are independently: 50-100° C. for pre-crystallization for 3-60 h, preferably 60-95° C. for pre-crystallization for 5-30 h;

[0037] The hydrothermal crystallization conditions in step b) and step d) are independently: crystallization at 110-180° C. for 12-240 h, preferably, pre-crystallization at 120-170° C. for 24-200 h;

[0038] In the system obtained in step c), the molar ratio of the silica source, the template, the alumina source, the sodium hydroxide and the water is (8-18): (0.5-2): 1: (0.005-0.015): (40-150), wherein the silica source is calculated as SiO2 and the alumina source is calculated as Al2O3;

[0039] The aluminum-rich ZSM-5 zeolite obtained in the step e) also needs to be treated by ammonium ion exchange and calcination. According to the present invention, the sodium-type aluminum-rich ZSM-5 zeolite is obtained by the above-mentioned preparation method. Before preparing the catalyst carrier, the sodium-type aluminum-rich ZSM-5 zeolite needs to be exchanged with ammonium-type aluminum-rich ZSM-5 zeolite, and then calcined to obtain hydrogen-type aluminum-rich ZSM-5 zeolite. Among them, the exchange treatment and calcination treatment can adopt the exchange treatment process and calcination treatment process commonly used in the art. For example, the sodium-type aluminum-rich ZSM-5 zeolite and the sodium-type aluminum-rich ZSM-5 zeolite are exchanged with ammonium-type aluminum-rich ZSM-5 zeolite using ammonium nitrate solution. After the exchange treatment is performed 3 times, it is calcined at a temperature of 510 to 580°C.

[0040] The third object of the present invention is to provide a diesel hydrocracking catalyst, comprising a catalyst with the above-mentioned aluminum-rich ZSM-5 zeolite as a carrier or a catalyst with the aluminum-rich ZSM-5 zeolite prepared by the above-mentioned preparation method as a carrier.

[0041] A fourth object of the present invention is to provide an application of the above-mentioned catalytic diesel hydrocracking catalyst in the hydrocracking reaction of rich aromatic diesel, comprising the following steps: respectively loading a hydrorefining catalyst and the catalytic diesel hydrocracking catalyst into an independent first reactor and a second reactor, adding the rich aromatic diesel into the first reactor for contact reaction with the hydrorefining catalyst, performing gas-liquid separation, and passing the obtained liquid phase oil into the second reactor for contact reaction with the catalytic diesel hydrocracking catalyst.

[0042] According to the present invention, in the aromatics-rich diesel hydrocracking reaction:

[0043] The aromatic content of the aromatic-rich diesel is not less than 50%;

[0044] The aromatic diesel is selected from at least one of catalytic diesel, coking diesel and ethylene tar; and / or,

[0045] The aromatics-rich diesel has a nitrogen content of ≤50ppm and a sulfur content of ≤800ppm after hydrofining treatment; preferably, the nitrogen content is ≤20ppm and the sulfur content is ≤500ppm;

[0046] The hydrorefining can adopt the catalytic diesel hydrorefining technology known in the art, and the hydrorefining reaction conditions can adopt the reaction conditions of catalytic diesel hydrorefining known in the art; the hydrorefining catalyst can adopt any type of hydrorefining catalyst available in the art, as long as the purpose of catalytic diesel hydrorefining can be achieved; preferably, the reaction conditions of the hydrorefining include: reaction temperature of 280-400°C, hydrogen partial pressure of 2.0-15.0MPa, liquid phase space velocity of 0.2-4.0h -1 , the volume ratio of hydrogen to hydrocarbon is 500 to 4000; preferably, the reaction temperature is 300 to 380°C, the hydrogen partial pressure is 5.0 to 12.0 MPa, and the liquid phase space velocity is 0.5 to 2.0 h -1 , the volume ratio of hydrogen to hydrocarbon is 1000 to 3000;

[0047] The reaction conditions of the hydrocracking include: reaction temperature of 300-450°C, hydrogen partial pressure of 2.0-15.0 MPa, liquid phase space velocity of 0.2-4.0 h -1 , the volume ratio of hydrogen to hydrocarbon is 500 to 4000; preferably, the reaction temperature is 320 to 420°C, the hydrogen partial pressure is 5.0 to 12.0 MPa, and the liquid phase space velocity is 0.5 to 2.0 h -1 , the volume ratio of hydrogen to hydrocarbon is 1000 to 3000;

[0048] The single-pass conversion rate of the hydrocracking reaction is greater than 85%;

[0049] In the hydrocracking reaction product, the benzene content in the C6 hydrocarbon is greater than 35wt%, and the toluene content in the C7 hydrocarbon is greater than 85wt%. The C6 hydrocarbon is a mixture of benzene and C6 non-aromatic hydrocarbons, and the C7 hydrocarbon is a mixture of toluene and C7 non-aromatic hydrocarbons.

[0050] The catalyst using aluminum-rich ZSM-5 zeolite as a carrier in the present invention is used as a diesel hydrocracking catalyst, which can be used to produce light aromatics and light hydrocarbons with chemical applications, and realize the conversion of low-value aromatic-rich oil products such as catalytic diesel into chemical products such as aromatics and olefins. In the catalyst of the present invention, ZSM-5 zeolite with a silicon-aluminum molecular ratio between 5 and 18 and an average length of zeolite particles less than 20nm in at least one dimension is used as an acidic functional component. The aluminum-rich ZSM-5 with a high skeleton aluminum content provides abundant B acid centers, and because the average length in at least one dimension is less than 20nm, tetralin hydrocarbons can contact the B acid centers near the open outer surface and the pores to produce cracking reactions. Compared with ordinary ZSM-5 catalysts, its conversion activity is greatly improved and the single-pass conversion rate is high. The traditional hydrodewaxing catalyst using a ZSM-5 carrier has a low single-pass conversion rate because the reactant molecules cannot effectively contact the acid sites on the zeolite particles. The present invention adopts a catalyst of Group VIB metal oxide loaded on aluminum-rich ZSM-5 zeolite as a carrier as a diesel hydrocracking catalyst, which is suitable for a two-stage process with a low sulfur content, has moderate hydrogenation activity, and has higher selectivity and purity in converting catalytic diesel into light aromatics. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is the TEM image of the aluminum-rich ZSM-5 zeolite prepared in Example 1. DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0053] The test instruments and test conditions used in the examples are as follows:

[0054] 1. The contents of Si, Al and other elements in the sample were determined by ICP (inductively coupled plasma atomic emission spectroscopy) and SiO2 / Al2O3 (silicon-aluminum ratio, SAR) was calculated. The instrument used was Thermo IR IS Intrepid IIXSP. The sample dosage was 20-40 mg. The sample was fully dissolved in 40-80 mL of 40% hydrofluoric acid solution before testing.

[0055] 2. The composition of the catalyst was determined by XRF (X-ray fluorescence spectrometry), using an S4Explorer X-ray fluorescence spectrometer produced by Bruker, Germany.

[0056] 3. Use XPS (X-ray photoelectron spectroscopy) to determine the composition and valence of VIB group metal oxides. XPS test conditions: Perkin Elmer PHI 5000C ESCA X-ray photoelectron spectrometer, using Mg K excitation light source, operating voltage 10 kV, current 40 mA, vacuum degree 4.0×10-8 Pa.

[0057] 4. 27 The Al MAS NMR test was carried out on a VARIAN VNMRS-400WB nuclear magnetic resonance instrument with a measurement frequency of 104.18 MHz, a rotation speed of 10000 r / s, a relaxation time of 4 s, and KAl(SO4)2.12H2O as the standard. The chemical shift signal peak of ~60 ppm corresponds to framework aluminum, and the chemical shift signal peak of ~0 ppm corresponds to non-framework aluminum.

[0058] 5. TEM test: FEI Tecnai G2 F20 S-Twin field emission transmission electron microscope was used to observe the crystal morphology of aluminum-rich ZSM-5 zeolite.

[0059] 6. Determine the composition of crude oil and light products by gas chromatography. The chromatographic model is Agilent7890A, equipped with FID detector, FFAP capillary column for separation, the chromatographic column adopts programmed temperature rise, the initial temperature is 90℃, maintained for 15 minutes, and then heated to 220℃ at a rate of 15℃ / min, maintained for 45 minutes.

[0060] The calculation basis of the test data in the specific implementation mode of the present invention is:

[0061] 1. The total conversion rate calculation formula is:

[0062]

[0063] 2. The calculation formula for light aromatics selectivity is:

[0064]

[0065] Wherein, BTX refers to light aromatics (benzene, toluene, ethylbenzene and xylene).

[0066] 3. In the hydrocracking products, the benzene content in C6 and the toluene content in C7 are used as indicators of aromatic purity.

[0067] The diesel raw materials and hydrotreating catalysts involved in the embodiments are:

[0068] 1. To illustrate the effect of the present invention, the raw material composition is shown in Table 1.

[0069] Table 1. Raw material composition

[0070]

[0071] 2. The hydrorefining catalyst involved in the embodiments and comparative examples of the present invention is the commercially available catalyst HT-1, which has a composition of 5.73wt% NiO-35.15wt% MoO3-4.66% P2O5-54.46% Al2O3. Hydrorefining catalysts in the art with compositions close to the above-mentioned performance indicators can be used in the technical scheme adopted by the present invention. A cyclohexane solution containing 0.5% carbon disulfide is injected into a fixed bed reactor containing a hydrorefining catalyst, and the temperature is raised from room temperature to a sulfurization end temperature of 340°C at a rate of 10°C / h, and maintained at this temperature for 12 hours to complete the presulfurization of the hydrorefining catalyst. The sulfurized HT-1 hydrorefining catalyst is used to refine the diesel raw material, and the hydrorefining reaction conditions are: 6.5Mpa, hydrogen-to-oil ratio of 2400, and catalyst space velocity (LHSV) of 0.8h -1 , inlet reaction temperature 315 ° C. After gas-liquid separation, the refined product was obtained to obtain refined catalytic fuel, the composition and properties of which are shown in Table 1.

[0072] 3. Other raw materials involved in the examples and comparative examples of the present invention are all commercially available products.

[0073] [Comparative Example 1]

[0074] Preparation of hydrocracking catalyst:

[0075] Hydrogen-type USY zeolite (SAR=12) was obtained from Sinopec Catalyst Branch, with an average particle size of 1.7 microns. 43g USY, 72.3g pseudo-boehmite, and 2g sesbania powder were uniformly mixed, 12ml nitric acid and 90ml water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 12h, and roasted at 550℃ in air atmosphere for 3h to obtain a hydrocracking catalyst carrier. 4.34g nickel nitrate, 5.75g ammonium molybdate and 20ml ammonia water were dissolved in water to obtain 50ml of a metal compound aqueous solution. 50g of the hydrocracking catalyst carrier was taken, and the above 50ml of the metal compound aqueous solution was added in an equal volume impregnation manner and allowed to stand for 3 hours, dried at 110℃ for 12h, and roasted at 500℃ in air atmosphere for 4h to obtain a hydrocracking catalyst precursor.

[0076] Catalyst reduction: The above hydrocracking catalyst precursor was loaded into a fixed bed reactor, and the temperature was raised from room temperature to the reduction end temperature of 400°C at a rate of 10°C / h, and maintained at this temperature for 12 hours to complete the reduction of the hydrocracking catalyst. The composition of the hydrocracking catalyst C0 after reduction was 1.6wt% Ni-8.1wt% MoO 2.6 / 40.2wt% USY (SAR=12)-50.1wt% Al2O3, see Table 2.

[0077] Catalyst Evaluation:

[0078] Using refined catalytic diesel raw materials, reaction pressure 6.5Mpa, hydrogen-to-oil ratio 2400, space velocity (LHSV) 1.0h -1 , reaction temperature 370℃. A high-pressure separator is set at the outlet of the hydrocracking reactor. After the device runs stably for 48 hours, the gas and liquid products are measured and analyzed for composition. The reaction products are classified into CH4, C2-C5 light hydrocarbons, C6-C 10 The total conversion rate and light aromatics selectivity of four groups of hydrocarbons, >200℃ unconverted components were calculated using the above formula, and the data are summarized in Table 3.

[0079] The single-pass conversion rate is 68.5 wt%, the selectivity of light aromatics is 40.2%, the benzene content in the C6 hydrocarbons and the toluene content in the C7 hydrocarbons are 23.8% and 67.3% respectively.

[0080] [Comparative Example 2]

[0081] Preparation of hydrocracking catalyst:

[0082] Hydrogenated ZSM-5 zeolite (SAR=38) was obtained from Sinopec Catalyst Branch, with an average particle size of 1.5 microns. 43g of hydrogenated ZSM-5 zeolite (SAR=38), 72.3g of pseudo-boehmite, and 2g of sesbania powder were uniformly mixed, 12ml of nitric acid and 90ml of water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 12h, and calcined at 550℃ in air atmosphere for 3h to obtain a hydrocracking catalyst carrier. 4.34g of nickel nitrate, 5.75g of ammonium molybdate and 20ml of ammonia water were dissolved in water to obtain 50ml of a metal compound aqueous solution. 50g of the hydrocracking catalyst carrier was taken, and the above 50ml of the metal compound solution was added in an equal volume impregnation manner and allowed to stand for 3 hours, dried at 110℃ for 12h, and calcined at 500℃ in air atmosphere for 4h to obtain a hydrocracking catalyst precursor.

[0083] Catalyst reduction: The above hydrocracking catalyst precursor was loaded into a fixed bed reactor, and the temperature was raised from room temperature to the reduction end temperature of 400°C at a rate of 10°C / h, and maintained at this temperature for 12 hours to complete the reduction of the hydrocracking catalyst. The composition of the hydrocracking catalyst C1 after reduction was 1.6wt% Ni-8.1wt% MoO 2.6 / 40.2wt% ZSM-5 (SAR=38)-50.1wt% Al2O3, see Table 2.

[0084] Catalyst Evaluation:

[0085] Using refined catalytic diesel raw materials, reaction pressure 6.5Mpa, hydrogen-to-oil ratio 2400, space velocity (LHSV) 1.0h -1, reaction temperature 370℃. A high-pressure separator is set at the outlet of the hydrocracking reactor. After the device runs stably for 48 hours, the gas and liquid products are measured and analyzed for composition. The reaction products are classified into CH4, C2-C5 light hydrocarbons, C6-C 10 The total conversion rate and light aromatics selectivity of four groups of hydrocarbons, >200℃ unconverted components were calculated using the above formula, and the data are summarized in Table 3.

[0086] The single-pass conversion rate is 39.2 wt%, the selectivity of light aromatics is 60.1%, the benzene content in the C6 hydrocarbons and the toluene content in the C7 hydrocarbons are 82.4% and 97.6% respectively.

[0087] [Example 1]

[0088] Preparation of aluminum-rich ZSM-5 zeolite:

[0089] First, silica sol, NaOH, sodium bromide and sodium aluminate were dissolved in deionized water, and then 25% tetrapropylammonium hydroxide (OSDA) was added. After stirring, a milky white gel solution was obtained. The molar ratio of SiO2, OSDA, Al2O3, NaOH and deionized water in the obtained gel solution was 40:5:1:3.5:200, and the molar ratio of NaOH and NaBr was 2:1. Then the gel solution was placed in a polytetrafluoroethylene-lined pressure steel autoclave, pre-crystallized at 90°C for 6 hours, and then placed in a rotary oven at 150°C and 20r / min for 160 hours of hydrothermal crystallization. Finally, it was cooled to room temperature with tap water to obtain a high-crystallinity ZSM-5 slurry.

[0090] An appropriate amount of sodium aluminate and solvent deionized water are directly added to the above ZSM-5 slurry to obtain a molar ratio of SiO2, OSDA, Al2O3, (NaOH and sodium bromide), and solvent deionized water of 40:5:3.2:0.03:240 in the slurry. The above crystallization procedure is repeated for secondary crystallization. The obtained product is filtered, washed and dried, and calcined at 550°C in an air atmosphere for 3 hours to obtain an aluminum-rich ZSM-5 molecular sieve.

[0091] XRD characterization shows that the obtained aluminum-rich ZSM-5 molecular sieve is a pure phase MFI configuration. 27 The results of Al MAS NMR show that 98% of the aluminum species in the aluminum-rich ZSM-5 molecular sieve are in a four-coordinated state. The silicon-aluminum ratio of the ZSM-5 molecular sieve obtained by ICP analysis is 13. Its TEM image is shown in Figure 1 , showing irregularly shaped particles with a particle size between 100-300 nm, and these particles are loosely agglomerated from basic particles with a particle size less than 20 nm.

[0092] The obtained aluminum-rich ZSM-5 molecular sieve was added with 1 mol / L ammonium nitrate solution at 90°C and exchanged three times to exchange the sodium-type aluminum-rich ZSM-5 (SAR=13) with ammonium-type aluminum-rich ZSM-5 (SAR=13), and then calcined at 550°C to obtain hydrogen-type aluminum-rich ZSM-5 (SAR=13).

[0093] Preparation of hydrocracking catalyst:

[0094] 43g hydrogen-type aluminum-rich ZSM-5 (SAR=13), 72.3g pseudo-boehmite, and 2g sesbania powder were uniformly mixed, 12ml nitric acid and 90ml water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 12h, and calcined at 550℃ in air atmosphere for 3h to obtain a hydrocracking catalyst carrier. 4.34g nickel nitrate, 5.75g ammonium molybdate and 20ml ammonia water were dissolved in water to obtain 50ml metal compound aqueous solution. 50g of the hydrocracking catalyst carrier was taken, and the above 50ml metal compound aqueous solution was added in an equal volume impregnation manner and allowed to stand for 3 hours, dried at 110℃ for 12h, and calcined at 500℃ in air atmosphere for 4h to obtain a hydrocracking catalyst precursor.

[0095] Catalyst reduction: The hydrocracking catalyst precursor was loaded into a fixed bed reactor, and the temperature was raised from room temperature to the reduction end temperature of 400°C at a rate of 10°C / h, and maintained at this temperature for 12 hours to complete the reduction of the hydrocracking catalyst. After reduction, the composition of the hydrocracking catalyst C2 was 1.6wt% Ni-8.1wt% MoO 2.6 / 40.2wt% ZSM-5 (SAR=13)-50.1wt% Al2O3, see Table 2.

[0096] Evaluation of hydrocracking catalysts:

[0097] Using refined catalytic diesel raw materials, reaction pressure 6.5Mpa, hydrogen-to-oil ratio 2400, space velocity (LHSV) 1.0h -1 , reaction temperature 370℃. A high-pressure separator is set at the outlet of the hydrocracking reactor. After the device runs stably for 48 hours, the gas and liquid products are measured and analyzed for composition. The reaction products are classified into CH4, C2-C5 light hydrocarbons, C6-C 10 The total conversion rate and light aromatics selectivity of four groups of hydrocarbons, >200℃ unconverted components were calculated using the above formula, and the data are summarized in Table 3.

[0098] The single-pass conversion rate is 89.5wt%, the selectivity of light aromatics is 56.9%, the benzene content in the C6 hydrocarbons and the toluene content in the C7 hydrocarbons are 56.2% and 93.7% respectively.

[0099] [Example 2]

[0100] Preparation of hydrocracking catalyst:

[0101] A hydrocracking catalyst carrier was prepared according to the method in [Example 1]. 4.34 g of nickel nitrate, 8.78 g of ammonium tungstate and 20 ml of ammonia water were dissolved in water to obtain 50 ml of a metal compound aqueous solution. 50 g of the hydrocracking catalyst carrier was taken, and the 50 ml of the metal compound solution was added in an equal volume impregnation manner and allowed to stand for 6 hours, dried at 90°C for 24 hours, and calcined at 510°C in an air atmosphere for 3 hours to obtain a hydrocracking catalyst precursor.

[0102] Catalyst reduction: The hydrocracking catalyst precursor was loaded into a fixed bed reactor, and the temperature was raised from room temperature to the reduction end temperature of 380°C at a rate of 10°C / h, and maintained at this temperature for 6 hours to complete the reduction of the hydrocracking catalyst. After reduction, the composition of the hydrocracking catalyst C3 was 1.6wt% NiO 0.3 -12.5wt%WO 2.8 / 38.2wt% ZSM-5 (SAR=13)-47.7wt% Al2O3, see Table 2.

[0103] Using refined catalytic diesel raw materials, reaction pressure 7.0Mpa, hydrogen-to-oil ratio 2000, space velocity (LHSV) 1.0h -1 , reaction temperature 375℃. A high-pressure separator is set at the outlet of the hydrocracking reactor. After the device runs stably for 48 hours, the gas and liquid products are measured and analyzed for composition. The reaction products are classified into CH4, C2-C5 light hydrocarbons, C6-C 10 The total conversion rate and light aromatics selectivity of four groups of hydrocarbons, >200℃ unconverted components were calculated using the above formula, and the data are summarized in Table 3.

[0104] The single-pass conversion rate is 97.5wt%, the selectivity of light aromatics is 53.6%, the benzene content in the C6 hydrocarbons and the toluene content in the C7 hydrocarbons are 51.8% and 93.7% respectively.

[0105] [Example 3]

[0106] Preparation of aluminum-rich ZSM-5 zeolite:

[0107] First, NaOH, sodium bromide and sodium aluminate were dissolved in deionized water, and then 25% tetrapropylammonium hydroxide (OSDA) was added. After stirring evenly, a milky white gel solution was obtained. In the obtained gel solution, the molar ratio of SiO2, OSDA, Al2O3, (NaOH and sodium bromide) and solvent deionized water was 25:3:1:0.02:135, and the molar ratio of NaOH and NaBr was 2:1. Then the gel solution was placed in a polytetrafluoroethylene-lined pressure steel autoclave, and after pre-crystallization for 12 hours at a temperature of 70°C, it was placed in a rotary oven at a temperature of 165°C and a speed of 20r / min for further hydrothermal crystallization for 36 hours, and finally cooled to room temperature with tap water to obtain a high-crystallinity ZSM-5 slurry.

[0108] An appropriate amount of aluminum hydroxide and deionized water are directly added to the above ZSM-5 slurry to obtain a molar ratio of SiO2, OSDA, Al2O3, (NaOH and sodium bromide), and deionized water of 25:3:2.8:0.02:135 in the slurry. The above crystallization procedure is repeated for secondary crystallization. The obtained product is filtered, washed and dried, and calcined at 550°C in an air atmosphere for 3 hours to obtain an aluminum-rich ZSM-5 molecular sieve.

[0109] XRD characterization showed that the aluminum-rich ZSM-5 molecular sieve was a pure phase MFI configuration. 27 The results of Al MAS NMR show that 96% of the aluminum species in the aluminum-rich ZSM-5 molecular sieve are in a tetracoordinated state. The silicon-aluminum ratio of the ZSM-5 molecular sieve obtained by ICP analysis is 8.6.

[0110] The obtained aluminum-rich ZSM-5 molecular sieve was added with 1 mol / L ammonium nitrate solution at 90°C and exchanged three times to convert the sodium-type aluminum-rich ZSM-5 (SAR=8.6) into ammonium-type aluminum-rich ZSM-5 (SAR=8.6), and then calcined at 550°C to obtain hydrogen-type aluminum-rich ZSM-5 (SAR=8.6).

[0111] Preparation of hydrocracking catalyst:

[0112] 60g hydrogen-type aluminum-rich ZSM-5 (SAR=8.6), 57g pseudo-boehmite, and 2g sesbania powder were uniformly mixed, 6ml nitric acid and 85ml water were added, kneaded into a mass, extruded, cured at room temperature for 24h, dried at 110℃ for 24h, and calcined at 550℃ in air atmosphere for 3h to obtain a hydrocracking catalyst carrier. 6.06g cobalt nitrate, 5.75g ammonium molybdate, 2.64g ammonium tungstate and 20ml ammonia water were dissolved in water to obtain 50ml of metal compound aqueous solution. 50g of the hydrocracking catalyst carrier was taken, and the above 50ml metal compound aqueous solution was added in an equal volume impregnation manner and allowed to stand for 3 hours, dried at 90℃ for 24h, and calcined at 480℃ in air atmosphere for 6h to obtain a hydrocracking catalyst precursor.

[0113] Catalyst reduction: The above hydrocracking catalyst precursor was loaded into a fixed bed reactor, and the temperature was raised from room temperature to the reduction end temperature of 430°C at a rate of 10°C / h, and maintained at this temperature for 4 hours to complete the reduction of the hydrocracking catalyst. After reduction, the composition of the hydrocracking catalyst C3 was 2.1wt% Co-7.7wt% MoO 2.5 -3.8wt% WO 2.4 / 51.9wt% ZSM-5 (SAR=8.6)-34.5wt% Al2O3, see Table 2.

[0114] Using refined catalytic diesel raw materials, reaction pressure 6.5Mpa, hydrogen-to-oil ratio 2000, space velocity (LHSV) 1.2h -1 , reaction temperature 385℃. A high-pressure separator is set at the outlet of the hydrocracking reactor. After the device runs stably for 48 hours, the gas and liquid products are measured and analyzed for composition. The reaction products are classified into CH4, C2-C5 light hydrocarbons, C6-C 10 The total conversion rate and light aromatics selectivity of four groups of hydrocarbons, >200℃ unconverted components were calculated using the above formula, and the data are summarized in Table 3.

[0115] The single-pass conversion rate is 98.9 wt %, the selectivity of light aromatics is 58.3%, the benzene content in the C6 hydrocarbons and the toluene content in the C7 hydrocarbons are 69.0% and 96.7% respectively.

[0116] Table 2. Catalyst compositions obtained in Comparative Examples 1 to 2 and Examples 1 to 3

[0117]

[0118] Table 3. Product yields obtained in Comparative Examples 1 to 2 and Examples 1 to 3

[0119]

[0120] It can be seen from the results in Table 3 that the hydrocracking catalyst using the aluminum-rich ZSM-5 zeolite of the present invention as a carrier component has a single-pass conversion rate of the hydrocracking reaction greater than 85%, a benzene content in C6 hydrocarbons in the hydrocracking reaction product greater than 50%, and a toluene content in C7 hydrocarbons greater than 93%. Compared with Comparative Examples 1 to 2, Examples 1 to 3 show more excellent feedstock conversion rate and light aromatics selectivity.

Claims

1. A catalyst with aluminum-rich ZSM-5 zeolite as a carrier, comprising: An aluminum-rich ZSM-5 zeolite carrier and a metal component loaded on the carrier, wherein the metal component comprises a VIB group metal oxide and an optional VIII group metal component, and the silicon-aluminum molecular ratio of the aluminum-rich ZSM-5 zeolite carrier is between 5 and 18.

2. The catalyst according to claim 1, characterized in that The catalyst further comprises a binder, preferably, the binder is selected from at least one of alumina and silica; and / or, Based on the total amount of the aluminum-rich ZSM-5 zeolite carrier and the binder as 100 parts by weight, the aluminum-rich ZSM-5 zeolite carrier is 5 to 80 parts, preferably 10 to 70 parts, and more preferably 15 to 60 parts; the Group VIB metal oxide is 1 to 20 parts, preferably 2 to 18 parts, and more preferably 3 to 15 parts; the Group VIII metal component is 0 to 10 parts, preferably 0.2 to 8 parts, and more preferably 0.5 to 6 parts, calculated as Group VIII metal.

3. The catalyst according to claim 1, characterized in that The content of framework aluminum in the aluminum-rich ZSM-5 zeolite carrier accounts for more than 92% of the total aluminum, preferably more than 95%; and / or, The average length of the particles of the aluminum-rich ZSM-5 zeolite carrier in at least one dimension is less than 20 nm; and / or The Group VIB metal oxide is selected from at least one of metal molybdenum oxide and metal tungsten oxide; and / or, The Group VIII metal component is selected from at least one of a nickel-containing component and a cobalt-containing component.

4. A method for preparing a catalyst with the aluminum-rich ZSM-5 zeolite as a carrier according to any one of claims 1 to 3, comprising: The components including the metal oxide of group VIB and the optional metal component of group VIII are loaded on a carrier including aluminum-rich ZSM-5 zeolite, and the catalyst is obtained through calcination and reduction.

5. The preparation method according to claim 4, characterized in that: The preparation method comprises the following steps: Step 1) forming the components including the aluminum-rich ZSM-5 zeolite, drying and calcining to obtain a catalyst carrier; Step 2) preparing a soluble Group VIB metal compound and a soluble Group VIII metal compound into a metal compound aqueous solution; Step 3) The catalyst carrier obtained in step 1) is immersed in the aqueous solution of the metal compound obtained in step 2), and then taken out, dried, calcined and reduced to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that: In the step 1): The aluminum-rich ZSM-5 zeolite is first mixed with a binder and then molded; and / or, The drying temperature is 50 to 180°C, preferably 60 to 150°C; and / or, The calcination temperature is 520-600°C, preferably 530-580°C; and / or, The calcination time is 1 to 8 hours, preferably 2 to 6 hours.

7. The preparation method according to claim 5, characterized in that: In the step 2): The soluble Group VIB metal compound is selected from at least one of a soluble molybdenum compound and a soluble tungsten compound, preferably at least one of ammonium tungstate and ammonium molybdate; and / or, The soluble Group VIII metal compound is selected from at least one of a soluble nickel compound and a soluble cobalt compound, preferably at least one of nickel nitrate, nickel sulfate, nickel halide, nickel oxalate, nickel acetate, cobalt nitrate, cobalt chloride and cobalt oxalate; and / or, The total concentration of the metal compound in the metal compound aqueous solution is 3 to 45 wt %, preferably 5 to 40 wt %.

8. The preparation method according to claim 5, characterized in that: In the step 3): The drying temperature is 50 to 150° C., preferably 60 to 120° C.; and / or, The calcination temperature is 450-600°C, preferably 480-580°C; and / or, The calcination time is 0.5 to 8 hours, preferably 1 to 6 hours; and / or, The reduction conditions are as follows: the reduction heating rate is 1-20°C / h, preferably 5-10°C / h; the reduction end temperature is 300-450°C, preferably 320-420°C; the end temperature is maintained for 1-24h, preferably 2-16h.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The aluminum-rich ZSM-5 zeolite is obtained by the following preparation method: a) dissolving sodium hydroxide and an alumina source in water, and then sequentially adding a silicon dioxide source and a template agent, and stirring to obtain a glue solution; b) pre-crystallizing and hydrothermally crystallizing the colloid obtained in step a) and then cooling it to obtain a high-crystallinity ZSM-5 slurry; c) continuing to add an alumina source and water to the high crystallinity ZSM-5 slurry obtained in step b); d) repeating the pre-crystallization and hydrothermal crystallization of step b) to perform secondary crystallization; e) filtering, washing, drying and calcining the product obtained after the secondary crystallization to obtain the aluminum-rich ZSM-5 zeolite.

10. The preparation method according to claim 9, characterized in that: The alumina source is selected from at least one of sodium aluminate, aluminum hydroxide and aluminum sulfate; and / or, The silicon dioxide source is selected from at least one of silica gel, silica sol and white carbon black; and / or, The template agent is selected from organic amines, preferably at least one selected from tetrapropylammonium hydroxide, tetrapropylammonium bromide and n-propylamine.

11. The preparation method according to claim 9, characterized in that: In the step a), the molar ratio of the silica source, the template, the alumina source, the sodium hydroxide and the water is (20-50): (2-10): 1: (0.01-0.20): (120-500), wherein the silica source is calculated as SiO2 and the alumina source is calculated as Al2O3; and / or, The pre-crystallization conditions in step b) and step d) are independently: 50-100° C. for 3-60 h, preferably 60-95° C. for 5-30 h; and / or, The hydrothermal crystallization conditions in step b) and step d) are independently: crystallization at 110-180° C. for 12-240 h, preferably, pre-crystallization at 120-170° C. for 24-200 h; and / or, In the system obtained in step c), the molar ratio of the silica source, the template, the alumina source, the sodium hydroxide and the water is (8-18): (0.5-2): 1: (0.005-0.015): (40-150), wherein the silica source is calculated as SiO2 and the alumina source is calculated as Al2O3; and / or, The aluminum-rich ZSM-5 zeolite obtained in step e) needs to be further treated by ammonium ion exchange and calcination.

12. A diesel hydrocracking catalyst, comprising a catalyst with the aluminum-rich ZSM-5 zeolite as a carrier as claimed in any one of claims 1 to 3 or a catalyst with the aluminum-rich ZSM-5 zeolite as a carrier as prepared by the preparation method as claimed in any one of claims 4 to 11.

13. Use of the catalytic diesel hydrocracking catalyst according to claim 12 in the hydrocracking reaction of aromatics-rich diesel, comprising the following steps: The hydrorefining catalyst and the catalytic diesel hydrocracking catalyst are respectively loaded into independent first and second reactors, the aromatics-rich diesel is added to the first reactor for contact reaction with the hydrorefining catalyst, and then gas-liquid separation is performed, and the obtained liquid phase oil is fed into the second reactor for contact reaction with the catalytic diesel hydrocracking catalyst.

14. The use according to claim 13, characterized in that The aromatic content of the aromatic-rich diesel is not less than 50%; and / or, The aromatic diesel is selected from at least one of catalytic diesel, coking diesel and ethylene tar; and / or, The aromatics-rich diesel has a nitrogen content of ≤50ppm and a sulfur content of ≤800ppm after hydrofining treatment; preferably, a nitrogen content of ≤20ppm and a sulfur content of ≤500ppm; and / or, The reaction conditions of the hydrofining include: reaction temperature of 280-400°C, hydrogen partial pressure of 2.0-15.0 MPa, liquid phase space velocity of 0.2-4.0 h -1 , the volume ratio of hydrogen to hydrocarbon is 500 to 4000; preferably, the reaction temperature is 300 to 380°C, the hydrogen partial pressure is 5.0 to 12.0 MPa, and the liquid phase space velocity is 0.5 to 2.0 h -1 , the volume ratio of hydrogen to hydrocarbon is 1000 to 3000; and / or, The reaction conditions of the hydrocracking include: reaction temperature of 300-450°C, hydrogen partial pressure of 2.0-15.0 MPa, liquid phase space velocity of 0.2-4.0 h -1 , the volume ratio of hydrogen to hydrocarbon is 500 to 4000; preferably, the reaction temperature is 320 to 420°C, the hydrogen partial pressure is 5.0 to 12.0 MPa, and the liquid phase space velocity is 0.5 to 2.0 h -1 , the volume ratio of hydrogen to hydrocarbon is 1000 to 3000; and / or, The single-pass conversion rate of the hydrocracking reaction is greater than 85%; and / or, In the hydrocracking reaction product, the benzene content in the C6 hydrocarbon is greater than 35wt%, and the toluene content in the C7 hydrocarbon is greater than 85wt%.

Images