A catalyst for hydrogenation and reforming of low-quality diesel rich in cyclic hydrocarbons, as well as its preparation method and application

Abstract

The present invention provides a cyclic hydrocarbon-rich low-quality diesel hydroreforming catalyst and its preparation method and application. Based on the weight of the final catalyst, it includes the following components: a) HZSM-23 molecular sieve, with a content of 5-25 wt%, preferably 5-22 wt%; b) modified Y molecular sieve, with a content of 5-35 wt%, preferably 7-28 wt%; c) macroporous alumina, with a content of 15-65 wt%, preferably 18-60 wt%; d) an active component is one or more of metal oxides of Group VIB and Group VIII, wherein the content of Group VIB metal as oxide is 10-30 wt%, and the content of Group VIII metal as oxide is 3-15 wt%; the catalyst has mesopores with a pore size of 3-6 nm accounting for 38-60% of the total pore volume; preferably, the mesopores with a pore size of 3-6 nm account for 40-55% of the total pore volume. The catalyst is used for hydrogenation reforming of low-quality diesel rich in cyclic hydrocarbons, which can effectively improve the catalyst's ability to treat large molecules in the oil product, increase the cetane number of the diesel while ensuring the diesel yield, and effectively reduce its pour point.

Description

Technical Field

[0001] The present invention relates to a catalyst for hydrogenating and reforming low-quality diesel fuel rich in cyclic hydrocarbons, a preparation method and an application thereof, and in particular to a catalyst for hydrogenating and reforming low-quality catalytic diesel fuel rich in cyclic hydrocarbons, a preparation method and an application thereof. Background Art

[0002] Crude oil is becoming increasingly heavier and lower quality worldwide, while environmental regulations are increasingly stringent regarding diesel fuel standards. Furthermore, as diesel fuel quality upgrades accelerate, national requirements for diesel fuel properties are becoming increasingly stringent. Low-freezing point diesel fuel must meet national emission standards for its pour point, cold filter plugging point, sulfur content, polycycloalkanes, and cetane number. Therefore, the development of diesel fuel hydro-reforming technology is crucial, and its core technology lies in the research and development of hydro-reforming catalysts.

[0003] Diesel hydro-reforming catalysts typically use cracking molecular sieves or amorphous silica-alumina as the acidic component, and supported VIB and Group VII metals as the hydrogenation active component. Y and β molecular sieves are the primary acidic components in publicly available hydro-reforming catalysts due to their excellent acidity and stability.

[0004] The active components of the diesel hydro-reforming catalyst carrier disclosed in patent CN10146327A are primarily Y molecular sieve and amorphous silica-alumina. A diesel hydro-conversion catalyst disclosed in patent CN1184843A similarly utilizes a mixture of Y molecular sieve, alumina, and amorphous silica-alumina with a SiO2 / Al2O3 molar ratio of 7-15 as a carrier. Patent CN107233913B discloses a low-quality diesel hydro-reforming catalyst carrier comprising a modified β molecular sieve with a Si / Al2O3 molar ratio of 50-70, amorphous silica-alumina, macroporous alumina, and SB powder. The β molecular sieve requires a series of modification processes, including dealumination, siliconization, hydrothermal treatment, and finally treatment with a mixed solution of aluminum salts and acids, to achieve the desired acidic properties and pore structure. This complex process results in a high product loss rate. Patent CN11131831 discloses a hydroreforming catalyst support composed of a Y-β composite molecular sieve loaded with organosilane as the primary acidic component. The SiO2 / Al2O3 molar ratio of the Y molecular sieve is 8-55, and that of the β molecular sieve is 35-155. However, when the Y and β molecular sieves are the primary active components of the catalyst support, the cracking performance exhibited is much stronger than the isomerization performance due to factors such as their pore structure and acidity matching. Therefore, although the catalyst exhibits good desulfurization and denitrification activity, it can lead to problems such as low diesel product yield and a high pour point.

[0005] Isomerization pour point depressant technology is an effective means of improving the low-temperature fluidity of oil products. It primarily utilizes precious metal-loaded molecular sieves such as SAPO-11, ZSM-22, and ZSM-23. This two-stage process isomerizes long-chain normal alkanes into branched alkanes, thereby lowering the pour point. However, these molecular sieves synthesized using conventional technology are all microporous, with pore sizes ranging from 0.45 to 0.6 nm. Consequently, their ability to handle macromolecular substances in oil products is limited.

[0006] Patent CN108435244B discloses a method for preparing a hydro-reforming catalyst for improving the cetane number of diesel. This composite material utilizes a SAPO-5 or Beta molecular sieve core, both of which exhibit excellent isomerization and ring-opening properties, and an amorphous silica-alumina shell. This catalyst removes sulfur and nitrogen from the feedstock while simultaneously achieving hydrosaturation and moderate ring-opening of polycyclic aromatic hydrocarbons. However, due to structural and component limitations, this catalyst's performance for heavy oil processing remains limited.

[0007] In view of the limitations of existing catalyst applications, there is an urgent need to develop a new diesel modification and pour point depressing catalyst that can cope with the trend of oil quality degradation and heaviness, while desulfurizing, denitrogenating, and lowering the diesel pour point, while appropriately increasing the cetane number of the diesel fraction to meet the market demand for high-quality diesel. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the present invention provides a catalyst for hydro-reforming low-quality diesel fuel rich in cyclic hydrocarbons, as well as its preparation method and application. The catalyst is used for hydro-reforming low-quality diesel fuel rich in cyclic hydrocarbons, effectively improving the catalyst's ability to handle macromolecules in the oil product, increasing the diesel's cetane number while maintaining diesel yield and effectively lowering its pour point.

[0009] A catalyst for hydrogenating and reforming low-quality diesel rich in cyclic hydrocarbons, wherein mesopores with a pore size of 3-6 nm in the catalyst account for 38-60% of the total pore volume; preferably, mesopores with a pore size of 3-6 nm account for 40-55% of the total pore volume.

[0010] The catalyst of the present invention comprises the following components based on the weight of the final catalyst:

[0011] a) HZSM-23 molecular sieve, with a content of 5 to 25 wt%, preferably 5 to 22 wt%;

[0012] b) modified Y molecular sieve, with a content of 5 to 35 wt%, preferably 7 to 28 wt%;

[0013] c) macroporous alumina, with a content of 15 to 65 wt%, preferably 18 to 60 wt%;

[0014] d) The active component is one or more metal oxides of Group VIB and Group VIII, wherein the content of the Group VIB metal as oxide is 10-30 wt%, and the content of the Group VIII metal as oxide is 3-15 wt%.

[0015] In the catalyst of the present invention, the specific surface area of ​​the catalyst is 270~434 m 2 / g, pore volume is 0.32~0.83 cm 3 / g; preferably a specific surface area of ​​310~425 m 2 / g, pore volume of 0.38~0.80 cm 3 / g.

[0016] In the catalyst of the present invention, the properties of the HZSM-23 molecular sieve are as follows: the mesopore volume with a pore diameter of 3 to 6 nm accounts for 45 to 90% of the total pore volume of the molecular sieve, preferably 50 to 85%, and more preferably 55 to 81%; the relative crystallinity of the molecular sieve is 95 to 120%, and the relative crystallinity after hydrothermal treatment with water vapor at 600°C for 2 hours is 95 to 110%.

[0017] In the catalyst of the present invention, the specific surface area of ​​the HZSM-23 molecular sieve is 300-430 m 2 / g, pore volume is 0.31~0.5 cm 3 / g, micropore specific surface area is 50~170 m 2 / g, and the mesopore specific surface area is 150~310 m 2 / g; preferably, the specific surface area is 320~405 m 2 / g, pore volume is 0.34~0.45 cm 3 / g, micropore specific surface area is 80~140 m 2 / g, and the mesopore specific surface area is 181~295 m 2 / g.

[0018] In the catalyst of the present invention, the properties of the modified Y molecular sieve are as follows: SiO2 / Al2O3 molar ratio is 10-60, unit cell parameter is 2.460-2.470, specific surface area is 700-850 m 2 / g, pore volume of 0.40~0.60 cm 3 / g.

[0019] In the catalyst of the present invention, the properties of the macroporous alumina are: specific surface area 375~450 m 2 / g, pore volume 0.74~1.15 cm 3 / g; preferably a specific surface area of ​​390~430 m 2 / g, pore volume 0.78~1.10 cm 3 / g.

[0020] In the catalyst of the present invention, the active component of the Group VIB metal is preferably tungsten and / or molybdenum, and the Group VIII metal is preferably nickel and / or cobalt.

[0021] The present invention provides a method for preparing a catalyst for hydroreforming low-quality diesel rich in cyclic hydrocarbons. The method includes preparing a carrier and loading an active metal. The carrier is prepared by mixing and shaping HZSM-23 molecular sieve, modified Y molecular sieve, macroporous alumina, and a binder, and then drying and calcining to obtain the carrier. The steps for preparing the HZSM-23 molecular sieve are as follows (the preparation of the ZSM-23 molecular sieve refers to the preparation method of CN202210011767.9):

[0022] (1) preparing or selecting amorphous silicon dioxide;

[0023] (2) alkaline treatment of amorphous silica;

[0024] (3) Preparation of NaZSM-23 molecular sieve using alkali-treated amorphous silica as silicon source;

[0025] (4) The molecular sieve obtained in (3) is subjected to ammonium exchange to obtain HZSM-23 molecular sieve.

[0026] In step (1) of the above method, the amorphous silica has a specific surface area of ​​600-1300 m 2 / g, preferably 700~1200 m 2 / g; pore volume is 0.6~1.3 cm 3 / g, preferably 0.7~1.2 cm 3 / g; the pore diameter is 1~15 nm, preferably 2~10 nm.

[0027] In step (1) of the above method, the amorphous silica preparation process is as follows: adding a silicon source to deionized water and dispersing it evenly, then adding a surfactant and stirring; adjusting the pH of the solution to 1-5, preferably 1.5-4, and heating it in a water bath for a period of time; filtering, washing, drying, and calcining to obtain amorphous mesoporous silica.

[0028] In the above method, during the preparation of the amorphous silicon dioxide, the silicon source is an inorganic silicon source, preferably one or more of water glass, silica sol or white carbon black.

[0029] In the above method, during the preparation of amorphous silicon dioxide, the surfactant is one or more of cetyltrimethylammonium chloride, cetyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and octadecyltrimethylammonium bromide.

[0030] In the above method, during the preparation of the amorphous silica, the molar ratio of the silicon source calculated as SiO2 to the surfactant is 1: (0.02~0.3), preferably 1: (0.05~0.2).

[0031] In the above method, during the preparation of the amorphous silica, the molar ratio of the silicon source, calculated as SiO2, to deionized water is 1: (30-300), preferably 1: (50-220);

[0032] In the above method, during the preparation of the amorphous silica, the heating temperature is 30-80° C., preferably 40-70° C.; the heating time is 0.5-8 hours, preferably 3-6 hours.

[0033] In step (2) of the above method, the alkali treatment is to add the amorphous silica prepared in step (1) into an alkaline solution and heat and stir.

[0034] In the above method, the alkali treatment adopts inorganic alkali treatment, and the inorganic alkali is one or more of sodium hydroxide, potassium hydroxide or ammonia water.

[0035] In the above method, the alkali treatment heating and stirring time is 0.5 to 12 hours, preferably 2 to 8 hours; the heating temperature is 25 to 60°C, preferably 30 to 50°C.

[0036] In the above method, the molar ratio of amorphous silica calculated as SiO2 to the inorganic base is 0.05 to 0.24, preferably 0.06 to 0.22.

[0037] In step (3) of the above method, amorphous silica treated with alkali is used as a silicon source, and the silicon source is mixed with an aluminum source, an alkali source, a template, and water to form a gel, which is then crystallized, filtered, washed, dried, and calcined to obtain a NaZSM-23 molecular sieve.

[0038] Preferably, the molar ratio of silicon source (calculated as SiO2): aluminum source (calculated as Al2O3): alkali source (calculated as hydroxide): template: H2O in the gel system is 1: (0.003~0.03): (0.03~0.3): (0.05~2): (10~90); further preferably, the molar ratio of silicon source (calculated as SiO2): aluminum source (calculated as Al2O3): alkali source (calculated as hydroxide): template: H2O in the gel system is 1: (0.005~0.02): (0.03~0.16): (0.08~1.6): (20~70);

[0039] Preferably, the gel is crystallized at 150-200° C., preferably 170-180° C., for 24-96 hours, preferably 36-72 hours, and then filtered, washed, dried, and calcined to obtain NaZSM-23 molecular sieve.

[0040] In step (3) of the above method, the drying temperature is 80-120°C, the drying time is 4-12 hours, the roasting temperature is 450-600°C, and the roasting time is 2-8 hours; preferably, the drying temperature is 90-110°C, the drying time is 6-8 hours, the roasting temperature is 500-550°C, and the roasting time is 3-6 hours.

[0041] In step (4) of the above method, ammonium exchange is carried out by conventional methods, such as one or more ammonium exchanges, and the Na2O content in the ZSM-23 molecular sieve after ammonium exchange is less than 0.2%; then washing, drying and calcination can be carried out, wherein the drying temperature is 60~130℃ and the time is 2~12 hours, preferably drying at 80~120℃ for 4~8 hours; the calcination temperature is 500~600℃ and the time is 2~8 hours, preferably calcining at 530~570℃ for 3~6 hours.

[0042] In the catalyst preparation method provided by the present invention, especially in the preparation method of NaZSM-23 molecular sieve, mesoporous amorphous silica is prepared in the early stage with the assistance of a surfactant, which has not yet crystallized into a stable crystalline form but has a regular mesoporous structure, and is further treated in an alkaline solution for a period of time. Part of the -Si-O- bond is opened, which helps to form the -Si-O-Al- bond in the molecular sieve structure later, but most of the mesoporous structure is retained, and later under the action of a microporous template, in a suitable NaZSM-23 molecular sieve synthesis system, a microporous structure is generated again, and the mesoporous structure is further crystallized and stabilized to obtain a micro-mesoporous composite NaZSM-23 molecular sieve. The obtained NaZSM-23 molecular sieve has both the acidic properties of the microporous structure being adjustable and the large pore characteristics of the mesoporous structure, and the mesopore channel size distribution is concentrated, the specific surface area and pore volume are high, and the crystallinity is high, the thermal stability and the hydrothermal stability are strong.

[0043] The catalyst support of the present invention is dried and calcined by conventional methods, specifically as follows: drying temperature is 60-130°C, time is 2-12 hours, preferably 80-120°C for 4-8 hours; calcination temperature is 500-600°C, time is 2-8 hours, preferably 530-570°C for 3-6 hours.

[0044] The active metal supporting method of the present invention can adopt conventional supporting methods in the prior art, preferably impregnation. After impregnation, the support is dried at 80-120°C for 4-12 hours and then calcined at 400-700°C for 3-12 hours to obtain the final catalyst.

[0045] The catalyst is used for hydro-reforming of low-quality diesel rich in cyclic hydrocarbons, wherein the low-quality diesel rich in cyclic hydrocarbons, for example, catalytic diesel, has a cyclic hydrocarbon content of 15-30% by mass, preferably 17-28%; a paraffin content of 6-20% by mass, preferably 7-18%; and an aromatic hydrocarbon content of 55-70% by mass, preferably 57-68%.

[0046] In the above application, the properties of the low-quality diesel rich in cyclic hydrocarbons are as follows: the diesel density is 0.930~0.980 g / cm 3 , preferably the distillation range is 180~400 ℃, the mass content of S is 0.5~1.8%, the mass content of N is 500~1500 μg / g, and the cetane number is 10~25.

[0047] In the above application, the reaction conditions are as follows: reaction temperature 350~400℃, total reaction pressure 4~12 MPa, liquid hourly space velocity 0.4~2 h -1 , hydrogen-oil volume ratio 400:1~1200:1.

[0048] Compared with the prior art, the catalyst for hydro-reforming of low-quality diesel fuel rich in cyclic hydrocarbons and its preparation method and application in the present invention have the following beneficial technical effects:

[0049] (1) The catalyst of the present invention contains a combination of micro-mesoporous HZSM-23 molecular sieve and modified Y molecular sieve. The obtained catalyst has a large number of mesoporous structures with concentrated pore size distribution and strong stability, which is conducive to the mass transfer and conversion of macromolecular reactants and improves the raw material adaptability and processing capacity of the catalyst; the large specific surface area can promote the dispersion of the metal active phase and improve the utilization rate of the active phase; at the same time, a large number of cycloalkanes, aromatic hydrocarbons and other components in the raw materials can freely pass through the mesoporous HZSM-23 molecular sieve and partially undergo cracking, avoiding coking, and most of them undergo ring opening and cracking reactions on the modified Y molecular sieve; and chain alkanes can undergo hydrogenation isomerization reactions in the HZSM-23 molecular sieve pores, avoiding excessive cracking, ensuring the diesel yield while improving the cetane number of the diesel product, lowering the pour point, and improving the diesel quality.

[0050] (2) The catalyst of the present invention is suitable for diesel hydro-reforming, especially for reforming low-quality diesel fuel containing a high concentration of cycloalkanes or di- or tri-cyclic aromatic hydrocarbons. The yield of the target high-quality diesel fuel can reach 97.5%, the cetane number can reach 52.2, and the pour point can be as low as -31°C. DETAILED DESCRIPTION

[0051] The analytical method of the present invention is as follows: Specific surface area and pore volume are determined by nitrogen physical adsorption, and the relative crystallinity of the molecular sieve is determined by X-ray powder diffraction (XRD). The sum of the heights of the diffraction peaks at 2θ values ​​of ~11.3 and 19.5-23° in the XRD spectrum of the microporous ZSM-23 molecular sieve in Comparative Example 1 is taken as 100% crystallinity, and the relative crystallinity of other samples is determined by comparison with this value.

[0052] In order to better illustrate the present invention, the following is further described in conjunction with Examples and Comparative Examples. However, the scope of the present invention is not limited to the scope of these Examples.

[0053] Example 1

[0054] (1) Preparation of mesoporous silicon source

[0055] Add 50 g of water glass (SiO2 mass fraction is 27%) to 250 g of deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C 18 TMAC1) was stirred for 0.5 hours, wherein SiO2 and C 18 The molar ratio of TMACl was 1:0.08. The solution was adjusted to pH 2 with hydrochloric acid and heated in a 50°C water bath for 4 hours. After the solution was filtered, washed, dried, and calcined at 550°C for 3 hours to obtain amorphous silica with a specific surface area of ​​1028 m2 / g, and a pore volume of 1.14 cm 3 / g, pore size is 2-10 nm.

[0056] (2) Preparation of micro-mesoporous NaZSM-23 molecular sieve:

[0057] a) Dissolve 0.35 g of NaOH in 35 mL of deionized water, add 3.7 g of the mesoporous silicon source prepared in (1), and stir in a 45°C water bath for 3 hours;

[0058] b) aluminum sulfate and isopropylamine (IPA) were sequentially dissolved in the remaining water, and the silicon source dispersion obtained in a) was added thereto to prepare a gel having a total molar ratio of SiO2 in the silicon source: Al2O3 in the aluminum source: NaOH: IPA: H2O = 1:0.01:0.08:1.0:50. After crystallization at 180°C for 48 hours, the gel was filtered, washed, dried, and calcined to obtain the product NaZSM-23-1.

[0059] (3) Ammonium exchange

[0060] A certain amount of NaZSM-23-1 molecular sieve sample was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80-90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an oven at 80-100°C for 8 hours and calcined in air at 550°C for 3 hours to obtain HZSM-23-1. The relative crystallinity of the HZSM-23-1 was measured by XRD. The relative crystallinity of the HZSM-23-1 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0061] (4) Catalyst preparation

[0062] Macroporous alumina (specific surface area 408 m 2 / g, pore volume 0.87 cm 3 / g), 10 wt% HZSM-23-1 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 30, unit cell parameter of 2.466, specific surface area of ​​801 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 22 wt% WO3 and 6 wt% NiO by conventional equal volume impregnation. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain Catalyst C-1. Specific properties are shown in Table 2.

[0063] Example 2

[0064] (1) Preparation of mesoporous silicon source

[0065] Add 50 g of water glass (SiO2 mass fraction is 27%) to 250 g of deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C 18 TMAC1) was stirred for 0.5 hours, wherein SiO2 and C 18 The molar ratio of TMACl was 1:0.08. The solution was adjusted to pH 2 with hydrochloric acid and heated in a 50°C water bath for 4 hours. After the solution was filtered, washed, dried, and calcined at 550°C for 3 hours to obtain amorphous silica with a specific surface area of ​​1028 m 2 / g, and a pore volume of 1.14 cm 3 / g, pore size is 2-10 nm.

[0066] (2) Preparation of micro-mesoporous NaZSM-23 molecular sieve:

[0067] a) Dissolve 0.42 g of NaOH in 40 mL of deionized water, add 3.7 g of the mesoporous silica source prepared in (1), and stir in a 35°C water bath for 6 hours;

[0068] b) Aluminum sulfate and isopropylamine (IPA) were sequentially dissolved in the remaining water, and the silicon source dispersion obtained in a) was added thereto to prepare a gel having a molar ratio of SiO2 in the silicon source: Al2O3 in the aluminum source: NaOH: IPA: H2O = 1:0.01:0.10:1.0:50. After crystallization at 180°C for 48 hours, the gel was filtered, washed, dried, and calcined, and named NaZSM-23-2.

[0069] (3) Ammonium exchange

[0070] A certain amount of NaZSM-23-2 molecular sieve sample was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80-90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an oven at 80-100°C for 8 hours and calcined in air at 550°C for 3 hours to obtain HZSM-23-2. The relative crystallinity of the HZSM-23-2 was measured by XRD. The relative crystallinity of the HZSM-23-2 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0071] (4) Catalyst preparation

[0072] Macroporous alumina (specific surface area 392 m 2 / g, pore volume 0.87 cm 3 / g), 7 wt% HZSM-23-2 molecular sieve, 25 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 30, unit cell parameter of 2.466, specific surface area of ​​791 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 18 wt% WO3 and 5 wt% NiO using a conventional equal volume impregnation method. A pre-prepared impregnation solution equal in volume to the carrier's water absorption capacity was added to the carrier strips, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain Catalyst C-2. Specific properties are shown in Table 2.

[0073] Example 3

[0074] (1) Preparation of mesoporous silicon source

[0075] Add 50 g of water glass (SiO2 mass fraction is 27%) to 1200 g of deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C 18 TMAC1) was stirred for 2 hours, wherein SiO2 and C 18 The molar ratio of TMACl was 1:0.2. The solution was adjusted to pH 3 with hydrochloric acid and heated in a 50°C water bath for 4 hours. After the reaction, the solution was filtered, washed, dried, and calcined at 550°C for 3 hours to obtain amorphous silica with a specific surface area of ​​1145 m 2 / g, and a pore volume of 1.17 cm 3 / g, pore size is 2-10nm.

[0076] (2) Preparation of micro-mesoporous NaZSM-23 molecular sieve:

[0077] a) Dissolve 0.15 g of NaOH in 35 mL of deionized water, add 3.7 g of the mesoporous silica source prepared in (1), and stir in a 45°C water bath for 3 hours;

[0078] b) Aluminum sulfate, isopropylamine (IPA), and sodium hydroxide were sequentially dissolved in the remaining water, and the silicon source dispersion obtained in a) was added thereto to prepare a gel having a molar ratio of SiO2 in the silicon source: Al2O3 in the aluminum source: NaOH: IPA: H2O = 1:0.01:0.08:1.0:50. After crystallization at 180°C for 48 hours, the gel was filtered, washed, dried, and calcined, and named NaZSM-23-3.

[0079] (3) Ammonium exchange

[0080] A certain amount of NaZSM-23-3 molecular sieve sample was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80-90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an oven at 80-100°C for 8 hours and calcined in air at 550°C for 3 hours to obtain HZSM-23-3. The relative crystallinity of the HZSM-23-3 was measured by XRD. The relative crystallinity of the HZSM-23-3 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0081] (4) Catalyst preparation

[0082] Macroporous alumina (specific surface area 408 m 2 / g, pore volume 0.87 cm 3 / g), 10 wt% HZSM-23-3 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 50, unit cell parameter of 2.462, specific surface area of ​​738 m 2 / g, pore volume 0.48 cm 3 / g), sesbania powder (1 wt% by weight of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 22 wt% WO3 and 6 wt% NiO by conventional equal volume impregnation. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain catalyst C-3. Specific properties are shown in Table 2.

[0083] Example 4

[0084] (1) Preparation of mesoporous silicon source

[0085] Add 50 g of water glass (SiO2 mass fraction is 27%) to 800 g of deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C 18 TMAC1) was stirred for 2 hours, wherein SiO2 and C 18 The molar ratio of TMACl was 1:0.15. The solution was adjusted to pH 4 with hydrochloric acid and heated in a 50°C water bath for 2 hours. After filtration, washing, drying, and calcination at 550°C for 3 hours, amorphous silica was obtained with a specific surface area of ​​814 m 2 / g, and a pore volume of 0.78 cm 3 / g, pore size is 2-10nm.

[0086] (2) Preparation of micro-mesoporous NaZSM-23 molecular sieve:

[0087] a) Dissolve 0.42 g of NaOH in 40 mL of deionized water, add 3.7 g of the mesoporous silicon source prepared in (1), and stir in a 40°C water bath for 3 hours;

[0088] b) Aluminum sulfate and isopropylamine (IPA) were sequentially dissolved in the remaining water, and the silicon source dispersion obtained in a) was added thereto to prepare a gel having a molar ratio of SiO2 in the silicon source: Al2O3 in the aluminum source: NaOH: IPA: H2O = 1:0.005:0.10:1.0:50. After crystallization at 180°C for 48 hours, the gel was filtered, washed, dried, and calcined, and named NaZSM-23-4.

[0089] (3) Ammonium exchange

[0090] A certain amount of NaZSM-23-4 molecular sieve sample was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80-90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an 80-100°C oven for 8 hours and calcined in air at 550°C for 3 hours to obtain HZSM-23-4. The relative crystallinity of the HZSM-23-4 was measured by XRD. The relative crystallinity of the HZSM-23-4 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0091] (4) Catalyst preparation

[0092] Macroporous alumina (specific surface area 426 m 2 / g, pore volume 0.99 cm 3 / g), 20 wt% HZSM-23-4 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 30, unit cell parameter of 2.466, specific surface area of ​​791 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 22 wt% WO3 and 6 wt% NiO by conventional equal volume impregnation. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain catalyst C-4. Specific properties are shown in Table 2.

[0093] Example 5

[0094] (1) Preparation of mesoporous silicon source

[0095] Add 50 g of water glass (SiO2 mass fraction is 27%) to 210 g of deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C 18 TMAC1) was stirred for 1 hour, wherein SiO2 and C 18 The molar ratio of TMACl was 1:0.06; the pH of the solution was adjusted to 2 with hydrochloric acid and then heated in a 60 °C water bath for 4 hours; after completion, the solution was filtered, washed, dried at 80 °C for 8 hours, and calcined at 550 °C for 3 hours to obtain amorphous silica with a specific surface area of ​​907 m 2 / g, and a pore volume of 0.96 cm 3 / g, pore size is 2-10 nm.

[0096] (2) Preparation of micro-mesoporous NaZSM-23 molecular sieve:

[0097] a) Dissolve 0.10 g NaOH and 1.36 g concentrated ammonia (mass fraction about 27%) in 35 mL deionized water, add 3.7 g of the mesoporous silica source prepared in (1), and place in a 40 °C water bath and stir for 6 h;

[0098] b) dissolving aluminum sulfate and isopropylamine (IPA) in the remaining water in sequence, and then adding the silicon source dispersion obtained in a) to the remaining water to obtain a total molar ratio of SiO2 in the silicon source: Al2O3 in the aluminum source: OH - : IPA : H2O = 1 : 0.01 : 0.15 : 1.0 : 50, after crystallization at 180 ° C for 48 hours, the NaZSM-23-5 molecular sieve sample was filtered, washed, dried and calcined.

[0099] (3) Ammonium exchange

[0100] A certain amount of NaZSM-23-5 molecular sieve sample was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80-90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an oven at 80-100°C for 8 hours and calcined in air at 550°C for 3 hours to obtain HZSM-23-5. The relative crystallinity of the HZSM-23-5 was measured by XRD. The relative crystallinity of the HZSM-23-5 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0101] (4) Catalyst preparation

[0102] Macroporous alumina (specific surface area 408 m 2 / g, pore volume 0.87 cm 3 / g), 10 wt% HZSM-23-5 molecular sieve, 22 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 50, unit cell parameter of 2.462, specific surface area of ​​738 m 2 / g, pore volume 0.48 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 18 wt% WO3 and 5 wt% NiO using a conventional equal volume impregnation method. A pre-prepared impregnation solution equal to the carrier's water absorption capacity was added to the carrier strips, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain Catalyst C-5. Specific properties are shown in Table 2.

[0103] Comparative Example 1 (refer to CN105540607A)

[0104] (1) Molecular sieve preparation

[0105] Under stirring at 35°C, 0.51 g of pseudo-boehmite and 0.3 g of sodium hydroxide were added to 26 mL of deionized water. After homogenization, 0.3 g of isopropylamine was added, followed by 21 g of silica, and homogenization was repeated for 1 hour. 24.5 g of corn starch was added, and the mixture was heated to 90°C and aged with stirring for 6 hours. Finally, the resulting mixture was transferred to a hydrothermal reactor with a polytetrafluoroethylene (PTFE) liner and statically crystallized at 160°C for 144 hours. The mixture was then removed, cooled, filtered, and dried at 80°C to obtain the raw molecular sieve powder. The resulting mixture was then calcined at 500°C in air for 12 hours to obtain the micro-mesoporous composite NaDZSM-23-1 molecular sieve.

[0106] (2) Ammonium exchange

[0107] A certain amount of NaDZSM-23-1 molecular sieve sample was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80-90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an oven at 80-100°C for 8 hours and calcined in air at 550°C for 3 hours to obtain H-DZSM-23-1. Its relative crystallinity was measured by XRD. The relative crystallinity after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0108] (3) Catalyst preparation

[0109] Macroporous alumina (specific surface area 408 m 2 / g, pore volume 0.87 cm 3 / g), 10 wt% H-DZSM-23-1 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 30, unit cell parameter of 2.466, specific surface area of ​​801 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 22 wt% WO3 and 6 wt% NiO by conventional equal volume impregnation. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain catalyst DC-1. Specific properties are shown in Table 2.

[0110] Comparative Example 2

[0111] (1) Molecular sieve sample preparation

[0112] Water glass, aluminum sulfate, isopropylamine (IPA), sodium hydroxide and water were mixed to prepare a gel with a total molar ratio of SiO2 in the silicon source: Al2O3 in the aluminum source: NaOH: IPA: H2O = 1:0.01:0.08:1.0:50. After heating at 180°C for 72 hours, the product was filtered, washed, dried and calcined to obtain a product named Na-DZSM-23-2.

[0113] (2) Ammonium exchange

[0114] A certain amount of NaDZSM-23-2 molecular sieve sample was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80-90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an oven at 80-100°C for 8 hours and calcined at 550°C in air for 3 hours to obtain H-DZSM-23-2. The relative crystallinity of the H-DZSM-23-2 was determined by XRD. The relative crystallinity of the H-DZSM-23-2 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0115] (3) Catalyst preparation

[0116] Macroporous alumina (specific surface area 408 m 2 / g, pore volume 0.87 cm 3 / g), 10 wt% H-DZSM-23-2 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 30, unit cell parameter of 2.466, specific surface area of ​​801 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 22 wt% WO3 and 6 wt% NiO by conventional equal volume impregnation. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain catalyst DC-2. Specific properties are shown in Table 2.

[0117] Comparative Example 3

[0118] Macroporous alumina (specific surface area 408 m 2 / g, pore volume 0.87 cm 3 / g), 27wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 30, unit cell parameter of 2.466, specific surface area of ​​801 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and modified Y molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 22 wt% WO3 and 6 wt% NiO by conventional equal volume impregnation. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain catalyst DC-3. Specific properties are shown in Table 2.

[0119] Table 1

[0120]

[0121] Table 2

[0122]

[0123] The catalytic performance of the above-mentioned catalysts C-1, C-2, C-3, C-4, and C-5 of the present invention and the comparative catalysts DC-1, DC-2, and DC-3 were evaluated. The reactions were carried out in a fixed-bed reactor under the following conditions: a pressure of 10.0 MPa, a hydrogen-to-oil volume ratio of 1000, and a liquid volume space velocity of 1.2 h -1 , using inferior diesel as raw oil, its properties are shown in Table 3, and the reaction results are shown in Table 4.

[0124] Analysis of the reaction results in Table 4 shows that, under the same process conditions, the catalyst of the present invention has better diesel yield and quality than the reference catalyst.

[0125] Table 3

[0126]

[0127] Table 4

[0128]

Claims

1. A catalyst for hydro-reforming of low-quality diesel fuel rich in cyclic hydrocarbons, characterized by: Based on the weight of the final catalyst, it includes the following components: a) HZSM-23 molecular sieve, content of 5~25 wt%; b) modified Y molecular sieve, with a content of 5 to 35 wt%; c) macroporous alumina, with a content of 15-65 wt%; d) the active component is one or more metal oxides of Group VIB and Group VIII, wherein the content of the Group VIB metal as oxide is 10-30 wt%, and the content of the Group VIII metal as oxide is 3-15 wt%; The mesopores in the catalyst have a pore size of 3-6 nm and account for 38-60% of the total pore volume; The properties of the HZSM-23 molecular sieve are as follows: the mesopore volume with a pore size of 3 to 6 nm accounts for 45 to 90% of the total pore volume of the molecular sieve, the relative crystallinity is 95 to 120%, and the relative crystallinity after hydrothermal treatment with steam at 600°C for 2 hours is 95 to 110%; The specific surface area of ​​the HZSM-23 molecular sieve is 300~430m 2 / g, pore volume is 0.31~0.5cm 3 / g, micropore specific surface area is 50~140m 2 / g, and the mesopore specific surface area is 181~310m 2 / g; The properties of the modified Y molecular sieve are as follows: SiO2 / Al2O3 molar ratio is 10-60, unit cell parameters are 2.460-2.470, specific surface area is 700-850 m 2 / g, pore volume is 0.40~0.60cm 3 / g.

2. The catalyst according to claim 1, characterized in that: The mesopores in the catalyst have a pore size of 3-6 nm and account for 40-55% of the total pore volume.

3. The catalyst according to claim 1, characterized in that: The specific surface area of ​​the catalyst is 270~434 m 2 / g, pore volume is 0.32~0.83 cm 3 / g.

4. The catalyst according to claim 3, characterized in that: The specific surface area of ​​the catalyst is 310~425 m 2 / g, pore volume of 0.38~0.80 cm 3 / g.

5. The catalyst according to claim 1, characterized in that: Based on the weight of the final catalyst, it includes the following components: a) HZSM-23 molecular sieve, content of 5~22 wt%; b) modified Y molecular sieve, content of 7~28 wt%; c) Macroporous alumina, content of 18~60 wt%.

6. The catalyst according to claim 1, characterized in that: The properties of the HZSM-23 molecular sieve are as follows: the mesopore volume with a pore diameter of 3 to 6 nm accounts for 50 to 85% of the total pore volume of the molecular sieve.

7. The catalyst according to claim 1, characterized in that: The properties of the HZSM-23 molecular sieve are as follows: the mesopore volume with a pore diameter of 3 to 6 nm accounts for 55 to 81% of the total pore volume of the molecular sieve.

8. The catalyst according to claim 1, characterized in that: The specific surface area of ​​the HZSM-23 molecular sieve is 320~405m 2 / g, pore volume is 0.34~0.45cm 3 / g, micropore specific surface area is 80~140m 2 / g, and the mesopore specific surface area is 181~295m 2 / g.

9. The catalyst according to claim 1, characterized in that: The properties of the macroporous alumina are: specific surface area 375~450 m 2 / g, pore volume 0.74~1.15 cm 3 / g.

10. The catalyst according to claim 9, characterized in that: The properties of the macroporous alumina are: specific surface area 390~430 m 2 / g, pore volume 0.78~1.10 cm 3 / g.

11. The catalyst according to claim 1, characterized in that: The active component of the Group VIB metal is tungsten and / or molybdenum, and the Group VIII metal is nickel and / or cobalt.

12. A method for preparing a catalyst for hydro-reforming of low-quality diesel fuel rich in cyclic hydrocarbons according to any one of claims 1 to 11, characterized in that: The method includes support preparation and active metal loading. The support is prepared by mixing HZSM-23 molecular sieve, modified Y molecular sieve, macroporous alumina and a binder, forming, and then drying and calcining to obtain the support. The preparation steps of the HZSM-23 molecular sieve are as follows: (1) preparing or selecting amorphous silicon dioxide; (2) alkaline treatment of amorphous silica; (3) Preparation of NaZSM-23 molecular sieve using alkali-treated amorphous silica as silicon source; (4) The molecular sieve obtained in (3) is subjected to ammonium exchange to obtain HZSM-23 molecular sieve.

13. The method according to claim 12, wherein: In step (2), the alkali treatment is to add the amorphous silica prepared in step (1) into an alkaline solution and heat and stir.

14. The method according to claim 13, wherein: The alkali treatment adopts inorganic alkali treatment, and the inorganic alkali is one or more of sodium hydroxide, potassium hydroxide or ammonia water. The heating and stirring time of the alkali treatment is 0.5 to 12 hours; and the heating temperature is 25 to 60°C.

15. The method according to claim 14, characterized in that: The alkali treatment heating and stirring time is 2 to 8 hours; the heating temperature is 30 to 50°C.

16. Use of the catalyst according to any one of claims 1 to 11 in the hydro-reforming of low-quality diesel rich in cyclic hydrocarbons, characterized in that: The low-quality diesel rich in cyclic hydrocarbons has a cyclic hydrocarbon content of 15-30% by mass, a paraffin content of 6-20% by mass, and an aromatic hydrocarbon content of 55-70% by mass.

17. The use according to claim 16, characterized in that: The low-quality diesel rich in cyclic hydrocarbons has a cyclic hydrocarbon content of 17-28% by mass, a paraffin content of 7-18% by mass, and an aromatic hydrocarbon content of 57-68% by mass.

18. The use according to claim 16, characterized in that: The properties of the low-quality diesel rich in cyclic hydrocarbons are as follows: diesel density is 0.930~0.980 g / cm 3 , distillation range 180~400 ℃, S mass content is 0.5~1.8%, N mass content is 500~1500 μg / g, and cetane number is 10~25.

19. The use according to claim 16, characterized in that: The reaction conditions are as follows: reaction temperature 350~400℃, total reaction pressure 4~12 MPa, liquid hourly space velocity 0.4~2 h -1 , hydrogen-oil volume ratio 400:1~1200:1.

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