A diesel hydro-upgrading catalyst rich in paraffins, its preparation method and application

Abstract

The present invention discloses a paraffin-rich diesel hydroreforming catalyst, a preparation method thereof, and an application thereof, wherein the catalyst has a total acid content of 0.100 to 0.170 mmol / g, preferably 0.105 to 0.165 mmol / g; and a weak acid content of 32 to 52%, preferably 34 to 50%. The catalyst preparation method comprises the following steps: (1) preparing an HZSM-23 molecular sieve, wherein the HZSM-23 molecular sieve has a total acid content of 0.12 to 0.25 mmol / g and a weak acid content of 55 to 80%; preferably, the total acid content is 0.14 to 0.24 mmol / g and the weak acid content is 57 to 78%. (2) mixing and shaping the HZSM-23 molecular sieve prepared in step (1), macroporous alumina, and a binder, drying, and calcining to obtain a carrier; and (3) introducing an active component into the carrier obtained in step (2), and drying and calcining to obtain a final catalyst. The catalyst is used for hydrogenation reforming of paraffin-rich diesel, which can improve the diesel yield while increasing the cetane number of the diesel and effectively lowering its pour point.

Description

Technical Field

[0001] The present invention relates to a catalyst for hydrogenating and reforming paraffin-rich diesel fuel, a preparation method and an application thereof, and in particular to a catalyst for hydrogenating and reforming paraffin-rich diesel fuel to produce more low-freezing-point diesel fuel, a preparation method and an application thereof. Background Art

[0002] With the continued growth of my country's national economy and the continuous improvement of people's living standards, the demand for low-freezing-point diesel in cold regions or the northern winter market continues to increase. At the same time, with the accelerated pace of diesel quality upgrades, the country's requirements for diesel product properties are becoming increasingly stringent. Low-freezing-point diesel's pour point, cold filter plugging point, sulfur content, polycyclic hydrocarbon content, cetane number, and other characteristics must all meet national emission standards. Therefore, the process technology for producing clean diesel continues to face new challenges.

[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 widely used due to their excellent acidity and stability.

[0004] CN1184843A discloses a diesel hydroconversion catalyst using a mixture of Y molecular sieve, alumina, and amorphous silica-alumina as a support with a SiO2 / Al2O3 molar ratio of 7 to 15. The diesel hydroconversion catalyst support disclosed in CN10146327A primarily contains Y molecular sieve and amorphous silica-alumina as active components. However, while using Y molecular sieve as the primary active component of the catalyst support exhibits good desulfurization and denitrification activity, it also results in low diesel product yield and minimal quality improvement.

[0005] CN107233913B discloses a catalyst carrier for hydro-reforming low-quality diesel fuel, comprising a modified β molecular sieve with a silicon-aluminum molar ratio of 50-70, amorphous silicon-aluminum, macroporous alumina, and SB powder. The β molecular sieve requires a series of modification steps, including dealumination, siliconization, hydrothermal treatment, and finally treatment with a mixed solution of aluminum salt and acid, to achieve the desired acidic properties and pore structure. This complex process results in a high product loss rate.

[0006] The hydroreforming catalyst support disclosed in CN111318312 utilizes a Y-β composite molecular sieve loaded with an organosilane as the primary acidic component, with the Y molecular sieve having a SiO2 / Al2O3 molar ratio of 8-55 and the β molecular sieve having a SiO2 / Al2O3 molar ratio of 35-155. However, when the Y molecular sieve and the β molecular sieve 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 the pore structure and acidity matching of the two. Therefore, although the catalyst exhibits good desulfurization and denitrification activity, it still leads to problems such as low diesel product yield and high pour point.

[0007] Hydrodeposition technology and isomerization technology are commonly used to improve the low-temperature fluidity of oil products. Hydrodeposition technology uses ZSM-5-type shape-selective molecular sieves as the main active component to shape-selectively crack the long-chain normal alkanes in the diesel component into light components to achieve deposition. However, it also suffers from problems such as low diesel yield and a small increase in the cetane number of the diesel product. Isomeration technology mainly uses molecular sieves such as SAPO-11, ZSM-22, and ZSM-23 loaded with precious metals. In a two-stage process, it isomerizes long-chain normal alkanes into branched alkanes, thereby lowering the pour point. However, this series of molecular sieves synthesized by existing conventional technologies have limited effect on improving the cetane number of diesel due to problems such as acid strength and acid site distribution. In addition, the price and cost of precious metals are high, which limits the scope of application.

[0008] Therefore, it is necessary to develop a diesel hydro-reforming catalyst that can improve the quality of diesel while ensuring the diesel yield and meet the market demand for high-quality diesel. Summary of the Invention

[0009] In order to overcome the deficiencies in the prior art, the present invention provides a catalyst for hydrogenation and reforming of paraffin-rich diesel, as well as a preparation method and application thereof. The catalyst is used for hydrogenation and reforming of paraffin-rich diesel, which can not only ensure an increase in diesel yield, but also increase the cetane number of diesel and effectively lower its pour point.

[0010] The first aspect of the present invention provides a paraffin-rich diesel hydro-reforming catalyst, which comprises the following components based on the weight of the final catalyst:

[0011] a) HZSM-23 molecular sieve, with a content of 10 to 55 wt%, preferably 12 to 52 wt%;

[0012] b) macroporous alumina, with a content of 15 to 75 wt%, preferably 18 to 70 wt%;

[0013] c) 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%;

[0014] The total acid content of the catalyst is 0.100-0.170 mmol / g, preferably 0.105-0.165 mmol / g; the weak acid content is 32-52%, preferably 34-50%.

[0015] In the catalyst of the present invention, the specific surface area of the catalyst is 200-350 m 2 / g, preferably 215~320 m 2 / g; pore volume is 0.20~0.60 cm 3 / g, preferably 0.26~0.55 cm 3 / g.

[0016] 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.

[0017] The second aspect of the present invention is to provide a method for preparing a paraffin-rich diesel hydro-reforming catalyst, the method comprising the following steps:

[0018] (1) Preparing HZSM-23 molecular sieve, wherein the total acid amount of the HZSM-23 molecular sieve is 0.12-0.25 mmol / g and the weak acid content is 55-80%; preferably, the total acid amount is 0.14-0.24 mmol / g and the weak acid content is 57-78%.

[0019] (2) mixing the HZSM-23 molecular sieve, macroporous alumina and binder prepared in step (1), forming, drying and calcining to obtain a carrier;

[0020] (3) The active component is introduced into the carrier obtained in step (2), and the final catalyst is obtained after drying and calcination.

[0021] In the method of the present invention, the HZSM-23 molecular sieve prepared in step (1) has a relative crystallinity of 95-120%, and the relative crystallinity after steam hydrothermal treatment is 93-115%; preferably, the relative crystallinity is 98-116%, and the relative crystallinity after steam hydrothermal treatment is 95-114%.

[0022] In step (1) of the method of the present invention, the properties of the HZSM-23 molecular sieve are as follows: a grain size of 100-700 nm, a SiO2 / Al2O3 molar ratio of 40-150, a specific surface area of 200-400 m 2 / g, pore volume of 0.25~0.50 cm 3 / g, preferably, the HZSM-23 molecular sieve has the following properties: a grain size of 200-500 nm, a SiO2 / Al2O3 molar ratio of 50-120, a specific surface area of 280-370 m 2 / g, pore volume 0.28~0.46 cm 3 / g.

[0023] In the method of the present invention, the properties of the macroporous alumina in step (2) are: a specific surface area of 375-430 m 2 / g, pore volume 0.74~1.05 cm 3 / g; preferably a specific surface area of 380~420 m2 / g, pore volume 0.75~1.00 cm 3 / g.

[0024] In the method of the present invention, the carrier in step (2) is dried and calcined by conventional methods, specifically as follows: the calcination temperature is 500-600°C and the time is 2-8 hours, preferably 530-570°C for 3-6 hours.

[0025] In the method of the present invention, in the method of introducing the active metal in step (3), a conventional loading method in the prior art can be adopted, preferably an impregnation method. After impregnation, the catalyst is dried at 80-120°C for 4-10 hours and then calcined at 400-600°C for 3-6 hours to obtain the final catalyst.

[0026] The catalyst is used for hydro-reforming of paraffin-rich diesel, wherein the paraffin content of the paraffin-rich diesel is 27-70%, preferably 30-67% by mass; the cycloparaffin content is 3-14%, preferably 5-12% by mass; and the aromatic content is 25-57%, preferably 27-55%.

[0027] In the above application, the properties of the paraffin-rich diesel are: density 0.850~0.905 g / cm 3 , preferably 0.850~0.900 g / cm 3 The distillation range is 140~370 ℃, the mass content of S is 0.3~1.5%, the mass content of N is 300~1000 μg / g, and the cetane number is 18~35.

[0028] In the above application, the reaction conditions of the hydro-reforming are: reaction temperature 350-390 °C, total reaction pressure 5-12 MPa, liquid hourly space velocity 0.4-2 h -1 , hydrogen-oil volume ratio 400:1~1200:1.

[0029] A method for hydroreforming paraffin-rich diesel, wherein the catalyst used contains HZSM-23 molecular sieve, wherein the HZSM-23 molecular sieve has a total acid content of 0.12-0.25 mmol / g, a weak acid content of 55-80%, a relative crystallinity of 95-120%, and a relative crystallinity of 93-115% after water vapor hydrothermal treatment; preferably, the total acid content is 0.14-0.24 mmol / g, the weak acid content is 57-78%, the relative crystallinity is 98-116%, and the relative crystallinity after water vapor hydrothermal treatment is 95-114%.

[0030] Compared with the prior art, the present invention provides a paraffin-rich diesel hydro-reforming catalyst and its preparation method and application, which have the following beneficial technical effects:

[0031] (1) In the catalyst composition of the present invention, the selected HZSM-23 molecular sieve has more weak acid sites and low strong acid content. Therefore, the weak acid content of the prepared catalyst is higher than that of conventional catalysts, the strong acid content is appropriate and it has a larger specific surface area. When treating low-quality diesel with high paraffin content and low cycloparaffin and cycloaromatic content, the cycloparaffins, polycyclic aromatic hydrocarbons and other components in the raw material can undergo ring opening and cracking at the strong acid sites, and the paraffins in the raw material and the cracked paraffins can undergo hydrogenation isomerization reaction at the weak acid sites without excessive cracking to generate light components, thereby ensuring the diesel yield while improving the cetane number of the product, significantly reducing the pour point of diesel, and improving the quality of diesel products;

[0032] (2) When the catalyst of the present invention is used for hydro-modification of low-quality diesel, it can significantly improve product quality while ensuring the yield of the target product. The yield of the target product, modified diesel, can reach 97.7%, the cetane number can reach 53.1, and the pour point can be as low as -30°C. DETAILED DESCRIPTION

[0033] In order to better illustrate the present invention, the present invention is further illustrated below in conjunction with Examples and Comparative Examples. However, the scope of the present invention is not limited to the scope of these Examples.

[0034] In the present invention, the specific surface area and pore volume are measured by using a low-temperature liquid nitrogen physical adsorption method using an ASAP 2405 physical adsorption instrument produced by Micromeritics Corporation of the United States.

[0035] The silicon to aluminum molar ratio was determined by chemical analysis.

[0036] XRD patterns of the samples were collected using a Dmax2500 X-ray diffractometer manufactured by Rigaku Corporation. The relative crystallinity of the molecular sieves was determined by X-ray powder diffraction (XRD). Specifically, the sum of the heights of the diffraction peaks at approximately 11.3 and 19.5-23° 2θ in the XRD spectrum of the HZSM-23 molecular sieve prepared in Comparative Example 1 was used as a benchmark, with the crystallinity of 100%. The relative crystallinity of the other samples was compared with this. The relative crystallinity was measured after calcining the dried HZSM-23 in air at 550°C for 3 hours; the relative crystallinity was again measured after hydrothermally treating the calcined HZSM-23 molecular sieve with steam at 600°C for 2 hours.

[0037] The grain size was obtained by a JSM-7500F field emission scanning electron microscope from JEOL, Japan.

[0038] The grain size was obtained by a JSM-7500F field emission scanning electron microscope from JEOL, Japan.

[0039] The acid distribution (including total acid content and weak acid content) was measured by NH3 temperature-programmed desorption (NH3-TPD), where the acid sites corresponding to the desorption temperature between 120 and 500 °C were regarded as the total acid content, the acid sites corresponding to the desorption temperature below 350 °C were regarded as weak acid sites, and the acid sites corresponding to the desorption temperature above 350 °C were regarded as strong acid sites.

[0040] In the present invention, wt% refers to mass fraction and v% refers to volume fraction.

[0041] In the present invention, the preparation of ZSM-23 molecular sieve refers to the preparation method of CN202210011752.2, and the specific preparation steps of the HZSM-23 molecular sieve are as follows:

[0042] (1) preparing a mixed solution containing a structure directing agent, amorphous silicon aluminum or an amorphous silicon aluminum precursor;

[0043] (2) adding a supplementary silicon source to the material of step (1);

[0044] (3) The material of step (2) is crystallized, filtered, washed, dried and calcined to obtain sodium ZSM-23 molecular sieve.

[0045] (4) The molecular sieve obtained in (3) is subjected to ammonium exchange to obtain HZSM-23 molecular sieve.

[0046] In step (1) of the above method, the structure directing agent is one or more of isopropylamine, pyrrolidine, N,N-dimethylformamide, and dimethylamine.

[0047] In step (1) of the above method, the molar ratio of silicon (calculated as silicon oxide) to aluminum (calculated as aluminum oxide) in the mixed solution is 1: (0.10-0.85), preferably 1: (0.20-0.79), and more preferably 1: (0.24-0.78); the molar ratio of aluminum (calculated as aluminum oxide) to structure directing agent is 1: (10-100), preferably 1: (15-85), and more preferably 1: (20-65).

[0048] In step (1) of the above method, a carbonization method is used to prepare an amorphous silicon-aluminum precursor mixture, and then a structure directing agent is added to the amorphous silicon-aluminum precursor mixture.

[0049] A non-limiting process for preparing an amorphous silicon-aluminum precursor mixture in an embodiment of the present invention is as follows: prepare an aluminum source (preferably sodium aluminate) solution and a silicon-containing compound solution separately; mix the sodium aluminate solution with part of the silicon-containing compound solution, and introduce CO2 gas to form a gel; when the volume of the introduced CO2 gas accounts for 50~100% of the total volume introduced, preferably 70~90%, add the remaining part of the silicon-containing compound solution, and then introduce the remaining CO2 gas, and optionally age it to obtain an amorphous silicon-aluminum precursor mixture.

[0050] During the preparation of the amorphous silicon-aluminum precursor mixed solution, the remaining portion of the silicon-containing compound solution, calculated as silicon dioxide, accounts for 5 to 85 wt %, preferably 30 to 70 wt %, of the total amount of the added silicon-containing compound solution, calculated as silicon dioxide.

[0051] During the preparation of the amorphous silicon-aluminum precursor mixture, the reaction temperature for gelation is 10-40°C, preferably 15-35°C, and the pH value after gelation is controlled to be 9-12.

[0052] During the preparation of the amorphous silicon-aluminum precursor mixed solution, the silicon-containing compound solution is water glass and / or sodium silicate solution.

[0053] During the preparation of the above-mentioned amorphous silicon-aluminum precursor mixture, the concentration of the aluminum source solution is 15~60 g Al2O3 / L based on the mass of Al2O3, the concentration of the silicon-containing compound solution is 40~260 g SiO2 / L based on the mass of SiO2, and the concentration of the CO2 gas is 30~60 v%.

[0054] During the preparation of the amorphous silicon-aluminum precursor mixture, the aging time is 5 to 60 minutes, preferably 10 to 30 minutes; and the aging temperature is 10 to 40°C, preferably 15 to 35°C.

[0055] In step (1) of the above method, the mixed solution is stirred at 10-35°C for 0.2-1.5 hours, preferably at 10-25°C for 0.5-1 hour.

[0056] In step (2) of the above method, based on the aluminum (calculated as alumina) in the mixed solution of step (1), a supplementary silicon source is added to the material of step (1) at a total feed molar ratio of SiO2:Al2O3:H2O=1:(0.008~0.025):(30~60) and SDA (structure directing agent) / SiO2=0.10~1.8.

[0057] In step (2) of the above method, the silicon source is one or more of fumed silica, silica sol and water glass.

[0058] In step (3) of the above method, the crystallization conditions are: crystallization at 160-180°C for 10-48 hours; drying temperature at 80-120°C for 4-8 hours; and calcination temperature at 500-600°C for 2-8 hours.

[0059] 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 HZSM-23 molecular sieve after ammonium exchange is less than 0.1%; washing, drying and calcination can then 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.

[0060] In the preparation method of the present invention, especially when preparing the sodium ZSM-23 molecular sieve, all the aluminum sources required for synthesis are added during the preparation of the amorphous silicon-aluminum precursor, which promotes the generation of the primary structural unit of the molecular sieve; when a structure directing agent is added to the amorphous silicon-aluminum precursor, the structure directing agent preferentially chelates with the Al species and is then adsorbed on the surface of the formed primary structural unit to achieve pre-assembly of the molecular sieve structure and generate a large number of crystal nuclei; at the same time, the binding sites of the Al atoms can be better controlled, which helps to obtain sodium ZSM-23 with more weak acid sites through later crystallization. After the addition of the silicon source to form the final gel, a large number of crystal nuclei can be rapidly grown into a sodium ZSM-23 molecular sieve with high crystallinity and small grain size through static crystallization. The molecular sieve has more weak acid sites, which are in a suitable ratio with the strong acid content, and has good thermal stability and hydrothermal stability. After ammonium exchange, it can be directly used in the diesel reforming reaction, and is an excellent catalytic material.

[0061] Example 1

[0062] (1) Preparation of amorphous silicon aluminum precursor

[0063] Prepare a sodium aluminate working solution with a concentration of 40 g Al₂O₃ / L. Take a sodium silicate solution containing 28 wt% SiO₂ and dilute it to a sodium silicate working solution with a concentration of 100 g SiO₂ / L. Place 150 mL of the sodium aluminate working solution in a gelling tank, then add 50 mL of the sodium silicate working solution. Control the reaction temperature at 20°C and introduce 50 vol% CO₂ gas. Stop the CO₂ flow when the pH reaches 10.0, then add 90 mL of the sodium silicate working solution. Continue bubbling with the remaining CO₂ gas to stabilize the mixture. After aging at 25°C for 30 minutes, an amorphous alumina-silica precursor is obtained. The amorphous alumina-silica precursor contains 70 wt% silica, based on the total weight of silica and alumina.

[0064] (2) Preparation of gel

[0065] According to the total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.02: 0.04: 0.7: 45 (IPA is the structure-directing agent isopropylamine), isopropylamine is added to the amorphous silica-alumina precursor obtained in step (1), and stirred at 15 ° C for 0.8 hours; then, a mixture consisting of silica sol and water is added thereto and stirred evenly to obtain silica-alumina gel.

[0066] (3) Crystallization

[0067] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 160°C for 20 hours. After the crystallization, the gel was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain molecular sieve raw powder.

[0068] (4) Ammonium exchange

[0069] A certain amount of molecular sieve powder 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 HZSM-23-1. The relative crystallinity of the HZSM-23-1 was measured by XRD. The relative crystallinity of the HZSM-23-1 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0070] (2) Catalyst preparation

[0071] The macroporous alumina (specific surface area 392 m 2 / g, pore volume 0.96 cm 3 / g), 30wt% HZSM-23-1 molecular sieve, 1% sesbania powder (compared to the total weight of alumina and HZSM-23-1 molecular sieve), and a 1% nitric acid aqueous solution were mixed and ground. Water was added, pressed into a paste, and 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 support strips. The support strips were loaded with 22 wt% WO3 and 6 wt% NiO using a conventional equal volume impregnation method. The support strips were added to a pre-prepared impregnation solution equal to the water absorption capacity of the support, 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.

[0072] Example 2

[0073] (1) Preparation of amorphous silicon aluminum precursor

[0074] A sodium aluminate working solution with a concentration of 40 g Al2O3 / L was prepared. A sodium silicate solution containing 28 wt% SiO2 was diluted to a sodium silicate working solution with a concentration of 150 g SiO2 / L. 200 mL of the sodium aluminate working solution was placed in a gelling tank, followed by the addition of 40 mL of the sodium silicate working solution. The reaction temperature was controlled at 25°C, and 50% CO2 gas was introduced. When the pH reached 10.5, the CO2 flow was stopped, and 40 mL of the sodium silicate working solution was added. The remaining CO2 gas was then introduced for stabilization. After aging at 20°C for 20 minutes, an amorphous silicon-alumina precursor was obtained. The amorphous silicon-alumina precursor had a silicon dioxide content of 60 wt%, based on the total weight of silicon dioxide and aluminum oxide.

[0075] (2) Preparation of gel

[0076] Isopropylamine was added to the amorphous silica-alumina precursor obtained in step (1) at a total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.01: 0.04: 0.15: 60, and the mixture was stirred at 20°C for 1 hour; thereafter, a mixture consisting of silica sol and water was added thereto and stirred uniformly to obtain silica-alumina gel.

[0077] (3) Crystallization

[0078] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 180°C for 18 hours. After the crystallization, the gel was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain molecular sieve raw powder.

[0079] (4) Ammonium exchange

[0080] A certain amount of molecular sieve powder 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.

[0081] (5) Catalyst preparation

[0082] Macroporous alumina (specific surface area 418 m 2 / g, pore volume 0.99 cm 3 / g), 52 wt% HZSM-23-2 molecular sieve, 1% sesbania powder (compared to the total weight of alumina and HZSM-23-2 molecular sieve), and a 1% nitric acid aqueous solution were mixed and ground, water was added, and the mixture was rolled into a paste, which was then extruded. 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 using a conventional equal volume impregnation method. 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-2. Specific properties are shown in Table 2.

[0083] Example 3

[0084] (1) Preparation of amorphous silicon aluminum precursor

[0085] Prepare a sodium aluminate working solution with a concentration of 20 g Al2O3 / L. Take a sodium silicate solution containing 28 wt% SiO2 and dilute it to a sodium silicate working solution with a concentration of 150 g SiO2 / L. Place 300 mL of the sodium aluminate working solution in a gelling tank, then add 20 mL of the sodium silicate working solution. Control the reaction temperature at 30°C and introduce 50 vol% CO2 gas. Stop the CO2 flow when the pH reaches 11.0, then add another 20 mL of the sodium silicate working solution. Continue bubbling with the remaining CO2 gas to stabilize the mixture. After aging at 20°C for 30 minutes, an amorphous silicon-alumina precursor is obtained. The amorphous silicon-alumina precursor contains 50 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0086] (2) Preparation of gel

[0087] Isopropylamine was added to the amorphous silica-alumina precursor obtained in step (1) at a total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.025: 0.3: 45, and the mixture was stirred at 15°C for 1 hour; thereafter, a mixture consisting of silica sol and water was added thereto and stirred uniformly to obtain silica-alumina gel.

[0088] (3) Crystallization

[0089] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 180°C for 24 hours. After the crystallization, the gel was filtered, washed until neutral, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain the molecular sieve raw powder.

[0090] (4) Ammonium exchange and template removal agent

[0091] A certain amount of molecular sieve powder 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 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0092] (5) Catalyst preparation

[0093] Macroporous alumina (specific surface area 382 m 2 / g, pore volume 0.91 cm 3 / g), 12 wt% HZSM-23-3 molecular sieve, 1% sesbania powder (compared to the total weight of alumina and HZSM-23-3 molecular sieve), and a 1% nitric acid aqueous solution were mixed and ground, water was added, and the mixture was rolled into a paste, which was then extruded. 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 using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal to the water absorption capacity of the carrier was added, the mixture was 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.

[0094] Example 4

[0095] (1) Preparation of amorphous silicon aluminum precursor

[0096] Prepare a sodium aluminate working solution with a concentration of 40 g Al₂O₃ / L. Take a sodium silicate solution containing 28 wt% SiO₂ and dilute it to a sodium silicate working solution with a concentration of 50 g SiO₂ / L. Place 150 mL of the sodium aluminate working solution in a gelling tank, then add 140 mL of the sodium silicate working solution. Control the reaction temperature at 20°C and introduce 50 vol% CO₂ gas. When the pH reaches 10.0, stop the CO₂ flow and add another 140 mL of the sodium silicate working solution. Continue bubbling with the remaining CO₂ gas to stabilize the mixture. After aging at 25°C for 20 minutes, an amorphous alumina-silica precursor is obtained. The amorphous alumina-silica precursor contains 70 wt% silica, based on the total weight of silica and alumina.

[0097] (2) Preparation of gel

[0098] Isopropylamine was added to the amorphous alumina-silica precursor obtained in step (1) at a total feed molar ratio of Al2O3: SiO2: IPA: H2O = 1: 0.02: 0.4: 45, and the mixture was stirred at 15°C for 1 hour; thereafter, a mixture of fumed silica and water was added thereto, and the mixture was stirred evenly to obtain alumina-silica gel.

[0099] (3) Crystallization

[0100] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 180°C for 12 hours. After the crystallization, the gel was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain the molecular sieve raw powder.

[0101] (4) Ammonium exchange

[0102] A certain amount of molecular sieve powder 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-23-4. 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.

[0103] (5) Catalyst preparation

[0104] Macroporous alumina (specific surface area 382 m 2 / g, pore volume 0.91 cm 3 / g), 12 wt% HZSM-23-4 molecular sieve, 1% sesbania powder (compared to the total weight of alumina and HZSM-23-4 molecular sieve), and a 1% 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 support strips. The support strips were loaded with 14 wt% WO3 and 4 wt% NiO using a conventional equal volume impregnation method. The support strips were added to a pre-prepared impregnation solution equal to the water absorption capacity of the support, 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.

[0105] Comparative Example 1 (Refer to CN101214971A)

[0106] A reaction mixture was prepared using a molar ratio of Al2O3 from the aluminum source: SiO2 from the silicon source: NaOH from the alkali source: isopropylamine: H2O of 0.02:1:0.06:0.8:12. The aluminum source was sodium metaaluminate, the silicon source was silica sol, and the alkali source was sodium hydroxide. First, the aluminum source was added to an aqueous sodium hydroxide solution and stirred evenly. The silicon source was added and stirred evenly. Finally, isopropylamine was added and stirred evenly to obtain a reaction mixture. The resulting reaction mixture was transferred to an autoclave and hydrothermally crystallized at 170°C for 3 days. The mixture was then filtered, washed until neutral, and dried at 120°C to obtain the raw molecular sieve powder.

[0107] A certain amount of molecular sieve powder 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-CNZSM-23-1. Its relative crystallinity was determined by XRD. The relative crystallinity of H-CNZSM-23-1 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0108] Macroporous alumina (specific surface area 392 m2) accounting for 28% of the catalyst weight 2 / g, pore volume 0.96 cm 3 / g), 71.3% H-CNZSM-23-1 molecular sieve, 1% sesbania powder (compared to the total weight of alumina and HCNZSM-23-1 molecular sieve), and a 1% nitric acid aqueous solution were mixed, ground, and water was added. The mixture was rolled into a paste and 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 using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal to the water absorption capacity of the carrier was added, the mixture was 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.

[0109] Comparative Example 2 (refer to CN102992346A)

[0110] 8.12 g of H₂O and 0.19 g of aluminum sulfate were mixed evenly, followed by the addition of 0.46 g of NaOH. Then, while stirring, 3.32 g of silica sol with a 30.5% silica content was added. Stirring was continued until the solution became homogeneous, and 10% ZSM-23 molecular sieve was added as seed crystals (the seed amount was calculated as a percentage of the mass of the SiO₂ input). The raw materials were added to a Teflon-lined stainless steel reactor and subjected to dynamic crystallization at 160°C for 10 hours. The product was then filtered and dried to obtain the product. The raw material ratio was SiO₂: 0.017 Al₂O₃: 0.32 Na₂O: 35 H₂O.

[0111] A certain amount of the above 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-CNZSM-23-2. The relative crystallinity of the H-CNZSM-23-2 was determined by XRD. The relative crystallinity of the H-CNZSM-23-2 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0112] The macroporous alumina (specific surface area 392 m2) accounting for 42% of the catalyst weight 2 / g, pore volume 0.96 cm 3 / g), 30% H-CNZSM-23-2 molecular sieve, 1% sesbania powder (compared to the total weight of alumina and H-CNZSM-23-2 molecular sieve), and a 1% nitric acid aqueous solution were mixed and ground, water was added, and the mixture was rolled into a paste, which was then extruded. 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 using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal to the water absorption capacity of the carrier was added, the mixture was 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.

[0113] Comparative Example 3

[0114] (1) Preparation of amorphous silicon aluminum precursor

[0115] Prepare a sodium aluminate working solution with a concentration of 50 g Al2O3 / L. Take a sodium silicate solution containing 28 wt% SiO2 and dilute it to a sodium silicate working solution with a concentration of 100 g SiO2 / L. Place 200 mL of the sodium aluminate working solution in a gelling tank, then add 60 mL of the sodium silicate working solution. Control the reaction temperature at 30°C and introduce 50% CO2 gas. When the pH reaches 10.0, stop the CO2 flow and add 40 mL of the sodium silicate working solution. Aerate the mixture until the remaining CO2 gas is stable. After aging at 25°C for 30 minutes, an amorphous silicon-alumina precursor is obtained. The amorphous silicon-alumina precursor contains 50 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0116] (2) Preparation of gel

[0117] A mixture of silica sol, isopropylamine and water was added to the amorphous silica-alumina precursor obtained in step (1) at a total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.02: 0.4: 30, and the mixture was stirred evenly to obtain silica-alumina gel.

[0118] (3) Crystallization

[0119] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 160°C for 24 hours. After the crystallization, the gel was filtered, washed to neutrality, and dried at 120°C to obtain molecular sieve raw powder.

[0120] (4) Ammonium exchange

[0121] A certain amount of 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-CNZSM-23-3. Its relative crystallinity was determined by XRD. The relative crystallinity of H-CNZSM-23-3 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0122] (5) Catalyst preparation

[0123] The macroporous alumina (specific surface area 392 m2) accounting for 42% of the catalyst weight 2 / g, pore volume 0.96 cm 3 / g), 30% H-CNZSM-23-3 molecular sieve, 1% sesbania powder (compared to the total weight of alumina and H-CNZSM-23-3 molecular sieve), and a 1% 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 using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal to the water absorption capacity of the carrier was added, the mixture was 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.

[0124] Table 1

[0125]

[0126] aThe actual SiO2 / Al2O3 molar ratio was obtained from XRF test.

[0127] Table 2

[0128]

[0129] The catalytic performance of the above-mentioned catalysts C-1, C-2, C-3, and C-4 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: pressure of 10.0 MPa, light oil volume ratio of 800, liquid volume space velocity of 1.5 h -1 Catalytic diesel was used as the raw oil, the properties of which are shown in Table 3, and the reaction results are shown in Table 4.

[0130] 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.

[0131] Table 3

[0132]

[0133] Table 4

[0134]

Claims

1. A method for hydro-reforming of paraffin-rich diesel, characterized by: The paraffin-rich diesel hydroreforming catalyst is used, and based on the weight of the final catalyst, contains the following components: a) HZSM-23 molecular sieve, content of 10~55wt%; b) Macroporous alumina, content of 15~75wt%; c) 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 total acid content of the catalyst is 0.100-0.170 mmol / g; the weak acid content is 32-52%; The total acid content of the HZSM-23 molecular sieve is 0.12-0.25 mmol / g, and the weak acid content is 55-80%; The acid distribution was measured by NH3 temperature-programmed desorption, where the acid sites corresponding to the desorption temperature between 120 and 500 °C were regarded as the total acid content, and the acid sites corresponding to the desorption temperature below 350 °C were regarded as weak acid sites. The paraffin content of the paraffin-rich diesel is 27-70% by mass.

2. The method for hydro-reforming of paraffin-rich diesel according to claim 1, wherein: Based on the weight of the final catalyst, the content of HZSM-23 molecular sieve is 12-52 wt%.

3. The method for hydro-upgrading of paraffin-rich diesel according to claim 1, wherein: The content of macroporous alumina is 18-70 wt % based on the weight of the final catalyst.

4. The method for hydro-upgrading of paraffin-rich diesel according to claim 1, wherein: The total acid content of the catalyst is 0.105-0.165 mmol / g; and the weak acid content is 34-50%.

5. The method for hydro-reforming of paraffin-rich diesel according to claim 1, wherein: The specific surface area of the catalyst is 200~350m 2 / g; pore volume is 0.20~0.60cm 3 / g.

6. The method for hydro-upgrading of paraffin-rich diesel according to claim 5, wherein: The specific surface area of the catalyst is 215~320m 2 / g; pore volume is 0.26~0.55cm 3 / g.

7. The method for hydro-upgrading of paraffin-rich diesel according to claim 1, wherein: The active component of the Group VIB metal is tungsten and / or molybdenum, and the Group VIII metal is nickel and / or cobalt.

8. The method for hydro-upgrading of paraffin-rich diesel according to claim 1, wherein: The preparation method of the paraffin-rich diesel hydro-reforming catalyst comprises the following steps: (1) preparing HZSM-23 molecular sieve, wherein the total acid content of the HZSM-23 molecular sieve is 0.12-0.25 mmol / g and the weak acid content is 55-80%; (2) mixing the HZSM-23 molecular sieve, macroporous alumina and binder prepared in step (1), forming, drying and calcining to obtain a carrier; (3) The active component is introduced into the carrier obtained in step (2), and the final catalyst is obtained after drying and calcination.

9. The method for hydro-upgrading of paraffin-rich diesel according to claim 8, wherein: In step (1), the total acid content of the HZSM-23 molecular sieve is 0.14-0.24 mmol / g, and the weak acid content is 57-78%.

10. The method for hydro-reforming of paraffin-rich diesel according to claim 8, characterized in that: The HZSM-23 molecular sieve prepared in step (1) has a relative crystallinity of 95-120%, and a relative crystallinity of 93-115% after steam hydrothermal treatment.

11. The method for hydro-reforming of paraffin-rich diesel according to claim 10, characterized in that: The HZSM-23 molecular sieve prepared in step (1) has a relative crystallinity of 98-116%, and a relative crystallinity of 95-114% after steam hydrothermal treatment.

12. The method for hydro-reforming of paraffin-rich diesel according to claim 10, characterized in that: In step (1), the properties of the HZSM-23 molecular sieve are as follows: a grain size of 100-700 nm, a SiO2 / Al2O3 molar ratio of 40-150, a specific surface area of 200-400 m 2 / g, pore volume is 0.25~0.50cm 3 / g.

13. The method for hydro-reforming of paraffin-rich diesel according to claim 12, characterized in that: In step (1), the properties of the HZSM-23 molecular sieve are as follows: a grain size of 200-500 nm, a SiO2 / Al2O3 molar ratio of 50-120, and a specific surface area of 280-370 m 2 / g, pore volume 0.28~0.46cm 3 / g.

14. The method for hydro-reforming of paraffin-rich diesel according to claim 8, characterized in that: The properties of the macroporous alumina in step (2) are: specific surface area 375~430m 2 / g, pore volume 0.74~1.05cm 3 / g.

15. The method for hydro-reforming of paraffin-rich diesel according to claim 14, characterized in that: The properties of the macroporous alumina in step (2) are: specific surface area 380~420m 2 / g, pore volume 0.75~1.00cm 3 / g.

16. The method for hydro-upgrading of paraffin-rich diesel according to claim 8, characterized in that: In step (2), the calcination temperature is 500-600° C. and the calcination time is 2-8 hours.

17. The method for hydro-upgrading of paraffin-rich diesel according to claim 16, characterized in that: In step (2), the calcination temperature is 530-570° C. and the calcination time is 3-6 hours.

18. The method for hydro-reforming of paraffin-rich diesel according to claim 8, characterized in that: In step (3), the active component is introduced by an impregnation method. After impregnation, the catalyst is dried at 80-120°C for 4-10 hours and then calcined at 400-600°C for 3-6 hours to obtain the final catalyst.

19. The method for hydro-reforming of paraffin-rich diesel according to claim 8, characterized in that: The paraffin-rich diesel has a cycloparaffin content of 3-14% by mass and an aromatic content of 25-57% by mass.

20. The method for hydro-upgrading of paraffin-rich diesel according to claim 19, characterized in that: The paraffin-rich diesel has a paraffin content of 30-67% by mass, a cycloparaffin content of 5-12% by mass, and an aromatic content of 27-55% by mass.

21. The method for hydro-reforming of paraffin-rich diesel according to claim 1, wherein: The HZSM-23 molecular sieve has a relative crystallinity of 95-120%, and after steam hydrothermal treatment, the relative crystallinity is 93-115%.

22. The method for hydro-upgrading of paraffin-rich diesel according to claim 1, characterized in that: The total acid content of the HZSM-23 molecular sieve is 0.14-0.24 mmol / g, the weak acid content is 57-78%, the relative crystallinity is 98-116%, and the relative crystallinity after steam hydrothermal treatment is 95-114%.

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